Colorectal cancer is a disease in which normal cells in the lining of the colon or rectum begin to change, start to grow uncontrollably, and no longer die. These changes usually take years to develop; however, in some cases of hereditary disease, changes can occur within months to years. Both genetic and environmental factors can cause the changes. Initially, the cell growth appears as a benign (noncancerous) polyp that can, over time, become a cancerous tumor. If not treated or removed, a polyp can become a potentially life-threatening cancer. Recognizing and removing precancerous polyps before they become cancer can prevent colorectal cancer.
Anatomy of the colon and rectum
The colon and rectum make up the large intestine, which plays an important role in the body's ability to process waste. The colon makes up the first 5 to 6 feet of the large intestine, and the rectum makes up the last 6 inches, ending at the anus.
The colon has four sections. The ascending colon is the portion of the colon that extends from a pouch called the cecum (the start of the large intestine into which the small intestine empties) on the right side of the abdomen. The transverse colon crosses the top of the abdomen. The descending colon takes waste down the left side. Finally, the sigmoid colon at the bottom takes waste a few more inches downward to the rectum.
Colorectal cancer can begin in either the colon or the rectum. Cancer that begins in the colon is called colon cancer, and cancer that begins in the rectum is called rectal cancer.
Colorectal cancer often begins in polyps, noncancerous growths that may develop on the inner wall of the colon and rectum, as people get older. There are several forms of polyps, but the ones that usually become cancerous are adenomatous polyps, or adenomas. Because this specific type of polyp may eventually turn cancerous, one way to prevent colorectal cancer is to detect and remove polyps before they become cancerous.
Most colon and rectal cancers are a type of tumor called adenocarcinoma, which is cancer of the cells that line the inside tissue of the colon and rectum. This section covers specifically adenocarcinoma. Other types of cancer that occur far less frequently but can begin in the colon or rectum include carcinoid tumor, gastrointestinal stromal tumor (GIST), and lymphoma.
Statistics
When colorectal cancer is detected early, it can often be cured. The death rate from this type of cancer has been declining for the past 20 years, possibly because more cases are now detected early and treatments have improved. Colorectal cancer is the third most common cancer among both men and women in the United States. It is also the third most common cause of cancer death among men and women separately (second most cause of cancer death if combining men and women) in the United States.
In 2008, an estimated 148,810 adults (77,250 men and 71,560 women) in the United States will be diagnosed with colorectal cancer. These numbers include 108,070 new cases of colon cancer and 40,740 new cases of rectal cancer. It is estimated that 49,960 deaths (24,260 men and 25,700 women) from this disease will occur this year.
If the cancer is detected at an early, localized stage, the five-year relative survival rate (the percentage of patients who survive at least five years after the cancer is detected, excluding those who die from other diseases) for patients with colorectal cancer is 90%. If the cancer has spread to adjacent lymph nodes or organs, the five-year relative survival rate is 68%. If the cancer has spread to distant parts of the body, the five-year relative survival rate is 10%.
Cancer survival statistics should be interpreted with caution. These estimates are based on data from thousands of cases of this type of cancer in the United States each year, but the actual risk for a particular individual may differ. It is not possible to tell a single individual how long he or she will live with colorectal cancer. Because the survival statistics are measured in five-year (or sometimes one-year) intervals, they may not represent advances made in the treatment or diagnosis of this cancer.
Statistics adapted from the American Cancer Society's publication, Cancer Facts & Figures 2008.
A risk factor is anything that increases a person's chance of developing cancer. Some risk factors can be controlled, such as smoking, and some cannot be controlled, such as age and family history. Although risk factors can influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do. However, knowing your risk factors and communicating them to your doctor may help you make more informed lifestyle and health-care choices.
The cause of colorectal cancer is not known, but certain factors appear to increase the risk of developing the disease. The following factors can raise a person's risk of developing colorectal cancer:
Adenomatous polyps (adenomas). Polyps are not cancer, but some types of polyps called adenomas are most likely to develop into colorectal cancer. Polyps can often be completely removed using a tool during colonoscopy, a test in which a doctor looks through a lighted tube into the colon after the patient has been sedated. Polyp removal can prevent colon cancer. People who have had adenomas have a greater risk of additional polyps and of colon cancer, so they should have follow-up screening tests regularly.
Age. The risk of colorectal cancer increases as people get older. Colorectal cancer can occur in young adults and teenagers, but more than 90% of colorectal cancers occur in people over 50. The average age of diagnosis in the United States is 72.
Inflammatory bowel disease (IBD). People with IBD, such as ulcerative colitis or Crohn's disease, may develop chronic inflammation of the large intestine, which increases the risk of colon cancer. IBD is not the same as irritable bowel syndrome.
Personal history of cancer. People with a personal history of cancer are more likely to develop colon cancer. Colorectal cancer is more likely to develop in women who have had cancer of the ovary or uterus.
Family history of cancer. Colorectal cancer is more likely to develop in a person whose parents, siblings, or children have had colorectal cancer, particularly if the family member developed colorectal cancer before age 60. Members of families with certain uncommon inherited conditions, such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (HNPCC), also have a significant increased risk of colorectal cancer. Relatives of women with uterine cancer may also be at higher risk. Learn more about The Genetics of Colorectal Cancer.
Physical inactivity and obesity. People who lead an inactive lifestyle (no regular exercise and a lot of sitting) and people who are overweight may have increased risk of colorectal cancer.
Smoking. Recent studies have shown that smokers are more likely to die from colorectal cancer than nonsmokers.
Nonsteroidal anti-inflammatory drugs (NSAIDs). Some studies suggest that aspirin and other NSAIDs may reduce the development of polyps in people with a history of colorectal cancer or polyps. However, regular use of NSAIDs may result in major side effects, including bleeding of the stomach lining and blood clots leading to stroke or heart attack. Taking aspirin or other NSAIDs cannot be substituted for regular colorectal cancer screening. People should talk with their doctor about the risks and benefits of taking aspirin on a regular basis.
Diet and supplements. A diet rich in fruits and vegetables and low in red meat may help reduce the risk of colon cancer. Some studies have also found that people who take folic acid and calcium supplements have a lower risk of colorectal cancer.
Race. Black people have the highest rates of sporadic (non-hereditary) colorectal cancer in the United States and colon cancer is a leading cause of cancer-related deaths among black people. Black women are more likely to die from colorectal cancer than women from any other racial group, and black men are even more likely to die from colorectal cancer than black women. Noting that black people are more likely to be diagnosed with colon cancer at a younger age, the American College of Gastroenterology suggests that black people begin screening with colonoscopies at age 45 (see below for details). Earlier screening could detect colon abnormalities at a more treatable stage.
Screening
Regular screening for colorectal cancer is important because screening can prevent colorectal cancer by finding and removing precancerous polyps and can allow colorectal cancers to be detected early, when there is a better chance of successfully treating them. Colorectal cancer can often be prevented through regular screening, which can identify precancerous polyps. Talk with your doctor about when screening should begin based on age and family history of the disease. Although some people should be screened earlier, people of average risk should begin screening at age 50, and black people should start at age 45. Because most colorectal cancer occurs without symptoms until the disease is advanced, it is important for people to talk with their doctor about the pros and cons of each screening test and how often each test should be given. In many cases, a screening test can find a colorectal cancer at an early stage when treatment is most likely to be successful.
People should begin colorectal cancer screening earlier and/or undergo screening more often if they have any of the following colorectal cancer risk factors:
A personal history of colorectal cancer or adenomatous polyps
A strong family history of colorectal cancer or polyps (cancer or polyps in a first-degree relative younger than 60 or in two first-degree relatives of any age). A first-degree relative is defined as a parent, sibling, or child.
A personal history of chronic inflammatory bowel disease
A family history of hereditary colorectal cancer syndromes (FAP and HNPCC)
The tests used to screen for colorectal cancer are described below:
Fecal occult blood test (FOBT). A test used to detect blood in the feces (stool), which can indicate the presence of polyps or cancer. Polyps and cancers do not bleed continually, so the FOBT must be done on several stool samples each year and should be repeated annually. Even then, the reduction in deaths from colorectal cancer is modest (in the range of 30% if done yearly and 18% if done every other year).
Flexible sigmoidoscopy. A sigmoidoscope (lighted tube) is inserted into the rectum and lower colon to check for polyps, cancer, and other abnormalities. During this procedure, a doctor can remove polyps or other tissue for later examination. The doctor cannot check the upper part of the colon (ascending and transverse colon) with this test. If polyps or cancer is detected using this test, a colonoscopy to view the entire colon is recommended.
Colonoscopy. This test allows the doctor to look inside the entire rectum and colon while a patient is sedated. A colonoscope (lighted tube) is inserted into the rectum and the entire colon to look for polyps or cancer. During this procedure, a doctor can remove polyps or other tissue for examination (see biopsy in the Diagnosis section).
Double contrast barium enema (DCBE). For patients who cannot have a colonoscopy, an enema containing barium is given, which helps the outline of the colon and rectum stand out on x-rays. A series of x-rays is then taken of the colon and rectum. This test has not been shown to improve outcomes and therefore is not a preferred screening approach.
Other. Computed tomography (CT or CAT) colonography and fecal DNA tests are experimental screening methods. CT colonography is offered in some institutions, but people should be aware that it is still considered to be under development and requires interpretation by a skilled radiologist in order to be used to best advantage.
Beginning at age 50, both men and women of average risk should follow one of these four testing schedules:
Yearly fecal occult blood test (FOBT)*
Flexible sigmoidoscopy every five years
Yearly fecal occult blood test plus flexible sigmoidoscopy every five years**
Colonoscopy every 10 years
*For FOBT, the take-home multiple sample method should be used.
**The combination of FOBT and flexible sigmoidoscopy is preferred over either of these two tests alone.
All tests that indicate an abnormality, including a FOBT, should be followed up with a colonoscopy.
By being alert to the symptoms of colorectal cancer, it may be possible to detect the disease early, when it is most likely to be treated successfully. Many people with colorectal cancer do not have any symptoms until the disease is advanced, so people need to be screened regularly.
People with colorectal cancer may experience the following symptoms. Sometimes, people with colorectal cancer do not show any of these symptoms. Or, these symptoms may be caused by a medical condition that is not cancer. If you are concerned about a symptom on this list, please talk with your doctor and ask that a colonoscopy be scheduled so that the underlying reason(s) for the symptom can be found.
A change in bowel habits
Diarrhea, constipation, or feeling that the bowel does not empty completely
Bright red or very dark blood in the stool
Stools that look narrower or thinner than normal
Discomfort in the abdomen, including frequent gas pains, bloating, fullness, and cramps
Weight loss with no known explanation
Constant tiredness or fatigue
Unexplained iron-deficiency anemia (low number of red blood cells)
Doctors use many tests to diagnose cancer and to determine if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer. Imaging tests may be used to find out whether the cancer has metastasized. Your doctor may consider these factors when choosing a diagnostic test:
Age and medical condition
The type of cancer
Severity of symptoms
Previous test results
In addition to a physical examination, the following tests may be used to diagnose colorectal cancer. The doctor will also ask about the person's medical and family history and will likely order a full-bowel examination, such as a colonoscopy, described in the Prevention section. If colorectal cancer is present, a complete diagnosis that accurately describes the location and spread of the cancer may not be possible until the tumor is surgically removed.
Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis of colorectal cancer. The sample removed from the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). A biopsy may be performed during a colonoscopy, or it may be done on any tissue that is removed during surgery. Sometimes, a CT scan or ultrasound is used to perform a needle biopsy (removing tissue through the skin with a needle that is guided into the tumor).
Blood tests. Because colorectal cancer often bleeds into the large intestine or rectum, people with the disease may become anemic. A test of the number of red cells in the blood, which is part of a complete blood count (CBC), can indicate that bleeding may be occurring.
Another blood test detects the levels of a protein called carcinoembryonic antigen (CEA). High levels of CEA may indicate that a cancer has spread to other parts of the body. CEA is not an absolute test for colorectal cancer because it is elevated in only about 60% of people with colorectal cancer that has spread to other organs from the colon. In addition, other conditions may cause a rise in CEA. CEA tests are most often used to monitor patients already treated for colorectal cancer.
Imaging tests
Imaging tests performed before treatment look for cancer that is outside of the colon and rectum.
CT scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then puts these images into a detailed, cross-sectional view that shows any abnormalities or tumors. In a person with colon cancer, a CT scan can check for the spread of cancer in the lungs, liver, and other organs.
Ultrasound. Ultrasound is a procedure that uses sound waves to produce images of the body to tell if cancer has spread to the liver or other organs. Endorectal ultrasound is commonly used to determine the depth of penetration of rectal cancer, and can be used to aid in planning treatment; however, this test cannot accurately detect metastatic lymph nodes (cancer that has spread to nearby lymph nodes) or metastatic disease beyond the pelvis.
Chest x-ray. An x-ray is a picture of the inside of the body. A chest x-ray may be used to see if cancer has spread to the lungs.
Positron emission tomography (PET) scan. In a PET scan, radioactive sugar molecules are injected into the body. Cancer cells absorb sugar more quickly than normal cells, so they light up on the PET scan. PET scans are often used to complement information gathered from CT scan and physical examination
Staging is a way of describing a cancer, such as where it is located, if or where it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer's stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis (chance of recovery). There are different stage descriptions for different types of cancer.
One tool that doctors use to describe the stage is the TNM system. This system uses three criteria to judge the stage of the cancer: the tumor itself, the lymph nodes around the tumor, and if the tumor has spread to other parts of the body. The results are combined to determine the stage of cancer for each person. There are five stages: stage 0 (zero) and stages I through IV (one through four). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.
TNM is an abbreviation for tumor (T), node (N), and metastasis (M). Doctors look at these three factors to determine the stage of cancer:
For colorectal cancer, "T" describes how deeply the primary tumor has penetrated the bowel lining. (Tumor, T)
Has the tumor spread to the lymph nodes? (Node, N)
Has the cancer metastasized to other parts of the body? (Metastasis, M)
Tumor. Using the TNM system, the "T" plus a letter or number (0 to 4) is used to describe how deeply the primary tumor has penetrated the bowel lining. Specific tumor penetration information is listed below.
TX: The primary tumor cannot be evaluated.
T0: There is no evidence of cancer in the colon or rectum.
Tis: Refers to carcinoma in situ (also called cancer in situ). Cancer cells are found only in the epithelium or lamina propria (the layers lining the inside of the colon or rectum).
T1: The tumor has grown into the submucosa (the layer of tissue underneath the mucosa or lining of the colon).
T2: The tumor has invaded the muscularis propria (a deeper, thick layer of muscle that contracts to force the contents of the intestines along).
T3: The tumor has grown through the muscularis propria and into the subserosa (a thin layer of connective tissue beneath the outer layer of some parts of the large intestine) or into tissues surrounding the colon or rectum.
T4: The tumor has invaded other organs or has caused a perforation (hole) in the wall of the colon or rectum.
Node. The "N" in the TNM system stands for lymph nodes. The lymph nodes are tiny, bean-shaped organs that are located throughout the body that help the body fight infections as part of the body's immune system. There are regional lymph nodes (lymph nodes near the colon and rectum). All others are distant lymph nodes (lymph nodes found in other parts of the body).
NX: The regional lymph nodes cannot be evaluated due to lack of information.
N0: There is no regional lymph node metastasis (the cancer has not spread into the regional lymph nodes).
N1: There is metastatic involvement in one to three regional lymph nodes.
N2: There is metastatic involvement in four or more regional lymph nodes.
Distant metastasis. The "M" in the TNM system describes cancer that has spread to other parts of the body (such as the liver or lungs).
MX: Distant metastasis cannot be evaluated.
M0: The disease has not metastasized.
M1: There is distant metastasis (the cancer has spread to other parts of the body beyond the colon or rectum).
Cancer stage grouping
Doctors assign the stage of the cancer by combining the T, N, and M classifications.
Stage 0: Refers to cancer in situ. The cancer cells are only in the mucosa (the inner lining) of the colon or rectum. Most colorectal cancers at this stage can be treated by polypectomy (removal of the mass of tissue that develops on the inside wall).
Stage I: The cancer has grown through the mucosa and has invaded the muscular layer of the colon or rectum. It has not spread into nearby tissue or lymph nodes (T1 or T2, N0, M0).
Stage IIA: The cancer has spread through the wall of the colon or rectum and may have spread to nearby tissue. It has not spread to the nearby lymph nodes (T3, N0, M0).
Stage IIB: The cancer has spread through the colon or rectum to nearby organs. It has not spread to the nearby lymph nodes (T4, N0, M0).
Stage IIIA: The cancer has grown through the inner lining or into the muscle layers of the intestine and to one to three lymph nodes, but has not spread to other parts of the body (T1 or T2; N1, M0).
Stage IIIB: The cancer has grown through the bowel wall or to surrounding organs and into one to three lymph nodes, but has not spread to other parts of the body (T3 or T4, N1, M0).
Recurrent: Recurrent cancer means the cancer has come back after treatment. The disease may be found in the colon, rectum, or in another part of the body.
Tumor grades. Doctors may also use the term "grade," which describes how much the tumor appears like normal tissue. The grade of a cancer can help the doctor predict how quickly the cancer might grow. In cancer that resembles normal tissue, doctors can clearly see different types of cells grouped together (called well differentiated). In a higher-grade cancer, the cancer cells usually look less like normal cells, or "wilder" (called poorly differentiated or undifferentiated). In general, better differentiated tumors have a better prognosis.
GX: The tumor grade cannot be identified.
G1: The cells look more like normal cells (well differentiated).
G2: The cells are somewhat different (moderately differentiated).
G3: The cells barely resemble normal cells (poorly differentiated).
G4: The cells do not resemble normal cells (undifferentiated).
Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Sixth Edition (2002) published by Springer-Verlag New York, www.springer-ny.com.
The treatment of colorectal cancer depends on the size and location of the tumor, whether the cancer has spread, and the person's overall health. In many cases, a team of specialists, including a gastroenterologist (a doctor who specializes in the function and disorders of the gastrointestinal tract), surgeon, medical oncologist, and radiation oncologist will work with the patient to determine the best treatment plan.
Overview of colorectal cancer treatment
This section provides a brief overview of treatment of colorectal cancer by stage. Details about each treatment option follow this section.
The usual treatment of stage 0 cancer in situ is a simple polypectomy (removal of a polyp) during colonoscopy. There is no additional surgery unless the polyp is unable to be fully removed by polypectomy.
If the cancer is stage I, surgical removal of the tumor and lymph nodes is usually the only treatment.
Patients with stage II colon cancer, which involves deeper penetration of the bowel lining without involving the regional lymph nodes, are advised to consult with their doctor, as some patients are treated after surgery with chemotherapy aimed at trying to destroy any remaining cancer cells (known as adjuvant chemotherapy). However, cure rates for surgery alone are quite good and the benefits of additional treatment are still uncertain in this setting. A clinical trial is also an option after surgery. Additional drugs are being investigated in clinical trials in combination with chemotherapy.
If the cancer is stage III and has spread to nearby lymph nodes, the treatment usually involves surgical removal of the tumor followed by adjuvant chemotherapy. A clinical trial is also an option.
For patients with stage II or III rectal cancer, radiation therapy is usually offered in combination with chemotherapy, either before or after surgery.
At stage IV, patients may or may not have surgery to remove the tumor in the colon. Standard treatment includes chemotherapy along with a targeted treatment. If possible, additional surgery to remove metastases (spread to other organs) may also be done. Generally, such surgery is possible if there are a limited number of spots where the tumor has spread that are identified.
Clinical trials may be an option for patients with all stages of colorectal cancer. Experimental treatments may be used to prevent the spread of cancer to other sites in the body or new techniques may be used to decrease the risk of developing new polyps or cancer.
Surgery
The most common treatment for colorectal cancer is surgery to remove the tumor. Part of the healthy colon or rectum and nearby lymph nodes will also be removed. While both general surgeons and specialists may perform colorectal surgery, many people consult specialists who have additional training and experience in colorectal surgery.
Some patients may be able to undergo laparoscopic colorectal cancer surgery. With this technique, several viewing scopes are passed into the abdomen while a patient is under anesthesia. The incisions are smaller and the recovery time is often shorter than with standard colon surgery. It appears that the laparoscopic surgery is as good as conventional colon surgery in terms of its effectiveness in removing the cancer. Surgeons who perform laparoscopic surgery have been specially trained in that technique.
In a minority of cases, a person with rectal cancer may need to have a colostomy, which is a surgical opening, or stoma, through which the colon is connected to the abdominal surface to provide a pathway for waste to exit the body; such waste is collected in a bag worn by the patient. Sometimes, the colostomy is only temporary to allow the rectum to heal, but it may be permanent. With modern surgical techniques and the use of radiation therapy and chemotherapy in selected cases before surgery, most people treated for rectal cancer do not require a permanent colostomy.
The side effects of surgery include pain and tenderness in the area of the operation. The operation may also cause constipation or diarrhea, which usually goes away after a while. People who receive a colostomy may have irritation around the stoma. The doctor, nurse, or a specialist in colostomy management (called an enterostomal therapist) can teach the patient how to clean the area and prevent infection.
Many people require retraining of the bowel after surgery; this may require some time and assistance. People should discuss with their doctor if they do not regain good control of bowel function. This is one of the most common side effects of those who have had a large part of the colon removed.
Radiation therapy
Radiation therapy is the use of high-energy x-rays to kill cancer cells and is commonly used in treating rectal cancer due to the tendency of this tumor to recur locally. Radiation therapy may be used before surgery (called neoadjuvant therapy) to shrink the tumor so that it is easier to remove, or after surgery to destroy any remaining cancer cells (called adjuvant therapy), as both have shown value in treating rectal cancer. One recent study found that pre-operative radiation therapy in combination with chemotherapy showed greater benefit compared with the same radiation therapy and chemotherapy given after surgery. The main benefits included a lower rate of the tumor coming back in the area where it started, fewer patients that needed permanent colostomies, and fewer problems with scarring of the bowel in the area where the radiation therapy was administered. Chemotherapy is often given at the same time as radiation therapy (called chemoradiation therapy) to increase the effectiveness of the radiation therapy. Chemoradiation therapy is often used in rectal cancer before surgery to avoid colostomy or reduce the chance that the cancer will recur.
External-beam radiation therapy uses a machine to deliver x-rays to the site of the body where the cancer is located. Radiation treatment is given five days a week for several weeks and may be given in the doctor's office or at the hospital.
In some cases, specialized radiation therapy techniques, such as intraoperative radiation therapy (a high, single dose of radiation therapy given during surgery) or brachytherapy (placing radioactive "seeds" inside the body,) may help eliminate small areas of tumor that could not be removed during surgery.
Radiation therapy, like chemotherapy, may damage healthy cells as well as cancerous cells. Side effects of radiation therapy include fatigue, skin irritation and damage at the site where the treatment is given, loss of appetite, nausea, and diarrhea. It may also cause bloody stools (bleeding through the rectum) or bowel obstruction.
Sexual problems, as well as infertility (the inability to have a baby) in both men and women, may occur after radiation therapy to the pelvis and need to be addressed. Talk with your doctor for more information.
Chemotherapy
Chemotherapy is the use of drugs to kill cancer cells. Systemic chemotherapy is delivered through the bloodstream, targeting cancer cells throughout the body.
Chemotherapy may be given after surgery to eliminate any remaining cancer cells. In some situations, a doctor will give chemotherapy and radiation therapy before surgery to reduce the size of a rectal tumor and reduce the chance of cancer returning. Chemotherapy is usually injected directly into a vein, although some chemotherapy can be given as a pill.
The most common chemotherapy given for colorectal cancer may cause vomiting, nausea, diarrhea, or mouth sores. However, medications to prevent these side effects are available. Because of the way drugs are administered, these side effects are less problematic than they have been in the past for most patients. In addition, patients may be unusually tired, and there is an increased risk of infection. Neuropathy (tingling or numbness in feet or hands) may also occur. Hair loss is an uncommon side effect with the drugs used to treat colorectal cancer. There are medications to ease most side effects, including nausea, neuropathy, and diarrhea. If side effects are particularly difficult, the dose of drug may be lowered or a treatment session may be postponed. Patients should talk with their health-care team to understand when to call their doctor about side effects. Read more about managing side effects. These side effects usually go away once treatment is finished.
Currently, seven drugs are approved for treatment of colorectal cancer in the United States. Your doctor may recommend one or several of them at various times during treatment. These drugs are fluorouracil (5-FU, Adrucil), capecitabine (Xeloda), irinotecan, oxaliplatin (Eloxatin), bevacizumab (Avastin), cetuximab (Erbitux), and panitumumab (Vectibix). (These last three are described under "Targeted treatments.") Many new drugs are in the process of being tested and may provide additional future options for treatment. Some common treatments are:
5-FU
5-FU with leucovorin (Wellcovorin), a vitamin that improves the effectiveness of 5-FU
Capecitabine (Xeloda), an oral form of 5-FU
5-FU with leucovorin and oxaliplatin (FOLFOX)
5-FU with leucovorin and irinotecan (FOLFIRI)
Irinotecan alone
Capecitabine with either irinotecan or oxaliplatin
Any of the above with either cetuximab or bevacizumab
The medications used to treat cancer are continually being evaluated. Talking with your doctor is often the best way to learn about the medications you've been prescribed, their purpose, and their potential side effects or interactions with other medications. Learn more about your prescriptions through Cancer.Net's Drug Information Resources, which provides links to searchable drug databases.
Targeted treatments
Targeted treatments are therapies that target cancer cells while minimizing damage to noncancerous cells. These drugs are becoming more important in the treatment of colorectal cancer.
Anti-angiogenesis therapy. Some of the first targeted treatments focused on stopping angiogenesis, the process of making new blood vessels. Because tumors need the nutrients found in blood vessels to grow and spread, the goal of anti-angiogenesis therapies is to "starve" the tumor. One such therapy is bevacizumab. When given with chemotherapy, bevacizumab improves survival in people with advanced colorectal cancer. The U.S. Food and Drug Administration (FDA) approved bevacizumab along with chemotherapy for the first-line treatment of patients with advanced colorectal cancer in 2004. Recent studies have shown it also to be effective as second-line therapy along with chemotherapy. Bevacizumab is a monoclonal antibody, a substance made in the laboratory that recognizes and attaches to specific proteins on the outside of cancer cells.
Epidermal growth factor receptor (EGFR) inhibitors. Researchers have found that the EGFR protein may contribute to the growth of colorectal cancer. Cetuximab and panitumumab are monoclonal antibodies that block the EGFR. Cetuximab is an antibody made from mouse cells that still has some of the mouse structure. Panitumumab is entirely made from human proteins and is less likely to cause an allergic reaction than cetuximab. In clinical trials, a combination of cetuximab and irinotecan (Camptosar) chemotherapy shrank tumors and slowed growth of new tumors in patients with advanced colorectal cancer. This led to approval of cetuximab for the treatment of selected patients with advanced colorectal cancer in 2004. In 2007, cetuximab was approved for patients with advanced colorectal cancer after irinotecan and oxaliplatin no longer work. In clinical trials, patients who received panitumumab compared to supportive care without drug therapy had a delay in the growth of the cancer and a small number of patients had evidence of tumor shrinkage. Research is underway to determine what role cetuximab and panitumumab might play in patients with metastatic colorectal cancer who’ve had surgery and who have not previously been given chemotherapy.
Advanced or recurrent colorectal cancer
Colorectal cancer can spread to distant organs, such as the liver, lungs, peritoneum (the tissue lining the abdomen), or a woman’s ovaries. A combination of surgery, radiation therapy, and chemotherapy can be used to slow the spread of the disease, and, in many cases, can temporarily shrink cancerous tumors.
At this stage, surgery to remove the portion of the colon where the cancer started usually cannot cure the cancer, but it can help relieve blockage of the colon or other complications. Surgery may also be used to remove parts of other organs that contain cancer (called resection), and can cure some people if a limited amount of cancer spreads to a single organ, such as the liver or lung.
Chemotherapy and radiation therapy at this stage can rarely cure cancer, but they may help to relieve pain and other symptoms and prolong survival. Clinical trials that test new treatments may also be an option.
In colon cancer, if spread is limited to the liver and if liver resection is possible-either before or after chemotherapy-the patient has a chance of complete cure. Even in cases where cure is not possible, surgery may add months or even years to an individual’s survival. Determining who can benefit from surgery in this setting is often a complicated process that involves collaboration between doctors of multiple specialties.
Treatment of recurrent cancer (cancer that has returned after initial treatment) depends on where the cancer is located and the person’s health. Generally, the treatment options for recurrent cancer are the same as those for metastatic cancer and include surgery, radiation therapy, and chemotherapy. Clinical trials of experimental treatments may also be an option.
For more information on colorectal cancer from the American Society of Clinical Oncology, please refer to the following Patient Guides:
The National Comprehensive Cancer Network (NCCN) has a series of treatment guidelines that have been translated into patient-friendly language. In accordance with Cancer.Net's Linking Policy, please note that this link does not imply ASCO's endorsement of the content, but rather it is an effort to provide additional information that may be helpful to people living with cancer and their families. The NCCN treatment guide for colorectal cancer can be found at www.nccn.org.
Doctors and scientists are always looking for better ways to treat patients with colorectal cancer. A clinical trial is a way to test a new treatment in order to prove that it is safe, effective, and possibly better than a standard treatment. Patients who participate in clinical trials are among the first to receive new treatments, such as new chemotherapeutic drugs, before they are widely available. However, there is no guarantee that the new treatment will be safe, effective, or better than a standard treatment.
Patients decide to participate in clinical trials for many reasons. For some patients, a clinical trial is the best treatment option available. Because standard treatments are not perfect, patients are often willing to face the added uncertainty of a clinical trial in the hope of a better result. Other patients volunteer for clinical trials because they know that this is the only way to make progress in treating colorectal cancer, such as finding new drugs. Even if they do not benefit directly from the clinical trial, their participation may benefit future patients with colorectal cancer.
To join a clinical trial, patients must complete a learning process known as informed consent. During informed consent, the doctor should list all of the patient’s options, so the person understands how the new treatment differs from the standard treatment. The doctor must also list all of the risks of the new treatment, which may or may not be different from the risks of standard treatment. Finally, the doctor must explain what will be required of each patient in order to participate in the clinical trial, including the number of doctor visits, tests, and the schedule of treatment. Learn more about clinical trials, including patient safety, phases of a clinical trial, deciding to participate in a clinical trial, questions to ask the research team, and links to find cancer clinical trials.
Cancer and cancer treatment can cause a variety of side effects, although some people experience very few side effects, and others experience more severe side effects. Some are easily controlled, and others require specialized care. Below are some of the side effects that are more common to colorectal cancer and its treatments. For more detailed information on managing these and other side effects of cancer and cancer treatment, visit the Cancer.Net Managing Side Effects section. In addition, your health care team may also have helpful information.
Side effects typical of many cancer treatments
Anemia. Anemia is common in patients with cancer, especially those receiving chemotherapy. Anemia is an abnormally low level of red blood cells (RBCs). RBCs contain hemoglobin (an iron protein) that carries oxygen to all parts of the body. If the level of RBCs is too low, parts of the body do not get enough oxygen and cannot work properly. Most patients with anemia feel tired or weak. The fatigue (tiredness) associated with anemia can seriously affect quality of life and make it more difficult for patients to cope with cancer and treatment side effects.
Blocked intestine (gastrointestinal [GI] obstruction). In some patients with colorectal cancer, the tumor can grow so it blocks the path that food and fluids take when they travel through the bowels. Scar tissue (commonly called adhesions) may also cause an obstruction of the bowel that is not due to cancer recurrence in patients who have previously had surgery. Normally, the intestines move food and fluids through the GI tract, and enzymes, fluid, and electrolytes help the body to absorb nutrients. In a GI obstruction, the food and fluids can't move through the system, and the normal contractions the intestines make to move the food (called peristalsis) can cause intense pain. If left untreated, a GI obstruction is a very serious and even life-threatening problem. Patients with a GI obstruction may experience nausea and/or vomiting, pain from the obstruction, and cramping from the movement of the intestine as it tries to move food along.
Constipation. Constipation is the infrequent or difficult passage of stool. About 40% of patients in palliative care (care given to improve a patient's quality of life) experience constipation, and about 90% of patients taking opioid medications (narcotics) experience constipation. Constipation includes fewer bowel movements, stools that are abnormally hard, discomfort, or a feeling of incomplete rectal emptying. Patients with constipation can experience pain, swelling in the abdomen, loss of appetite, nausea and/or vomiting, inability to urinate, and confusion.
Diarrhea. Diarrhea is frequent, loose, or watery bowel movements. It is a common side effect of certain chemotherapeutic drugs or of radiation therapy. Medications are available to manage diarrhea if it occurs. In some cases, diarrhea can lead to dehydration and needs to be managed in the hospital or clinic with intravenous fluids and replacement of minerals that can be lost when diarrhea occurs.
Fatigue. Fatigue is extreme exhaustion or tiredness and is the most common problem patients with cancer experience. More than half of patients experience fatigue during chemotherapy or radiation therapy, and up to 70% of patients with advanced cancer experience fatigue. Patients who feel fatigue often say that even a small effort, such as walking across a room, can seem like too much. Fatigue can seriously affect family and other daily activities, can make patients avoid or skip cancer treatments, and may even affect the will to live.
Fluid in the abdomen (ascites). Ascites is the buildup of fluid in the abdomen, in the area around the organs known as the peritoneal cavity. Ten percent of all ascites is caused by cancer and is called malignant ascites. Most cancer-related ascites appear in patients with cancers of the ovary, endometrium (lining of the uterus), breast, colon, GI system, or pancreas. These cancers can cause fluid to build up in the body. People with ascites may experience weight gain, abdominal swelling, a sense of fullness or bloating, a sense of heaviness, indigestion, nausea and/or vomiting, changes to the navel, hemorrhoids (a condition that causes painful swelling near the anus), or ankle swelling.
Mouth sores (mucositis). Mucositis is an inflammation of the inside of the mouth and throat, leading to painful ulcers and mouth sores. It occurs in up to 40% of patients receiving chemotherapy treatments. Mucositis can be caused by a chemotherapeutic drug directly or the reduced immunity brought on by chemotherapy.
Nausea and vomiting. Vomiting, also called emesis or throwing up, is the act of expelling the contents of the stomach through the mouth. It is a natural way for the body to rid itself of harmful substances. Nausea is the urge to vomit. Nausea and vomiting are common in patients receiving chemotherapy for cancer and in some patients receiving radiation therapy. Many patients with cancer say they fear nausea and vomiting more than any other side effects of treatment. When it is minor and treated quickly, nausea and vomiting can be quite uncomfortable but cause no serious problems. Persistent vomiting can cause dehydration, electrolyte imbalance, weight loss, depression, and avoidance of chemotherapy.
Neutropenia. Neutropenia is an abnormally low level of neutrophils, a type of white blood cell. All white blood cells help the body fight infection. Neutrophils fight infection by destroying bacteria. Patients who have neutropenia are at increased risk for developing serious bacterial infections because there are not enough neutrophils to destroy harmful bacteria. Neutropenia occurs in about 50% of patients receiving chemotherapy and is common in patients with leukemia.
Pain. Depending on the stage of disease, 30% to 75% of all patients experience pain from cancer. About 85% to 95% of cancer pain can be treated successfully. Pain can make other aspects of cancer seem worse, such as fatigue, weakness, sleep disturbance, and confusion. Pain can come from the tumor itself or may be a result of cancer treatment. Pain from a tumor can be a result of the tumor growing and spreading to the bones or other organs and putting pressure on and damaging nerves. Pain from surgery is normal and may persist for months or years. Pain may develop after radiation therapy and go away on its own. It can also develop months or years after treatment, especially after radiation therapy to the chest, breast, or spinal cord. Certain chemotherapeutic drugs can cause pain along with numbness in the fingers and toes. Usually this pain goes away when treatment is finished, but sometimes the damage can be permanent.
Sexual dysfunction. Sexual dysfunction is common in all people, affecting up to 43% of women and 31% of men without cancer. It may be even more common in patients with cancer, as a result of treatments, the tumor, or stress. Many people, with or without cancer, find it intimidating to discuss sexual problems with their doctors. Sexual problems are most commonly caused by body changes from cancer surgery, chemotherapy or radiation therapy, hormone changes, fatigue, pain, nausea and/or vomiting, medications that reduce libido (desire for sex), fear of recurrence, stress, depression, and anxiety. Symptoms of sexual dysfunction generally fall into four categories: desire disorders, arousal disorders, orgasmic disorders, and pain disorders.
Side effects specific to colorectal cancer treatment
Hand-foot syndrome. Hand-foot syndrome is a side effect of some types of chemotherapy. It occurs when small amounts of chemotherapy leak out of the capillaries (small blood vessels) in the hands and feet. Once out of the blood vessels, the chemotherapy damages the surrounding tissues. Symptoms include redness, swelling, burning, tenderness, and rash. In more severe cases, people may also experience cracked or peeling skin, blisters, pain, and difficulty walking or using the hands. Tell your doctor right away if you are experiencing these symptoms. For more information on treatment and management of hand-foot syndrome, read Managing Side Effects: Hand-Foot Syndrome.
High blood pressure. Bevacizumab may cause an increase in blood pressure, which is treatable with medication. Talk with your doctor for more information.
Peripheral sensory neuropathy (numbness and tingling of the fingers and toes). Some patients treated with oxaliplatin will develop this form of nerve damage. It can occur during and shortly after treatment (acute sensory neuropathy) and be aggravated by exposure to cold. It generally disappears within a day or two. With prolonged courses of oxaliplatin, chronic sensory neuropathy (persistent numbness and tingling) may develop. Neither of these types of neuropathy interferes with strength, but they can be irritating and interfere with activities such as buttoning clothes or other activities that depend on normal sensation such as sewing or playing a musical instrument. Tell your doctor right away if you are experiencing these symptoms. See Managing Side Effects: Nervous System Disturbances for the more information.
Reactions to chemotherapy. Some people are allergic to platinum-based chemotherapy, such as cisplatin. Others have a life-threatening reaction to cetuximab.
Skin toxicity. Some targeted therapies, such as cetuximab and panitumumab, may also cause a serious, acne-like rash and/or other hair, nail, or skin problems. Tell your doctor right away about your symptoms. For information on additional symptoms and ways to manage these skin problems, read Skin Reactions to Targeted Therapies.
After treatment for colorectal cancer ends, talk with your doctor about developing a follow-up care plan. This plan may include regular physical examinations and/or medical tests to monitor your recovery for the coming months and years. Specific recommendations for colorectal cancer follow-up care can be found in the ASCO Patient Guide: Follow-Up Care for Colorectal Cancer.
People recovering from colorectal cancer are encouraged to follow established guidelines for good health, such as maintaining a healthy weight and diet and having recommended cancer screening tests. Talk with your doctor to develop a plan that is best for your needs. Moderate exercise can help rebuild your strength and energy level. Your doctor can help you create a safe exercise plan based upon your needs, physical abilities, and fitness level. Learn more about Healthy Living After Cancer.
Research for colorectal cancer is ongoing. The following advances may still be under investigation in clinical trials and may not be approved or available at this current time. Always discuss all diagnostic and treatment options with your doctor.
Improved detection methods. Scientists are developing tests to analyze stool samples to detect genetic changes associated with colorectal cancer. By identifying cancer early, doctors have a better chance of curing a person with colorectal cancer. Examining the bowel with a special CT scanning technique, known as virtual colonoscopy, is also under investigation.
Cancer vaccines. Cancer vaccines are another type of biologic therapy. They are experimental treatments that stimulate the patient's own immune system to fight cancer.
Combination therapy. Researchers are learning that combining different treatments, such as chemotherapy and radiation therapy, is an efficient way to treat cancer.
Regular communication with your doctor is important in making informed decisions about your health care. Consider asking the following questions of your doctor:
Before surgery
What do you know about my cancer at this point?
What other tests will be run before surgery?
Can you describe the surgery I will be having?
What are you planning to remove during surgery (the colon, rectum, lymph nodes)?
Is a biopsy part of the surgery?
How soon after surgery will I have all test results and a firm diagnosis?
Do you think I may need a temporary or permanent colostomy?
Is this the standard type of surgery for my condition?
How many times have you performed this type of operation successfully?
Who will give me information about how I should get ready for surgery and a hospital stay? How long will I be in the hospital?
How will my pain be controlled after surgery?
For rectal cancer
Should I have radiation therapy and chemotherapy before my rectal cancer surgery?
After surgery
What is my diagnosis based on the results of surgery and biopsy reports, in TNM format?
What is my prognosis?
What are my treatment options based on my diagnosis?
Is it a standard treatment or part of a clinical trial?
What treatment do you recommend? Why?
What is the goal of this treatment?
What are the risks and possible side effects?
How long will it be before I can go back to work after surgery? Can I work during chemotherapy?
Does my diagnosis mean that my blood relatives are at higher risk for colorectal cancer? Should they talk with their doctors about screening?
Question related to a colostomy (if needed)
Will you refer me to a specially trained nurse to decide on the best place for my colostomy and help me learn to manage it after the surgery?
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