The fourth annual multidisciplinary symposium on gastrointestinal (GI) cancers is a forum that brings together leading experts to present and discuss new research on prevention, screening, and treatment. GI cancers include cancers of the esophagus, stomach, pancreas, small bowel, liver, colon, and rectum.

Cosponsored by the American Society of Clinical Oncology (ASCO), the American Gastroenterological Association (AGA), the American Society for Therapeutic Radiology and Oncology (ASTRO), and the Society of Surgical Oncology (SSO), the 2007 Gastrointestinal Cancers Symposium was held January 19 - 21 in Orlando, Florida.

Cancer.Net talked with A. William Blackstock, MD, to learn more about the recent advances highlighted at this meeting.

Q: What are the challenges in treating and diagnosing many of the GI cancers?

A: Unfortunately, there is a lack of adequate screening tools for many GI cancers. This limits our ability to diagnosis patients when the disease is in an early stage and more likely curable. With the exception of colon cancer (for which a colonoscopy is available), we often find cancers of the esophagus, stomach, and pancreas at an advanced stage. While we have made some moderate progress in the successful treatment of cancers of the esophagus and stomach over the last 15 years, pancreatic cancer remains a difficult disease to diagnose and treat.

Q: Please tell us about the therapeutic pancreatic cancer vaccine.

A: There have been some encouraging results using a vaccine strategy recently reported from Johns Hopkins University. In this clinical trial, patients who had their pancreatic tumors surgically removed were treated with an injection of the vaccine and then received standard chemotherapy and radiation therapy, followed by additional injections of the vaccine. The vaccine uses irradiated pancreatic cancer cells that are incapable of growing, but genetically altered to secrete a molecule called granulocyte macrophage colony stimulating factor (GM-CSF). GM-CSF attracts the immune system cells to the site of the tumor vaccine, where they encounter pancreas cancer antigens (substances that produce an immune response) on the surface of the irradiated cells. Then, these newly armed immune cells patrol the rest of the patient's body, destroying any remaining circulating pancreatic cancer cells that have similar antigens to the irradiated pancreatic cells.

We are hopeful about the results of this clinical trial, as it allows us to bring in an additional treatment strategy in a disease where few therapies work well. Because the outcome with standard therapy for pancreatic cancer does not have consistent results, it is important that patients with pancreatic cancer participate in clinical trials.

Q: In one study, bevacizumab (Avastin) improved survival for patients with metastatic colorectal cancer. What does this mean for patients with this cancer?

A: The research community has made significant progress in the last 10 years for the treatment of patients with colorectal cancer. In the mid-1990s, the standard therapy for patients with metastatic colorectal cancer was fluorouracil  (5-FU, Efudex). This drug only achieved an average survival of nine to 12 months after diagnosis. Several clinical trials combining 5-FU with the relatively new compound, oxaliplatin (Eloxatin), and now bevacizumab, have increased average survival times from diagnosis to approximately two years. The range of effective drugs for colorectal cancer has increased dramatically over the last five years and includes drugs such as irinotecan (Camptosar) and capecitabine (Xeloda), which is an oral 5-FU. It is our hope that novel, molecularly targeted compounds like bevacizumab, cetuximab (Erbitux), panitumumab (Vectibix), and others will further improve survival for patients with colorectal cancer.

Q: In another study of advanced pancreatic cancer, adding bevacizumab to chemotherapy did not improve survival as expected. Why does one drug work in one type of cancer and not in another? What is the next step?

A: The results of this pancreatic trial were very disappointing. Unfortunately, it is not clear why a compound will work in one disease or cancer but not another. This clinical trial, named The Cancer and Leukemia Group B (CALGB) trial, was important in the sense patients were able to receive a novel combination by participating in the study, and the study was well conceived, patients joined the trial quickly, and results were reported to the public as soon as they were known.

Clearly, pancreatic cancer remains one of the most difficult cancers to treat because patients tend to be diagnosed with very advanced disease. (Patients in the CALGB study all had advanced pancreatic cancer.) There is a current clinical trial evaluating bevacizumab for patients who have early-stage pancreatic cancer, and perhaps bevacizumab will be beneficial to those patients.

Q: What is being learned about adjuvant therapy for stomach cancer?

A: The standard approach for patients with stomach cancer has been surgical removal of the tumor, followed by radiation therapy and chemotherapy. This treatment was based on a large clinical trial in the United States showing longer survival for patients receiving post-operative chemotherapy and radiation therapy. In the last year or so, the results of a European study adding epirubicin (Ellence)/cisplatin (Platinol, CDDP)/5-FU (ECF) chemotherapy to surgery (without radiation therapy) also seems to show a survival advantage. While this was not necessarily planned, the current U.S. clinical trial is combining the superior European chemotherapy (ECF) with standard radiation therapy. It is our hope that this clinical trial will show an advantage in giving the newer chemotherapy and radiation therapy. I would encourage patients with stomach cancer to ask about participating in this clinical trial.

Q: What are some of the areas of research for colorectal cancer?

A: While not necessarily new, doctors are looking at how best to optimally sequence the various treatment options for patients with advanced colorectal cancer and to manage the side effects of the treatments. Fortunately, because the newer therapies have significantly extended the lives of patients with advanced colorectal cancer, quality of life has become important. In addition, there is a renewed interest in deciding what the role of surgery is for patients who are diagnosed with metastatic disease. Should they be treated with aggressive chemotherapy followed by surgical removal of all remaining tumor? Some smaller clinical trials have suggested that a limited number of patients treated in this fashion can indeed be cured. As you can see, there has been significant progress and improvements in the outcome for patients, even those with advanced colorectal cancer.

Q: Is there any other information from this meeting that should be highlighted?

A: I would encourage patients to take note of research findings that address quality of life.  Although we have improved survival in a number of GI cancers, it is now clear that researchers must also weigh the potential effects of these improved treatments on quality of life.

Perhaps the next most significant advance in oncology will be our ability to better tailor our treatments for each individual patient. Although data at this meeting were somewhat limited, there were presentations that discussed attempts to discern which patients would benefit from specific treatments by assessing specific tumor markers or molecular parameters or signatures.

Dr. A. William Blackstock is Professor of Radiation Oncology and Attending Physician at the Wake Forest University Comprehensive Cancer Center in Winston-Salem, North Carolina. He is a member of ASCO's Cancer Communications Committee.