Listen to the Special Cancer.Net Podcast: 2008 Gastrointestinal Cancers Symposium Highlights, with Nicholas Petrelli, MD, adapted from this feature.

Leading experts in gastrointestinal (GI) cancers met in Orlando, Florida, to present and discuss new research related to prevention, screening, and treatment. GI cancers include cancers of the esophagus, stomach, pancreas, small bowel, liver, bile duct, colon, and rectum. Held January 25-27, the event is co-sponsored by the American Society of Clinical Oncology (ASCO), American Gastroenterological Association (AGA) Institute, American Society for Therapeutic Radiology and Oncology (ASTRO), and the Society of Surgical Oncology (SSO). Cancer.Net talked with Nicholas Petrelli, MD, to learn more about the recent advances highlighted at this meeting.

Q: One study found that uninsured and Medicaid patients with colorectal cancer are more likely to have advanced disease at diagnosis compared with patients with private insurance. What does this mean for these patients and what can be done to improve screening?

A: This study consisted of 493,419 patients, the majority of whom had Medicare (63.2%) or private insurance (32.4%), with about 2% being uninsured and 2.5% covered by Medicaid. The bottom line is that it demonstrated that we need to improve screening and access to medical care among the underserved populations in order to reduce this disparity. It is important to note that the number one issue in health disparities is the lack of a “medical home” for patients. Part of the solution is getting individuals into the medical care system so they have a physician and making sure they have adequate insurance coverage. Once they have a physician, they can be placed into screening programs. So, if they are diagnosed with cancer, it will be at an early stage or with a precancerous condition, such as adenomatous polyps at the time of colonoscopy. Detecting and removing these will prevent colorectal cancer.

Q: What are biomarkers and what are we learning about how they can be used to detect colorectal cancer?

A: A biomarker is a substance that is detected in a person's blood or tissue and may point to a particular disease state. It may indicate a change in expression or state of a protein that correlates with the risk or development of cancer, or with the susceptibility of the cancer to a specific treatment. Once a biomarker has been validated (proven in clinical studies), it potentially can be used to assess colorectal cancer risk, to find colorectal cancer in an individual, or to tailor certain treatments for colorectal cancer in an individual patient. In the arena of evaluating potential drug therapies, a biomarker may be used as a surrogate (substitute) for a clinical trial endpoint, such as survival. An example of a biomarker and its utility in colorectal cancer treatment is explained below in the discussion of the gene KRAS.

Another example of a biomarker reported at the meeting is the colorectal cancer specific antigen -2 (CCSA-2), which is a blood-based marker with the potential to detect colorectal cancer with a low false-positive and false-negative rate. Just as important, the CCSA-2 is a biomarker that can not only detect the presence of colorectal cancer, but has the potential to indicate whether a patient has a high-risk precancerous condition, such as an adenomatous polyp. Additional studies are needed to confirm this exciting research, since at present there is no blood marker for colorectal cancer or adenomatous polyp detection.

Q: In another study, patients with advanced colorectal cancer benefited from the drug panitumumab (Vectibix) only if they had a normal form of the gene KRAS present in their tumors. Why is this significant and what does this mean for patients with this cancer?

A: This gets back to the previous question concerning biomarkers. The gene KRAS is considered a biomarker. In this particular study, patients with unresectable, metastatic colorectal cancer (cancer that has spread and cannot be removed by surgery) were treated with panitumumab, which is a monoclonal antibody against the epidermal growth factor receptor. Those patients, who upon testing their tumor had the normal gene, responded better to treatment and had better survival than those patients who had a mutation in the KRAS gene. This study is an example of tailoring treatment to patients based upon the result of a biomarker. It is one example of a physician being able to select those patients who will do well with a specific drug based upon the tumor's gene status. Research in this area continues.

Q: What are some advances from other types of GI cancers that were presented at this symposium?

A: Two randomized phase III studies reported on the treatment of esophageal cancers. The first, from Japan, randomized 330 patients with clinical stage II and III esophageal cancer to two courses of fluorouracil (5-FU, Adrucil) and cisplatin (Platinol) after surgery versus the same chemotherapy before surgery. Patients who received chemotherapy before surgery lived longer than those patients who underwent surgery first and then received chemotherapy.

The second trial recruited 802 patients with resectable esophageal cancer (cancer that can be removed by surgery) and randomized patients to surgery alone versus two cycles of 5-FU and cisplatin before surgery. This report is an update from the original trial published in 2002. With further follow up, the clinical trial confirmed that preoperative chemotherapy improved survival in operable esophageal cancer compared with surgery alone.

Q: Is there additional information about GI cancers from this meeting that should be highlighted?

A: One area concerns patients who have liver-only metastases (spread of cancer to only the liver) from colorectal cancer. The newer systemic chemotherapy (oxaliplatin [Eloxatin] and irinotecan [Camptosar]) have allowed about 15% of patients with unresectable, liver-only metastases to be converted to resectable disease, potentially curing these patients. This treatment has been coined “conversion therapy,” and continues to undergo investigation. In a second group of patients with resectable liver metastases from colorectal cancer, administering chemotherapy before surgery has the potential to improve survival, as opposed to surgery alone. However, this approach has potential liver toxicity, especially in people who are obese, have diabetes, or abuse alcohol.

Dr. Petrelli is Medical Director of the Helen F. Graham Cancer Center in Newark, Delaware, and Professor of Surgery at Thomas Jefferson University in Philadelphia. He is also President of the Society of Surgical Oncology and is a member of ASCO's Cancer Communications Committee.

More Information

Gastrointestinal Cancer Advances: News from the 2008 Gastrointestinal Cancers Symposium

2008 Gastrointestinal Cancers Symposium