ONCOLOGICAL GASTROENTEROLOGY PROGRAM

Gastrointestinal (GI) malignancies are common throughout the world. In the United States, colon cancer is the third most common solid tumor, and gastric cancer is the sixth most common cause of cancer death. Great strides have been made in the early detection and prevention of these tumors, although the therapeutic options for advanced disease remain limited. Aggressive treatment of these tumors often results in debilitating side effects in the surviving patients. Fortunately, significant advances have been made in the understanding of the tumor biology of these GI malignancies, which may lead to more effective and less debilitating therapies. The goal of the Gastroenterology Program at Fox Chase is to enhance the understanding of GI tumor biology, to improve our ability to detect GI malignancies early, to investigate treatment approaches, and to understand the pathophysiology of adverse treatment effects.

The importance of radiation therapy in the treatment of GI malignancies has continued to grow. As a result, escalating doses of radiation are being administered to patients. Untoward effects of these treatments include radiation esophagitis in patients receiving therapy for lung or esophageal cancer, and radiation proctitis in patients receiving therapy for gynecological or prostate cancers. The pathophysiology of these effects is poorly understood. We have initiated studies and recruited patients to two double-blind placebo-controlled trials in an attempt to decrease, as well as understand, the adverse effects of radiation therapy.

The first of these two studies involves the use of omeprazole, a potent gastric acid inhibitor, as a prophylactic agent for radiation esophagitis. To date, we have recruited 17 patients to this study. The goal of the trial is to determine if administration of omeprazole can decrease the frequency and severity of radiation esophagitis. In addition, a pathophysiological understanding of radiation esophagitis should be obtained.

The second trial uses carafate, which protects mucosa, as a prophylactic agent in radiation proctitis. To date, we have recruited 50 patients to this study. Once again, we hope to determine if this agent can decrease the frequency and severity of adverse effects of radiation therapy in patients with prostate cancer and gynecological malignancies, as well as understand the pathophysiology of radiation proctitis.

Several modalities are presently available for screening and surveillance of colorectal cancers. Among these are guaiac testing for fecal occult blood and endoscopic examinations, including sigmoidoscopy and colonoscopy. Although inexpensive, fecal occult blood testing has limited value due to its poor sensitivity and frequent need for endoscopic follow-up. Manpower and cost limitations make endoscopic examinations impractical for screening and surveillance of the entire population.

One of the goals of the GI outpatient program is to identify patients with varying risks for colon cancer and to determine appropriate screening and surveillance interventions. Risk factors for GI cancers include a personal history of colonic polyps or cancer, a personal history of breast or endometrial cancers, or a family history of colonic polyps and cancer. Patients deemed to be at average risk for colon cancer are advised to undergo fecal occult blood testing and flexible sigmoidoscopy, as recommended by the American Cancer Society and the American College of Physicians. Patients with an increased risk are evaluated for possible inherited disorders such as familial polyposis coli and hereditary non-polyposis colorectal cancer syndromes. The greater the possibility of an inherited familial syndrome, the more extensive a clinical evaluation and pedigree evaluation that is performed. This ongoing clinical program provides patients with access to gastroenterological expertise, genetic counseling, and epidemiological research.

Patients with cancer frequently develop clinical symptoms or abnormalities directly related to tumor growth, or resulting from palliative and definitive treatment approaches. These patients are seen in the outpatient gastroenterology clinics where they are diagnosed, and appropriate treatment is recommended. Patients are often recruited for studies such as those described in the previous section.

Many chemotherapy regimens have adverse effects on the gastroenterology tract with subsequent need for endoscopic evaluation. These patients present to the gastroenterology clinic for evaluation of possible endoscopy, often as part of an ongoing clinical trial.

^§   Fox Chase researcher

^a   S.A. Wank: NIDDK, NIH, Bethesda, MD 20892

Illustrations or unpublished data in these reports should not be used without permission of the author.

Fox Chase Cancer Center

Scientific Report 1998