Researchers at Jefferson Medical College and the Kimmel Cancer Center at Thomas Jefferson University in Philadelphia, buoyed by a new five-year, $5 million grant from the National Cancer Institute, are beginning a clinical trial to determine whether a simple test for the protein that causes traveler's diarrhea will help provide surgeons and oncologists with a more accurate picture of the extent of colorectal cancer in patients. The scientists hope the test will enable them to determine whether or not cancer has spread from the colon to the lymph nodes, and at the same time, result in improved diagnoses and more appropriate treatment.
The work, led by Scott Waldman, M.D., Ph.D., Samuel M.V. Hamilton Family Professor of Medicine and director of the Division of Clinical Pharmacology at Jefferson Medical College, may ultimately result in a blood test that could tell patients whether their colorectal cancer thought cured has returned.
The test looks for evidence of a protein, guanylyl cyclase C, or GCC, which is expressed only by intestinal cells and colorectal cancer cells. Most colorectal cancers originate in the cells that line the intestine - cells that normally make GCC. When the cells become cancerous, they continue to make GCC.
According to Dr. Waldman, knowing the extent of disease is crucial to managing patients with colorectal cancer. Patients typically undergo surgery to remove the cancer and the nearby lymph nodes, which are the first place cancer usually spreads. After surgery, a pathologist examines lymph node tissue for cancer cells. If none are found, the patient is "staged" as having cancer confined to the bowel. But if cancer is found in the lymph nodes, the patient's prognosis and management changes.
"It's apparent that the further the progression of disease, the worse the prognosis of the patient," he says. If the disease is found outside of the intestine, for example, most patients are given chemotherapy.