Findings published in the Journal of the American Medical Association by researchers at Thomas Jefferson University show that the presence of a biomarker in regional lymph nodes is an independent predictor of disease recurrence in patients with colorectal cancer.
Detection of the biomarker, guanylyl cyclase 2C (GUCY2C), indicates the presence of occult metastases in lymph nodes that may not have been identified by current cancer staging methods, according to Scott Waldman, M.D., Ph.D., chairman of the Department of Pharmacology and Experimental Therapeutics at Jefferson Medical College of Thomas Jefferson University.
According to Dr. Waldman, who is also the Samuel M.V. Hamilton Professor of Clinical Pharmacology in the Department of Medicine at Jefferson Medical College, colorectal cancer that has metastasized, or spread, to the regional lymph nodes carries a worse prognosis and a higher risk for recurrence. However, these metastases are often missed, and the cancer is understaged.
"One of the unmet needs in colorectal cancer is an accurate staging method to determine how far the disease has spread," said Dr. Waldman, who is also director of the Gastrointestinal Malignancies Program at the Kimmel Cancer Center at Jefferson. "The current standard method, histopathology, is imperfect since it only involves looking at a very small sample of the regional lymph nodes under a microscope. There is no way to know whether occult metastases are present in the rest of the tissue."
Dr. Waldman and his colleagues conducted a prospective, multicenter study of 257 patients with colorectal cancer that had no metastases identified in the lymph nodes (node-negative) according to current standards. They analyzed the lymph nodes for GUCY2C expression using a technique called reverse transcriptase-polymerase chain reaction (RT-PCR). This technique, according to Dr. Waldman, amplifies the sensitivity to detect cancer cells compared to histopathology.
The majority of patients – 87.5 percent – had lymph nodes that were positive for GUCY2C. Among those patients, 20.9 percent developed recurrent disease. By comparison, only 6.3 percent of the patients whose lymph nodes were negative for GUCY2C developed recurrent disease.