A preliminary report suggests that genetic testing may help identify a marker in lymph nodes that is associated with an increased risk of colorectal cancer recurrence among patients in whom conventional testing indicates that those lymph nodes show no evidence of cancer spread, according to a study in the February 18 issue of JAMA.
Metastasis of tumor cells to regional lymph nodes is the single most important prognostic factor in patients with colorectal cancer. Recurrence rates increase from approximately 25 percent in patients with lymph nodes free of tumor cells as determined by biopsy (pN0 colorectal cancer) to approximately 50 percent in patients with four or more lymph nodes with metastases, according to background information in the article.
"Given the established relationship between lymph node metastasis and prognosis, recurrence in a substantial fraction of patients with pN0 colorectal cancer suggests the presence of occult [undetected] metastases (pN0 [mol+]) in regional lymph nodes that escape [biopsy] detection. Conversely, patients with pN0 colorectal cancer who are free of lymph node metastases may be at lowest risk for developing recurrent disease. Thus, a more accurate assessment of occult metastases in regional lymph nodes in patients with pN0 colorectal cancer could improve risk stratification in this clinically heterogeneous population," the authors write.
Research suggests that guanylyl cyclase C (GUCY2C), an intestinal tumor suppressing receptor, is a specific molecular marker for metastatic colorectal cancer that could reveal occult metastases in lymph nodes and better estimate recurrence risk.