Testing lymph nodes for the presence of a protein known as guanylyl cyclase 2C (GUCY2C) may help predict risk of recurrence among colorectal cancer patients with no apparent lymph node metastases. These results were published in the Journal of the American Medical Association.
Each year in the United States, an estimated 77,000 men and 72,000 women are diagnosed with colorectal cancer. When colorectal cancer is detected early-before it spreads to nearby lymph nodes or other parts of the body-survival rates are high and treatment often consists of surgery alone. Nevertheless, an estimated 25% of patients with early, apparently node-negative colorectal cancer will develop a cancer recurrence following treatment. Some of these patients may have had undetectable lymph node metastases at the time of their initial diagnosis.
Newer approaches to testing lymph nodes may better identify patients with early signs of lymph node metastasis and a higher risk of recurrence. These patients may benefit from more aggressive approaches to treatment.
GUCY2C is a protein that is expressed by colorectal cancers. Researchers hypothesized that the presence of this protein in lymph nodes-where it is not usually found-could indicate that the cancer has spread to the lymph nodes, and that the patient is at increased risk of recurrence.
To evaluate the relationship between GUCY2C in lymph nodes and risk of colorectal cancer recurrence, researchers conducted a study among 257 colorectal cancer patients who had no histologic evidence of lymph node metastasis. Tests for GUCY2C were performed on lymph nodes, and patients were then followed for a median of two years.
- 87.5% of patients had lymph nodes that tested positive for GUCY2C.
- The risk of recurrence was 21% among patients with lymph nodes that tested positive for GUCY2C, but only 6.3% among patients with lymph nodes that tested negative for GUCY2C.
These results suggest that testing lymph nodes for GUCY2C provides information about recurrence risk among patients with early colorectal cancer. This information could help guide treatment decisions.
Reference: Waldman SA, Hyslop T, Schulz S et al. Association of GUCY2C expression in lymph nodes with time to recurrence and disease-free survival in pN0 colorectal cancer. Journal of the American Medical Association. 2009;301:745-752.