Adjuvant Rx yields minor benefit in less aggressive colon cancer

Stage II colon cancer patients who are negative for microsatellite instability and lymphocytic infiltrate should not undergo adjuvant chemotherapy, according to surgeons at Oregon Health and Science University and Legacy Health System, both in Portland.

These patients tend to have a less favorable prognosis and may be candidates for more aggressive adjunctive therapy, wrote Sandeep Kumar, MD, and colleagues (Arch Surg 144:835-840, 2009).

The authors prospectively evaluated 167 colon cancer patients for MSI and LI status and then retrospectively evaluated their chemotherapy regimens. Disease-free survival (DFS) with and without chemotherapy according to combined MSI and LI status was the main outcome.

In the 140 patients for whom data were available, the five-year DFS was 50% for patients who underwent chemotherapy vs 76% for those who did not (P = .02). In the group negative for MSI and LI, five-year DFS was 29% for those undergoing chemotherapy and 91% for those who did not (P = .001).