Risk assessment in Stage II colorectal cancer

In the treatment of colon cancer today, the decision-making involved in the treatment of stage II disease is probably the most challenging aspect. The major question is whether or not these patients should receive postoperative adjuvant chemotherapy. Approximately 75% of stage II colon cancer is cured by surgery alone. For the remaining 25% of cases, there is great debate over whether adjuvant chemotherapy is sufficiently effective in enough patients to warrant the exposure to potentially toxic treatments. In the important QUASAR clinical trial, stage II patients were randomized to either fluorouracil (5-FU)-based therapy or observation. The results demonstrated an approximate 3% improvement in outcome for the 5-FU-treated patients. This leads to the assumption that treating all stage II patients with adjuvant chemotherapy is gross overtreatment, when essentially 97% of these patients will not benefit. Clearly the only way to approach this decision is through risk determination. In this article, I will describe the current state of defining high- and low-risk disease, which is mainly through histopathologic characteristics, as well as discuss emerging approaches such as molecular markers and genomic profiling.