Stage II colon cancer.

Colorectal cancer (CRC) is the third commonest cancer in the Western world. Approximately one-quarter of cases are classified as Stage II/Dukes' B, meaning that the disease has breached the bowel wall but not spread to draining lymph nodes or distant sites. Stage II colon cancer is a heterogeneous disease both biologically and in terms of outcome. Although pivotal data have confirmed the benefit of adjuvant 5-fluorouracil (FU) chemotherapy following resection of stage II tumours the absolute reduction in risk of recurrence is small - 3 to 4 percentage points - and so most patients treated fail to gain from therapy. In contrast to stage III disease, the addition of oxaliplatin to FU as adjuvant chemotherapy for stage II disease does not improve outcome. Much attention has focused on the identification of biomarkers that identify patients more or less likely to benefit from treatment. Recent data confirm that patients with T3 primary and tumour microsatellite instability (MSI) have excellent prognosis and do not require adjuvant chemotherapy. For patients with microsatellite-stable disease, a validated recurrence score based on gene expression provides greater prognostic information than conventional clinicopathological features alone and can be used to inform discussion on the benefits of adjuvant chemotherapy.