Adjuvant Therapy for Stage II Colon Cancer: ASCO Guideline Update

PURPOSE To develop recommendations for adjuvant therapy for patients with resected stage II colon cancer. METHODS ASCO convened an Expert Panel to conduct a systematic review of relevant studies and develop recommendations for clinical practice. RESULTS Twenty-one observational studies and six randomized controlled trials met the systematic review inclusion criteria. RECOMMENDATIONS Adjuvant chemotherapy (ACT) is not routinely recommended for patients with stage II colon cancer who are not in a high-risk subgroup. Patients with T4 tumors are at higher risk of recurrence and should be offered ACT, whereas patients with other high-risk factors, including sampling of fewer than 12 lymph nodes in the surgical specimen, perineural or lymphovascular invasion, poorly or undifferentiated tumor grade, intestinal obstruction, tumor perforation, or grade BD3 tumor budding, may be offered ACT. The addition of oxaliplatin to fluoropyrimidine-based ACT is not routinely recommended, but may be offered as a result of shared decision making. Patients with mismatch repair deficiency/microsatellite instability tumors should not be routinely offered ACT; if the combination of mismatch repair deficiency/microsatellite instability and high-risk factors results in a decision to offer ACT, oxaliplatin-containing chemotherapy is recommended. Duration of oxaliplatin-containing chemotherapy is also addressed, with recommendations for 3 or 6 months of treatment with capecitabine and oxaliplatin or fluorouracil, leucovorin, and oxaliplatin, with decision making informed by key evidence of 5-year disease-free survival in each treatment subgroup and the rate of adverse events, including peripheral neuropathy.