The role of high-risk features in stage II colon cancer after surgical treatment^⁎

Background: A proportion of patients with stage II colon cancer treated surgically will have either local or distal recurrence; this group is not well identified. High-risk features (HRF) have been proposed to aid in the determination of which patients would benefit from additional treatment and surveillance. In this study, we analyzed the relationship between HRF in resected stage II colon cancer patients and long-term outcomes. Methods: A single institution colorectal database from 2011 to 2017 was queried and patients undergoing resection for stage II colon cancer were included. Analyzed HRF included: lymphovascular invasion, perineural invasion, tumor perforation, differentiation, and T4 status. Patients younger than 18 years, synchronous malignancy, inflammatory bowel disease, or rectal cancer were excluded. Statistical analysis included frequency testing and regression modeling for recurrence and survival. Results: Of the 165 included patients; 108 (65%) presented with at least one HRF. Overall 28 patients (17%) received adjuvant chemotherapy (ACT) Disease free survival (DFS) was 89% at 3 years; there was no significant difference in DFS between patients with or without HRF. On univariable analysis, only the presence of T4 tumor and older age were associated with worse DFS. Neither the presence nor number of high-risk features significantly affected overall survival (OS). ACT did not significantly affect OS or DFS in patients with or without HRF. Conclusions: In this cohort of stage II colon cancer patients, only T4 tumor status and older age were associated with worse DFS, while OS was similar between low- and high-risk groups. ACT was under-indicated and did not significantly affect DFS or OS. Improved risk-stratification strategies are necessary for this special population.