The prognostic effect of adjuvant chemotherapy in the colon cancer patients with solitary lymph node metastasis

Purpose Previous studies have reported paradoxical survival prognoses for some node-negative and node-positive colon cancer patients. However, current guidelines recommend adjuvant chemotherapy (CT) only for node-positive patients. This study investigated the efficacy of adjuvant CT for patients who underwent radical surgery for colon cancer with solitary lymph node (LN) metastasis. Methods This study included 281 patients treated between 2004 and 2015. Patients were classified into no-CT (n=39) and CT (n=242) groups, and the survival outcomes and recurrence-related follow-up data were analyzed. Results The groups exhibited similarities in tumor sidedness, tumor differentiation, and pathologic stage. However, the age, ASA class, and preoperative CEA level were relatively lower in the CT group. Although the CT group had a higher 5-year overall survival (OS) rate than the no-CT group (88.4% vs. 65.3%, p<0.001), the groups did not differ in terms of 5-year disease-free survival (DFS) (CT, 84.1% vs. no-CT, 83.3%, p=0.490). A multivariate analysis identified adjuvant CT as an independent factor for OS but not for DFS. A highly examined LN count (>= 12) was associated with improved DFS improvement. However, D3 LN dissection was not associated with DFS or OS. For DFS, intermediate/apical positive LNs received a high hazard ratio relative to pericolic/epicolic LNs (2.080, 95% confidence interval: 0.979-4.416), but this was not significant (p=0.057). Conclusions Adjuvant chemotherapy did not provide clear advantages for colon cancer with solitary LN metastasis. Further large studies that analyze several prognostic factors are needed to establish tailored adjuvant CT administration guidelines.