Adjuvant Chemotherapy Is Associated with Improved Survival for Stage III Colon Cancer When Initiated Beyond 8 Weeks.

BACKGROUND: The National Comprehensive Cancer Network (NCCN) guidelines recommend adjuvant chemotherapy (AC) within 6-8 weeks of surgical resection for patients with stage III colon cancer. However, postoperative complications or prolonged surgical recovery may affect the receipt of AC. The aim of this study was to assess the utility of AC for patients with prolonged postoperative recovery. METHODS: We queried the National Cancer Database (2010-2018) for patients with resected stage III colon cancer. Patients were categorized as having either normal or prolonged length of stay (PLOS: >7 days, 75th percentile). Multivariable Cox proportional hazard regression and logistic regressions were used to identify factors associated with overall survival and receipt of AC. RESULTS: Of the 113,387 patients included, 30,196 (26.6%) experienced PLOS. Of the 88,115 (77.7%) patients who received AC, 22,707 (25.8%) initiated AC more than 8 weeks after surgery. Patients with PLOS were less likely to receive AC (71.5% vs. 80.0%, OR: 0.72, 95%CI=0.70-0.75) and displayed inferior survival (75 vs. 116 months, HR: 1.39, 95%CI=1.36-1.43). Receipt of AC was also associated with patient factors such as high socioeconomic status, private insurance, and White race (p<0.05 for all). AC within and after 8 weeks of surgery was associated with improved survival for patients with both normal LOS and PLOS (normal LOS: <8 weeks HR: 0.56, 95% CI: 0.54-0.59, >8 weeks HR: 0.68, 95% CI: 0.65-0.71; PLOS: <8 weeks HR: 0.51, 95% CI: 0.48-0.54, >8 weeks HR: 0.63, 95% CI 0.60-0.67). AC was associated with significantly improved survival if initiated up to 15 weeks postoperatively (normal LOS: HR: 0.72, 95%CI=0.61-0.85; PLOS: HR: 0.75, 95%CI=0.62-0.90), and very few patients (<3.0%) initiated AC beyond this time. CONCLUSION: Receipt of AC for stage III colon cancer may be affected by surgical complications or otherwise prolonged recovery. Timely and even delayed AC (>8 weeks) are both associated with improved overall survival. These findings highlight the importance of delivering guideline-based systemic therapies, even after complicated surgical recovery.