Benefit of Postresection Adjuvant Chemotherapy for Stage III Colon Cancer in Octogenarians: Analysis of the National Cancer Database.

Background: Clinical trials demonstrate that postresection chemotherapy conveys survival benefit to patients with stage III colon cancer. It is unclear whether this benefit can be extrapolated to the elderly, who are underenrolled in clinical trials.

Objective: The purpose of this study was to determine outcomes of selected octogenarians with stage III colon cancer with/without postresection adjuvant therapy.

Design: This was a retrospective cohort study (2006-2011) using unadjusted Kaplan-Meier and adjusted Cox proportional hazards analyses of overall survival.

Setting: The study was conducted with the National Cancer Database.

Patients: We included patients 80 to 89 years of age who were undergoing curative-intent surgery for stage III colon cancer and excluded patients who received neoadjuvant therapy, died within 6 weeks of surgery, or had high comorbidity.

Main Outcome Measures: Overall survival was the main measure.

Results: A total of 8141 octogenarians were included; 3483 (42.8%) received postresection chemotherapy, and 4658 (57.2%) underwent surgery alone. Patients receiving chemotherapy were younger (82.0 vs 84.0 years; p < 0.001), healthier (73.1% vs 70.4% with no comorbidities; p = 0.009), and more likely to have N2 disease (40.4% vs 32.8%; p < 0.001). Overall survival was improved in patients receiving adjuvant chemotherapy (median = 61.7 vs 35.0 months; p < 0.001). Subgroup analysis of patients offered chemotherapy but refusing (n = 1315) demonstrated overall survival worse than those receiving adjuvant chemotherapy (median = 42.7 vs 61.7 months; p < 0.001). Multivariable analysis adjusting for potential confounders showed therapy with surgery alone to be independently associated with increased mortality hazard (HR = 1.83; p < 0.001), and the mortality hazard remained elevated in patients who voluntarily refused adjuvant therapy (HR = 1.45; p < 0.001).

Limitations: The study was limited by its retrospective, nonrandomized design.

Conclusions: In selected octogenarians with stage III colon cancer, postresection adjuvant chemotherapy was associated with superior overall survival. However, less than half of the octogenarians with stage III colon cancer in the National Cancer Database received it. The remaining majority, who were all fit and survived ≥6 weeks postsurgery, could have derived benefit from adjuvant chemotherapy. This represents a substantial opportunity for quality improvement in treating octogenarians with stage III colon cancer.