P. M. Schroder1, M. C. Turner1, B. Ezekian1, Z. Sun1, M. A. Adam1, C. R. Mantyh1, J. Migaly1 1Duke University Medical Center,Department Of Surgery,Durham, NC, USA
Introduction: Standard of care for stage III colon cancer includes adjuvant chemotherapy, which increases survival by nearly 30%. Despite these results, many patients fail to receive adjuvant chemotherapy. We aim to describe the benefit of adjuvant chemotherapy for stage III colon cancer and to determine factors that influence the likelihood of receiving this treatment.
Methods: We queried the National Cancer Data Base 2006-2013 for patients with a single primary stage III colon adenocarcinoma and defined two groups: patients who did and did not receive adjuvant chemotherapy. Subgroup analyses were performed for healthy patients (Charlson-Deyo [CD] score = 0), comorbid patients (CD score ≥ 2), and those with post-operative complications (readmitted within 30 days of surgery). Kaplan-Meier (KM) curves were generated and Cox proportional hazard ratios (HR) were calculated to compare overall survival. Odds ratios (OR) for receiving chemotherapy were calculated to identify factors associated with failure to receive adjuvant chemotherapy.
Results: Of the 74,588 patients included in this study, 54,235 received adjuvant chemotherapy and 20,353 did not. Overall survival was significantly better in the group that received adjuvant chemotherapy (HR of 0.477, p<0.001). Similar results were obtained in our subgroup analyses (see Figure). Adjuvant chemotherapy conferred a survival advantage for healthy patients (HR 0.485, p<0.001), comorbid patients (HR 0.492, p<0.001), and those with post-operative complications (HR 0.358, p<0.001). Several factors were associated with a reduced likelihood of receiving chemotherapy including older age (OR 0.9, p<0.001), black race (OR 0.728, p<0.001), comorbid patients with CD score ≥2 (OR 0.563, p<0.001), positive surgical margins (OR 0.83, p<0.001), and those with post-operative complications (OR 0.605, p<0.001). Patients with private insurance (OR 1.997, p<0.001) or Medicare (OR 2.184, p<0.001) were comparatively more likely to receive adjuvant chemotherapy.
Conclusion: We demonstrate a consistent survival benefit with adjuvant chemotherapy for patients with stage III colon cancer, even for comorbid patients or those with early post-operative complications. Factors such as older age, black race, more comorbidities, positive margins, post-operative complications, and lack of insurance were associated with a reduced likelihood of receiving adjuvant chemotherapy. These data suggest that adjuvant chemotherapy remains critically important for all patients with stage III colon cancer, but particular attention should be paid to utilizing this therapy in higher risk and underserved patients to avoid undertreating these vulnerable populations.
