Q. D. Chu1, M. Zhou2, K. Medeiros2, R. H. Kim1, X. Wu2 1Louisiana State University Health Sciences Center-Shreveport,Surgical Oncology,Shreveport, LA, USA 2Louisiana State University Health Sciences Center,Louisiana Tumor Registry & Epidemiology And School Of Public Health,New Orleans, LA, USA
Introduction: We found a persistence of a survival paradox between Stage 3A and Stage 2B/C colon cancer who had optimal treatment. The underlying reasons are elusive. We hypothesized that positive surgical margins contribute significantly to this paradox.
Methods: We evaluated a cohort of 16,471 patients with stage 3A or stage 2B/C with ≥ 12 lymph nodes (LNs) retrieved (N=5,670) from 709,583 patients diagnosed with colon cancer in 2003-2012 from the National Cancer Data Base. All received chemotherapy. Patients with Stage 3A were further subdivided into those with < 12 LNs retrieved (N=3,195) and those with ≥ 12 LNs retrieved (N=7,606). Univariate and multivariate survival analysis were employed.
Results: The 5-year overall survival (OS) rate was 70.8% for stage 2B/C ≥ 12 LNs, 81.6% for stage 3A with < 12 LNs, and 85.6% for Stage 3A with ≥ 12 LNs (P<0.0001). Patients with stage 2B/C had significantly higher rate of positive surgical margins compared to stage 3A (19% vs 1%; P<0.0001). Significant predictors (P<0.01) of poor OS include stage 2B/C, community cancer program, advanced age, African-American ethnicity, Medicaid, low education level, high comorbidity index, and positive surgical margins.
Conclusion: Positive surgical margins contribute to the survival paradox between optimally treated Stage 2B/C and Stage 3A colon cancer patients.
