Outcomes of elderly patients with node-positive colon cancer: A multi-center population-based cohort study.

Abstract

33 Background: Patients with stage III colon cancer are at high risk of recurrent disease. In this large population based cohort study we examined prognostic significance of chemotherapy and other clinical, pathological & contextual variables that are associated with inferior outcomes in elderly patients with stage III colon cancer. Methods: Patients ≥ 70 years with stage III colon cancer diagnosed in Saskatchewan, a Canadian province, and underwent resection of the primary tumor during 2012-2018 were evaluated. A Cox proportional multivariate survival analysis was performed to determine factors correlated with overall survival (OS) and disease-free survival (DFS). Results: 404 eligible patients with median age of 79 yrs & M:F of 1:1 were identified. 48% were ≥80 years, 60% were rural resident, 66% had ≥ 1 major comorbid illness, 34% had WHO performance status >1, 14% has an ostomy formation, 46% had a T4 or N2 high-risk disease, and 50% had node positive to node harvested (NPNH) ratio of >0.1. 43% patients received adjuvant chemotherapy. Median time to start chemo was 9 weeks. Patients who did not receive adjuvant chemotherapy were significantly older, had low performance status or experienced high rate of post-operative complications, high serum creatinine, low albumin, anemia, elevated WBC count and platelets. Median OS of all patients was 51 months (95%CI: 42.4-59.6), with estimated 5 & 10-yr OS of 45% and 30%. Median DFS of entire cohort was 32 months (26.3-37.7) with 5 & 10-yr DFS of 34% and 20%. Patients who received adjuvant chemotherapy had median OS of 106 months (83.8-128.5) vs. 30 months (23.4-36.6), p<0.001 with 5 & 10-yr OS of 64% and 49% vs. 31% and 19% (p<0.001). Patients who received adjuvant chemotherapy had median DFS of 56 months (28.2-83.9) vs. 22 months (16.5-27.5), p<0.001 with 5 & 10-yr DFS of was 49% and 30% vs. 24% and 13% (p=<0.001). The Cox-multivariate analysis revealed a past history of cancer, HR, 1.32 (1.03-1.72); ostomy, HR, 1.33 (1.02-1.74); NPNH ratio >0.1, 1.34 (1.04-1.78); grade III tumor, 1.36 (1.04-1.78); WHO performance status >1, HR, 1.38 (1.05-1.82); no adjuvant chemo, HR, 1.38 (1.03-1.85); high-risk stage III disease, HR, 1.39 (1.10-1.79), and baseline CEA >5, HR, 1.75 (1.34-2.29), were independently correlated with DFS whereas past history of cancer, HR, 1.47 (1.12-1.94); ostomy, HR, 1.53 (1.16-2.03); NPNH ratio >0.1, 1.51 (1.15-1.98); grade III tumor, 1.54 (1.16-2.04); WHO performance status >1, HR, 1.42 (1.06-1.90); no adjuvant chemo, HR, 1.82 (1.32-2.50); high-risk stage III disease, HR, 1.60 (1.22-2.11), and CEA >5, HR, 1.98 (1.50-2.61) were independently correlated with OS. Conclusions: In elderly patients with stage III colon cancer lack of adjuvant chemotherapy, poor performance status, T4 or N2 disease, grade III tumor, elevated baseline CEA, past history of a secondary cancer, elevate NPNH ratio >0.1 and an ostomy formation correlate with inferior outcomes.