The hazard of death decreases after surgical treatment for colon cancer but not after surgical treatment for rectal cancer

Abstract

INTRODUCTION AND OBJECTIVES: Prognosis in cancer is usually assessed by survival patterns. In this study we evaluated both survival patterns and hazard of death as indices of prognosis to compare colon and rectal cancer. METHOD: Colon and rectal cancer patients who underwent surgical resection from 1996 to 2011 were studied using Kaplan-Meier survival function estimate curves and Weibull Hazard models. RESULTS; Of 369 patients {119 (32%) colon cancer and 250 (68%) rectal cancer), overall 5-year survival rate for colon and rectal cancer was 72% and 60% respectively (P = 0.03). For colon cancer, survival indices diminished when tumor disseminated outside the region of the colon (Stage IV), while in rectal cancer survival indices reduced as cancer progressed from stage I to I! and beyond. As expected, stage for stage survival for colon and rectal cancer were similar for stages 1 and IV (Stage 1, 5 year survival colon vs. rectum; 77% vs. 82% and stage IV; 25% vs. 22%). However, survival in intermediate stages (stage II and stage III) was better for colon cancer compared to rectal cancer (Stage M, 5 year survival colon vs. rectum; 81% vs. 62% and stage III; 70% vs. 55%). After curative resection, colon cancer showed a 6% decrease in hazard of death with time compared with rectal cancer which showed a 1% increase in the hazard of death with time. CONCLUSION: Overall, underwent curative resection, colon cancer had better survival indices compared with rectal cancer.