Background: This investigation assessed the baseline mortality-adjusted 5-year survival after open rectal cancer resection.
Methods: The 5-year survival rate was analyzed in 885 consecutive American Joint Committee on Cancer (AJCC) stage I-IV rectal cancer patients undergoing open resection between 2002 and 2011 using risk-adjusted Cox proportional hazards regression models adjusted for population-based baseline mortality.
Results: The 5-year relative and overall survival rates were 80.9%(95% confidence interval (CI): 77.0-85.0%) and 71.9%(95% CI, 68.4-75.5%), respectively. The 5-year relative survival rates for stage I, II, III, and IV cancer were 97.8% (95% CI, 93.1-102.8%), 90.9%(95% CI, 84.3-98.1%), 72.0% (95% CI, 64.7-80.1%), and 24.4% (95% CI: 16.0-37.0%), respectively. After the curative resection of stage I-III rectal cancer, fewer than every other observed death was cancer-related. The 5-year relative survival rate for stage I cancer did not differ from the matched average national baseline mortality rate (P = 0.419). Higher age (hazard ratio (HR) 0.94, 95% CI: 0.92-0.95, P < 0.001) was protective for relative survival but unfavorable for overall survival (HR 1.04, 95% CI: 1.02-1.05, P < 0.001). Female gender was only unfavorable for relative survival (HR 1.59, 95% CI: 1.11-2.29, P = 0.014).
Conclusion: The analysis of relative survival in a large cohort of rectal cancer patients revealed that stage I rectal cancer is fully curable. The findings regarding age and gender may explain the conflicting results obtained to date from studies based on overall survival.