Aspirin use after diagnosis improves survival in older adults with colon cancer: a retrospective cohort study.

OBJECTIVES: To assess survival in relation to aspirin use after diagnosis in older adults with colon cancer. DESIGN: Subgroup analysis of a previously published cohort and retrospective study. SETTING: Individuals registered in the Eindhoven Cancer Registry (ECR) between 1998 and 2007, linked to prescriptions of low-dose aspirin (80 mg) registered in a community pharmacy database. PARTICIPANTS: Five hundred thirty-six individuals aged 70 and older diagnosed with colon cancer with or without aspirin use after diagnosis. MEASUREMENTS: Survival was analyzed with user status as a time-dependent covariate. Multivariate Poisson regression survival models were used to study the effect of aspirin on overall survival. RESULTS: One hundred seven participants (20.0%) started aspirin after being diagnosed with colon cancer; 429 (80.0%) were not prescribed aspirin. Three hundred thirty-nine participants (63.2%) had died by the end of follow-up. Aspirin use after diagnosis was associated with longer overall survival (rate ratio (RR) = 0.51, 95% confidence interval (CI) = 0.38-0.70, P < .001). Multivariate proportional hazards regression analysis revealed that aspirin use was associated with longer overall survival (adjusted RR = 0.59, 95% CI = 0.44-0.81, P = .001). CONCLUSION: Aspirin use after the diagnosis of colon cancer in older adults was associated with longer survival. Low-dose aspirin could be used as an effective adjuvant therapy in older adults with colon cancer.