Aspirin and other non-steroidal anti-inflammatory drug use and colorectal cancer survival: a cohort study.

BACKGROUND: Aspirin has been widely reported to reduce the incidence of colorectal cancer. Recently, a survival benefit after diagnosis has also been suggested. Data regarding such a benefit are to date contradictory. This study examines the effect of non-steroidal anti-inflammatory drug (NSAID) use on mortality in colorectal cancer in a larger patient cohort than previously to further clarify this effect, especially in terms of exposure timing and dosing. METHODS: A study using the General Practice Research Database assessed whether aspirin or NSAID exposure in the year immediately following diagnosis affected all-cause mortality in a cohort of 13 994 colorectal cancer patients. Cox proportional hazards modelling adjusted for age, gender, smoking, body mass index and comorbidity. RESULTS: Overall mortality was slightly lower in patients treated with aspirin, (hazard ratio (HR)=0.91; 95% confidence interval (CI)=0.82-1.00). This effect was observed only in patients treated with prophylaxis-dose aspirin (HR=0.89, CI=0.80-0.98) and only in patients taking aspirin before diagnosis (HR=0.86, CI=0.76-0.98). Differential effects were observed depending on the time after diagnosis. Up to 5 years, a reduction in mortality was observed for aspirin users (HR=0.83, CI=0.75-0.92), whereas after 10 years there was an increase in mortality (HR=1.94, CI=1.26-2.99). For NSAID use, no significant effect was observed on overall mortality (HR=1.07, CI=0.98-1.15). High-dose NSAID use was associated with a slight increase in mortality (HR=1.41, CI=1.26-1.56). INTERPRETATION: These findings provide further indication that aspirin may be beneficial in reducing mortality in colorectal cancer during the first 5 years. The same cannot be said for other NSAIDs, where a small increase in mortality was observed.