In a case-control study, regular use of 75 mg/day of aspirin— lower than the standard 81-mg dose of baby aspirin—significantly reduced the risk of developing colorectal cancer (CRC). The effect was evident after 1 year and increased with longer use.
The findings of this large population-based study are applicable to the general population, not just high-risk patients, according to the authors.
Previous studies have shown a reduced risk of CRC in users of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs), but did not define the lowest effective dose, treatment duration, or effects on survival. In this study, Farhat V. N. Din, MBBS, of the University of Edinburgh, and coworkers examined the relationship between NSAID dose and duration, CRC risk, and CRC-specific mortality in 2279 cases and 2907 controls. The study is reported in the September 15 online issue of Gut.
Subjects, who were between 16 and 79 years of age, completed food-frequency and lifestyle questionnaires. NSAID use was categorized as low-dose (75 mg) aspirin, non-aspirin NSAIDs, and any NSAID use. Users were defined as taking >4 tablets/week for >1 month.
Of the 2279 cases, 354 (15.5%) used low-dose aspirin compared with 526 (18.1%) of the control subjects. After 1 year, subjects who took 75 mg of aspirin per day (had a 22% lower risk of CRC than did controls. At 5 years, the relative risk reduction was 37%. Risk reduction was greatest in subject who took >525 mg of aspirin per week and persisted for 10 years. Use of non-aspirin NSAIDs and any NSAID also lowered CRC risk.
Aspirin or NSAID use had no demonstrable effect on all-cause mortality or CRC-specific mortality. This lack of effect may have been due to sample size or limited duration of intake, the researchers suggest.
No significant difference was found between aspirin or NSAID users and nonusers in the number of deaths resulting from bleeds or cerebrovascular accidents.