Long-term aspirin use may prevent colorectal cancer, analysis shows
The benefit of aspirin on GI tract cancers was seen at a minimum of 6 years of regular use and appeared to be dose-dependent, developing at 0.5 to 1.5 standard (325 mg) aspirin tablets per week.
Regular aspirin use is associated with a lower incidence of gastrointestinal (GI) tract cancers, particularly colorectal cancer, a recent study found.
Researchers used data from 135,965 women and men enrolled in 2 large prospective cohort studies that recorded aspirin use for more than 32 years: the Nurses' Health Study and the Health Professionals Follow-up Study. Results were published online on March 3 by JAMA Oncology.
Over the course of follow-up, researchers documented 20,414 cancers among 88,084 women and 7,571 cancers among 47,881 men (excluding nonmelanoma skin cancers and non-advanced prostate cancers). In their main analysis, they looked at the relationship between regular aspirin use and the risk for any type of cancer, GI tract cancers, and non-GI tract cancers.
Compared with nonregular use of aspirin, regular aspirin use was associated with a slightly lower risk for overall cancer (relative risk, 0.97; 95% CI, 0.94 to 0.99) and a lower incidence of GI tract cancers (relative risk, 0.85; 95% CI, 0.80 to 0.91), especially colorectal cancer (relative risk, 0.81; 95% CI, 0.75 to 0.88). No association was seen between aspirin use and non-GI tract cancers. Results for GI tract cancer and colorectal cancer were similar for women and men and did not change with age, family history of cancer, and several other potential confounders.
The benefit of aspirin on GI tract cancers was seen at a minimum of 6 years of regular use and appeared to be dose-dependent, developing at 0.5 to 1.5 standard aspirin tablets per week. (A standard aspirin tablet was defined as 325 mg.) The partial population-attributable risk was 1.8% for overall cancer, 8.0% for GI tract cancer, and 10.8% for colorectal cancer.
For patients older than age 50 years, researchers estimated that regular aspirin use could prevent 33 colorectal cancers per 100,000 person-years among those who did not have lower endoscopy and 18 colorectal cancers per 100,000 person-years among those who had lower endoscopy. These results suggest that aspirin use may be a relatively low-cost primary prevention method that may complement colorectal cancer screening with polypectomy, according to an accompanying editorial.
The study authors noted limitations to their work, which has the restrictions that accompany observational studies. They also noted that most participants were white and that results relating to overall cancer risk may not be generalizable to populations in which colorectal, breast, and prostate cancers do not account for a substantial proportion of cancer incidence. In addition, the study did not assess the potential harms of aspirin or the full range of its potential benefits beyond that of cancer prevention, the editorialist noted.