Taking aspirin contributes to a reduced risk of several gastrointestinal (GI) malignancies, such as colorectal cancer (CRC), liver cancer, stomach cancer, and pancreatic cancer, as shown by the results of a 20-year study presented at ASCO GI 2025. However, no association isseenwith most non-GI cancers. 

“In general, results on the effect of aspirin on GI cancer prevention were consistent with the previously presented 10-year cohort,” according to study authors Professor Kelvin Tsoi from The Chinese University of Hong Kong, Hong Kong, and Professor Joseph Sung from the Lee Kong Chian School of Medicine at the Nanyang Technological University, Singapore. 

Tsoi and Sung investigated the 20-year risk of cancer using aspirin in a territory-wide Hong Kong population cohort and included all aspirin users from 2000 to 2019, as well as nonaspirin users matched by age and sex at a ratio of 1:2. They excluded individuals with a history of cancer at enrollment, cancer incidence, or death within 6 months. 

The primary outcome was the incidence of individual GI and non-GI cancer. Tsoi and Sung used inverse probability of treatment weighting to adjust the baseline characteristics between aspirin and nonaspirin users in the survival analysis. They also used the fine-grey model to address bias from the competing risk of death. 

Overall, 538,147 aspirin users were matched to 968,378 nonusers (mean age 64.8 years). A total of 36,683 cases of GI cancer (2.4 percent) and 47,196 non-GI cancers (3.1 percent) were reported.[ASCO GI 2025, abstract 830] 

Individuals who used aspirin benefitted from a reduced risk of several common GI cancers, including CRC (subdistribution hazard ratio [SHR], 0.78, 95 percent confidence interval [CI], 0.76?0.81), liver cancer (SHR, 0.67, 95 percent CI, 0.64?0.70), stomach cancer (SHR, 0.79, 95 percent CI, 0.75?0.84), and pancreatic cancer (SHR, 0.85, 95 percent CI, 0.79?0.91), but not esophageal cancer. 

Non-GI cancers 

The use of aspirin also resulted in a decreased risk of developing prostate (SHR, 0.95, 95 percent CI, 0.91?1.00) and breast cancers (SHR, 0.76, 95 percent CI, 0.73?0.79), but not lung and kidney cancers. 

Overall, Tsoi and Sung noted that aspirin users had a 24-percent reduced risk of GI cancers (SHR, 0.76, 95 percent CI, 0.74?0.78) and a 3-percent decreased risk of non-GI cancers (SHR, 0.97, 95 percent CI, 0.95?0.99). 

Previous studies have shown the association between aspirin use and a reduction in the risk of several GI and non-GI cancers, but there was little evidence regarding the age aspirin should be first taken to benefit from its chemoprotective effects against GI cancer, according to the authors. [Ann Oncol2020;31:558-568; Int J Cancer2021;148:1372-1382] 

On the other hand, a randomized controlled trial exploring aspirin for primary prevention use in healthy older adults found no significant association between aspirin and cancer incidence despite the limitation of short follow-up duration. [J Natl Cancer Inst2021;113:258-265]