The study included men from the Health Professionals Follow-Up Study (HPFS) and women from the Nurses’ Health Study (NHS). The NHS started in 1976 with 121,700 female nurses aged 30 to 55, while the HPFS began in 1986 with 51,529 male health professionals aged 40 to 75. Participants with a history of cancer or inflammatory bowel disease, or incomplete data, were excluded.
Researchers followed participants until they were diagnosed with colon cancer, died, or the study ended (June 30, 2018, for NHS and January 31, 2018, for HPFS). They analyzed data from October 2021 to May 2023. Most participants completed surveys every two years about their diet, lifestyle, medication, and health outcomes.
Information on regular aspirin use was collected every two years starting in 1980 for NHS and 1986 for HPFS. Regular aspirin use meant taking two or more standard 325 mg tablets or six or more low-dose 81 mg tablets weekly.
Researchers assessed lifestyle factors like smoking, body weight, physical activity, alcohol consumption, and diet, creating a healthy lifestyle score from zero to five, where higher scores indicated healthier habits.
To determine the benefits of regular aspirin use, researchers calculated the 10-year risk of colon cancer, adjusting for age, lifestyle, sex, family history, and screening. They also looked at the long-term impact of aspirin by analyzing 20-year cancer risk.
The study used statistical models to estimate how aspirin use affected colon cancer risk based on lifestyle scores and tested for interactions between aspirin use and these scores.
Aspirin may help prevent colon cancer by stopping abnormal cell growth in the colon or rectum. However, because long-term use of aspirin can have risks, it’s important to determine which people would benefit most from taking it.
Research suggests that aspirin’s effectiveness in preventing cancer can vary depending on a person’s diet, body weight, and smoking habits. More research is needed to understand how lifestyle factors influence aspirin’s impact on colon cancer risk.