Studies have linked the regular use of aspirin, an over-the-counter painkiller, to lower risks of heart attack and stroke. The risk-reducing benefits may also extend to death from certain types of cancer. What isn't yet known is how much aspirin is needed to protect against an early death from cancer, and how long people have to take it.
To clear up the link, researchers led by Yin Cao at Massachusetts General Hospital and Harvard Medical School have been combing through data from two large studies: the Nurses' Health Study and the Health Professionals Follow-Up Study. They analyzed the aspirin use and cancer outcomes of more than 130,000 adults over 32 years. The researchers reported their latest findings at the annual meeting of the American Association for Cancer Research.
Overall, people who took aspirin regularly had a 7% to 11% lower risk of dying from cancer, compared to people who did not take it consistently. The biggest benefits came from reducing colon cancer deaths; aspirin-users had a 30% lower risk of dying from this disease than those who didn’t take it regularly. Women taking aspirin also had a lower risk of dying from breast cancer, and men showed a lower risk of dying from prostate cancer.
The benefit seemed to be greatest for people taking two to seven doses of regular-strength aspirin—325 mg per tablet—each week for much of the study period. People who took as little as half a tablet to 1.5 tablets a week also showed reductions in cancer-related death. The drop in cancer deaths appeared for most people after they took aspirin for about six years.
Previous studies have shown similar benefits, especially for reducing deaths from colon cancer. How aspirin lowers cancer risk isn’t entirely clear, but the scientists believe that aspirin’s ability to lower inflammation and control inflammatory factors that may contribute to abnormal cell growth in tumors may play help keep risk down. Aspirin belongs to a group of analgesics called non-steroidal anti-inflammatory drugs (NSAIDs) that includes ibuprofen, acetaminophen and naproxen. These drugs don’t always act in the same way, but other studies suggest that NSAIDs may have the same effect in lowering cancer risk as aspirin does.
The connection between aspirin and a lower risk of cancer death is encouraging. But doctors say it shouldn’t prompt people to start taking aspirin if they don’t need to, simply to lower their risk of cancer. Even at recommended doses, aspirin also comes with side effects, especially if taken over long periods of time. It can block an enzyme produced in the stomach that protects delicate intestinal tissues from the acids that digest food, leading to potentially severe damage, including bleeding of gut tissues. People should seek the counsel of their doctors to weigh the latest evidence.