A new study from Massachusetts General Hospital reports that long-term regular aspirin was associated with a lower risk of dying from various types of cancer.

Lead author, Yin Cao, MPH, ScD, a researcher in the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital, and her team studied the health outcomes of approximately 86,000 women and 44,000 men who had been prescribed aspirin at various doses and duration over the course of 32 years.

The biggest benefit came from reducing colorectal cancer deaths: Men and women who regularly took aspirin reduced their chances of dying from colorectal cancer by a third. Women also reduced their risk of dying from breast cancer by 11 percent, while men were 23 percent less likely to die 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.

It’s still not entirely clear how aspirin lowers cancer risk. Researchers suspect that aspirin’s ability to lower inflammation and control inflammatory factors that may contribute to abnormal cell growth in tumors may reduce risk. Plus, its anticoagulant properties that prevent clots from forming may prevent cancerous cells that break away from tumors from sticking to other areas in the body and growing into metastatic tumors.

Regular aspirin use has already been recommended as a preventative measure against cardiovascular disease and colorectal cancer.

Cao cautions that patients and physicians should consider all potential benefits and risks before beginning any new aspirin regimens. More work is needed to weigh these potential benefits against the risks of long-term use, which include gastrointestinal bleeding and hemorrhagic stroke.

The data of this study was presented at the American Association for Cancer Research Annual Meeting 2017, which took place earlier this month in Washington, DC.

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