Healthy older adults who take daily low-dose aspirin have increased risk of being diagnosed with advanced cancers and dying from cancer, according to findings from a new study published in the Journal of the National Cancer Institute.

Researchers in the Aspirin in Reducing Events in the Elderly (ASPREE) clinical trial looked at 19,114 people aged 70 and older and compared use of 100 mg of aspirin daily to use of a daily placebo. After a median follow-up of 4.7 years, 981 cancer events occurred in the aspirin and 952 in the placebo groups. Although the researchers found no significant difference between the groups in their overall risk for developing cancer, aspirin use was associated with an increased risk of cancer that had metastasized or that was diagnosed at stage IV and with higher risk of death for cancers that presented at stages III or IV.

Many previous studies have shown that regular low-dose aspirin use is associated with a reduced risk for colorectal cancer, but the new study findings suggested that the benefit doesn’t apply with older adults.

“In older adults, aspirin treatment had an adverse effect on later stages of cancer evolution,” the researchers concluded. “These findings suggest that in older persons, aspirin may accelerate the progression of cancer and thus suggest caution with its use in this age group.”