The study also found that the longer the women took the drug, the lower the risk of developing this type of skin cancer.
The findings suggest that aspirin's anti-inflammatory effects may help protect against the cancer.
In the Women's Health Initiative, researchers observed US women aged 50 to 79 years for an average of 12 years and noted which individuals developed cancer.
At the beginning of the study, the women were asked which medications they took, what they ate, and what activities they performed.
More From This Section
Overall, women who used aspirin had a 21 per cent lower risk of melanoma relative to non-users. Each incremental increase in duration of aspirin use (less than one year of use, one to four years of use, and five or more years of use) was associated with an 11 per cent lower risk of melanoma.
The researchers controlled for differences in pigmentation, tanning practices, sunscreen use, and other factors that may affect skin cancer risk.
"Aspirin works by reducing inflammation and this may be why using aspirin may lower your risk of developing melanoma," said Tang.
Other pain medications, such as acetaminophen, did not lower women's melanoma risk. Tang noted that the findings support the design of a clinical trial to directly test whether aspirin can be taken to prevent melanoma.