Aspirin may prevent melanoma in women

Aspirin may have another benefit in addition to relieving pain and preventing heart attacks. The common, over-the-counter tablet may also help reduce a woman's risk for melanoma, the most dangerous type of skin cancer, a new study suggests.

Researchers found that postmenopausal women who used aspirin two or more times a week had a 21 percent lower risk of developing melanoma than women who did not take the pain reliever. These results held true for aspirin use only and did not apply to other nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, or to acetaminophen, which is not an NSAID.

"Aspirin works on a slightly different inflammatory pathway than NSAIDs, and some of these pathways may be specific to melanoma," said study author Dr. Jean Tang, an associate professor of dermatology at Stanford University School of Medicine in Palo Alto, Calif.

The study is available online today (March 11) in the journal Cancer.

For the study, researchers used data collected from women ages 50 to 79 who were enrolled in the Women's Health Initiative, a long-term national health study. Scientists evaluated the use of pain relievers in nearly 60,000 postmenopausal Caucasian women, who described their current medication use after enrolling in the study, and again three years later.

Aspirin and melanoma risk

Women completed a questionnaire that asked them to recall whether they took aspirin or non-aspirin NSAIDs, such asibuprofen or naproxen. If they had used these medications at least twice a week during the previous two weeks, the women then recorded how long they had been taking the drug and at what strength.

Among the women, 25 percent were considered aspirin users; about 15 percent took non-aspirin NSAIDs; and close to 60 percent didn't use aspirin or other NSAIDs. Women who took aspirin typically had a history of heart disease, while those who took NSAIDs had a history of arthritis.

According to Tang, 75 percent of aspirin users reported taking a regular strength aspirin, which is usually 325 milligrams, at least twice a week, while 25 percent took low-dose baby aspirin. The exact dosage and frequency of their overall aspirin use is not known.

During an average follow-up period of 12 years, 548 cases of melanoma were diagnosed in the 60,000 women.  After controlling for factors that might influence a person's skin cancer risk, such as a prior history of the disease, sun exposure, sunscreen use, skin type and tanning habits, the researchers found that women who had taken aspirin were 21 percent less likely to develop melanoma than women who had not used the medicine.

The findings also showed that the longer the women took aspirin, the greater the protection it offered against this type of skin cancer. Women who had used aspirin at least twice a week for five or more years reduced their odds of developing melanoma by 30 percent compared to non-aspirin users.

Cancer-protective potential

The idea that aspirin and other common painkillers might offer cancer-protective benefits is not new. Previous research has shown a link between the use of NSAIDs, including aspirin, and a reduced risk for stomach, colorectal and breast cancers.

Other studies have also established a connection between both NSAID use and a reduced risk for melanoma. However, the current study found an association only between aspirin use and melanoma — not between other NSAIDs and melanoma. Tang suspects that this is because aspirin may be taken more regularly than other NSAIDs. Also, because fewer women in the study reported taking ibuprofen or naproxen, there was a smaller sample size of non-aspirin users.

"Aspirin could be used as a way to prevent melanoma, however clinical trial testing has to be done first before it can be recommended," Tang explained. She said the researchers plan to do follow-up studies to see if aspirin might also protect against melanoma in younger women and men.

It's too soon to advise that people at high risk for melanoma start taking an aspirin a day. Regular use of the pain reliever is not without risks. One possible side effect of routine aspirin use is bleeding ulcers.

For now, "the evidence for reducing sun exposure and using sunscreen to protect against melanoma is stronger than that for aspirin use," Tang said.

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