All estimates of reduced risk were driven primarily by the use of nonselective NSAIDs and older COX-2 inhibitors, including diclofenac, etodolac and meloxicam. —Researchers

Aspirin and other nonsteroid anti-inflammatory medications such as ibuprofen and naproxen may protect against some types of skin cancer, according to research published in the journal Cancer.

But the research comes with a caution about reading too much into it. As WebMD notes, "The new study hints at a possible link between NSAID use and skin cancer risk. It does not prove that a link exists or speak to how these medications may stave off skin cancer risk. Other studies have produced conflicting results."

Researchers from Denmark's Aarhus University Hospital and two California hospitals, the Cancer Prevention Institute and Stanford University School of Medicine, examined 19 years of skin cancer records in north Denmark against documented skin cancer, paying attention to who used prescription NSAIDs compared to those who didn't. They did not consider over-the-counter NSAIDs in the analysis.

It wasn't a shot in the dark. Other studies have shown that cyclooxygenase (COX) enzymes are involved in development of some changes that turn into cancer. Since some NSAIDs inhibit one of both of the COX enzymes, the researchers went after records collected before 1991 and 2009 on use of NSAIDs and skin cancer cases.

A Los Angeles Times article said that the researchers were able to "do a pretty thorough job because of extensive medical registries in Denmark, as well as the fact that patients get a partial price break when they get NSAIDs via prescription as opposed to over the counter."

The study considered the three types of skin cancer, looking at about 1.8 million people over nearly two decades. Among the records they found 1,974 cases of squamous cell carcinoma, 13,316 cases of basal cell carcinoma and 3,232 cases of malignant melanoma. Then they compared each individual with 10 people from the same population, taking care to match age, gender and county of residence. When they looked at the medical rcords and prescription registry, they discovered those who had used more than two prescriptions of NSAIDS were 15 percent less likely to have gotten squamous cell carcinoma and 13 percent less likely to have developed malignant melanoma.

As the medications were used longer or more intensively, the risk of developing those skin cancers dropped. The researchers said that "all estimates of reduced risk were driven primarily by the use of nonselective NSAIDs and older COX-2 inhibitors, including diclofenac, etodolac and meloxicam."

As for the most common form of skin cancer, basal cell carcinoma, the reduced risk was not present, but when they looked at skin cancer sites other than the head and neck, they did find an association with a lower risk. That was also true in cases where people had used the NSAID drugs longer or at higher doses.

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The L.A. Times article also said that "though they don't know why, they saw that rates dropped too with acetaminophen, though that puzzed them." The researchers had included the drug, which does not inhibit either Cox enzyme, as a control. "It turned out that acetominophen use was also linked to a reduction in basal cell carcinomas and malignant melanoma," it said.

Experts warn that NSAIDs do not reduce the need for other protective measures to prevent skin cancer, including using sunscreen and wearing protective clothing to reduce the risk of sun damage to the skin. "The only safe tan is the one you get from a bottle of self-tanning cream," Dr. Joshua Zeichner of Mount Sinai Medical Center in New York City told WebMD. "If you protect yourself from the sun, you won't need any preventive treatments."

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