The findings add to growing evidence that long-term use of the medications, known as nonsteroidal anti-inflammatory drugs, or NSAIDs, may help protect people against skin cancers, including melanoma, the deadliest type.
Still, research has not been unanimous in that finding: one large 2008 report found no link between NSAIDs and melanoma.
The drugs have also been linked to an increased risk of kidney cancer and come with known bleeding risks -- so more research is needed to weigh the possible harms and benefits of the drugs outside of pain relief, researchers said.
But the lead author on the new study said it would make sense if NSAIDs were tied to skin cancer risk.
"NSAIDs work by inhibiting specific enzymes involved in inflammation," Sigrun Alba Johannesdottir, from Aarhus University Hospital...
"Previous studies show that elevated levels of these enzymes are found in skin cancer and that they are involved in important steps of cancer development such as inhibition of cell death, suppression of the immune system, and stimulation of invasiveness and blood vessel growth," she explained.
For the new research, Johannesdottir and her colleagues looked back at records from more than 18,000 people in northern Denmark with skin cancer, both melanoma and less-risky forms of the disease, between 1991 and 2009.
They matched each of those cancer cases with another ten people of the same age and gender without cancer and compared their prescription drug records for the years before the cancer patients were diagnosed.
Thirty-eight percent of people without cancer had filled more than two prescriptions for an NSAID, according to their medical records.
The researchers found that people with a history of using aspirin and other NSAIDs had a 13 percent lower risk of melanoma compared to non-NSAID users, and a 15 percent lower risk of squamous cell carcinoma, another less-deadly form of skin cancer.
There was no difference in the risk of basal cell carcinoma, a third cancer type, based on whether or not Danes had used NSAIDs, according to findings published in Cancer.
When the researchers looked specifically at people who had filled prescriptions for the drugs over at least seven years, and used them twice a week or more, they found a stronger link: long-term, high-intensity NSAID users had a 46 percent lower risk of melanoma, a 35 percent lower risk of squamous cell carcinoma and a 17 percent lower chance of getting basal cell carcinoma.