Aspirin and other NSAIDs may protect against skin cancer
Aspirin and other nonsteroidal anti-inflammatory painkillers may help protect against skin cancer, according to a new research article.
The findings, reported in the journal Cancer, were made after scientists looked at 19 years of skin cancer records in northern Denmark and compared the rates of skin cancer in those who took one or more of these drugs with those who didn’t.
The scientists at Aarhus University Hospital and two California institutions (the Cancer Prevention Institute in Fremont and Stanford University School of Medicine) 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.
They looked at various types of skin cancer:
Squamous cell carcinoma. This is a cancer that typically develops on sun-exposed areas and is usually cured if caught early.
Basal cell carcinoma. About 75% of skin cancers in the U.S. are of this type. It’s slow-growing. Again, more common in sun-exposed areas.
Malignant melanoma. The most life-threatening kind of skin cancer. It develops from cells in the skin that produce pigment (melanocytes) and can also develop from moles.
The scientists found 1,974 cases of squamous cell carcinoma, 13,316 cases of basal cell carcinoma and 3,242 cases of malignant melanoma in their population of about 1.8 million over the period they were studying. They compared each of these individuals with 10 people from the same population, matched for age, gender and the county they lived in. Then they looked at the medical records and prescription registry to see what kind of use of aspirin and NSAIDS (including ones known as Cox-2 inhibitors that are more selective in the enzymes in the body they suppress) each person had.
They found that people who had ever used NSAIDS (meaning more than two prescriptions) were 15% and 13% less likely to have gotten squamous cell carcinoma or malignant melanoma, respectively. The risk-lowering was stronger in those who used the drugs for longer periods of time or more intensively.
They didn’t find a reduced risk for basal cell carcinoma overall. But they did find an association when they looked at sites other than the head and neck and also in people who’d used the drugs for longer time periods or more intensively.
And, though they don’t know why, they saw that rates dropped too with acetaminophen, though that puzzled them. We’ll get to why in a second.
How might nonsteroidal anti-inflammatory drugs help protect against skin cancers? First off, the observation does not come out of the blue. Lots of studies have linked NSAID use to reduced risk of colorectal cancer. Read about that on the website of the American Cancer Society (but also note what it says about the risks of these drugs, such as gastrointestinal bleeding -- these are drugs, not candy.)
Scientists have reported on the link before for skin cancer too (although the authors of this latest study say the findings were deemed somewhat controversial).
Aspirin and other NSAIDs act in the body in a variety of ways. They fight pain, fevers and inflammation through blocking the action of two enzymes, Cox-1 and Cox-2, that are involved in the production of substances called prostaglandins. Prostaglandins do a broad array of jobs in the body -- among them are pain mediation, fever production and promotion of inflammation. By reducing the output of prostaglandins, therefore, all these three things are reduced.
Some NSAIDs block both Cox-1 and Cox-2 inhibitors, but Cox-2 inhibitors only block the Cox-2 enzyme, which is more involved in inflammation.
One theory is that the cancer reduction could be linked to this supression of Cox-enzyme activity. That would damp down processes such as formation of blood vessels (tumors need them to grow), inflammation (linked to cancer formation) and enhance others, such as a kind of cell suicide that cancers can undergo. But NSAIDs may fight cancers in other ways that don’t have anything to do with the Cox enzymes. A variety of studies in recent years have suggested what those other ways might be.
Now to acetominophen. The scientists said they didn’t expect to see any cancer reduction in people who took this drug because it only acts against pain and does not suppress Cox-1 and Cox-2 enzymes. So they tossed this drug into the analysis as a sort of control, to see if any cancer-reduction they spotted was not about the drugs but was due to the so-called “healthy user” effect. What that means: People who take these drugs may just see the doctor more often and thus are more likely to get their skin examined and any skin cancers diagnosed.
But it turned out that acetominphen use was also linked to a reduction in basal cell carcinomas and malignant melanoma use. If the cancer-protection effect is not (or not only) caused by inhibiting Cox-1 and Cox-2, that would be reasonable.
Two more things:
A cautionary note. The NSAIDs have side effects of their own, as a WebMD article notes.
Pay attention to any moles you have. Here’s a guide, courtesy of the American Academy of Dermatology. (Look for the A, B, C, D and Es.)