It has been previously observed that nonsteroidal anti-inflammatory drugs (NSAIDs) including ibuprofen(Drug information on ibuprofen) and aspirin(Drug information on aspirin) may help to prevent the development of certain types of cancer. Now, researchers in Denmark have specifically analyzed the association between daily intake of a NSAID and risk of skin cancer. Their findings, published in the journal Cancer, show that those who use NSAIDs were less likely to develop three types of skin cancer—basal-cell carcinoma, squamous cell carcinoma, and the deadliest form of skin cancer, malignant melanoma.[1]
The study tracked 18,532 skin cancer cases from 1991 through 2009 in northern Denmark and 178,655 population controls matched by age, gender, and county of residence. Aspirin and other NSAID use were derived from prescription databases.
The study found that those who filled more than two prescriptions (users) for an NSAID had a 15% decreased risk of squamous cell carcinoma and a 13% lower risk of malignant melanoma compared with those who filled two or less prescriptions (nonusers). The risk was particularly lower for long-term NSAID users of 7 years or more, or high-intensity users who used the drugs frequently over a specific amount of time. While risk of basal-cell carcinoma was not reduced overall with NSAID use, the risk of basal-cell carcinoma on sites other than the head and neck was reduced with long-term and high-intensity NSAID use. This result suggests that the NSAID effect on basal-cell carcinomas is only on the skin that is not exposed to the sun frequently.
Other studies have shown a link with lower cancer risk and NSAID use. A recent study published in the Lancet analyzed five large randomized, controlled studies in Britain. The analysis found that those who took a daily aspirin reduced their risk of colon, lung, and prostate cancers by 46% compared to those who rarely took aspirin. The studies were analyses of large cardiovascular research studies of subjects who took aspirin over a long period of time to assess the risk of stroke or heart attack incidence.
The link may be due to lower inflammation. NSAIDs inhibit cyclooxygenase (COX) enzymes which are implicated in tumor initiation and progression pathways. Inflammation can contribute to tumor growth when it is chronic and epidemiological data shows that approximately 25% of cancers are related to chronic infections or other chronic inflammation.
The lead study author of the current Cancer study, Sigrun Johannesdottir, department of clinical epidemiology at the Aarhus University Hospital, in Aarhus, Denmark, believes that there is a general mechanism of NSAIDs that helps prevent the development of various types of cancer. “It may be that the cancer-preventive effect depends on the expression of these enzymes within various tissues,” said Johannesdottir.
“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,” said Johannesdottir. “Therefore, inhibition of these enzymes may protect against skin cancer development. However, it is important to note that we could not examine the molecular mechanism behind our results.”
Johannesdottir cautions that this result does not suggest people should take a daily aspirin to help prevent skin cancer. Taking NSAIDs can cause ulcers, bleeding in certain individuals, and thinning of the blood, among other side effects.
The effect of NSAIDs on skin cancer risk will likely vary for different populations and geographies. “Skin cancer risk depends on both race and the level of UV exposure,” explained Johannesdottir. “For example, skin cancer risk is lower for Caucasians in Denmark than in Australia. Thus, the effect could potentially vary. Studies in various populations are needed to examine this question.”
Another reason to hold off on the daily painkiller is the current study is not a causation study. Further work is necessary to demonstrate a cause and effect relationship between NSAID intake and skin cancer prevention. Johannesdottir indicates that he and his team are planning on doing more studies to probe the link between skin cancer and NSAID use.
A long term randomized trial would be necessary to add robust evidence of the anti-carcinogenic effects of aspirin. Such a study, however, would require many participants and is unlikely to easily find a sponsor since aspirin is an inexpensive and generic drug.
Reference
1. Johannesdottir SA, Chang ET, Mehnert F, et al. Nonsteroidal anti-inflammatory drugs and the risk of skin cancer: A population-based case-control study. Cancer. 2012 May 29. [Epub ahead of print]
