ALBUQUERQUE – Postmenopausal women who had a history of nonmelanoma skin cancer and regularly used nonsteroidal anti-inflammatory drugs had an 18% lower risk of developing subsequent skin cancers, based on a large prospective longitudinal study.
The effect was evident regardless of NSAID type and in women who had used NSAIDs regularly for less than 5 years, said Dr. Mina Ally at the annual meeting of the Society for Investigative Dermatology.
Data on how NSAID use affects the risk of nonmelanoma skin cancer (NMSC) have been inconsistent, noted Dr. Ally, who is a postdoctoral research fellow in dermatology at Stanford University in Redwood City, Calif.
Previously, a double-blind, placebo-controlled trial found that NSAID use reduced the risk of NMSC in patients with a skin cancer history, Dr. Ally said (J. Natl. Cancer Inst. 2010;102:1835-44). In contrast, the Nurses Health Study found no association, but excluded women with a history of skin cancer (Cancer Causes Control 2012;23:1451-61).
In the current study, self-reported skin cancer was not confirmed by reviewing medical records, and data on NMSC subtype was not collected, Dr. Ally said.
Dr. Ally and her associates analyzed data from standardized medication questionnaires given at baseline and 3 years later to postmenopausal women aged 50-79 years. Respondents were from the Women\'s Health Initiative, which began in 1991 and includes more than 161,000 women enrolled at 40 centers in the United States.
The analysis was limited to participants who were white, immunocompetent, and had no missing data, yielding a final cohort of 54,728 women. NSAID users were defined as those who reported using the medications at least twice in the past 2 weeks in the baseline and year-3 questionnaires. The researchers collected data on the type, strength, and duration of NSAID use, and validated participants’ responses with data from pill bottle labels and prescription records, although they did not examine dose-response associations, Dr. Ally said.
The women were followed for a median of 6.9 years, during which there were 7,652 incident cases of NMSC, Dr. Ally said. After adjusting for skin type, sun exposure history, reason for using NSAIDs, and other potential confounders, women who regularly used any type of NSAID had no significant difference in risk of NMSC compared with women who did not use NSAIDs or used them inconsistently, she added.
But in the subgroup of 5,488 women who reported a prior history of skin cancer, the odds of incident NMSC were significantly lower with regular NSAID use, whether for less than 5 years (odds ratio, 0.82; 95% confidence interval, 0.70-0.95) or 5 years or longer (OR, 0.82; 95% CI, 0.69-0.98), the researchers reported.
Cyclooxygenase-2 enzymes are unregulated in several cancers, including NMSC, Dr. Ally noted. High levels of ultraviolet exposure increase epidermal COX-2 expression, which might explain why women with a prior history of skin cancer appear to be more responsive to chemoprevention with NSAID treatment, she said.
The National Institutes of Health funded the study. Dr. Ally reported no conflicts of interest.