Malignant melanoma may be associated with chronic once-daily aspirin exposure in men, but not in women, according to the results of a large, single-center cohort study from the Research on Adverse Drug events And Reports (RADAR) project published in the Journal of the American Academy of Dermatology.

The investigators sought to determine whether a detectable risk for malignant melanoma exists following ≥1 year of chronic aspirin use. Using RADAR methodology, the Northwestern Medicine Enterprise Data Warehouse (NMEDW) — a large, urban, single-center, medical record data repository of information on >5 million individuals — was searched between January 2005 and December 2006.

In the current study, inclusion criteria were age 18 to 89 years, no previous history of malignant melanoma, and a minimum follow-up of 5 years after continuous once-daily aspirin exposure (81 mg or 325 mg) for ≥1 year. The control population included all patients within the same time frame with no documented aspirin use. The primary outcome was incident malignant melanoma diagnosis ≥12 months following the index date using the diagnosis codes International Classification of Diseases, Ninth Revision: 172.0-172.9 and International Classification of Diseases, Tenth Revision: C43.0-C43.9.

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In the overall population, a significant association between aspirin exposure and subsequent diagnosis of malignant melanoma was demonstrated in men (unadjusted relative risk [RR] 3.38; 95% CI, 2.25-5.09; P <.0001 and adjusted RR 1.83; 95% CI, 1.22-2.76; P =.004) but not in women (unadjusted RR 0.73; 95% CI, 0.24-2.27; P =.590 and adjusted RR 0.53; 95% CI, 0.17-1.63; P =.266). No dose-response relationship was observed.

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Study limitations included the inability to verify patient adherence with a daily aspirin regimen and the diagnostic codes that were assigned. In addition, other risk factors for malignant melanoma, including sun exposure and skin phototype, were not considered. Strengths included the large study population and the multiyear follow up.

The researchers concluded that in view of the potential clinical impact reported in this study, further investigation into the link between chronic, once-daily aspirin use and malignant melanoma is warranted.


Orrell KA, Cices AD, Guido N, et al. Malignant melanoma associated with chronic once daily aspirin exposure in males: a large, single-center, urban, U.S. patient population cohort study from the Research on Adverse Drug events And Reports (RADAR) project [published online March 27, 2018]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2018.03.031