Association Between Topical Calcineurin Inhibitor Use and Keratinocyte Carcinoma Risk Among Adults With Atopic Dermatitis

Topical calcineurin inhibitors (TCIs), primarily used to treat atopic dermatitis (AD), carry a black box label warning users about the potential for increased skin cancer risk. The risk associated with keratinocyte carcinoma (KC), the most common cancer, defined as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), remains poorly defined because findings from large-scale postmarketing surveillance studies have not been reported.To examine KC risk overall and by subtype (BCC and SCC) among adults with AD exposed to TCIs compared with those exposed to topical corticosteroids (primary comparator group) and those unexposed to TCIs or topical corticosteroids (alternative comparator group) as well as alterations in risk with TCI dose, frequency, and duration of exposure.A retrospective cohort study was conducted at Kaiser Permanente Northern California, a large, integrated health care delivery system, of adults 40 years or older (n = 93 746) with a physician-rendered diagnosis of AD or dermatitis. Patients who were diagnosed from January 1, 2002, to December 31, 2013, were included, with follow-up through December 31, 2017. Data analysis was conducted from June 1, 2016, to October 1, 2018.Time-varying pharmacy-dispensed TCI exposure (n = 7033) over the study period was compared with topical corticosteroids (n = 73 674) and no TCI or topical corticosteroid exposure (n = 46 141).Electronic pathologic testing-validated incident KCs (n = 7744).Among a cohort of 93 746 members, the mean (SD) age was 58.5 (12.7) years, and 55 023 patients (58.7%) were women. Multivariable Cox proportional hazards regression revealed no association between TCI exposure and KC risk (adjusted hazard ratio [aHR], 1.02; 95% CI, 0.93-1.13) compared with topical corticosteroid exposure. Similarly, there were no significant differences in BCC risk (aHR, 1.01; 95% CI, 0.90-1.14, TCI vs topical corticosteroids) or SCC risk (aHR, 0.94; 95% CI, 0.82-1.08, TCI vs topical corticosteroids). Changing the comparator group to unexposed individuals yielded similar findings (aHR, 1.04; 95% CI, 0.91-1.19, TCI vs unexposed for basal cell carcinoma). There were no associations between TCI dose, frequency, and duration of use and BCC, SCC, or overall KC risk.The results of this postmarketing surveillance study of adult health plan members with AD revealed no apparent association between TCI exposure and overall KC, BCC, or SCC risk. Secondary analyses examining dose, frequency, and duration of TCI exposure revealed no associations. These findings suggest that use of TCIs may be safe with respect to KC risk among adults with AD.