Oral contraceptive use and risk of melanoma in a large cohort of Dutch nurses

Abstract

Background: Epidemiological studies evaluating the potential association between oral contraceptive (OC) use and melanoma risk have reported conflicting results. We assessed the association of OC use with melanoma risk in a large prospective cohort. Methods: The Nightingale Study comprises 59 944 Dutch female nurses at ages 19–65years (mean, 46.9years; SD, 11.0) who completed a baseline questionnaire in 2011, including information on lifetime OC use. Melanoma incidence was retrieved through linkage with the Netherlands Cancer Registry. Associations between lifetime OC use and risk of melanoma were assessed by using Cox proportional hazard models. Women who used OCs at baseline were considered current users and women who had used OCs but stopped before baseline were considered former users. Never OC users were defined as the reference. Results: During 10years of follow-up, 447 women were diagnosed with melanoma. Melanoma risk was not increased among women who used OCs for a duration of <9, 10–15, or ≥16years compared with never CO users. Melanoma risk was increased for current OC users [hazard ratio (HR), 1.53; 95% confidence interval (CI), 1.03–2.29], without a trend with duration of use (P-trend =.42) and age at cohort entry (P-trend =.05). Melanoma risk was not increased among former OC users (HR, 0.99; 95% CI, 0.72–1.38) nor when they had last used OC <2years before baseline (HR, 0.69; 95% CI, 0.36–1.32). Conclusion: Current OC use was associated with increased melanoma risk, irrespective of the duration or recency of use.