Cutaneous melanoma has been suspected to be influenced by female hormones. Several studies reported a positive association between oral contraceptive (OC) use and melanoma risk. However, findings were conflicting and data from large prospective studies are lacking. E3N is a prospective cohort of 98,995 French women aged 40-65 years at inclusion in 1990. Exposure to lifetime OC use was assessed in 1992 and through biennial questionnaire updates. To assess the association between OC use and melanoma risk, we used Cox models adjusted for age, pigmentary traits, residential ultraviolet (UV) exposure in county of birth and at inclusion and family history of skin cancer. Over 1992-2008, 539 melanoma cases were ascertained among 79,365 women. In age-adjusted models, we found a modest positive association between ever use of OCs and melanoma risk (hazard ratio (HR) = 1.18, 95% confidence intervals (CIs) = 0.98-1.42), which was reduced after adjustment (HR = 1.14, 95% CI = 0.95-1.38). The association was stronger in long-term users (duration ≥10 years: HR = 1.33, 95% CI = 1.00-1.75) and in women who used high-estrogen OCs (HR = 1.27, 95% CI = 1.04-1.56). Among users, there was an inverse association with age at first use (ptrend < 0.01), but no evidence of an association with age at last use or time since last use. OC use was positively associated with tanning bed use (OR = 1.14, CI = 1.01-1.29), sunburns (ptrend = 0.5) and sunscreen use (OR = 1.13, CI = 1.00-1.28) since age 25. Overall, our findings do not support a strong association between OC use and melanoma risk and suggest intentional UV exposure in OC users, which supports a potential confusion by UV exposure in this relationship.
Keywords: cohort studies; cutaneous melanoma; epidemiology; oral contraceptives.
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