Menopausal hormone therapy and risk of melanoma: a nationwide register-based study in Finland
Menée en Finlande à partir de données portant sur 293 570 femmes ayant utilisé un traitement hormonal substitutif de la ménopause (THS) entre 1994 et 2007, cette étude analyse l'association entre deux types de THS et le risque de mélanome (1 695 cas ; durée moyenne de suivi : 15,6 ans)
Background: The association between use of menopausal hormone therapy (HT) and risk of cutaneous melanoma (CM) is highly debated. We investigated the issue in a Finnish nationwide cohort of women aged 50 years or more. Methods: All women who had purchased HT between 1994 and 2007 were identified from the national Medical Reimbursement Registry and linked to the Finnish Cancer Registry. We calculated standardized incidence ratios (SIR) to compare incidence of CM among HT users to that of the general population. Results: During a mean follow-up of 15.6 years, 1,695 incident CM cases were identified among 293,570 women who had used HT for at least 6 months. The SIRs for women who used unopposed estrogen therapy (ET) and combined estrogen-progestin therapy (EPT) for 6-59 months were 1.20 (95% CI 1.06-1.35) and 1.00 (95% CI 0.87-1.14; p-heterogeneity=0.04). The SIRs for women who used ET and EPT for at least 60 months were 1.37 (95% CI 1.22-1.52) and 1.23 (95% CI 1.13-1.34; p-heterogeneity=0.15). We did not find significant differences between oral and transdermal administrations, nor between doses of estrogens. Conclusions: Use of HT, especially ET, was associated with an increased risk of CM. EPT use of less than five years was not associated with an increased risk of CM. Impact: Our results add to the growing body of epidemiological evidence that the use of unopposed estrogens in menopause increases the risk of CM, while the addition of progestins might counteract the detrimental effect.