Role of BMI and hormone therapy in melanoma risk: a case-control study.

Background: Currently, the association between body mass index (BMI) and hormone therapies and Cutaneous Melanoma (CM) development is strongly debated. This study was carried out to assess the association between BMI, hormone therapies, and CM risk.
Methods: The present study is a hospital-based case-control study with 605 consecutive CM patients and 592 controls treated for non-neoplastic conditions at the Department of Dermatology in Florence. The associations of melanoma risk with BMI and hormone therapies were assessed performing unconditional logistic regression to estimate odds ratios (OR) and their 95% confidence intervals, adjusting for potential confounders.
Results: We found a significant interaction of BMI with age (P < 0.0001): being overweight significantly increased CM risk among individuals less than 50 years old (OR = 1.85 with 95% CI 1.14-2.94), whereas the association was not significant for individuals over 50 years old (OR = 1.15 with 95% CI 0.77-1.71). For oestrogen therapy, women taking oral contraceptives (OCs)/hormone replacement therapy (HRT) showed a lower CM risk than men (OR = 0.63, 95% CI 0.44-0.89), with risk estimates significantly lower (P < 0.0001) than in non OCs/HRT users, which had an increased risk compared to men (OR = 1.81, 95% CI 1.29-2.53).
Conclusions: Being overweight was significantly associated with CM risk, and this relationship was highly age-conditioned; the second finding was the protective effect of oestrogen therapies for women. Both findings may have a significant impact on melanoma prevention, as the prevalence of obesity and hormone therapy use is increasing worldwide.