Differences in mean age at diagnosis of invasive melanoma for men and women, by anatomic site, thickness, and subtype

Abstract Background Understanding the factors influencing age at melanoma diagnosis by sex and anatomic site is crucial for developing effective prevention and early detection strategies. While previous research has highlighted sex-based differences in melanoma incidence by age and anatomic distribution, the underlying mechanisms remain unclear. We aimed to investigate sex-specific patterns in melanoma age at diagnosis across different anatomic sites and thickness categories, considering the potential influence of disease progression and detection rates. Methods We conducted a registry-based study to examine mean age at diagnosis of invasive melanoma over two decades for men and women in the US (limited to white race), and Queensland, Australia. Mean age at diagnosis was calculated for men and women according to anatomic site (head/neck, trunk, upper limb, lower limb), and further by Breslow thickness (<1.00 mm, 1.01-2.00 mm, 2.01-4.00 mm, >4.00 mm) and histologic subtype (superficial spreading, nodular, lentigo maligna, ‘other’ subtypes, and subtype ‘not otherwise specified’). Case-listings of all invasive melanoma diagnoses between 1 January 1999 and 31 December 2018 were obtained from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program (9 registries) and from the Queensland Cancer Registry. Sensitivity analyses were performed restricting the data to the most recent 5-year time period (2014-2018). All analyses were conducted between 15 July and 19 August 2024. Results On average, women were diagnosed with invasive melanoma 3-8 years younger than men. The sex-difference in mean age at diagnosis was observed at all body sites and across most thickness categories in the US White and Queensland populations, but was most marked for thinner melanomas (<1.00 mm) and melanoma of the trunk. Women were significantly younger than men at diagnosis of superficial spreading and nodular melanoma at all body sites in both populations, even within 0.1mm thickness strata. Conclusions Sex may be a factor that influences melanocytic progression. The consistently younger age of melanoma diagnosis in women compared with men suggests a need for tailored approaches to melanoma control.