Utilizing relative survival to investigate melanoma subtypes across intersectional demographics: a Surveillance, Epidemiology, and End Results (SEER) cohort study

Background Melanoma accounts for nearly 8000 skin cancer-related deaths annually in the USA. Its impact on survival across intersectional sociodemographic factors remains unclear. Objectives To characterize relative survival rates (RSRs) in patients with melanoma stratified by various intersecting ­sociodemographic factors. Methods In this retrospective cohort study, relative survival analysis was conducted on patients with acral lentiginous (ALM), nodular (NM), superficial spreading (SSM) and lentigo maligna melanoma (LMM). Relative survival is advantageous as it compares survival in patients with cancer with the expected survival of individuals without cancer with matched characteristics to minimize noncancer mortality differences. This study utilized the Surveillance, Epidemiology, and End Results (SEER) database, established on cancer registries covering ∼48% of the US population. Age-standardized 5-year RSRs and 95% log–log confidence intervals (CIs) were calculated for each melanoma subtype for subgroups stratified by intersections of age, race, sex, marital status and Breslow thickness. Results All melanoma subtypes except LMM had significant survival reductions, with NM having the lowest RSR (73.5%, log–log CI 72.7–74.3). ALM impacted survival most in male patients, followed by older populations, with younger male patients having lower RSRs than older female patients but younger female patients having similar survival to their counterparts without cancer. Male patients of all races or ethnicities other than White had lower RSRs than White male patients at every Breslow stage, whereas female patients had similar RSRs across all races or ethnicities. In NM, younger male patients had lower RSRs than younger female patients, but this difference narrowed with age. Asian and Black patients with NM experienced the most impact on survival. Patients with NM and SSM who were married had higher SSRs than patients who were not married. With regard to SSM and LMM, many age groups had RSRs of 100%; younger patients had slight but significant survival reductions. In SSM, Asian male patients had a particularly low RSR (85.9%), while other race–sex subgroups had RSRs >94%, a pattern observed across all Breslow thicknesses. Conclusions The impact of melanoma on survival is largest on older male patients with ALM of all races or ethnicities other than White; Asian, Black and older patients with NM; and Black female patients and Asian patients with SSM. White patients with all melanoma subtypes, older patients with SSM and LMM, and younger female patients with ALM and NM were the least affected. Our findings demonstrate the varying survival impact of melanoma on different subpopulations, underscoring the importance of investigating intersectional sociodemographic factors.