Differences in Thickness-Specific Incidence and Factors Associated With Cutaneous Melanoma in the US From 2010 to 2018

IMPORTANCE The recent incidence of cutaneous melanoma of different thicknesses in the US is not well described. OBJECTIVE To evaluate recent patterns in the incidence of melanoma by tumor thickness and examine associations of sex, race and ethnicity, and socioeconomic status with melanoma thickness-specific incidence. DESIGN, SETTING, AND PARTICIPANTS This population-based cohort study analyzed data for 187 487 patients with a new diagnosis of invasive cutaneous melanoma from the Surveillance, Epidemiology, and End Results Registry from January 1, 2010, to December 31, 2018. The study was conducted from May 27 to December 29, 2021. Data were analyzed from June 21to October 24, 2021. MAIN OUTCOMES AND MEASURES Age-adjusted incidence rates of melanoma were calculated by tumor thickness (categorized by Breslow thickness) and annual percentage change (APC) in incidence rates. Analyses were stratified by sex and race and ethnicity. The associations with socioeconomic status were evaluated in 134 359 patients diagnosed with melanoma from 2010 to 2016. RESULTS This study included 187 487 patients with a median (IQR) age of 62 (52-72) years and 58.4% men. Melanoma incidence was higher in men compared with women across all tumor thickness groups. Individuals in lower socioeconomic status quintiles and members of minority groups were more likely to be diagnosed with thicker (T4) tumors (20.7% [169 of 816] among non-Hispanic Black patients, 11.2% [674 of 6042] among Hispanic patients, and 6.3% [10 774 of 170155] among non-Hispanic White patients). Between 2010 and 2018, there was no significant increase in incidence of cutaneous melanoma across the full population (APC, 0.39%; 95% CI, -0.40% to 1.18%). The incidence of the thickest melanomas (T4, >4.0 mm) increased between 2010 and 2018, with an APC of 3.32% (95% CI, 2.06%-4.60%) overall, 2.50% (95% CI, 1.27%-3.73%) in men, and 4.64% (95% CI, 2.56%-6.75%) in women. CONCLUSIONS AND RELEVANCE In this population-based cohort study, the incidence of the thickest cutaneous melanoma tumors increased from 2010 to 2018, in contrast with the incidence patterns for thinner melanomas. The findings suggest potential stabilization of overall melanoma incidence rates in the US after nearly a century of continuous increase in incidence. Patients with low socioeconomic status and Hispanic patients were more likely to be diagnosed with thick melanoma. The continued rise in incidence of thick melanoma is unlikely to be attributable to overdiagnosis given the stability of thin melanoma rates.