In a population-based cohort study reported in JAMA Oncology, Chen et al found that the incidence of overall cutaneous melanoma and thinner tumors was stable in the United States from 2010 to 2018, with an increased incidence of the thickest (T4) melanomas being observed. Lower socioeconomic status and race/ethnicity were associated with an increased risk of diagnosis of the thickest melanomas.
Study Details
The study involved data on 187,487 patients with a new diagnosis of invasive cutaneous melanoma from the Surveillance, Epidemiology, and End Results Registry from January 2010 to December 2018. Age-adjusted incidence rates of melanoma were calculated by tumor thickness (Breslow thickness) and annual percentage change in incidence rates. The associations of tumor thickness with socioeconomic status were evaluated in 134,359 patients diagnosed with melanoma from 2010 to 2016.
The continued rise in incidence of thick melanoma is unlikely to be attributable to overdiagnosis given the stability of thin melanoma rates.— Chen et al
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Key Findings
Among all patients, 62.4% had T1 (≤ 1.0 mm), 12.7% had T2 (> 1.0 to 2.0 mm), 7.9% had T3 (> 2 to 4.0 mm), and 6.4% had T4 (> 4 .0 mm) tumors, with 10.7% having unknown thickness. A total of 58.4% of patients were men and 41.6% were women, with men having higher incidence rates across all tumor thickness groups.
Between 2010 and 2018, there was no significant increase in incidence of overall cutaneous melanoma in the total population (annual percentage change [APC] = 0.39%, 95% confidence interval [CI] = –0.40% to 1.18%). Annual percentage changes were –0.28% (95% CI = –1.98% to 1.46%) for T1, –0.70% (95% CI = –1.67% to 0.29%) for T2, –0.66 % (95% CI = –1.69% to 0.38%) for T3 tumors, and 5.00% (95% CI = 0.28%–9.94%) for tumors of unknown thickness.
The annual percentage change for T4 tumors significantly increased at 3.32% (95% CI = 2.06%–4.60%). The annual percentage change of T4 tumors was 2.50% (95% CI = 1 .27%–3.73%) in men and 4.64% (95% CI = 2.56%–6.75%) in women.
For T1 through T3 melanomas, incidence rates peaked between 2013 and 2015, and steadily decreased thereafter. Regarding this trend, the investigators stated, “To our knowledge, this is the first study suggesting potential stabilization of melanoma incidence rates in the U.S. after nearly a century of continuous increase in incidence.”
T4 tumors were more likely to be diagnosed in non-Hispanic Black patients (169 of 816; 20.7%) and Hispanic patients (674 of 6,042; 11.2%) compared with White patients (10,774 of 170,155; 6.3%). White patients were more likely to be diagnosed with T1 tumors (106,099 of 170,155; 62.4%) compared with non-Hispanic Black patients (217 of 816; 26.6%). Among patients with available socioeconomic data, T4 tumors were more common in those in the lowest quintile (1,157 of 11,304; 10.2%) compared with those in the highest quintile (1,973 of 43,023l; 4.6%).
The investigators concluded, “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 U.S. after nearly a century of continuous increase in incidence. Patients with low socioeconomic status and non-Hispanic Black 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.”
Eleni Linos, MD, DrPH, of the Department of Dermatology, Stanford University School of Medicine, is the corresponding author for the JAMA Oncology article.
Disclosure: The study was supported by grants from the National Institutes of Health. For full disclosures of the study authors, visit jamanetwork.com.
