A comparative epidemiological analysis of epithelioid, spindle cell, and mixed epithelioid‐spindle cell tumor subtypes of uveal melanoma, 1975–2016

Abstract

AbstractPurposeTo compare epidemiological trends of epithelioid (ED), spindle cell (SC), and mixed epithelioid‐spindle cell (MES) tumor subtypes of uveal melanoma (UM) using a population‐based study.MethodsData were extracted from the Surveillance, Epidemiology, and End Results U.S. cancer database from 1975–2016. Incidence (IR) was estimated in number of cases/million/year. Incidence (IR) trends across the study's timeframe were assessed by measuring the annual percent change (APC). Disease‐specific survival (DSS) data were available only since 1995 and was calculated using the Kaplan‐Meier method. Cox regression analyses were used to calculate hazard ratios (HR).ResultsTwo thousand nine hundred thirty‐eight cases were identified: MES‐UM (38%), SC‐UM (49%), ED‐UM (13%). Mean age at diagnosis in years for SC‐UM (58) patients was significantly lower than that for MES‐UM (63) and ED‐UM (63) patients (p < 0.01). Incidence (IR) also statistically differed among subtypes: MES‐UM, 0.8; SC‐UM, 0.7; ED‐UM, 0.2 (p < 0.01). Incidence (IR) significantly declined over the study's time period with APC values of −4.5 (p < 0.01; MES‐UM), −2.8 (p < 0.01; SC‐UM), and −2.7 (p = 0.04; ED‐UM). 5‐year DSS for patients diagnosed during 1995–2000 were 74.6% (MES‐UM), 86.4% (SC‐UM), and 56.2% (ED‐UM). In comparison, 5‐year DSS during 2006–2011 was similar for SC‐UM (91.8%; p = 0.07) and ED‐UM (58.4%; p = 0.35), but significantly declined for MES‐UM (57.6%; p < 0.01). Mixed epithelioid‐spindle cell (MES)‐UM patients aged 30–50 years old exhibited favorable prognosis compared to those of other age groups (HR: 0.53; p = 0.023). Asian and black races portended poor prognoses in ED‐UM (HR: 2.7; p = 0.04) and SC‐UM (HR: 2.9; p = 0.03), respectively. Advanced disease stage at diagnosis was not a survival predictor in MES‐UM patients, but it predicted poor prognosis in ED‐UM (HR: 4.8; p < 0.01) and SC‐UM (HR: 5.7; p < 0.001) patients.ConclusionsAge at diagnosis is youngest for SC‐UM patients. IR for all subtypes has declined. DSS has been stable for SC‐UM and ED‐UM but has substantially worsened for MES‐UM. Age impacts MES‐UM prognosis. Asian and black races are negative prognostic factors for ED‐UM and SC‐UM, respectively. Disease stage is a survival predictor only for ED‐UM and SC‐UM.BibliographySurveillance Research Program, National Cancer Institute SEER*Stat software (www.seer.cancer.gov/seerstat) version 8.3.6.1.