Estimating Overdiagnosis of Melanoma Using Trends Among Black and White Patients in the US

IMPORTANCE The incidence of cutaneous melanoma has been rising rapidly among White patients in the US; however, a commensurate increase in mortality due to melanoma has not been observed. These trends suggest overdiagnosis is occurring. OBJECTIVE To quantify melanoma overdiagnosis among White patients compared with Black patients in the US. DESIGN, SETTING, AND PARTICIPANTS This cohort study used joinpoint regression of Surveillance, Epidemiology, and End Results data from 1975 to 2014 to determine melanoma incidence and mortality trends among Black and White patients in the US. Using trends in mortality due to melanoma in Black patients as a marker for improvements in medical care, the expected mortality trends in White patients if medical care had not improved were estimated. This served as a marker for the change in true cancer occurrence. Overdiagnosis was calculated as the difference between observed incidence and estimated true cancer occurrence. Analyses were stratified by sex. Data were analyzed from September to December 2017. Main OUTCOMES AND MEASURES Proportion of melanoma cases overdiagnosed among White patients in 2014. RESULTS From 1975 to 2014, melanoma incidence increased approximately 4-fold in White women (incidence rate ratio [IRR], 4.01 [95% CI, 3.65-4.41]) and 6-fold in White men (IRR, 5.97 [95% CI, 5.47-6.52]), whereas it increased less than 25% in Black women (IRR, 1.21 [95% CI, 0.97-1.49]) and men (IRR, 1.17; [95% CI, 0.77-1.78]). Mortality due to melanoma decreased approximately 25% in Black women (morality rate ratio [MRR], 0.76 [95% CI, 0.63-0.90]) and men (MRR, 0.72 [95% CI, 0.62-0.84]), was stable in White women (MRR, 1.02 [95% CI, 0.96-1.09]), and increased almost 50% in White men (MRR, 1.49 [95% CI, 1.25-1.77]). Had medical care not improved, estimated mortality would have increased 60% in White women and more than doubled in White men. Based on these trends, an estimated 59% (95% CI, 45%-70%) of White women and 60% (95% CI, 32%-75%) of White men with melanoma were overdiagnosed in 2014. CONCLUSIONS AND RELEVANCE The discrepancies in incidence and mortality trends found in this cohort study suggest considerable overdiagnosis of melanoma occurring among White patients in the US.