Melanoma overdiagnosis may be common in US white men, women
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Trends in melanoma diagnosis and mortality suggest that white individuals in the United States were over-diagnosed with the disease, according to a study.
“The rate of melanoma diagnosis has increased sixfold over the past 40 years, yet melanoma mortality has remained relatively stable,” Adewole S. Adamson, MD, MPP, assistant professor in the division of dermatology in the department of internal medicine at Dell Medical School at the University of Texas, Austin, told Healio. “These epidemiologic features are concerning for overdiagnosis, which is the diagnosis of cancer that would never have caused any symptoms or problems in a patient’s lifetime.”
Adamson added that melanoma overdiagnosis had not previously been estimated in the U.S.
“In our study we want to estimate what proportion of melanoma is overdiagnoses,” Adamson said. “We focused on the white U.S. population because overdiagnosis is concentrated in that group as they are most likely to get skin exams.”
In the cohort study, Adamson and colleagues compared melanoma rates among U.S. white and Black patients. Data from the Surveillance, Epidemiology and End Results database from 1975 through 2014 underwent analysis.
The researchers used trends in melanoma-associated mortality among white patients as the trend in true cancer incidence. In order to correct for improvements in medical care over time they used incidence and mortality trends in Black Americans. This marker was then used to estimate expected mortality among white patients if no improvements in medical care were made, which the researchers suggested would serve as a marker for change in the true cancer occurrence. They defined overdiagnosis as the difference between the observed incidence of melanoma and the calculated true cancer occurrence.
Results were presented as a function of rates between 1975 and 2014. During that span, a four-fold increase in melanoma incidence was reported among white women (incidence rate ratio [IRR], 4.01; 95% CI, 3.65-4.41). The increase was six-fold among white men (IRR, 5.97; 95% CI, 5.47-6.52).
By comparison, melanoma incidence increased by less than 25% among Black women (IRR, 1.21; 95% CI, 0.97-1.49) and Black men (IRR, 1.17; 95% CI, 0.77-1.78) during that same time period.
A decrease in melanoma-related mortality of approximately one-quarter was reported among both Black women (morality rate ratio [MRR], 0.76; 95% CI, 0.63-0.9) and Black men (MRR, 0.72; 95% CI, 0.62-0.84) during the study period.
By comparison, mortality due to melanoma remained stable among white women (MRR, 1.02; 95% CI, 0.96-1.09) and increased almost 50% among white men (MRR, 1.49; 95% CI, 1.25-1.77).
From these findings, the researchers concluded that melanoma overdiagnosis occurred in some 59% (95% CI, 45%-70%) of white women and 60% (95% CI, 32%-75%) of white men in 2014.
“The most important finding is that most melanomas diagnosed likely represent overdiagnosis,” Adamson said. “This is important because overdiagnosis is a potential harm we are causing patients that we screen for melanoma.”
Speaking directly to the dermatology community, Adamson stressed that overdiagnosis of melanoma is an “underdiscussed but growing” concern for the specialty. “We have yet to show in a prospective clinical trial that screening for melanoma saves lives,” he said. “Screening the general population for melanoma is likely the source of the melanoma epidemic and not its solution.”