Melanoma Screening Study Stokes Overdiagnosis Debate

Nancy A. Melville

April 14, 2022

Screening for melanoma at the primary care level is associated with significant increases in the detection of in situ and invasive thin melanomas but not thicker, more worrisome disease, new research shows.

Without a corresponding decrease in melanoma mortality, an increase in the detection of those thin melanomas "raises the concern that early detection efforts, such as visual skin screening, may result in overdiagnosis," the study authors write. "The value of a cancer screening program should most rigorously be measured not by the number of new, early cancers detected, but by its impact on the development of late-stage disease and its associated morbidity, cost, and mortality."

The research, published this month in JAMA Dermatology, has reignited the controversy over the benefits and harms of primary care skin cancer screening, garnering two editorials that reflect different sides of the debate.

In one, Robert A. Swerlick, MD, points out that "despite public messaging to the contrary, to my knowledge there is no evidence that routine skin examinations have any effect on melanoma mortality.

"The stage shift to smaller tumors should not be viewed as success and is very strong evidence of overdiagnosis," writes Swerlick, of the Department of Dermatology, Emory University School of Medicine, in Atlanta, Georgia.

The other editorial, however, argues that routine screening saves lives. "Most melanoma deaths are because of stage I disease, with an estimated 3% to 15% of thin melanomas (≤1 mm) being lethal," a trio of editorialists from Oregon Health and Science University in Portland write.

When considering the high mutation rate associated with melanoma and the current limits of treatment options, early diagnosis becomes "particularly important and counterbalances the risk of overdiagnosis," the editorialists assert.

Primary Care Screening Study

The new findings come from an observational study of a quality improvement initiative conducted at the University of Pittsburgh Medical Center system between 2014 and 2018, in which primary care clinicians were offered training in melanoma identification through skin examination and were encouraged to offer annual skin cancer screening to patients aged 35 years and older.

Of 595,799 eligible patients, 144,851 (24.3%) were screened at least once during the study period. Those who received screening were more likely than unscreened patients to be older (median age, 59 vs 55 years), women, and non-Hispanic White persons.

During a follow-up of 5 years, the researchers found that patients who received screening were significantly more likely than unscreened patients to be diagnosed with in situ melanoma (incidence, 30.4 vs 14.4; hazard ratio [HR], 2.6; P < .001) or thin invasive melanoma (incidence, 24.5 vs 16.1; HR, 1.8; P < .001), after adjusting for factors that included age, sex, and race.

The screened patients were also more likely than unscreened patients to be diagnosed with in situ interval melanomas, defined as melanomas occurring at least 60 days after initial screening (incidence, 26.7 vs 12.9; HR, 2.1; P < .001), as well as thin invasive interval melanomas (incidence, 18.5 vs 14.4; HR, 1.3; P = .03).

The 60-day interval was included to account for the possible time to referral to a specialist for definitive diagnosis, the authors explain.

The incidence of the detection of melanomas thicker than 4 mm was lower in screened vs unscreened patients, but the difference was not statistically significant for all melanomas (2.7 vs 3.3; HR, 0.8; P = .38) or interval melanomas (1.5 vs 2.7; HR, 0.6; P = .15).

Experts Weigh In

Although the follow-up period was of 5 years, not all patients were followed that long after undergoing screening. For instance, for some patients, follow-up occurred only 1 year after they had been screened.

The study's senior author, Laura K Ferris, MD, PhD, of the Department of Dermatology, University of Pittsburgh School of Medicine, noted that a longer follow-up could shift the results.

"When you look at the curves in our figures, you do start to see them separate more and more over time for the thicker melanomas," Ferris told Medscape Medical News. "I do suspect that that if we followed patients longer, we might start to see a more significant difference."

The findings nevertheless add to evidence that although routine screening substantially increases the detection of melanomas overall, these melanomas are often not the ones doctors are most worried about or that increase a person's risk of mortality, Ferris noted.

When it comes to melanoma screening, balancing the risks and benefits is key. One major downside, Ferris noted, is in regard to the burden such screening could place on the healthcare system, with potentially unproductive screenings causing delays in care for patients with more urgent needs.

"We are undersupplied in the dermatology workforce, and there is often a long wait to see dermatologists, so we really want to make sure, as trained professionals, that patients have access to us," she said. "If we're doing something that doesn't have proven benefit and is increasing the wait time, that will come at the expense of other patients' access."

Costs involved in skin biopsies and excisions of borderline lesions as well as the potential to increase patients' anxiety represent other important considerations, Ferris noted.

However, Sancy A. Leachman, MD, PhD, a co-author of the editorial in favor of screening, tells Medscape Medical News that "at the individual level, there are an almost infinite number of individual circumstances that could lead a person to decide that the potential benefits outweigh the harms."

According to Leachman, who is chair of the Department of Dermatology, Oregon Health and Science University, these individual priorities may not align with those of the various decision makers or with guidelines, such as those from the United States Preventive Services Task Force, which gives visual skin cancer screening of asymptomatic patients an "I" rating, indicating "insufficient evidence."

"Many federal agencies and payer groups focus on minimizing costs and optimizing outcomes," Leachman and her co-authors write. As the only professional advocates for individual patients, physicians "have a responsibility to assure that the best interests of patients are served."

The study was funded by the University of Pittsburgh Melanoma and Skin Cancer Program. Ferris and Swerlick have disclosed no relevant financial relationships. Leachman is the principal investigator for War on Melanoma, an early-detection program in Oregon.

JAMA Dermatol. Published April 6, 2022. Abstract, Swerlick Editorial, Kulkarni et al Editorial

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