Review of skin cancer in primary care: more harm than good

Kenneth W. Lin, MD, MPH

Hello everyone. I am Dr. Kenny Lin. I’m a family physician and Associate Director of Family Medicine Residency at Lancaster General Hospital, and I blog at Common Sense Family Doctor.

An important part of my practice is adult health maintenance visits. Acknowledging the endless debate about the value of general health checkups in healthy people, I always view these visits as opportunities to provide recommended vaccinations, screening tests, and advice on healthy lifestyles. I also perform a physical examination. Whether this review should include a head-to-toe investigation for skin cancer has long been unclear.

The US Preventive Services Task Force (USPSTF) recently released a draft recommendation statement that reiterates previous assessments that there is insufficient evidence to judge whether screening a patient for skin cancer at average risk without a history of cancer is beneficial. Nevertheless, many family physicians and general internists perform full-body skin exams or refer patients to dermatologists to have them done. In the spirit of reassessing established screening practices, I will argue that skin cancer screening does more harm than good, so we should stop doing it.

Using data from the National Cancer Institute’s Surveillance, Epidemiology and Endpoints Program, a research team has shown that the incidence of cutaneous melanoma has increased six-fold over the past 40 years, while the incidence of non-cutaneous melanoma did not change. Sunburn and tanning beds cannot explain this dramatic rise in skin cancers, they argued; instead, more in-depth diagnostic examination (more whole-body skin exams), the increasing use of skin biopsies, and lower pathological thresholds for diagnosing melanoma are the most likely culprits. Since the melanoma death rate has not budged, it is likely that most of the additional skin cancers detected by screening did not require treatment and were overdiagnosed.

How can we conclude that more screening leads to more skin cancer diagnoses rather than an environmental risk factor? Several years ago, a national study found a correlation between density of primary care physicians and increased risk of melanoma diagnosis: “Per 100,000 people, 10 additional PCPs per county were associated with 1.62 additional cases of melanoma per year. These additional melanomas were predominantly early-stage, with no association with advanced-stage melanoma or melanoma deaths. A recent cross-sectional study confirmed that the incidence of melanoma in US counties increases as the supply of primary care physicians and dermatologists increases, while proxies for UV exposure had no association with the incidence of melanoma.

To be sure, overdiagnosis also occurs in breast, lung and prostate cancer screening, and that doesn’t mean these tests aren’t worth doing if patients are properly informed of this possible harm. Likewise, detecting “extra” melanomas through skin examinations could be useful if treating all these lesions at an early stage saves lives or reduces the morbidity associated with treatments at a later stage. Unfortunately, the evidence suggests that this does not happen. In a German study reviewed by the USPSTF, after the introduction of a nationwide routine skin cancer screening program covered by health insurance, melanoma mortality increased, not decreased. Closer to home, a primary care-based skin cancer screening initiative at the University of Pittsburgh Medical Center found that after 5 years, screened patients were more likely to be diagnosed with melanomas thin, but no less likely to be diagnosed with thicker melanomas, which an accompanying editorial observed is “a classic signature of overdiagnosis.”

Don’t get me wrong: I don’t encourage my colleagues to ignore patient concerns about changing moles or look away if they see a suspicious lesion during a physical exam for other reasons. What I’m saying is that the time it takes to do a thorough skin exam could be better spent providing effective preventive services that don’t expose patients to the inconvenience and risk of unnecessary skin procedures.

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