LAS VEGAS – Counties that have up to two dermatologists per 100,000 people have the lowest mortality from melanoma, compared with counties with no dermatologists, according to an analysis of national data.
The analysis also found that having more dermatologists does not decrease melanoma mortality further.
A "dermatologist density" greater than zero and up to one dermatologist per 100,000 people was associated with a 35% reduction in deaths from melanoma compared with counties with no dermatologists, Dr. Jeremy S. Bordeaux reported at the annual meeting of the American College of Mohs Surgery.
Counties with more than one and up to two dermatologists per 100,000 people had an even greater reduction in melanoma mortality – 53% lower than counties with no dermatologists, the multivariate analysis showed. Beyond that, counties with more than two dermatologists had slightly but not significantly higher melanoma mortality rates, compared with counties with more than one and up to two dermatologists.
"Once you get past two per 100,000, it didn't make any difference. If you had 10 per 100,000, it didn't change mortality," said Dr. Bordeaux of the department of dermatology at Case Western Reserve University, Cleveland.
A map of dermatologist density created from U.S. Department of Health and Human Services data showed huge swaths of counties in the middle part of the country with no dermatologists. The study's findings suggest that enticing some dermatologists on the East and West coasts to move to those counties could reduce melanoma mortality.
"If we could get people to go where people don't want to live, I guess that could save lives, but people don’t want to live there for a reason," he said. Perhaps dermatology residency programs could place dermatologists in underserved counties, or loan repayment programs could be tied to contracts to serve in those counties, he suggested.
Dr. Bordeaux and his associates analyzed data from 3,141 U.S. counties from multiple databases, including the National Cancer Institute's Surveillance, Epidemiology and End Results database, the National Program of Cancer Registries, the Centers for Disease Control and Prevention’s National Vital Statistics System, and the U.S. Census Bureau.
Two other factors were associated with decreased melanoma mortality. Counties classified as metropolitan had a 30% lower death rate from melanoma, compared with nonmetropolitan counties. Each hospital that provided oncology services conferred nearly a 2% reduction in melanoma mortality. In Dr. Bordeaux’s county, for example, which has a dozen or so hospitals that offer oncology services, melanoma mortality would be more than 20% lower than in a county with no hospital-based oncology services.
Several factors were associated with higher melanoma mortality. For every 1% increase in the proportion of the population that was white, the melanoma mortality increased 1.5%. Not surprisingly, a higher incidence of melanoma was associated with higher mortality; for each additional case of melanoma per 100,000 people, mortality increased 2.3%. A third factor puzzled Dr. Bordeaux. For each additional percent of the population covered by health insurance, the melanoma mortality rate increased by 1.5%.
Factors that appeared to have no effect on melanoma mortality included the density of primary care providers, the percentage of the population older than 65 years, education level, median household income, and unemployment rate.
Dr. Bordeaux speculated the "plateau effect" that limited mortality reductions to a density of two dermatologists per 100,000 people may reflect the limitations of current therapeutics. Or, areas with greater dermatologist density may represent academic centers, and dermatologists may not be working full time.
Multiple studies have found the need to increase the number of primary care physicians, but the density of primary care physicians did not affect melanoma mortality in the current study, Dr. Bordeaux noted. Other articles in the literature, however, have shown specialist care to be associated with better cancer outcomes in both urology and dermatology.
In one study, higher densities of either dermatologists or internists were associated with better prognosis in patients with melanoma, but a higher density of family physicians was associated with a worse prognosis (J. Amer. Acad. Dermatol. 2009;60:51-8).
Dr. Bordeaux and his fellow investigators had no relevant conflicts of interest to report.