Primary Care Research

For patients with melanoma, longer distance to a provider means later stage of diagnosis

Melanoma is a potentially deadly form of skin cancer, and early diagnosis is critical to survival. For example, if diagnosed when the melanoma is less than 1 mm thick (Breslow thickness), the 5-year survival rate is over 85 percent compared with less than 50 percent for 4 mm melanomas. Longer travel distance to a provider who can diagnose melanoma means the cancer is diagnosed at a later stage, suggests a new study. Researchers found that each 10-mile increase in distance corresponded to a 6 percent increase in Breslow thickness. Also, patients who traveled more than 15 miles had 20 percent thicker tumors on average than patients who traveled 15 miles or less.

Researchers geocoded the street addresses of patients with at least 1 invasive melanoma and providers from 42 North Carolina counties. They examined the association between Breslow thickness and sociodemographic factors, provider supply, and distance to a diagnosing provider. Within a given region, some patients traveled short distances while others traveled much longer distances to their providers.

The median Breslow thickness of 643 eligible cases was 0.6 mm. The median distance to a diagnosing provider was 9 miles, with a range of 0 to 386 miles. For each 1 mile increase in distance, Breslow thickness increased by 0.6 percent. Breslow thickness was also associated with age. It was 19 percent greater for patients aged 51 to 80 years than for those aged 0 to 50 years.

Patient sex, rurality of location, and supply of dermatologists were not associated with Breslow thickness. However, the median Breslow thickness for cases diagnosed by dermatologists (0.5 mm) was significantly less than that diagnosed by surgeons (1.04 mm) or by other providers (0.62 mm).

The study was supported in part by the Agency for Healthcare Research and Quality (T32 HS00032).

See "Distance to diagnosing provider as a measure of access for patients with melanoma," by Karyn B. Stitzenberg, M.D., M.P.H., Nancy E. Thomas, M.D., Ph.D., Kathleen Dalton, Ph.D., and others, in the August 2007 Archives of Dermatology 143(8), pp. 991-998.

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