Plantar melanoma: is the incidence of melanoma of the sole of the foot really higher in blacks than whites?

The overall incidence of malignant melanoma in black populations is considerably lower than that in whites. There have been repeated suggestions in the literature that black persons may have an increased incidence of melanoma of the sole, relative to whites, because among blacks with melanoma there is a high proportion with tumors of the sole of the foot. Whether this observed difference in site distribution represents a difference in incidence rates has never been demonstrated. Data on cancer incidence from 2 areas, western Washington State (1974-1983) and metropolitan Atlanta (1975-1984), were analyzed to examine this question. The annual area- and age-adjusted incidence of plantar melanoma was 1.7 per million per year for blacks and 2.0 per million per year for whites (relative risk for blacks as compared with whites = 0.88, 95% confidence interval = 0.36-2.11). These data argue that in North America there is little difference between blacks and whites in the incidence of plantar melanoma, and that the well known proportional difference appears to be due instead to the decreased incidence in blacks of melanoma on skin surfaces other than the soles of the feet.