All forms of skin cancer are uncommon among southwestern American Indians. The estimated average annual incidence of melanoma is approximately 1 per hundred thousand population or less than one tenth of that currently reported for Anglos (non-Hispanic whites) residing in the same region. This study correlates the clinical and pathologic features of melanoma in 18 American Indian patients. A marked predilection for palms, soles, and subungual locations was displayed. Additionally, three patients presented with mucous membrane primaries and two with ocular melanomas. Advanced disease stage at diagnosis was common. The protective influence of natural pigmentation in skin cancer is discussed.
Cancer 52899-2902. 1985. i c . 1 ~ CANCER is predictably uncommon in darkly S pigmented races throughout the world.' This observation is one of the historical links between ultraviolet (UV) exposure and the induction of skin cancers and reflects the classical view that skin pigment has a protective influence. It is known that the frequency of melainoma among southwestern American Indians is very low compared with the observed frequency within the white population residing in this region.' Indian peoplle display relatively dark skin pigmentation, suggesting correlations with the low frequency of melanoma in other racial groups such as blacks. This study describes the clinical and pathologic characteristics of melanomas in I 8 American Indians residing in New Mexico or northern Arizona and identified in the lbyear period, 1970 through 1983. Methods Individual cases were identified through the combined facilities of the New Mexico Tumor Registry and New Mexico Melanoma Registry with the cooperation of United States Public Health Service facilities in New Mexico and Arizona. The New Mexico Tumor Registry is one of ten population-based participants in the National Cancer Institute's Surveillance, Epidemiology and End Results P r ~g r a m . ~ Established in 1966, the New