Geographic Patterns of Prostate Cancer Mortality and Variations in Access to Medical Care in the United States

Abstract

Striking geographic variation in prostate cancer death rates have been observed in the United States since at least the 1950s; reasons for these variations are unknown. Here we examine the association between geographic variations in prostate cancer mortality and regional variations in access to medical care, as reflected by the incidence of late-stage disease, prostate-specific antigen (PSA) utilization, and residence in rural counties. We analyzed mortality data from the National Center for Health Statistics, 1996 to 2000, and incidence data from 30 population-based central cancer registries from the North American Association of Central Cancer Registries, 1995 to 2000. Ecological data on the rate of PSA screening by registry area were obtained from the 2001 Behavioral Risk Factor Surveillance System. Counties were grouped into metro and nonmetro areas according to Beale codes from the Department of Agriculture. Pearson correlation analyses were used to examine associations. Significant correlations were observed between the incidence of late-stage prostate cancer and death rates for Whites (r = 0.38, P = 0.04) and Blacks (r = 0.53, P = 0.03). The variation in late-stage disease corresponded to about 14% of the variation in prostate cancer death rates in White men and 28% in Black men. PSA screening rate was positively associated with total prostate cancer incidence (r = 0.42, P = 0.02) but inversely associated with the incidence of late-stage disease (r = -0.58, P = 0.009) among White men. Nonmetro counties generally had higher death rates and incidence of late-stage disease and lower prevalence of PSA screening (53%) than metro areas (58%), despite lower overall incidence rates. These ecological data suggest that 10% to 30% of the geographic variation in mortality rates may relate to variations in access to medical care.