Female breast cancer mortality clusters within racial groups in the United States.

Although breast cancer is the second leading cause of cancer deaths among women in the Unites States, to date there have been no nationwide studies systematically analyzing geographic variation and clustering. An assessment of spatial-temporal clusters of cancer mortality by age and race at the county level in the lower 48 United States indicated a primary cluster in the Northeast US for both younger (RR = 1.349; all RR are p < or = 0.001) and older (RR = 1.283) women in the all-race category. Similar cluster patterns in the North were detected for younger (RR = 1.390) and older (RR = 1.292) white women. The cluster for both younger (RR = 1.337) and older (RR = 1.251) black women was found in the Midwest. The clusters for all other racial groups combined were in the West for both younger (RR = 1.682) and older (RR = 1.542) groups. Regression model results suggest that lower socioeconomic status (SES) was more protective than higher status at every quartile step (Medium-high SES, OR = 0.374; Medium-low, OR = 0.137; Low, OR = 0.061). This study may provide insight to aid in identifying geographic areas and subpopulations at increased risk for breast cancer.