Lower mammography use is associated with the geographic clustering of late-stage breast cancer in Saint Louis City

Women age 50 or older living in north St. Louis from 1996 through 1998 were two times more likely to be diagnosed with late-stage breast cancer than elsewhere in Missouri. We used random-digit-dialing from 2004 through 2006 to recruit women age 40 or older living in the City of St. Louis to 1) examine differences in breast cancer screening between women who lived in this cluster versus those who did not and 2) identify factors associated with lower screening use among women in the cluster area. The telephone interview inquired about receipt of mammography and clinical breast examination (CBE) as well as race/ethnicity, socioeconomic status, breast cancer knowledge, access to medical care, and health-related behaviors. The overall mammography screening rate according to standard guidelines was 70.8%. Using geographic information systems, we found that women living within the cluster area were less likely to have mammograms compared with women not living within the cluster area (OR=0.68, 95% CI: 0.47-0.99) when adjusted for all factors. No significant difference in CBE rates was found between women who lived and did not live in the cluster area. Targeted efforts to improve mammography use among women age 40 or older in the cluster area would not be effective if aimed at improving breast cancer knowledge or targeting women of lower socioeconomic status. In addition to improving availability of health insurance and access to medical care, which were associated with mammography use, other avenues need to be explored to increase mammography use in the cluster area.