Rural-urban differences in ductal carcinoma in situ as a proxy for mammography use over time

With emphasis on increasing use of mammography, the rate of ductal carcinoma in situ (DCIS) of the breast has increased dramatically in the United States starting in the early 1980s. It is unclear if rural and urban women have experienced similar increases.

To describe differences in incidence of DCIS between rural and urban women 50 to 69 years of age over time. This may be a proxy indicator of mammography use for the early detection of breast cancer.

The study population consisted of women 50 to 69 years of age who were diagnosed with DCIS during 1973-1997 and resided in Iowa, Utah, or New Mexico. Data from the Surveillance, Epidemiology, and End Results (SEER) programs in these states were used in the analysis. Location of the woman's residence was classified into urban when she lived in a county considered a Metropolitan Statistical Area, while she was considered rural if she resided elsewhere at the time of her diagnosis.

Increases in rates were different between rural (annual percentage change [APC]: 15.1) and urban women (APC: 34.4). During the 1990s among urban women, the rate of DCIS was still increasing (APC: 3.8), while there was no increase among rural women (APC: 0.2). Differences between rural and urban women within these 3 states were also identified.

The data suggest differences in utilization of mammography between both populations; the increase was lower and started later for rural women. Possible reasons for such differences over time are discussed.