The study findings suggest that questions of overdiagnosis in screening mammography must be considered in light of the fact that not all U.S. women have equal access to breast cancer screening.
Roger Anderson, PhD, from Pennsylvania State University, and colleagues examined regional disparities in breast cancer screening and diagnosis by evaluating Central Cancer Registry and Medicare claims data between 2006 and 2008 from 138 counties in three Appalachian states (Kentucky, Ohio, and Pennsylvania). They measured the incidence of later stage breast cancer in the region's poorest counties compared with its more affluent ones, determining each county's economic status based on unemployment rates, average home values, and average monthly wages (HSR, September 26, 2013).
Roger Anderson, PhD, from Penn State.
Late-stage tumors were defined as stages III or IV and included those that had spread to multiple mammary or supraclavicular lymph nodes, those that had invaded the chest wall or the skin, and those that had spread to other organs.
Large on area, short on resources
Appalachia is made up of 420 contiguous counties across 13 states. In 2010, 69% of these counties were classified as "health professional shortage areas," and 91% of the most economically stressed counties in Appalachia were designated as shortage areas, according to Anderson's team. The incidence of late-stage breast cancer in Appalachia is a strong indicator of preventable breast cancer disparity, and it is influenced, in part, by a lack of regular access to mammography, the researchers wrote.
"Appalachia has been designated by the National Cancer Institute as a special area based on its higher cancer incidence and poorer outcomes for most leading cancers," the authors wrote. "Healthcare access and breast cancer screening rates are of particular importance for subregions within Appalachia which have excess later stage tumor rates."
The group investigated the correlation of a county's characteristics and late-stage breast cancer, in addition to performing a geographical weighted regression analysis, which measured whether the connections found in the regression model were equivalent across the study's geographical areas.
The researchers categorized the counties' economic status as follows:
- Distressed (worst 10% ranking)
- At-risk (10% to 25%)
- Transitional (25% to 75%)
- Competitive (75% to 90%)
- Attainment (best 10% ranking)
The researchers further sorted counties using an "area deprivation index" that took into account factors related to household wealth, stability, and family structure. These included percent employed, income disparity, median home value, median monthly wage, percent owner occupied housing, labor force population, percent below poverty threshold, percent single-parent households, households without a motor vehicle, households without a telephone, households without complete plumbing, and households with less than one person per room.
Anderson's group found that women living in the most economically deprived counties, particularly in eastern Kentucky and southeastern Ohio, had 3.31 times as many late-stage tumors compared to those in the least deprived counties. Appalachian women older than 65 had a 17.3% incidence of late-stage breast cancer, compared with a national average of 16% for the same age group.
"In the regression model analysis, we found that poverty is related to an increased rate of later stage breast tumor, and in the geographical regression analysis, we found that that relationship was true across all the states we studied," Anderson told AuntMinnie.com.
There were also disparities in how often women received recommended mammography screening. Although women older than 65 had Medicare insurance coverage, only 53% had mammography screening within the two years before their cancer diagnosis, compared with the national average of 67%.
"The issue is access to care -- having adequate nearby healthcare resources," Anderson said.
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