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Title:Disparities in breast cancer subtype, staging, and access to mammography services in the Lower Mississippi Delta Region
Author(s):Zahnd, Whitney Elizabeth
Director of Research:Rosenblatt, Karin
Doctoral Committee Chair(s):Rosenblatt, Karin
Doctoral Committee Member(s):Farner, Susan; Klonoff-Cohen, Hillary; McLafferty, Sara; Sherman, Recinda
Department / Program:Kinesiology & Community Health
Discipline:Community Health
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):breast cancer
health disparities
geographic information systems
Mississippi Delta Region
Abstract:The Delta Regional Authority (Delta Region) is a federal-state partnership aiming to improve socioeconomic conditions in 252 counties and parishes in the eight state Lower Mississippi Delta Region (LMDR). The Delta Region has a higher proportion of black residents, is poorer, and is more rural than the country as a whole. It also has far higher breast cancer mortality rates than the nation. Black women in the Region have higher breast cancer mortality rates than white women in the Delta Region and have higher breast cancer mortality rates than black women in other parts of the country. More aggressive breast cancer subtypes, more advanced stage at diagnosis, and less access to screening mammography may play a role in these high mortality rates. Studies have shown that black women have higher rates of the most aggressive breast cancer subtype-- triple-negative--than white women and are often diagnosed at a more advanced stage. Additionally, while poor and rural women tend to have lower incidence rates of breast cancer, they often have a higher odds of late-stage cancer and less access to screening services. This dissertation sought to elucidate the Delta Region’s breast cancer mortality disparity by determining differences between the Delta and non-Delta Regions of the LMDR and by exploring racial differences within the Delta Region among the following areas: breast cancer subtype, breast cancer staging, and spatial access to mammography services. Population-based cancer surveillance data from the North American Association of Central Cancer Registries were analyzed to determine age-adjusted, subtype-specific incidence rates and rate ratios in the Delta and non-Delta Regions of the LMDR. Multilevel negative binomial regression models were constructed to evaluate if identified disparities were attenuated after accounting for race/ethnicity, age, and contextual factors. These analyses were performed for all cases by subtype and separately for early stage and late stage cancers by subtype. Higher rates of triple-negative breast cancer were identified in the Delta Region compared to the non-Delta Region, but this was attenuated in multivariable models. However, triple-negative breast cancer rates were higher in the urban Delta compared to the urban non-Delta, even after accounting for race/ethnicity, age, and contextual factors. Black residents in the Delta Region had higher rates of hormone receptor-negative breast cancers and higher rates of breast cancer overall compared to white women in the Region. Further, there were no particularly notable differences in late-stage breast cancers between the Delta and non-Delta Regions. However, black women in the Delta Region had lower rates of early-stage breast cancer, but higher rates of late-stage breast cancers compared to white, Delta Region women, even after accounting for age and contextual factors. To evaluate spatial access to mammography services, this study applied the enhanced two-step floating catchment area method to Food and Drug Administration data and census tract level American Community Survey data. The Food and Drug Administration data provided addresses of all approved mammography facilities in the LMDR and adjacent states while American Community Survey data were used to estimate populations of women of recommended screening age at the census tract level. For the most part, women in the Delta Region had similar spatial access to mammography services as non-Delta Region women. However, clusters of low spatial access within the Delta Region were identified in parts of Arkansas, Tennessee, and Mississippi. The identified higher incidence of breast cancer in black women in the Delta compared to white women was driven by higher rates of hormone receptor-positive cancers, but further research is needed to determine what individual or contextual factors may be driving the higher incidence rates. Additionally, this dissertation underscores the importance of community-based, culturally tailored interventions to improve mammography utilization rates and subsequently improve early detection of hormone receptor-positive breast cancers. Furthermore, this dissertation signaled a need for improved state-level policy and geographically targeted regional resource allocation to improve screening access and utilization. Additionally, these findings provide the foundation for further research to explore regional breast cancer disparities at other points along the cancer control continuum (e.g. treatment), to examine regional disparities for other cancers, and to promote collaborative academic partnerships across the Delta Region.
Issue Date:2018-04-10
Rights Information:Copyright 2018 Whitney Zahnd
Date Available in IDEALS:2018-09-04
Date Deposited:2018-05

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