Year of Publication
Master of Public Health (M.P.H.)
Stephen Wyatt, DMD, MPH
Tom Tucker, PhD, MPH
F. Douglas Scutchfield, MD
Breast cancer survival is heavily dependent on stage at diagnosis. Recent evidence supports rural women are more likely than urban women to be diagnosed with advanced stage disease but historically these findings have been mixed when investigated at the state level. Cancer surveillance in the Appalachian region suggests Kentucky females are at significantly greater risk of premature breast cancer mortality due to consistently lower prevalence of screening mammography utilization. In the literature, disparities in breast cancer outcomes have been largely explained by population demographics, areabased measures of socioeconomic deprivation, shortages of referring providers as well as differences in spatial access to mammography based on a women’s place of residence. Results from community-based participatory research in Appalachian-designated counties of KY have uncovered concordant cultural beliefs, knowledge and attitudes towards breast cancer prevention, which may be contributory to the level of risk present in these communities. This study investigates factors associated with late stage breast cancer diagnosis among KY women aged 40 years and older to determine if county level factors may impact breast cancer outcomes among women, even when controlling for known risk factors of advanced disease. Since the high level of socioeconomic distress in KY may serve to mask the effects of a woman’s place of residence on the risk of late stage presentation, we will assess the effects of available census tract estimates to better understand how socioeconomic context modulates risk in the rural and Appalachian communities of KY. Secondary objectives include assessing for the presence of effect modification based on available measures of locality and monitoring for dose response 2 effects which may be present with increasing poverty, declining educational attainment and other area-based indicators of the economic hardship present in these communities. Methods: This study utilizes all incident cases of in situ and invasive breast cancer diagnosed from 2001-2011 in the Kentucky Cancer Registry (KCR). Two separate staging criteria were used to create outcome variables of interest in an attempt to compare measures of association with independent predictors and further support the validity of findings. Utilizing the American Joint Committee on Cancer’s (AJCC) TNM staging system and the National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) summary staging criteria, a total of 23,100 and 23,769 women respectively with no previous history of cancer, aged 40 and older at diagnosis with known cancer stage were included in the study samples. Estimates for socioeconomic context were obtained from the State Data Center and linked to the health record using geocodes for the county of residence at time of breast cancer diagnosis. Hierarchical multivariate logistic regression models were used to analyze the relationship between measures of locality and advanced stage diagnosis. Using a step-wise backward elimination strategy, a final mixed effects random intercept model was fit to evaluate the effects of county-based socioeconomic indicators on the odds of advanced breast cancer among rural and Appalachian women of Kentucky. 3 Results: KY females with Appalachian residence were most likely to reside in counties with the highest levels of socioeconomic deprivation. Clear dose response relationships were established between increasing levels of socioeconomic distress in the county of residence and the risk of advanced breast cancer. After adjusting for age, race, insurance and marital status, the odds of a late stage breast cancer diagnosis were significantly greater in KY females with rural residence compared to urban residence (adjusted OR = 1.13, 95% CI = 1.06 – 1.21) and Appalachian residence compared to non-Appalachian residence (adjusted OR = 1.22, 95% CI = 1.13 – 1.31). The validity of these findings was corroborated by results from the SEER-based analysis. Additive effect modification was present using an interaction term for residence type in the SEER-based analysis, suggesting the odds of advanced stage breast cancer was greatest in rural Appalachian women when compared to urban, non-Appalachian women (adjusted OR = 1.25, 95% CI = 1.17 – 1.34). Results from the mixed model analysis indicated differences in county income levels largely explained the effect of rural residence on the odds of advanced diagnosis, but was not a significant confounder for Appalachian residence. When controlling separately for county level poverty and education in the mixed models, the effect of rural and Appalachian residence on the odds of a late stage diagnosis was no longer significant. However, even when controlling for poverty and education, Appalachian residence still increased the odds of late stage diagnosis compared to non- Appalachian residence, (adjusted OR = 1.046, 95% CI= 0.92 – 1.18) though the result was not statistically significant. 4 Conclusion: Although age, race, insurance type and marital status may help explain advanced breast cancer diagnoses, the influence of high levels of socioeconomic distress present in rural and Appalachian communities of KY largely account for the effects of residence on the risk of advanced breast cancer. Since individual socioeconomic status is unavailable in the individual health record, these measures of locality will serve as an important tool in the surveillance of vulnerable populations and gauging progress of strategies to rectify disparities in breast cancer outcomes in our state. Community-based interventions designed to increase mammography utilization should continue to target impoverished and highly uneducated women, especially in the most rural and isolated counties of KY Appalachia. Finally, innovative health policies, which fosters both educational opportunity and economic development in distressed counties of rural, and Appalachian KY will likely have the greatest impact on breast cancer outcomes long term.
Sither, Michael Jacob, "Effects of Locality and Risk of Late Stage Breast Cancer Diagnosis in Kentucky Females, 2001-2011" (2014). Theses and Dissertations--Public Health (M.P.H. & Dr.P.H.). 26.