Predicting Late-stage Breast Cancer Diagnosis and Receipt of Adjuvant Therapy: Applying Current Spatial Access to Care Methods in Appalachia.

PURPOSE: The 2-step floating catchment area (2SFCA) method of measuring access to care has never been used to study cancer disparities in Appalachia. First, we evaluated the 2SFCA method in relation to traditional methods. We then examined the impact of access to mammography centers and primary care on late-stage breast cancer diagnosis and receipt of adjuvant hormonal therapy.
METHODS: Cancer registries from Pennsylvania, Ohio, Kentucky, and North Carolina were linked with Medicare data to identify the stage of breast cancer diagnosis for Appalachia women diagnosed between 2006 and 2008. Women eligible for adjuvant therapy had stage I, II, or III diagnosis; mastectomy or breast-conserving surgery; and hormone receptor-positive breast cancers. Geographically weighted regression was used to explore nonstationarity in the demographic and spatial access predictor variables.
RESULTS: Over 21% of 15,299 women diagnosed with breast cancer had late-stage (stages III-IV) diagnosis. Predictors included age at diagnosis [odds ratio (OR)=0.86; P<0.001], insurance status (OR=1.32; P<0.001), county primary care to population ratio (OR=0.95; P<0.001), and primary-care 2SFCA score (OR=0.96; P=0.006). Only 46.9% of eligible women received adjuvant hormonal therapy, and predictors included comorbidity status (OR=1.18; P=0.047), county economic status (OR=1.32; P=0.006), and mammography center 2SFCA scores (OR=1.12; P=0.021).
CONCLUSIONS: Methodologically, the 2SFCA method offered the greatest predictive validity of the access measures examined. Substantively, rates of late-stage breast cancer diagnosis and adjuvant hormonal therapy are substandard in Appalachia.