Examining Oncotype DX testing among a diverse patient population in North Carolina.

Abstract

154 Background: The Oncotype DX (ODX) is a 21-gene assay that quantifies the risk of breast cancer recurrence and predicts chemotherapy benefit among early stage, hormone-receptor positive patients. Most major insurance carriers now cover testing. We sought to determine factors associated with ODX testing in a diverse patient population. Methods: Data from the Carolina Mammography Registry (CMR), a breast imaging registry in North Carolina (NC) was used for this analysis. We included women ages 18 and over diagnosed with breast cancer from 2010-2017 who had a breast imaging exam at a CMR facility with no personal history of breast cancer. ODX testing was obtained through linkage with the NC Central Cancer Registry. Using a backwards elimination selection strategy, we explored the association of patient residence (urban versus rural), age, race, breast density, and family history of breast cancer on receipt of ODX testing. Results: Our population included 12,329 breast cancers among women that were 24.2% non-white with a median age of 64 years (11.2% < 50 years at time of diagnosis). The majority of our sample had dense breasts (52.0%), no family history of breast cancer (80.9%), and lived in urban areas (66.3%). Use of ODX testing increased from 15.7% in 2010 to 24.8% in 2017 (p-value for time trend < 0.00001). Compared with white women, black women were less likely to receive ODX testing (aOR = 0.57; 95% CI: 0.51-0.65), as were women of other races (aOR = 0.68; 95% CI: 0.51-0.90). We found that for every year age increased, the likelihood of receiving ODX testing decreased (aOR = 0.98, 95% CI: 0.97-0.98). Patient residence and breast density influenced the association of ODX testing. Among women in urban areas, women with dense versus non-dense breasts were more likely to receive ODX testing (aOR = 1.13; 95% CI: 1.01-1.27). Among women in rural areas, density was not associated with ODX testing (aOR = 0.91; 95% CI: 0.78-1.06). Conclusions: In our cohort, ODX testing was more common among younger white women with dense breast tissue living in urban areas of NC. Additional research to understand differences in testing by rural/urban areas are warranted to ensure that all appropriate patients receive this genetic assay.