The Relationship of Race, Oncotype DX, and Ki67 in a Population Highly Screened For Breast Cancer

Oncotype DX recurrence score (ODX) can predict risk of invasive breast cancer recurrence and benefit of chemotherapy. Literature is limited on the relationship of ODX and race in women with hormone receptor positive and node negative/positive disease. Our study examines the relationship between race and clinical characteristics within a population of highly screened women with newly diagnosed breast cancer. The institutional Breast Cancer Database was queried for patients with newly diagnosed breast cancer between January2010 and March2015. We analyzed clinical and tumor characteristics including ODX. Statistical analyses included Pearson's Chi-Square and Fisher's Exact Tests. There were 2,092 women in our study cohort. The majority had college-level education (84%), regular screening (78%), and clinical breast exams (88%). The majority had invasive ductal carcinoma (IDC) (62%), early stage (0, I, II) tumors (93%), ER+ (84%), PR+ (71%), Her2 negative (86%), and node negative disease (83%). There was a significantly higher proportion of later stage disease among African-Americans (p = 0.001) and Asians (p = 0.006) and more triple negative breast cancers among African-Americans (p < 0.0001). A majority of patients had a low ODX (56%). While ODX was not different among the race categories (p = 0.97), there were significant racial differences in Ki-67 (p < 0.0001). In a population of highly screened women, differences were found between races regarding tumor histology. No statistical difference between race and ODX was noted, but there were racial differences in Ki67. Therefore we recommend that further research be focused on refining management algorithms by ethnicity.