Expression of Forkhead-box protein A1, a marker of luminal A type breast cancer, parallels low Oncotype DX 21-gene recurrence scores.

The Oncotype DX assay is one of the molecular tests that provide predictive and prognostic information to breast cancer patients with estrogen receptor (ER)-positive and node-negative disease. This study evaluates the association of Forkhead-box protein A1 (FOXA1) and GATA-binding protein 3 (GATA3) expressions with Oncotype DX recurrences scores in 77 cases of patients with ER-positive node-negative breast carcinomas diagnosed at Indiana University. The data were correlated with patient age, tumor size, histologic type, Scarff-Bloom-Richardson score, histologic grade, and progesterone receptor status. The median FOXA1 and GATA3 scores were 240 and 200, respectively. The Oncotype DX recurrence scores were low in 57%, intermediate in 30%, and high in 13% of cases. FOXA1 expression correlated negatively with Oncotype DX recurrence scores (P=0.004), and histologic type (P=0.0004). Oncotype DX recurrences score also correlated negatively with progesterone receptor (P=0.035) with 100% of progesterone receptor-negative cases having high or intermediate Oncotype DX scores. FOXA1 and GATA3 expressions correlated positively (P=0.014). The correlation between FOXA1 expression and Oncotype DX recurrence scores remained significant after adjusting for multiple comparisons and controlling for confounders such as histological type, grade, and progesterone receptor. A statistically significant correlation between the Oncotype DX recurrence scores and FOXA1 expression in our diverse cohort of ER-positive breast cancer patients was observed. We propose that this may represent a more cost-effective strategy to further risk stratify patients with good prognosis in whom chemotherapy may be omitted. To confirm these findings, further studies in a larger cohort of patients are warranted.