Folate Receptor α Associated With Triple-Negative Breast Cancer and Poor Prognosis

CONTEXT: Folate receptor α (FRA) has been shown to be selectively expressed in several types of human cancer, including breast cancer. Currently, several FRA target therapies are under intensive study. OBJECTIVE: To investigate the expression pattern of FRA in a large cohort of patients with breast cancer and analyze its relationship with different clinicopathologic features, with expression of several key biomarkers, and with clinical outcome. DESIGN: Four hundred forty-seven cases of infiltrating ductal carcinoma diagnosed between 1997 and 2008 at the University of Rochester Medical Center were identified and reviewed, and 25 blocks of tissue microassays were constructed. The association between expression of FRA and clinicopathologic features; expression of estrogen receptor (ER), progesterone receptor (PR), HER2/neu, and Ki-67; and clinical outcome of these tumors were evaluated. RESULTS: The expression of FRA was significantly associated with tumors with high histologic grade, higher nodal stages, ER/PR negativity, and high proliferative activity (Ki-67 ≥ 15%), and was independent of HER2/neu overexpression. In all, 74% of ER/PR-negative and 80% of triple-negative breast cancers expressed FRA. The expression of FRA was significantly associated with a worse disease-free survival. CONCLUSIONS: Our data demonstrate that a significant subgroup of ER/PR-negative and triple-negative breast cancers express FRA, and its expression is associated with worse clinical outcome.