Background This retrospective study investigated the therapeutic benefit of adjuvant endocrine therapy (ET) in breast cancer patients with hormone receptor (HR) status change from positive to negative after neoadjuvant chemotherapy (NAC). Methods From December 2000 to November 2010, 97 eligible patients with a positive-to-negative switch of HR status after NAC were identified. All patients were categorized into 2 groups on the basis of the administration of ET: 57 ET-administered patients and 40 ET-naïve patients. Survival analyses were performed to examine the prognostic value of ET administration as well as other clinical and pathologic variables. Results The administration of ET was significantly associated with improved disease-free survival (p=0.018) in patients with a positive-to-negative switch of HR status. The 5-year disease-free survival rates were 77.0% and 55.5%, respectively, in ET-administered patients and ET-naïve patients. The 5-year overall survival rate for ET-administered patients was also higher than that of ET-naïve patients (81.3% vs. 72.7%, p=0.053), albeit this was statistically insignificant. Conclusions This study revealed that patients with HR altered from positive to negative after NAC still benefit from ET. The HR status should be evaluated not only in specimens obtained during post-NAC surgery but also in specimens biopsied before NAC.
Establishment and external validation of a prognostic model for predicting disease-free survival and risk stratification in breast cancer patients treated with neoadjuvant chemotherapy