109P - Early prediction of non-pCR using ultrasound-guided serial core needle biopsy in HER2-positive breast cancer patients

Abstract

Background: Pathological complete remission (pCR) distinguishes the prognosis of breast cancer patients undergoing neoadjuvant chemotherapy (NAC). On the contrary, non-pCR patients have poorer prognosis and may benefit from escalation or alteration of systemic therapy. Early and accurate identification of non-pCR remains a focused issue. Methods: From December 2013 to January 2017, 805 patients undergoing NAC and serial breast core needle biopsy (CNB) were recruited at our center. Serial CNB was performed under ultrasound guidance after 2-4 cycles of NAC. The results of contrast enhanced-magnetic resonance imaging (CE-MRI) performed by the time of serial CNB and were evaluated per the RECIST1.1 criteria. An objective response was defined as complete or partial remission. Diagnostic values of serial CNB pathology and simultaneous CE-MRI were compared for predicting non-pCR. Results: A total of 653 patients were eligible for analysis and underwent a median of 6 (IQR: 4-7) cycles of chemotherapy. Serial CNB was performed after 2 (IQR: 2-3) cycles. Serial CNB pathology predicted non-pCR more accurately than simultaneous CE-MRI (0.793 vs 0.516, p < 0.001) with higher sensitivity (0.851 vs 0.365, p < 0.001). Multivariate analysis revealed the estrogen receptor, human epidermal receptor (HER2) status and serial CNB pathology as independent factors of non-pCR. Superior non-pCR prediction was evident in the HER2+ subgroup population. Conclusions: Serial CNB pathology predicted non-pCR more accurately, early before the completion of NAC. HER2+ patients who received 2-3 cycles of NAC plus trastuzumab and still had residual malignancy on serial CNB might be suitable candidates for early treatment escalation or alteration. Legal entity responsible for the study: Fudan University Shanghai Cancer Center. Funding: Grants from the National Natural Science Foundation of China (81874113 and 81572583), the Municipal Project for Developing Emerging and Frontier Technology in Shanghai Hospitals (SHDC12010116), the Cooperation Project of Conquering Major Diseases in Shanghai Municipality Health System (2013ZYJB0302), the Innovation Team of Ministry of Education (IRT1223), and the Shanghai Key Laboratory of Breast Cancer (12DZ2260100). Disclosure: All authors have declared no conflicts of interest.