Abstract P4-03-01: Vacuum assisted core-needle biopsy after neoadjuvant therapy in breast cancer to predict the status of pathologic response

Abstract

Abstract Introduction: Neoadjuvant breast cancer therapy trials have documented impressive rates of pathologic complete response (pCR) of up to 70% and above, depending on grade, hormone receptor and HER2 receptor status and type of therapy. The purpose of our prospective single institution trial is to examine the predictive value of a standardized vacuum assisted core-needle biopsy (VAB) of the tumor site after neoadjuvant therapy with respect to pathologic response status. Methods: From 2011-2017, all patients who had completed neoadjuvant breast cancer therapy at our institution were informed about this trial regardless of their clinical response status. In case of consent, a VAB of the clip-marked tumor site was performed directly before the operation. At least 3, in most cases 6 biopsy cylinders were obtained. Results: A total of 113 patients completing neoadjuvant therapy consented to the trial. Four patients presented with bilateral breast cancer, resulting in 117 cases of breast cancer. The pCR rate (ypT0ypN0) was 36% (n=42). In 14 cases, the biopsy did not show any sign of residual disease, although residual disease was detected upon operation, resulting in an accuracy of 88% for correct prediction of pathologic response. Pre-operative VAB correctly predicted residual tumor in 81%. The negative predictive value was 75%. Conclusions: Although the results of this trial are encouraging, a false negative rate of 19% is entirely insufficient. The method may be useful in guiding decisions regarding the modification of neoadjuvant therapy based on pathological response. Whether or not correct prediction of pathologic response may be improved by further standardizing the tumor marking procedure as well as better defining and increasing the volume of tissue removal by VAB should be examined in a further prospective trial. The omission of operative therapy in case of pCR in a preoperative biopsy after completion of NACT cannot be recommended. Citation Format: Regina Große, Antonia Lebioda, Jana Saegenschnitter, Tin Dao Nguyen, Holger Zentgraf, Joerg Buchmann, Christine Fathke, Susanne Steer, Christoph Thomssen. Vacuum assisted core-needle biopsy after neoadjuvant therapy in breast cancer to predict the status of pathologic response [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-03-01.