110P An in-depth analysis of pathology results of surgical specimen and biopsies performed after NST in an attempt to identify patients with pCR: Time to reconsider the omission of surgery?

Neoadjuvant systemic treatment (NST) is increasingly part of tailored breast cancer treatment resulting in de-escalation of surgery and escalation of adjuvant systemic treatment for triple-negative (TN) and HER2+ patients with residual disease. It is questionable whether surgical resection contributes to local control in patients with pathologic complete response (pCR) after NST. However, current imaging and biopsy modalities aiming to detect pCR are not accurate enough. To gain more insight in the reason for this lack of accuracy, an in-depth analysis of the pathology results of the patients participating in the MICRA trial was performed.