Abstract PS3-11: Correlation of pathological complete response and radiological response with Contrast-enhanced mammography in breast cancer patients after neoadjuvant chemotherapy

Abstract

Abstract Background: Pathological complete response (pCR) after neoadjuvant chemotherapy (NAC) has been reported as a surrogate endpoint for prediction of disease-free survival (DFS) and overall survival (OS) particularly in HER2-positive and triple-negative (TN) breast cancer. NAC requires imaging techniques to accurately predict pathological response and subsequently surgical planning. Magnetic resonance imaging (MRI) has been the most sensitive technique to assess response to NAC, although it is expensive and time consuming. In our hospital we use Contrast-enhanced mammography (CEM) that is easy to perform, fast, reproducible and its signs are superimposable to the MRI, with the advantages of lower cost. It allows diagnosing multifocal, multicenter and bilateral involvement, and monitoring the response to treatment with NAC.Aims: Analyze the correlation between complete radiological response (rRC) with CEM and pCR in patients treated with NAC. Analyze this correlation based on the different immunophenotypes (IF)Methods: Retrospective analysis of 112 patients with stage II-III breast cancer treated with NAC, from January 2018 to April 2020, in the Complejo Hospitalario Universitario Insular-Materno Infantil de Gran Canaria, with CEM performed before and after NAC. pCR categorization using the Miller and Payne system, defined pCR as a non-invasive tumor in the breast and axilla (ypT0/is N0).Results: Of 112 analyzed patients, 8 did not undergo surgery (6 patients with T4d tumors received radical radiotherapy, 1 progressed during NAC and 1 did not undergo surgery for liver failure). Median age 53 years (range 31-89). Stages: IIA 26%, IIB 47%, IIIA 16%, IIIB 10%, IIIC 1%. IF: Luminal A: 11%, Luminal B Her2-: 33%, Luminal B Her2 +: 23%, pure HER2: 21%, TN: 12%. NAC received: doxorubicin-cyclophosphamide (AC)-weekly paclitaxel 53%, Taxanes + pertuzumab + trastuzumab (PT) 39%, AC-paclitaxel + PT 4%, other 4%. 99 patients obtained radiological response: 60 (54%) rRC and 39 (35%) partial response. In 14 patients (12%) there was no response. 36% pCR (N = 37). The sensitivity (S) and specificity (E) of CEM for the evaluation of pCR were 67% and 95% respectively. S was 100% in pure HER2 and 78% in TN. The positive and negative predictive values (PPV and NPV) were 96% and 61% respectively. After a median follow-up of 19 months, 6 patients have relapsed and 2 have died.Conclusion: CSEM has an S and E to detect pCR after NAC of 67 and 95% respectively; rates higher than those offered in other series by the MRI. S and E are higher in pure HER2 and TN tumors. Citation Format: Elisenda Llabrés Valentí, Jose Carlos Antela López, Mónica Cejuela Solís, Alfonso Gómez de Liaño, Victor Vega Benítez, Marta Pavcovich, Concepción Jimenez Medina, Joel Joselito Aranda Sánchez, Isabel Reyes Rodriguez, Manuel Cazorla Betancor, Maria Eugenia Galan Garcia, Ana Alicia Tejera Hernández, Pedro Pérez Correa, Paula Junquera Rionda, Avinash Ramchandani Vaswani, Elena Vicente Rubio. Correlation of pathological complete response and radiological response with Contrast-enhanced mammography in breast cancer patients after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS3-11.