Predictors of response and surgical approach after neoadjuvant chemotherapy in receptor-positive/HER2-negative stage II-III breast cancer patients treated in two private cancer care centers in Lima, Peru: Real-world data.

Abstract

e12659 Background: The role of neoadjuvant chemotherapy (NAC) in hormone receptor-positive HER2-negative breast cancer (BC) is controversial, its main benefit being to improve the surgical outcome in both breast and axilla. The aim of this study was to evaluate the response to NAC, as well as possible predictors and the type surgery performed after primary treatment. Methods: Observational, retrospective study from a database of 1356 consecutive cases of BC between 2016 and 2022 in two private oncology centers in Lima Metropolitana. There were 726 new cases of hormone receptor-positive HER2-negative BC (53.5%), of which those patients with clinical stage II-III who received NAC were considered (n=122, 16.8 % of luminal HER2-negative). Results: The average age of the sample was 46.6 years (range 25-72) with a predominance of luminal B subtype (60.7%) and clinical stage II disease (51.6%), as well as an average delay time to treatment of 33.9 days. Chemotherapy choice was AC every 3 weeks followed by weekly paclitaxel (98.4%). The pathological complete response (pCR) rate was of 16.4% in the breast, 29.1% in the lymph nodes and 13.9% in both. None of the variables studied (age, histologic grade and type, clinical stage, tumor size, number of nodes, hormone receptors, Ki-67 and HER2 low) were predictors of pCR. According to RECIST criteria, tumor shrinking in the breast occurred in the majority of patients (partial and complete response: 86.1%) and eight out of ten patients achieved a tumor size reduction of more than 50%. The rate of mastectomy was 67.2% and radical axillary dissection, 70.5%. Conclusions: In our cohort, we found a pCR rate similar to that reported in the world literature. No predictors of pCR were found. Despite the high proportion of tumor response at breast and node level, the surgical approach was mostly radical. The multidisciplinary BC committee in our setting should be strengthened in order to make better decisions on the surgical approach for patients with hormone receptor-positive HER2-negative stage II-III BC who receive NAC.