6ER-003 Effectiveness of neoadjuvant treatment in locally advanced breast cancer

Background and importance Neoadjuvant chemotherapy has become the standard treatment for patients with inoperable locally advanced tumours, and it is also optional for operable stages. The literature reports rates of 20–30% and 56–66% for pathological complete response (pCR) in patients treated with combinations of anthracyclines and taxanes, and dual blockade of human epidermal growth factor receptor 2 (HER2), respectively. Aim and objectives To assess the effectiveness of neoadjuvant chemotherapy in stage II/III breast cancer according to expression of HER2 and hormonal receptors (HR) based on pCR. Material and methods A retrospective observational study was carried out between January 2016 and December 2018 in a second level hospital. Through the Farmatools software, patients were identified. Clinical histories were obtained through Selene software to compile demographic (sex and age) and clinical (stage, HR and HER2, lymph nodes, treatment regimen and pCR results) data. Results Within the study period, 35 patients received neoadjuvant chemotherapy regimens for breast cancer. Median age of the women was 50 years (IQR 18 years), 54.3% were diagnosed with stage II neoplasia and 62.9% had lymph nodes involved: 40% reached pCR. Patients were classified according to HER2 expression: 45.7% showed positive HER2 expression (HER+), 50% of whom reached pCR after neoadjuvant treatment. In 81.25%, treatment was a docetaxel–carboplatin–trastuzumab regimen plus pertuzumab, obtaining pCR in 53.85%, and 18.75% received chemotherapy regimens based on anthracyclines+taxane+trastuzumab+ pertuzumab, reaching a pCR of 33.33%. In the 54.3% of HER2 negative (HER2−) patients, 31.58% reached pCR: 94.74% received combinations of anthracyclines+taxanes, obtaining a pCR of 33.33%. Only one patient was treated with docetaxel–cyclofosfamide (TC), not achieving pCR. Within the HER2− group, 57.89% did not overexpress any receptor, qualifying as triple negative (TN). All of these patients received regimens based on anthracyclines and reached a pCR of 45.45%. Conclusion and relevance pCR rates obtained in our centre were correlated with the results described in the literature, and slightly lower in HER2+ patients. In the case of the TN subgroup, a pCR rate greater than in reported data was found, despite being the subgroup with the worst prognosis. References and/or acknowledgements No conflict of interest.