P10 Clinical and pathologic tumor response following response-guided neoadjuvant chemotherapy for locally advanced breast cancer in the Philippine General Hospital – Breast Care Center

Abstract

Background and purpose Neoadjuvant chemotherapy is recommended for locally advanced breast cancer (LABC) to improve surgical options and to provide an in-vivo assessment of response to treatment. The Philippine General Hospital (PGH) Breast Care Center has adopted a protocol of response-guided approach to allow for tailoring of the chemotherapy regimen being administered. This study aims to describe the clinical and pathologic tumor response of LABC patients after response-guided neoadjuvant chemotherapy. Methods This is a retrospective cohort of 128 patients with LABC who underwent neoadjuvant chemotherapy at the PGH Breast Care Center using sequential doxorubicin/cyclophosphamide-docetaxel (AC-T) regimen from July 2013 to June 2018. Clinical and pathologic response rates were obtained. Patients were categorized into either good or poor responders and were analyzed according to specific clinicopathologic factors. Results The mean clinical tumor response was at 80% with 14 patients (11%) achieving a pathologic complete response (PCR). The Her2 enriched subtype had the highest PCR rate (23.5%). Interestingly, 2 patients who initially had poor response to AC but had good response upon shifting to T attained PCR. A comparison of the clinicopathologic variables in patients with good or poor response to chemotherapy showed that there are significantly more patients with good response to the AC regimen if the patient is pre-menopausal (p=0.04), those with ductal histology (p=0.03), those with a triple negative subtype (p=0.002) and those with HR+HER2+ subtype (p=0.03). Intrinsic subtype did not appear to be a significant factor for a better response in those who received Docetaxel. A Spearman’s Rho score of 0.69 (p-value <0.0001) indicates a strong association between the pathologic and clinical responses. Conclusion Neoadjuvant chemotherapy allows direct and early evaluation of treatment response. This promotes personalized treatment and may justify early shifting to another chemotherapy regimen for non-responders as in response-guided neoadjuvant chemotherapy. 1. von Minckwitz, et. al. Response-Guided Neoadjuvant Chemotherapy for Breast Cancer. J Clin Oncol 31:3623-3630. DOI: 10.1200/JCO.2012.45.09402. Kim S.I, et. al. Molecular subtypes and Tumor Response to Neoadjuvant Chemotherapy in Patients with Locally Advanced Breast Cancer. Oncology 2010;79:324-330. http://doi.org/10.1159/000322192