Evaluation of therapeutic response to neoadjuvant chemotherapy in breast carcinoma in a low-middle-income country.

e12642 Background: Neoadjuvant chemotherapy (NCT) is an established component of breast cancer management, offering tumor downstaging and providing an opportunity to assess in vivo response to systemic therapy. Pathological complete response (pCR) following NACT has prognostic significance, particularly in biologically aggressive breast cancer subtypes. This study aimed to evaluate therapeutic response to NACT in breast carcinoma using standardized histopathological criteria. Methods: This hospital-based observational study included 141 patients with biopsy-proven breast carcinoma who received NCT followed by definitive surgical management. Tumors were classified according to the WHO 2019/2022 classification of breast tumors, and histological grading was performed using the Nottingham histologic grading system. pCR was defined as the absence of residual invasive carcinoma in both the breast and axillary lymph nodes (ypT0N0). The association between NCT regimen and pCR was assessed using Fisher’s exact test. Results: The mean age of the study population was 46.9 years (range: 27–65 years). Invasive carcinoma of no special type was the predominant histological category. pCR was achieved in 21 patients (14.9%), while 120 patients (85.1%) demonstrated residual invasive disease. Numerically higher pCR rates were observed in patients treated with anthracycline–taxane–based and HER2- targeted regimens; however, no statistically significant association was identified between NCT regimen and pCR achievement (p = 0.96). Grade 3 thrombocytopenia occurred in three patient, and reduction in left ventricular ejection fraction was observed in six patients. No treatment- related mortality was recorded. Conclusions: Despite the established role of NCT, the likelihood of achieving pCR remains variable, and real-world data often demonstrate lower response rates compared with controlled clinical trials, individualized treatment strategies, and larger prospective studies to better define predictors of pCR and optimize neoadjuvant treatment outcomes. Pathological complete response according to NCT regimen. NCT regimen pCR achieved (n) No pCR (n) Total Anthracycline-based regimens 0 18 18 Anthracycline + taxane–based regimens 12 51 63 HER2-targeted regimens (TCH-based) 9 48 57 Other regimens 0 3 3 Total 21 120 141