Pathologic Predictors of Chemotherapy Response in Post Neo-Adjuvant Breast Cancer

Introduction: Pathological complete response (pCR) is the most important prognostic factor in determining survival in post-neoadjuvant breast cancer. In this study, we evaluated the pathologic predictors that are associated with pCR in post-neoadjuvant breast cancer.

Methods: It was a retrospective observational study conducted in Liaquat National Hospital and Medical College, Pakistan, from January 2019 to December 2020 over a period of two years. All patients with primary breast cancer that received neo-adjuvant chemotherapy at Liaquat National Hospital were included in the study. Pathological parameters from pre-chemotherapy specimens like tumor type, grade, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2/neu) and proliferative index Ki67 status were recorded. Pathological response to chemotherapy from post-chemotherapy specimens was recorded as complete or partial responses to chemotherapy.

Results: A total of 287 patients were included in the study, among whom pCR was noted in 65 (22.6%) cases. A significant association of pCR was noted with Ki67 proliferative index, estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2/neu) statuses, whereas no significant association was noted with tumor size, histological type, grade, or nodal metastasis.

Conclusion: The pCR was significantly seen more in cases with higher Ki67 index, hormone receptor negativity and HER2/neu positivity. These pathological predictors can help develop post-neoadjuvant chemotherapy protocols and guide patients regarding their likely chemotherapy response and prognosis.