Role of Tumor Subtypes in Response to Neoadjuvant Chemotherapy in Non-metastatic Breast Cancer.

BACKGROUND: Neoadjuvant chemotherapy (NAC) is an integral part of breast cancer treatment. Determination of the factors that can distinguish patients who will have best response to NAC is invaluable. In this study, we aimed to elucidate the factors influencing patient response to NAC. METHODS: We retrospectively collected data of female patients with non-metastatic breast cancer that had received NAC followed by surgery, admitted to Imam Khomeini hospital between 2015-2019. We investigated the association between various tumor and patients' characteristics with pathologic complete response (PCR). RESULTS: Overall data of 205 female patients were collected. PCR was observed in 27.6% of cases. PCR rate in luminal A, luminal B, HER2 enriched, and TNB tumors was reported in 11.1%, 30.2%, 35.7%, and 36.4% of patients respectively (P=0.27). In patients with luminal B tumors, PCR was more prevalent in patients with positive HER2 only (P=0.006). In our study factors which was significantly associated with PCR were: tumor grade, progesterone receptor (PR) status, and HER2 status. In the multiple regression model, positive PR in the tumor lowered the odds of pathologic response 3.6 times (P=0.004). CONCLUSION: In our study, tumor grade, PR status, and HER2 status was associated with response to NAC. PCR was more prevalent in non-luminal tumors; however, PCR rate in luminal B patients-especially those with HER2 positive status- was slightly less than non-luminals.

Evaluation of Pathologic Complete Response (pCR) to Neoadjuvant Chemotherapy in Iranian Breast Cancer Patients with Estrogen Receptor Positive and HER2 Negative and impact of predicting variables on pCR.

OBJECTIVE: The pathologic complete response (pCR) in the breast and axillary lymph node after neoadjuvant chemotherapy (NAC) would improve outcomes and it is used as a surrogate marker for survival. Our objective was to evaluate the breast and nodal pCR in breast cancer patients with estrogen receptor-positive (ER) and HER2 negative subtypes. Meanwhile, we sought to examine the impact of predicting factors on the rate of pCR. MATERIALS AND METHODS: In this multicenter retrospective study, medical records data of 314 women with ER+/HER2- breast cancer subtype who received neoadjuvant chemotherapy was extracted from oncology centers' data between 2011 and 2018. Breast and axillary lymph node pCR were assessed. Meanwhile, receiver operating characteristic (ROC) curve analysis was performed to assess the predictive value for proliferative index (Ki-67%) expression. RESULTS: Breast pCR was seen in 25.2% (n=79) of the 314 cancer patients and partial response was seen in 47.8% (n=150), too. Nodal pCR was reported in 30.9% (n=97) of the 249 node-positive patients. The overall pCR (both breast & node) was observed in 14.6 % (n=46) of the 272 patients in which the data of breast and nodal were available. We identified 22.5% as the best cut-off value for ki-67 expression in predicting complete response to NAC. CONCLUSION: The pCR rate after NAC in ER+/HER2- subtypes of breast cancer is low. Therefore, the optimal therapy for these patients should be further investigated.