Altay Aliyev, Natavan Azizova, Tarana Huseynli, Arturan Ibrahimli, Iqbal Babazade, Farida Aghayarli, Aydan Ismayilsoy, Mirjavad Abdullazade, Adila Adilli, Parvana Asgarova, Ceyhun Isayev, Elgun Samadov, Arzu Jafarova
Eurasian Journal of Medical Investigation - 2025;9(3):161-171
Over the past years, Neoadjuvant chemotherapy has become an essential part of the oncologist's armamentarium, reducing the tumor size and increasing the number of breast-conserving surgeries performed. Furthermore, it has several advantages in evaluating the response of the primary tumor and lymph nodes to systemic therapy. Pathologic complete response (pCR), also known as excellent response to neoadjuvant chemotherapy (NACT), is a strong predictor of survival in breast cancer patients.[1] Several valuable papers in the literature state significant differences in pCR rates between the breast cancer subtypes.[1,2] Breast cancer subtypes are defined by St. Gallen International Breast Cancer Expert Consensus according to their immunohistochemical properties: luminal A, luminal B, HER2-positive, triple-negative. Estrogen (ER), Progesterone (PR), and HER2 receptor status combined with Ki-67 % levels differ among these subtypes.[3,4] Luminal A tumors can be defined as any ER or PR positivity with <14% Ki-67, and they are clinically low-grade, slow-growing subtypes with the best prognosis with higher disease-free and overall survival rates. For these types of carcinomas, hormone therapy (aromatase inhibitors or tamoxifen) has more favorable outcomes than chemotherapy.[5] Luminal B subtype tumors are also ER or PR positive but with high Ki-67% (>=14%) levels. Luminal B is divided into two subgroups due to HER2 expression:HER2- negative Luminal B and HER2-positive Luminal B. Because of the high Ki-67 rates, tumors in this subgroup are more aggressive and have a worse prognosis compared to luminal A variants with high visceral recurrence rates.[6] In addition to hormone therapy, chemotherapy is also a treatment option in the luminal B subtype with a better response than luminal A.[7] On the other hand, HER2-positive are fast-growing and more aggressive tumors compared to luminals. They are defined as ER/PR negative but HER2-positive tumors regardless of the Ki-67% status. Chemotherapy plus HER2/neu protein-directed drugs (trastuzumab combined with pertuzumab, trastuzumab combined with emtasin (T-DM1), and trastuzumab combined with deruxtecan) is the treatment option for this subtype.[8] Triple-negative breast cancer is characterized by a lack of ER, PR, and HER2 expression and is distinguished by its aggressiveness, early relapse, and a greater tendency to present in advanced stages. Although with the latest advances in the molecular oncology field, the unique molecular pathophysiology of triple-negative tumors is enigmatic.[9] There is still limited research on the survival and clinicopathological differences among patients with various molecular subtypes of breast cancer who receive neoadjuvant chemotherapy. In this context, investigation of the differences among breast cancer subtypes was necessary. The aim of this study was to evaluate clinicopathological and survival differences among breast cancer subtypes in patients receiving NACT, thereby contributing real-world evidence to the existing literature.
