Relationship Between Axillary Metastasis and Tumoral Response and Biomarkers in Breast Cancer Patients Who Received Neoadjuvant Chemotherapy

ABSTRACT Introduction: The molecular subtype of the disease is related to the patient's clinical course, response to chemotherapy, and pathological response rates. Objective: The molecular subtype of the disease is related to the patient's clinical course, response to chemotherapy, and pathological response rates. This research aimed to elucidate the relationship between neoadjuvant chemotherapy and treatment response in breast cancer patients who received neoadjuvant therapy and were evaluated with axillary lymph nodes after surgery. Method: This retrospective analysis investigated the relationship between axillary metastasis status, tumoral and pathological complete response status, and molecular subtypes in 103 patients who received neoadjuvant chemotherapy for breast cancer and whose axillary lymph nodes were evaluated. Patients' age, menopause status, type of surgery, tumor side, axillary involvement, nodal involvement, T staging, histopathological type and subtypes, tumor receptors, perineural invasion, lymphovascular invasion, and tumor necrosis data were obtained from hospital records. Results: A total of 103 female patients were included in the study. Histopathologically, the most common subtype was invasive ductal carcinoma (89.3%), and hormone receptor status was determined as ER-positive (73.8%) and PR positive (63.1%). Molecular subtypes were defined as Luminal B (36.9%) and Luminal A (34%), and the most common tumor grade was grade 2 (57.3%). The most common surgical method after neoadjuvant chemotherapy was radical mastectomy (97.1%). Among the cancer subgroups evaluated after neoadjuvant therapy, the most frequent subgroups with tumoral complete response were HER2 positive (47.4%), and triple-negative (45.5%) groups, the most frequent groups showing nodal complete response were HER2 positive (47.4%) and triple negative (63.6%) groups. The most frequent subgroups showing pathological complete response were HER2 positive (21.1%) and triple negative (36.4%) groups. Conclusion: Breast cancer genetic subgroups are associated with treatment responses following neoadjuvant chemotherapy. Among breast cancer subgroups, the subgroups that provide the best tumoral, nodal, and pathological complete response to neoadjuvant chemotherapy are HER2-positive breast cancers and triple-negative breast cancer types. Keywords: Breast Cancer, Neoadjuvant Chemotherapy, Tumor Subtype, Tumor Biology, Pathological Response.