IMMUNOHISTOCHEMICAL ANALYSIS OF PATIENTS WITH LUMINAL B BREAST CANCER: PATHOLOGICAL PARAMETERS AND THERAPEUTIC STRATEGIES

Introduction: Breast cancer (BC) is one of the leading malignancies among women, exhibiting significant molecular and histological heterogeneity. The Luminal B subtype is a hormone-dependent neoplasia characterized by high cellular proliferation, greater aggressiveness, and a higher likelihood of metastasis, often diagnosed at advanced stages. Identifying of an immunohistochemical profile and analyzing genetic mutations have proven essential for personalizing treatment and improving prognosis2,4,5. This study aims to characterize the immunohistochemical profile of patients with Luminal B Breast Cancer (LBBC) and explore its relationship with mutations in genes such as AKT, PIK3CA, BRCA1, BRCA2, and TP53, which are associated with the risk of disease progression and treatment resistance. The data used in this study were collected from patients at the Mário Penna Research Institute, using samples from the Tumor Biobank. Objectives: The main aim is to analyze the immunohistochemical profile in patients with LBBC, identifying specific markers related to prognosis and therapeutic decisions. The study also aims to investigate the relationship between these immunohistochemical characteristics and clinicopathological data, focusing on molecular subtypes, histological grades, and staging. Design and Methods: This study is based on clinicopathological data from 18 patients diagnosed with LBBC, sourced from the Tumor Biobank of the Mário Penna Research Institute (CAAE - 82703418.8.0000.5121). Immunohistochemical analysis will include FOXP3, PDL-1, PDL-2, CD3, CD4, CD8, Ki-67, HER2, Estrogen (ER), and Progesterone (PR) markers1,3. In addition, the following parameters will be evaluated: age, staging, histopathological grade, treatments administered (neoadjuvant, adjuvant, surgery, hormone therapy), and the presence of metastasis. Results The average age of the patients was 51 years (ranging from 33 to 77 years). Regarding staging, 56% presented tumors in the early stages (IA and IIA), while 44% were diagnosed at advanced stages (IIIA, IIIB, and III). The predominant histopathological grade was G1 (72%), followed by G2 (17%) and G3 (5.5%). The most common treatment was neoadjuvant therapy (50%), while 39% received adjuvant therapy. Metastasis was observed in 44% of the cases. Immunohistochemical analysis will help identify key protein expression patterns that may influence tumor behavior and therapeutic response. Conclusions/Final Considerations: This study will contribute to understanding the immunohistochemical and genetic profile of LBBC, providing crucial data for developing prognostic biomarkers. It is expected that immunohistochemical analyses, together with clinical data, will offer a solid foundation for developing personalized therapeutic strategies, helping to optimize treatment for patients with this subtype of BC. The use of Tumor Biobank data emphasizes the importance of translational research in oncology, allowing scientific advancements to be applied in clinical practice.   Keywords: Breast cancer; Immunohistochemical; Luminal B; Molecular subtypes; Genetic mutations.