Introduction: Breast cancer (BC) is the second most common cancer worldwide and one of the well-known malignant tumors among women. Breast cancer is classified into 3 major groups based on the presence or absence of molecular markers for estrogen or progesterone receptors and human epidermal growth factor 2 (ERBB2; formerly HER2): ERBB2 positive (15%-20%), hormone receptor positive/ERBB2 negative (70% of patients), and triple-negative (tumors lacking all 3 standard molecular markers; 15%). Each of these subtypes has different risk factors for incidence, therapeutic response, disease progression, and preferential organ sites of metastases. With the advancements in the chemotherapy for BC, the mortality rate from BC is decreasing in the last decade. Targeting ER has proved one of the most powerful treatment modalities against HR+ BC. Moreover, the success of the biological drugs such as anti-HER2 monoclonal antibody, also highlighted the feasibility and significance of the molecular targeting approach in BC therapy. However, among all BC subtypes, TNBC has the fewest therapeutic options due to the lack of well-defined molecular target(s). Identification of new therapeutic targets and development of effective targeted agents is urgently needed. So, Metastasizing TNBC remains a deadly disease with limited treatment options.
Methods: review article
Results: In recent years, the molecular mechanisms driving the heterogeneous treatment response in BC are better elucidated. This has fueled the development of novel targeted agents, including inhibitors of PARP, CDK4/6, PI3K/AKT/mTOR, multiple kinases, or immune checkpoint, for the treatment of specific molecular subtypes of BC. Treatment options should be tailored to individual patient accordingly.
Conclusion: Breast cancer consists of 3 major tumor subtypes categorized according to estrogen or progesterone receptor expression and ERBB2 gene amplification. The 3 subtypes have distinct risk profiles and treatment strategies. Optimal therapy for each patient depends on tumor subtype, anatomic cancer stage, and patient preferences.
Keywords: Breast cancer, TNBC, treatment, subtypes