Histopathological and Immunohistochemical Correlation of Triple-Negative Breast Cancer with Clinical Outcomes

Background: The aggressive subtype of breast cancer known as triple-negative breast cancer (TNBC) is distinguished by the lack of expression of the HER2 gene, the progesterone receptor (PR), and the estrogen receptor (ER). Because of its high likelihood of recurrence, lack of targeted medicines, and restricted treatment options, it is linked to a poor prognosis. Aim: To evaluate the correlation between histopathological and immunohistochemical features of TNBC with clinical outcomes, and to identify key prognostic indicators that could guide therapeutic decisions. Methods: At IGIMS, Patna, 125 patients with histologically proven TNBC participated in 24-month prospective observational research. Clinical information, immunohistochemical markers (Ki-67, p53, CK5/6), lymphovascular invasion, and histological grading were all documented. In order to evaluate survival, metastasis, and recurrence, patients were routinely monitored. SPSS version 23.0 was used for the statistical analysis, and p < 0.05 was chosen as the significance level. Results: Invasive ductal carcinoma was the most common histological type (89.6%), and 62.4% of tumors were grade III. High Ki-67 expression (>20%) was noted in 72.8% of cases, p53 positivity in 63.2%, and CK5/6 positivity in 46.4%. Disease-free survival (DFS) at 2 years was 61.6%, and the overall survival rate was 86.4%. Significant associations were observed between DFS and high Ki-67 index (p = 0.002), grade III tumors (p = 0.001), and lymph node positivity (p < 0.001). CK5/6 and p53 expression did not show significant correlation with clinical outcomes. Conclusion: TNBC is predominantly a high-grade, high-proliferation breast cancer with poor clinical outcomes. Important prognostic variables include lymph node involvement, Ki-67 index, and histological grade. These results highlight the necessity of strong multimodal treatment plans and early identification. Recommendations: Routine assessment of Ki-67 and nodal status should be incorporated into TNBC workups to better stratify patient risk. To investigate the possible role of additional biomarkers and immunotherapy in the treatment of TNBC, long-term follow-up and additional research are advised. Keywords: Triple-negative breast cancer, Ki-67, histopathology, immunohistochemistry, prognosis.