Assessment of PDL-1 expression in triple-negative breast cancer via immunohistochemistry

Objective: To assess the frequency of PDL1 positivity triple-negative breast carcinoma (TNBC) and correlate it with the clinicopathological parameters. Material and Methods: This cross-sectional study was conducted at Histopathology Department, Rehman Medical Institute Peshawar September 2023 to October 2024. Biopsy specimen of 41 female patients diagnosed with TNBC were received in the Histopathology department. Specimen underwent eosin/hematoxylin staining and immunohistochemistry analysis. Demographic and histopathological parameters were recorded. Results: Mean age was 54.58(6.14) years, and the most common type of TNBC was invasive breast carcinoma of no special type in 23(56.1%). Out of 41 specimens, we observed that stage N2 and stage T3 were the most prevalent as observed in 18(43.9%) and 19(46.3%) specimens respectively. Frequency of PDL1 positivity was observed in 16(39.02%) with a trend towards higher PDL1 positivity observed in invasive ductal carcinoma of no special type and tumors exhibiting size of >20mm. Lymphovascular invasion was seen in 17 (41.46%) out of which 09 (56.3%) were PDL1 positive. Tumor-infiltrating lymphocytes of the moderate category were significantly associated with PDL1 positivity with a p-value of 0.024. Conclusion: PDL1 expression is observed in a substantial number (39.02%) of TNBC patients. Our research concludes an important association between PDL1 expression and tumor-infiltrating lymphocytes in TNBC which enlightens new avenues for immunotherapy. This association may have profound implications in the future for prompt diagnosis and targeted treatment. Keywords: Breast carcinoma, Lymphocytes, Triple-negative breast neoplasms