The Prevalence of PD-L1 Expression in Triple-Negative Breast Cancer Patients and Its Correlation with Survival Rates and Other Prognostic Factors: A Survival Analysis

Background: Triple-negative breast cancer (TNBC) is a leading cause of cancer-related mortality among women, with a poor prognosis. The programmed cell death 1 (PD-1) pathway has emerged as a potential immunotherapy target. This study aimed to assess PD-L1 expression in TNBC patients and its relationship with prognostic variables. Materials and Methods: This cross-sectional study included 107 TNBC patients recruited between 2016 and 2020. Patient age, tumor grade, and Ki67 expression were obtained from pathology reports. Immunohistochemistry was utilized to determine PD-L1 status, and 2-year survival data were collected through telephone follow-up. Results: PD-L1 expression frequency in TNBC patients was 76.6%. Grade 3 was the most common cancer grade, significantly more prevalent in the PD-L1 positive group ( P = 0.01). High Ki67 expression (≥14%) was observed in 89% of patients, significantly higher in the PD-L1 positive group ( P = 0.003). The 2-year survival rates for the PD-L1 positive and negative groups were 84.1% and 92%, respectively, with no significant difference between the groups ( P = 0.512). Conclusion: This study investigated PD-L1 expression prevalence in TNBC patients and its correlation with prognostic variables. PD-L1 expression was associated with higher tumor grade and elevated Ki67 expression, indicating a potential role in tumor aggressiveness. However, despite these associations, PD-L1 expression did not significantly impact the 2-year survival rate in TNBC patients. These results emphasize the complexity of the immune microenvironment in TNBC and the necessity for further research to elucidate the precise role of PD-L1 in disease progression and patient outcomes.