IMMUNOHISTOCHEMICAL EXPRESSION AND MOLECULAR PROFILING OF PD-L1 AND KI-67 IN TRIPLE-NEGATIVE BREAST CARCINOMA: CORRELATION WITH CLINICOPATHOLOGICAL PARAMETERS

Abstract

Background: Triple-negative breast carcinoma (TNBC) is an aggressive subtype of breast cancer lacking targeted hormonal therapies. Biomarkers such as programmed death-ligand 1 (PD-L1) and Ki-67 have gained importance in understanding tumor behavior, immune evasion, and proliferative activity.

Objective: To evaluate the immunohistochemical expression and molecular profiling of PD-L1 and Ki-67 in TNBC and to assess their correlation with clinicopathological parameters.

Methods: This was a cross-sectional analytical study conducted in the Pathology Department ( Histopathology section) of Fauji Foundation Hospital Lahore, from March 2025 to December 2025, including 85 patients diagnosed with triple-negative breast carcinoma (TNBC) to evaluate the immunohistochemical expression and molecular profiling of PD-L1 and Ki-67 and their correlation with clinicopathological parameters.

Results: PD-L1 positivity was observed in 60.0% of patients and was significantly associated with larger tumor size (4.2 ± 1.5 cm vs 3.3 ± 1.2 cm; p=0.008), higher grade tumors (67.9% vs 46.9%; p=0.041), lymph node positivity (69.6% vs 50.0%; p=0.012), and advanced stage disease (72.9% vs 38.2%; p=0.006). High Ki-67 expression was seen in 77.6% of patients and was significantly associated with larger tumor size (4.1 ± 1.4 cm vs 3.0 ± 1.1 cm; p=0.004), higher grade (90.6% vs 56.3%; p=0.009), and lymph node involvement (83.9% vs 47.4%; p=0.047). The combined PD-L1+/high Ki-67 group showed the most aggressive tumor profile, with highest tumor size (4.4 ± 1.5 cm), nodal involvement (81.0%), and advanced stage (73.8%) (p<0.001).

Conclusion: PD-L1 and Ki-67 expression are significantly associated with aggressive tumor characteristics in TNBC, and their combined assessment provides enhanced prognostic value for disease stratification and management.