[PD-L1 status in breast cancer]

Area of Science:

• Oncology
• Immunology
• Pathology

Background:

• Programmed death-ligand 1 (PD-L1) is an immune checkpoint protein.
• PD-L1 expression varies across different breast cancer subtypes.
• Understanding PD-L1 expression is crucial for predicting treatment response and prognosis.

Purpose of the Study:

• To compare PD-L1 expression in triple-negative breast cancer (TNBC) and luminal B, HER2-negative breast cancer.
• To evaluate the association between PD-L1 status and prognosis in these breast cancer subtypes.
• To investigate the correlation between PD-L1 expression and residual tumor burden after neoadjuvant therapy.

Main Methods:

• Immunohistochemical analysis of PD-L1 expression in primary tumor samples.
• Study included 72 patients with breast cancer.
• Tumor samples were classified by molecular subtype and assessed for residual cancer burden (RCB) after neoadjuvant therapy.

Main Results:

• PD-L1 expression was detected in 37.78% of TNBC cases (17/45) versus 14.81% of luminal B, HER2-negative cases (4/27).
• PD-L1 positivity was significantly higher in TNBC compared to luminal B, HER2-negative breast cancer.
• A strong correlation was observed between high RCB and positive PD-L1 status (46.15% in high RCB vs. 5.56% in moderate RCB).

Conclusions:

• Triple-negative breast cancer exhibits a higher frequency of PD-L1 expression than luminal B, HER2-negative breast cancer.
• Positive PD-L1 status is associated with a higher residual tumor load after neoadjuvant therapy.
• PD-L1 expression may serve as a prognostic biomarker in specific breast cancer subtypes.