CK5/6 Expression in Molecular Subtypes of Invasive Ductal Carcinoma

Area of Science:

• Oncology
• Pathology
• Biomarker Research

Background:

• Breast cancer (BC) is a leading cause of cancer-related deaths globally, with rising incidence in Pakistan.
• Invasive ductal carcinoma (IDC) is the most common histological subtype of BC.
• Molecular subtypes (Luminal A, Luminal B, HER-2 enriched, triple-negative) impact prognosis, with triple-negative BC having the worst outlook.

Purpose of the Study:

• To evaluate the expression of Cytokeratin 5/6 (CK5/6) in IDC.
• To compare CK5/6 expression across different molecular subtypes of BC.
• To correlate CK5/6 expression with established prognostic factors in IDC.

Main Methods:

• A cross-sectional study involving 85 mastectomy samples diagnosed with IDC.
• Immunohistochemical assessment of estrogen receptor, progesterone receptor, HER-2, and CK5/6.
• Segregation of cases into molecular subtypes based on receptor status.
• Statistical analysis using SPSS version 25.0.

Main Results:

• CK5/6 positivity was observed in 19 (22.3%) of the 85 IDC cases.
• The majority of CK5/6-positive cases (68%) were triple-negative breast cancer.
• No Luminal A cases expressed CK5/6, while Luminal B (10.8%) and HER-2 enriched (33.3%) subtypes showed some positivity.
• CK5/6 positivity correlated with lymphovascular invasion (42%) and high histological grade (57.8%).

Conclusions:

• CK5/6 expression in IDC is significantly associated with triple-negative molecular subtypes.
• CK5/6 positivity indicates a correlation with adverse prognostic factors including high tumor grade, lymphovascular invasion, positive nodal status, and advanced pathological stage.