EXPRESSION OF EGFR, ALK, AND ROS1 BY IMMUNOHISTOCHEMISTRY AND THEIR MOLECULAR ALTERATIONS IN NON-SMALL CELL LUNG CARCINOMA

Abstract

Background: Non-small cell lung carcinoma is the most common type of lung cancer and remains a major cause of cancer-related mortality worldwide.

Objective: To assess the expression of EGFR, ALK, and ROS1 by immunohistochemistry and evaluate their molecular alterations in patients with non-small cell lung carcinoma.

Methodology: This cross-sectional study was conducted at Pathology Department ( Histopathology section) of Fauji Foundation Hospital Lahore, from February 2025 to December 2025, including 65 patients with histopathologically confirmed non-small cell lung carcinoma. Demographic and clinicopathological data including age, gender, smoking history, histological subtype, tumor grade, and stage were recorded.

Results: The mean age of the patients was 59.4 ± 10.7 years, and 42 (64.6%) were male. Smoking history was present in 41 (63.1%) patients. Adenocarcinoma was the most common histological subtype, seen in 37 (56.9%) cases. Immunohistochemical expression of EGFR, ALK, and ROS1 was observed in 24 (36.9%), 7 (10.8%), and 5 (7.7%) patients, respectively. Molecular analysis showed EGFR mutations in 20 (30.8%) cases, ALK rearrangements in 6 (9.2%), and ROS1 alterations in 4 (6.2%).

Conclusion: EGFR was the most frequently expressed and altered biomarker in non-small cell lung carcinoma, followed by ALK and ROS1.