Lung Cancer Spectrum, Molecular Alterations and PD-L1 Expression

Abstract

Aim
This audit evaluated lung cancer cases diagnosed in 2024, focusing on histological subtypes, molecular testing, and PD-L1 expression to assess diagnostic trends and biomarker testing compliance.

Methods
All lung malignancy cases on core biopsy or cytology between January 1 and December 31, 2024, were included. Data were extracted from the institutional lab information system (Win-Path and Power-chart).

Results
Adenocarcinoma was the most common subtype, accounting for 91 (55%) cases, followed by squamous cell carcinoma 32 (19%) cases, small cell carcinoma, 17 (10%) cases, carcinoma NOS, 24 (14%) cases, and High-grade Neuroendocrine carcinoma, 1 (1%) case. Molecular testing was performed in 83 (50%) cases. Reflex testing by pathologists was done in 76 (92%) cases and testing was done on clinician’s request in 7 (8%) cases. Mutations were identified in 38 (46%) cases of them. KRAS mutations were detected in 19 (50%), EGFR in 8 (21%), BRAF in 6 (16%), MET exon 14 skipping in 2 (5%), and PIK3CA in 3 (8%). PD-L1 immunohistochemistry was performed on 110 (66%) of total cases. Among these, the tumour proportion score was <1% in 50 (45.5%) cases, 1–49% in 28 (25.5%) cases, and ≥50% in 32 (29%) cases.

Discussion
Adenocarcinoma predominated, KRAS was the most common driver mutation, and PD-L1 expression influenced treatment decisions, aligning with global trends in precision oncology.