Reverse Hybridization as a Molecular Tool for EGFR Mutation Analysis in Small Biopsies of Lung Cancer

In recent years, the management of advanced Non–Small-Cell Lung Cancer (NSCLC) has increasingly relied on molecular testing for key driver alterations, particularly Epidermal Growth Factor Receptor (EGFR) mutations and Anaplastic Lymphoma Kinase (ALK) rearrangements. This study aimed to estimate the prevalence of EGFR mutations in NSCLC, characterize the spectrum of EGFR variants across NSCLC subtypes, and compare mutation frequencies between smokers and non-smokers.

This hospital-based observational study utilized DNA extracted from Formalin-Fixed Paraffin-Embedded (FFPE) tumor samples. Polymerase Chain Reaction (PCR) followed by reverse hybridization was performed using oligonucleotide probe–based EGFR strip assays capable of detecting 16 distinct mutations spanning exons 18–21 of the EGFR gene.

Data analysis was conducted using Microsoft Excel 2013 and SPSS version 17. Associations between EGFR mutation status and clinicopathologic variables were examined using the chi-square test. A p-value < 0.05 was considered statistically significant.

EGFR mutations were identified in 18 cases (66.7%). Among patients with adenocarcinoma, the mutation frequency was 52.6%, whereas all squamous cell carcinoma cases demonstrated EGFR mutations. Within the adenocarcinoma subgroup, EGFR alterations were more frequently observed in females (60%) than in males (50%). Exon 19 in-frame deletions were the most prevalent mutation type detected.

The EGFR Strip-Assay represents a sensitive, cost-effective, and less labor-intensive approach with a rapid turnaround time.

This assay may serve as a practical alternative to direct sequencing for EGFR mutation analysis, particularly when working with limited tissue samples in resource-constrained settings such as those in developing countries, including India.