Frequency of the L858R Mutation in Exon 21 of the Epidermal Growth Factor Receptor in Patients with Non-Small Cell Lung Cancer.

Background & Objective: Epidermal growth factor receptor (EGFR) mutations are among the most common oncogenic drivers in non-small cell lung cancer (NSCLC). The L858R mutation in exon 21 of the EGFR gene is associated with responsiveness to targeted therapies in NSCLC patients. This study aimed to evaluate the frequency of L858R mutation and its correlation with clinicopathological characteristics in NSCLC patients. Methods: In this cross-sectional study, Allele-specific Polymerase Chain Reaction (ASPCR) was used to detect L858R mutation in genomic DNA obtained from 336 patients diagnosed with NSCLC. Patients were categorized into mutation-positive groups and mutation-negative subgroups. Associations between the L858R mutation, clinicopathological features, and overall survival were analyzed using appropriate statistical methods. Results: The L858R mutation was identified in 6% of patients (20 out of 336) and showed no significant association with clinicopathological features such as age, gender, tumor grade, histology subtypes, or metastasis (all P > 0.05). Survival analysis indicated an overall mortality rate of 81.8%, with no statistically significant difference in median survival between mutation-negative (11 months) and mutation-positive groups (8 months, P=0.246). Cox regression analysis identified Tumor Grade I as a b significant prognostic factor in both Univariate (HR=0.46, P=0.031) and multivariate (HR=0.46, P=0.040) models. Conclusion: The frequency of the L858R mutation in this Iranian cohort with NSCLC was lower than that reported in global studies. However, its association with metastasis and mortality indicates the potential clinical relevance of this mutation in treatment planning.