VE1 immunohistochemistry as a screening tool for BRAFV600E mutation in lung adenocarcinoma: evidence from a Montenegro National Cohort.

Abstract

Introduction: Lung cancer remains the leading cause of cancer-related mortality worldwide, with non-small cell lung cancer (NSCLC) representing the majority of cases. Molecular profiling of NSCLC has identified multiple genomic alterations, including BRAFV600E mutation, which occurs in 1-5% of patients, predominantly in adenocarcinomas. Detection of this mutation is clinically relevant due to the availability of targeted therapies. Immunohistochemistry using the VE1 antibody offers a rapid and practical screening method, although interpretation criteria and methodological variability remain challenging.

Material and methods: This study represents the first systematic evaluation of BRAFV600E immunohistochemical (IHC) and molecular status in the Montenegrin population. A total of 135 patients undergoing surgical resection for primary lung adenocarcinoma were analyzed retrospectively. Clinicopathological data were collected, and tissue microarrays (TMA) were constructed. Immunohistochemical staining was performed with the VE1 monoclonal antibody, and results were scored based on cytoplasmic staining intensity and homogeneity. Positive cases, along with matched negative controls, were further analyzed using fully automated Biocartis Idylla real-time polymerase chain reaction (PCR).

Results: VE1 IHC positivity was observed in 7 patients (5.2%), with strong, homogeneous staining (3+) in 2 cases. BRAFV600E mutations were confirmed by PCR exclusively in these 3+ cases, giving a prevalence of 1.5% overall and 28.6% relative to IHC-positive cases. Statistical analysis demonstrated perfect concordance between strong, homogeneous VE1 staining and PCR results. Weak or focal staining presented interpretative challenges, highlighting the need for standardized criteria and molecular confirmation.

Conclusions: Immunohistochemistry using VE1 antibody is a reliable and accessible initial screening tool for BRAFV600E mutation in lung adenocarcinoma. Strong, homogeneous cytoplasmic staining predicts mutation status with high accuracy, while weak or heterogeneous staining requires confirmatory molecular testing. The present findings provide essential local epidemiological data and support universal IHC testing to guide personalized therapy in NSCLC.