Abstract

COMPARATIVE STUDY OF EGFR MUTATION ANALYSIS WITH EGFR PROTEIN EXPRESSION IN PATIENTS WITH LUNG CANCER IN BASRAH

*Daniah Husam Ibrahim, Dr. Sawsan Salih Al-Haroon

Abstract

Background: Lung cancer is a leading cause of cancer-related mortality worldwide, with most cases diagnosed at advanced stages and associated with poor prognosis. Non-small cell lung cancer accounts for the majority of cases, and cigarette smoking remains the main risk factor, alongside genetic and environmental influences. Advances in molecular profiling, including Epidermal Growth Factor Receptor (EGFR) and other driver mutations, together with immunohistochemical (IHC) analysis and improved imaging techniques, have enhanced diagnostic accuracy and enabled the use of targeted and immunotherapy-based treatments, leading to improved outcomes in selected patients. Aim of the study: To evaluate EGFR protein expression in different types of EGFR mutation in lung cancer. Patient and method: This was a prospective study, carried out in Basrah province. The data were collected incidentally from Al-Sader Teaching Hospital and private laboratories during the period from the First of October 2024 to the end of October 2025. All cases of lung cancer diagnosed during the period of study were included. Formalin fixed paraffin embedded blocks were collected. Three to Five micrometers thickness sections were obtained and stained with routine hematoxylin and eosin stains. The slides were examined to confirm the diagnosis and define the histological subtype. Then Additional sections using positively charged slides were provided for IHC staining for EGFR mutations. The piece of tumor tissue in appropriate size was taken from the wax block for DNA extraction for detection of EGFR mutation by using Real-time PCR. Results: Forty six cases of proved lung cancer were included in this study. Thirty five cases (76.1%) were males and 11 cases (23.9 %) were females with mean age of 63.91 years (range 40-85 years). Thirty three cases (71.7%) diagnosed as adenocarcinoma, 9 cases (19.6%) diagnosed as squamous cell carcinoma and 4 cases (8.7%) diagnosed as metastatic adenocarcinoma. Using IHC, 10 cases (21.8%) were moderately positive (score +2) for EGFR protein expression, 2 cases (4.3%) were strongly positive (score +3), 23 cases (50.0%) were negative and 11 cases (23.9%) showed equivocal expression (score +1). Among the negative cases, 19 cases were males and 4 cases were females, while among the positive cases (scores +2 and +3), 8 cases were males and 4 cases were females. Using Real -Time PCR, 5 cases (10.9%) were positive for exon-19 mutation, 1 case (2.1%) positive for exon-18 mutation and 40 cases (87.0%) were negative for EGFR mutation. Among the positive cases, 5 cases were males and 1 case was female. The sensitivity of IHC in detecting EGFR mutation is (0%) with specificity (70%). The positive predictive value is (0%) and the negative predictive value is (82.4%). The ROC curve shows that the consistency between the IHC and RT-PCR is (31.3%). Conclusion: The findings from this study reveal a discrepancy between IHC and RT-PCR in identifying EGFR mutations. It is important to note that IHC should not be relied upon to evaluate different types of EGFR mutation. Depending solely on IHC may be unreliable due to its low sensitivity, which could potentially increase time, cost, and effort in the diagnostic process.

Keywords: .