A Comparative Study of Cell Block versus Biopsy for Detection of Epidermal Growth Factor Receptor Mutations and Anaplastic Lymphoma Kinase Rearrangement in Adenocarcinoma Lung

BACKGROUND: Lung cancer is a leading cause of deaths attributed to cancer worldwide. Epidermal growth factor receptor (EGFR) mutation and anaplastic lymphoma kinase (ALK) rearrangement are commonly found in patients of adenocarcinoma lung against, which targeted therapy is available. In this era of personalized medicine, it is a rationale to detect these molecular alterations in cases of lung carcinomas. AIMS: The objectives were to compare the diagnostic efficacy of cytological samples for the detection of EGFR and ALK protein expression using immunocytochemistry in nonsmall cell lung carcinoma. MATERIALS AND METHODS: We compared 22 cell blocks and biopsies for the detection of EGFR and ALK protein expression by immunohistochemistry (IHC). EGFR IHC was performed using EGFR Receptor (E746-A750 del Specific) (6B6) monoclonal antibody and ALK IHC was done using Ventana anti-ALK (D5F3) monoclonal primary antibody. RESULTS: Two cases were found to be positive; 20 cases were negative for EGFR IHC both in biopsies and cell blocks. ALK IHC was positive in one case; negative in 21 cases. The results of IHC were also concordant for biopsies and cell blocks. The sensitivity and specificity were 100% for immunocytochemical detection of ALK and EGFR in cell blocks with respect to biopsies. CONCLUSION: We conclude that cell blocks can serve as a potential substitute for biopsies for detection of EGFR and ALK protein by immunocytochemistry, whenever patient presents with effusion and biopsy cannot be done or when tissue is not adequate.