Diagnostic Utility of TTF-1 and P40 Immunohistochemical Markers for Subtyping of Non-Small Cell Lung Carcinoma

Abstract

Background : Lung cancer is the leading cause of cancer-related mortality over worldwide. Although the pathological diagnosis of lung carcinoma is limited as only small specimen available for diagnosis, the availability of targeted therapies has created a need for precise subtyping of non-small cell lung carcinoma. Several recent studies have demonstrated that the use of immunohistochemical markers can be helpful in differentiating squamous cell carcinoma from adenocarcinoma not only on surgically resected specimen but also on small biopsy samples. Material and Methods: A cross-sectional study of one year duration including 50 cases of lung carcinomas on guided biopsies were first reported on Haematoxylin and Eosin sections and later subjected for IHC using relevant markers TTF-1 and p40. Results: In our study IHC with TTF-1 and p40 aided in subtyping of 35 (92.1%) cases of non-small cell lung carcinoma and this diagnostic accuracy was found to be statistically significant with p value <0.001. On statistical analysis, p40 showed 100% sensitivity and 85.7% specificity for squamous differentiation whereas TTF-1 showed sensitivity of 85.7% and specificity of 100% for adenocarcinoma. Out of 50 cases, after IHC, 29 (58%) were diagnosed as squamous cell carcinoma, 18 (36%) as adenocarcinoma, 3 (6%) as non-small cell lung carcinoma. Conclusion: The minimalist IHC based model of p40 and TTF-1 on biopsy samples were effective to correctly subtype most cases of non-small cell lung carcinoma and contribute in sparing material for molecular testing. Keywords: Non-small cell lung carcinoma, immunohistochemistry, squamous cell carcinoma