Abstract
It is now important to distinguish between adenocarcinoma and squamous cell carcinoma of the lung because of target-specific treatments. Our study aimed to study the efficiency of Thyroid Transcription Factor-1 (TTF-1), cytokeratin 5/6 (CK5/6) and p63 in distinguishing between adenocarcinoma and squamous cell carcinoma and to study the contribution of these markers to the diagnosis in non-small cell lung cancer. Immunohistochemically, TTF-1, CK 5/6 and p63 were used in 72 cases of squamous cell carcinoma, 19 cases of adenocarcinoma, and 29 cases of non-small cell lung cancer whose final diagnosis was decided with the subsequent resection material. The specificity, sensitivity, and positive and negative predictive value were calculated for each marker. TTF-1 positivity was seen in none of the 72 squamous cell carcinomas but in all of 19 adenocarcinoma cases. CK5/6 negativity was seen in all cases of adenocarcinoma and in two cases of squamous cell carcinoma. p63 was positive in all squamous cell carcinomas and in 4 adenocarcinomas. Cytokeratin 5/6, p63 positivity and TTF-1 negativity were observed in 17 non-small cell lung cancers whose final diagnosis was squamous cell carcinoma. None of the 12 non-small cell lung cancers whose final diagnosis was adenocarcinoma exhibited positive staining for CK5/6. However, p63 staining was not seen in the biopsy but was focal in the surgical specimen in one case. All the 12 non-small cell lung cancers whose certain diagnosis was adenocarcinoma were positive for TTF-1. TTF-1, CK 5/6 and p63 seem to be useful for differentiating adenocarcinoma from squamous cell carcinoma with 100% specificity, 100% sensitivity and 100% specificity, 97% sensitivity and 87% specificity, and 100% sensitivity, respectively. We concluded that TTF-1 is a reliable marker for subtyping lung cancer. Different staining patterns can be seen with CK5/6 and p63; however, if they are used together with TTF-1 and interpreted correctly, they can be of help for the final diagnosis even in cases in which the morphology is unclear.
Highlights
Lung cancer is the number one cause of cancer-related mortality in men and women worldwide [1]
cytokeratin 5/6 (CK5/6) negativity was seen in all cases of adenocarcinoma and in two cases of squamous cell carcinoma. p63 was positive in all squamous cell carcinomas and in 4 adenocarcinomas
Cytokeratin 5/6, p63 positivity and Transcription Factor-1 (TTF-1) negativity were observed in 17 non-small cell lung cancers whose final diagnosis was squamous cell carcinoma
Summary
Lung cancer is the number one cause of cancer-related mortality in men and women worldwide [1]. Various histological types of lung cancer have been described. Lung cancers were divided into two major groups as small-cell lung cancer and non-small-cell lung cancer (NSCLC) [2]. Adenocarcinoma (AC), squamous cell carcinoma (SCC) and large cell carcinoma are the most common types of NSCLC [3]. Bevacizumab, a VEGF drug/inhibitor, is an important drug in the treatment of some ACs. For example, bevacizumab, a VEGF drug/inhibitor, is an important drug in the treatment of some ACs When it is used for SCC, it may cause life-threatening hemorrhage [3,4]. When the pulmonary carcinomas are classified, their histological features are considered first. Immunohistochemistry (IHC) and gene expression profiling have been studied to solve this problem, but usually immunohistochemistry is the most practical solution [6,7,8]
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