Potential utility of p63 expression in differential diagnosis of non-small-cell lung carcinoma and its effect on prognosis of the disease

BACKGROUND: P63 is a gene located in chromosome 3q27–29, which has been implicated in regulation of stem cell commitment and promotion of squamous differentiation in various tissues. The aim of this study was to investigate whether there was a correlation between p63 expression, differential diagnosis of lung carcinoma, and prognosis. MATERIAL/METHODS: Immunohistochemical expression of p63 in 62 lung carcinomas was investigated and mRNA analysis using RT-PCR method was done in 6 selected cases. RESULTS: When cases were evaluated for p63 staining, 24 of 25 (96%) squamous cell carcinomas were strongly positive. Six of 20 adenocarcinomas (25%) and 1 (100%) large cell carcinoma (except neuroendocrine carcinoma) were mildly positive. p63 staining was statistically significant in favor of squamous cell carcinoma than other tumors (p<0.001). Forty percent of squamous cell carcinomas had squamous carcinoma in situ, whereas adenocarcinomas had none. There was a significant statistical difference between squamous cell carcinoma and adenocarcinoma (p=0.002). p63 was strongly positive in all of 12 squamous carcinoma in situ cases. In 6 cases where mRNA analysis was performed by RT-PCR method, DNp63 was strongly positive in 3 squamous cell carcinomas, mildly positive in 1 adenocarcinoma, and negative in 1 carcinoid tumor. TAp63 was strongly positive in non-tumoral lung tissue but negative in all tumors, except 1 squamous cell carcinoma. CONCLUSIONS: Our data suggest that poorly differentiated squamous cell carcinoma had strong and widespread staining for immunohistochemical expression of p63. Therefore, p63 can be a useful marker in differentiating squamous cell carcinoma from poorly differentiated adenocarcinoma and squamous cell carcinoma from large cell neuroendocrine carcinoma.