Altered patterns of retinoblastoma gene product expression in benign, premalignant and malignant epithelium of the larynx: an immunohistochemical study including correlation with p53, bcl-2 and proliferating indices.

In order to study the altered Rb, bcl-2 and p53 proteins expression during laryngeal carcinogenesis and to elucidate the role of these molecules in the development and progression of the lesions, we have examined the immunohistochemical expression of these markers in a series of 41 squamous cell carcinomas, 14 cases of in situ carcinoma, 47 with epithelial dysplasia, 11 papillomas and 20 cases of keratosis. Rb protein was expressed in 69.7% (> 5% positive neoplastic cells) of squamous cell carcinomas and p53 in 40% (> 5% positive cells). There was a strong statistically significant difference for Rb, Ki-67 and PCNA immunostaining between malignant, premalignant and benign lesions, increasing from keratosis, papillomas, dysplasia to carcinoma in situ or infiltrating squamous Ca. Rb protein expression was also strongly correlated with p53, Ki-67 and PCNA, while p53 protein was strongly correlated with Ki-67 (p = 0023) and PCNA (p = 0.0031) indices, in all lesions. In conclusion Rb and p53 altered proteins expression seems to play an active role in laryngeal carcinogenesis, probably from the early phase, and is correlated with proliferative activity. Also, Rb protein expression is correlated with the progression of the lesion and could be considered as indication of poor prognosis in laryngeal lesions.