Loss of retinoblastoma protein expression in laryngeal squamous cell carcinoma.

Laryngeal carcinomas are among the most curable malignancies, but some of them show poor clinical outcomes with local recurrence or regional neck metastasis. Multiple genetic alterations of oncogenes and tumor suppressor genes are thought to occur in the development some tumors. The frequency, however, and the prognostic significance of these genes or gene products still remain unknown in laryngeal carcinoma. Epidemiologic data suggest that cigarette smoking is closely related to the development of these neoplasms; and human papillomavirus (HPV) infections have also been postulated to play a role in development of laryngeal tumor. The objective of this study was to investigate the presence of retinoblastoma protein (pRb), p53 protein, and HPV infection in laryngeal squamous cell carcinoma, as well as the correlation of these factors with clinicopathologic and carcinogenic factors. Tumors from 79 patients with primary laryngeal squamous cell carcinoma were studied. The expression of pRb was immunohistochemically assessed in 79 such tumors, and the expression of p53 was assessed in 76 tumors. HPV Type 16 expression was estimated by nonisotopic in situ hybridization in 78 cases. Follow-up periods ranged from 15 to 90 months. pRb was detected in 82% of the tumors and p53 in 43%. Lack of staining for pRb was significantly associated with a high-histologic grade (P<.05), high T classification (P<.05), recurrence (P<.05), and a relatively short disease-free interval (P<.01). p53 overexpression was observed frequently in heavy smokers with an average Brinkman index of more than 800, but it was not associated with any of the clinicopathologic factors studied. These findings suggest that tumors exhibiting loss of pRb expression have a more aggressive biologic behavior than do those that express pRb and that loss of pRb expression might predict clinical outcome in patients with primary laryngeal squamous cell carcinoma.