bcl-2 protein expression correlates with recurrence and survival in early stage head and neck cancer treated by radiotherapy

• Published in: Clinical cancer research 1996-02, Vol.2 (2), p.261-267
• Main Authors: Gallo, O, Boddi, V, Calzolari, A, Simonetti, L, Trovati, M, Bianchi, S
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Carcinoma, Squamous Cell - chemistry; Carcinoma, Squamous Cell - mortality; Carcinoma, Squamous Cell - radiotherapy; Female; Head and Neck Neoplasms - chemistry; Head and Neck Neoplasms - mortality; Head and Neck Neoplasms - radiotherapy; Humans; Immunohistochemistry; Male; Middle Aged; Neoplasm Recurrence, Local - chemistry; Proto-Oncogene Proteins c-bcl-2 - analysis; Survival Rate
• ISSN: 1078-0432; 1557-3265

Inherent cellular radioresistance plays a critical role in the failure of radiation therapy (RT). The proto-oncogene bcl-2 encodes a protein that inhibits apoptosis, a common mechanism of cell death induced by several genotoxic agents, including gamma-radiation. Thus, it is likely that bcl-2 gene expression could be involved in the complex mechanisms of radioresistance in human tumors with some prognostic implications. In this study, we analyzed the predictive relevance of bcl-2 expression on 5-year disease-free and overall survival in patients with early stage squamous cell carcinoma of the head and neck (SCCHN) primary treated with RT. The expression of bcl-2 was analyzed by immunohistochemistry on paraffin-embedded sections from 71 consecutive stage I-II SCCHN patients treated with curative RT. We detected bcl-2 protein in 21% of SCCHN studied. A suggestive association was observed between tobacco exposure and bcl-2 protein expression (P < 0.1); this association was stronger in those patients who failed primary RT (P = 0.03). Moreover, we documented a higher rate of bcl-2 immunoreactive tumors in postirradiated biopsies from relapsed patients than in preirradiated ones (P = 0.03). In both univariate and multivariate analyses, bcl-2 expression was the most important indicator for disease-free survival (P = 0.08 and P = 0.01, respectively) and overall survival (P = 0.004 and P = 0.05) within 5 years of RT. The present study indicates that the proto-oncogene bcl-2 is abnormally expressed in some SCCHN, and its expression may prove to be a useful tool in selecting patients for conventional RT with clear prognostic implications.