Bcl-2 expression correlates with favourable outcome in head and neck cancer treated by accelerated radiotherapy

The aim of this study was to investigate bcl-2 expression in head and neck cancer patients and to investigate its correlation with biological and clinical characteristics and outcome of accelerated radiotherapy. A series of 93 patients with squamous cell carcinoma of the head and neck who had been uniformly treated with continuous hyperfractionated accelerated radiation treatment (CHART) were investigated. These patients had also been injected with bromodeoxyuridine (BrdUrd) to measure cell kinetic parameters using flow cytometry (FCM) and their p53 protein status had also previously been described. Bcl-2 expression was assessed using immunohistochemistry. Sixteen of the 93 (17.2%) patients stained positively for bcl-2 proto-oncogene. The percentage of positive tumour cells within the specimens was highly variable, ranging from a few percent to complete positivity. Bcl-2 positivity was correlated with improved local control (p > 0.0016) and survival (p > 0.012) in comparison with non-expressing tumours. There was no correlation between bcl-2 expression and histological grade, T stage or site but overexpressors were almost exclusively node negative. The significance of bcl-2 was reduced when node negative tumours were analysed alone. There was no correlation of bcl-2 with p53 expression but there was a trend for overexpression to be associated with diploidy and rapidly proliferating tumours. These data suggest that bcl-2 expression in head and neck cancer is not associated with disease progression.