P53 and radiotherapy for oesophageal carcinoma: A comparison between 4 different antibodies

Wild-type p53 protein plays an important role in the cellular response to ionising radiation and other DNA damaging agents and is mutated in many human tumours. Immunohistochemistry is a rapid method to detect elevated protein levels. The p53 status in a group of patients treated by radiotherapy exclusively for oesophagus carcinoma was examined and correlated with pre-treatment parameters and treatment outcome with regard to overall survival, local recurrence-free survival and distant metastases-free survival. Four different antibodies were used to evaluate their predictive power to detect p53 expression. Immunostaining for p53 protein with 4 different antibodies was performed on paraffin-embedded specimens from 69 patients with adenocarcinoma and squamous cell carcinoma of the oesophagus. All patients were treated with radiotherapy exclusively, consisting of external irradiation combined with intraluminal brachytherapy. Detection of p53 using the antibody (DO7) was significantly correlated with overall survival and distant metastases-free survival. For local recurrence-free survival no statistical significance was reached. The use of the other 3 antibodies all showed the same trend with regard to distant metastases, however statistical significance was not reached. The use of multiple antibodies did not increase the predictive value of DO7. Both for survival and metastases-free survival the use of DO7 alone was sufficient as a significant prognostic factor. We conclude that in this series, only the use of DO7 was correlated with prognosis in oesophagus carcinoma treated by radiotherapy only and that addition of 3 antibodies did not improve the predictive power.