Role of Bcl‐2 and Ki‐67 Expressions in Predicting the Response to Radiotherapy in Cancer Larynx

Abstract

Objectives: Study of Bcl-2 protein and nuclear antigen Ki-67 expressions in laryngeal squamous cell carcinoma and its importance in predicting the tumor response to radiotherapy. Methods: Retrospective and prospective study. This study was conducted on 60 paraffin blocks of patients with laryngeal squamous cell carcinoma (T1 and T2 N0M0) who were treated with radiotherapy between 2003 and 2009.Thirty blocks were collected from patients who failed radiotherapy and thirty blocks from patients who successfully improved by radiotherapy. The response to radiotherapy was assessed during the follow up period by direct laryngoscopy and biopsy every 3 months. Sections (4um) were cut to be stained with H&E and for immunohistochemical staining for Bcl-2 and nuclear antigen Ki-67. Results: Immunohistochemical study of Bcl-2 revealed positive expression in 70% of radioresistant cases compared with 10% of radiosensitive cases. Negative expression of B-cl2 occurred in 30% of radioresistant cases compared with 90% of radiosensitive cases. Bcl2 is 70% sensitive and 90% specific and has a 80% accuracy in predicting patient response to radiotherapy. On the other hand, the study revealed non significant expression of the proliferative marker Ki-67 between radioresistant and radiosensitive group. Conclusions: Bcl-2 predicts radioresistance in patients with squamous cell carcinoma of the larynx. It can be used as a marker of poor radiotherapy outcome. Bcl-2 positive patients could be offered an established and equally effective alternative treatment to radiotherapy, eg, partial laryngectomy, resulting in improved patient survival and quality of life.