Bax, cytochrome c, and caspase-8 staining in parotid cancer patients: Markers of susceptibility in radiotherapy?

Abstract

Objective: Negative bcl-2 and HLA-DR protein expression have been associated with responsiveness to adjuvant radiotherapy in surgically treated parotid cancer patients. The aim of this study was to investigate the prognostic significance of bax, cytochrome c, and caspase-8 protein expression in a group of surgically treated patients to determine whether they also suggest markers of responsiveness to adjuvant radiotherapy. Study Design: Historical cohort study. Setting: Otolaryngology department in a university hospital. Subjects and Methods: The immunohistochemical expression of bax, cytochrome c, and caspase-8 were studied in paraffin-embedded tissue specimens originating from 27 surgically treated parotid cancer patients and nine patients with Warthin parotid tumors (control group) and correlated with the patients' clinicopathological characteristics and clinical outcome. Results: Caspase-8 negative staining was more frequently observed in higher TNM stages and in tumors measuring more than 4 cm ( P = 0.009 and P = 0.018, respectively). Caspase-8 (−)/cytochrome c (−) patients carried low-grade lesions without nodal involvement ( P = 0.01 and P = 0.05, respectively). Caspase-8 (−) patients who received postoperative radiotherapy presented a significantly increased disease-free survival compared to those who did not ( P = 0.04). Patients bearing bax (−) tumors who received postoperative radiotherapy presented an improved four-year disease-free survival compared to bax (−) patients who did not receive any type of adjuvant radiotherapy ( P = 0.017). Conclusion: Bax, cytochrome c, and caspase-8 protein expression failed to independently predict survival in parotid cancer patients. However, patients with bax (−) or caspase-8 (−) tumors should be considered as candidates for adjuvant radiotherapy in order to achieve better local disease control.