Prognostic value of bax, cytochrome C, and caspase-8 protein expression in primary osteosarcoma. The prognostic significance of bax, cytochrome c, and caspase-8 in patients with primary osteosarcoma is unknown. We examined the immunohistochemical expression of these genes in 35 surgically treated patients with primary osteosarcoma. Clinicopathological and survival data were correlated with the staining result. Eighteen tissue specimens from non-malignant osseous lesions were used as controls. Bax, cytochrome c, and caspase-8 positive staining was observed in 29 (82.9%), 16 (45.7%), and 0 (0%) patients, respectively, but did not stain any of the 18 benign osseous lesions used as controls. None of the genes studied predicted overall or disease-free survival. Patients, however, bearing bax(+)/cytochrome c(+) or bax(+)/cytochrome c(+ +) tumors had a decreased 4-year disease-free survival rate compared to the rest of the group (p = 0.0489 and p = 0.0208, respectively), identifying two groups of patients where more intensive adjuvant treatment could possibly be applied to prevent high postoperative recurrence rates.