Prognostic value of bax, bcl-2, and p53 staining in primary osteosarcoma. To investigate the immunohistochemical expression of three apoptosis-related genes (bax, bcl-2, and p53) and apoptosis (TUNEL) in patients with primary osteosarcoma, and examine potential correlations between gene expression and clinicopathological characteristics in these patients.Thirty-five primary osteosarcoma specimens and 18 tissue specimens deriving from non-malignant osseous lesions were immunohistochemically stained for bax, bcl-2, and p53 proteins, while apoptosis was investigated by the TUNEL method. The results were statistically analyzed.P53, bax, and bcl-2 protein expression was observed in 22 (62.9%), 29 (82.9%), and 18 (51.4%) osteosarcoma patients, respectively. Non-specific positive TUNEL staining (+/-) was observed in two primary osteosarcoma cases (5.7%). None of the benign controls expressed any of the genes studied. None of the apoptosis-related genes studied was able to predict overall or disease-free survival in our group of patients. Nevertheless, increased bax/bcl-2 protein expression ratio was associated with a decreased 4-year survival and disease free survival (P = 0.0229 and P = 0.0370, respectively). Furthermore, all the patients who were bax(+)/bcl-2(-)/p53(+) relapsed within the 4-year follow-up period (P = 0.0385).The increased apoptotic rate as determined by an elevated bax/bcl-2 protein expression ratio or by the bax(+)/bcl-2(-)/p53(+) protein expression pattern, appears to identify groups of osteosarcoma patients with unfavorable prognosis.2007 Wiley-Liss, Inc