Objective: To analyze the expression of Ki-67, CD99, P53 and S100 proteins in osteosarcoma tissues by immunohistochemistry, and evaluate the feasibility of these protein expressions in prognosis of malignant bone tumor.
Materials and Methods: Paraffin embedded blocks of osteosarcoma tissues of thirty-two patients were obtained from the Department of Pathology, Faculty of Medicine, Khon Kaen University, Thailand, were analyzed for protein Ki-67, CD99,
P53 and S100 expressions by immunohistochemical technique. The clinical data were collected from pathological record
forms, medical record forms, and database of Tumor Registration Unit. The correlations of protein expressions and survival time were analyzed and evaluated by Kaplan-Meier analysis with log rank test and Cox’s proportional hazards model.
Results: The Ki-67, CD99, P53 and S100 proteins were immunohistochemistrical expressed in osteosarcoma tissues in
93.75%, 68.75%, 37.5% and 12.5% of the cases, respectively. The Ki-67 was statistic significantly correlated with survival
time (p = 0.0116). The osteosarcoma tissue with Ki-67 signal <0.4 showed better prognosis than those with Ki-67 >0.4 (p
= 0.016, adjust HR = 0.156, 95% CI = 0.035 to 0.704), while negatively-stained P53 yielded poor prognostic value when
compared to those with positively-stained P53 (p = 0.027, adjust HR = 5.332, 95% CI = 1.214 to 23.406).
Conclusion: The ki-67 and P53 proteins are likely to be feasible prognostic factors of osteosarcoma. Expression of high signal Ki-67 (signal >0.4) and negative P53 expressions predict poor prognosis in osteosarcoma patients. The study of protein expressions in larger cohort is suggested to affirm the feasibility of clinical use.

Keywords: Osteosarcoma, Immunohistochemistry, Ki-67, CD99, P53, S100, Tumor markers, Prognostic factor