Ki-67 is strongly prognostic in synovial sarcoma: analysis based on 86 patients from the Scandinavian Sarcoma group register.

In a study based on formalin-fixed paraffin-embedded material from 86 patients with primary synovial sarcoma located in the extremities or on the trunk wall, the prognostic importance of MIB-1 index, p53-expession and tumour size was analysed. Multivariate analysis identified two metastatic risk factors: increasing tumour size and MIB-1 > 9%. The 5-year metastasis-free survival-rate for patients with tumour size < or = 5 cm + MIB-1 < 10% was 0.83 (95% confidence interval (CI) 0.64-0.92) compared to 0.31 (95% CI 0.11-0.53) in cases with tumour size > 5 cm + MIB-1 > or = 10%. Our study shows that metastatic disease in synovial sarcoma is closely related to MIB-1 index. Using our model based on tumour size and MIB-1 index, cases with good and poor prognosis can easily be discriminated. Therefore our model can be used to identify patients who should be considered for adjuvant chemotherapy.