Background: Prognostic factors for metastasis in soft tissue sarcoma govern decisions regarding adjuvant treatment. However, the significance of initial tumor-related prognostic factors over time is largely unknown.
Methods: The current study included 338 patients with malignant fibrous histiocytoma (MFH) of the extremities or the trunk wall whose tumors were reviewed by the Scandinavian Sarcoma Pathology Review Group. Of these 338 patients, 329 (97%) had high-grade tumors. The median follow-up period was 7 years. Metastases occurred in 110 of 338 of patients after a median follow-up period of 14 months, with roughly one-third (32 of 110) occurring after 2 years. The authors investigated the prognostic significance of tumor size, tumor depth, histologic grade, microscopic tumor necrosis, vascular invasion, mitotic rate, and local tumor recurrence at various time intervals using metastases as an endpoint.
Results: On univariate analysis, all investigated factors were found to be correlated with metastases for the entire follow-up period and also for the first 2 years of follow-up; beyond this time point, only size, tumor depth, and local recurrence were significant. On multivariate analysis, necrosis and local tumor recurrence were significant for the entire follow-up duration and also for the first 2 years of follow-up, whereas only tumor depth and local recurrence were significant beyond 2 years of follow-up. For all initial factors, the annual metastasis risks in the high-risk and low-risk groups converged to < 0.1 after 2 years and to near 0 after 5 years.
Conclusions: Prognostic factors for metastasis in MFH were time dependent. The predictive value of the initial prognostic factors was limited to the first 2 years of follow-up. The lack of observed prognostic value beyond 2 years of follow-up probably was attributable to heterogeneity within risk categories as a result of measurement errors and unknown biologic variations.
Copyright 2004 American Cancer Society.