Low-grade soft tissue sarcomas of the extremities. Analysis of risk factors for metastasis.

Of 130 patients with low-grade localized soft tissue sarcomas of the extremities treated at Memorial Hospital between 1968 and 1978, 18 (14%) developed metastases. The risk of metastasis could not be predicted by the clinical or pathologic size, tumor depth, proximal location, recurrence before presentation or subsequent to treatment at our institution, the type of surgical and adjuvant therapies, and the adequacy of surgical margins. The median age of patients with metastases was 10 years older than the other patients (57.5 years and 47.5 years, respectively). Of the more common sarcomas in this study, malignant peripheral nerve tumors and malignant fibrous histiocytomas had the highest prevalence of metastasis (27% (three of 11) and 17% (three of 18), respectively). Although patients with low-grade extremity sarcomas treated during the first 5 years of this review had an increased rate of metastasis, no other patient, tumor, or treatment variable examined significantly differed between the two time periods. Although grade alone is a good predictor of the risk of metastasis from soft tissue sarcomas of the extremity, 14% of patients in this series with low-grade histology developed metastases. Further review of larger numbers of these tumors should be undertaken in an effort to more definitively identify risk factors predictive of metastatic potential in low-grade sarcomas.