Prognosis following locally recurrent soft-tissue sarcoma. A staging system based on primary and recurrent tumour characteristics.

We have shown that the clinical growth rate of local recurrence from soft-tissue sarcoma could be expressed as a growth-rate index (GRI) which was predictive for metastasis, and which was able to identify 2 equal populations of good (80% 2-year MFS) and poor survivors (33%). We now report the associations between characteristics of the primary and GRI, and combine primary and locally recurrent tumour characteristics in a staging system. We studied 460 adult patients with soft-tissue sarcomas of the extremities and trunk wall who were diagnosed and treated between 1964 and 1990, of whom 134 developed local recurrences and 151 metastases. The association of primary tumour size, histologic malignancy grade, depth, spontaneous necrosis, intratumoral vascular invasion and S-phase fraction with local recurrence, GRI and metastasis were examined. High GRI was associated with primary tumours that were larger, deeper, more malignant, underwent spontaneous tumour necrosis, demonstrated intravascular invasion and had a higher S-phase fraction. The same factors were also strongly associated with the incidence of metastasis. A multivariate analysis found GRI and primary tumour necrosis to be the strongest and most significant prognostic factors. GRI and tumour necrosis were combined in a staging system that identified groups with good survival (79 to 94% 2-year MFS), intermediate survival (61% 2-year MFS) and exceptionally poor survival (6% 2-year MFS). These findings validate our earlier assertion that high GRI reflects highly malignant tumours. A staging system composed of primary tumour necrosis and GRI can identify patients who may be suitable candidates for trials of adjuvant chemotherapy.