Size and tinning of local recurrence predicts metastasis in soft tissue sarcoma Growth rate index retrospectively analyzed in 134 patients

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Abstract
Our study combined size and timing of the first local recurrence to create a growth rate index (GRI- ratio of size (cm) to timing (mo)) which we analyzed for an association with metastasis. We analyzed 134 locally recurrent tumors from a series of 460 adult patients with soft tissue sarcoma of the extremities and trunk wall who were diagnosed and treated between 1964 and 1990, with a median follow-up of 10 (2-28) years for survivors. None of the patients had metastases at diagnosis. One half (74) of local recurrences were from inadequately treated primaries, one half (71) were associated with metastases, and two thirds (89) were seen in non-center-treated patients. There were equal numbers of patients with GRI < 0.4 (low) and > 0.4 (high). Patients with a low GRI had a better 2-year metastasis-free survival (80 percent) than those with a high GRI (30 percent). High GRIs were associated with large, high grade primary tumors and a short metastasis-free interval in comparison to low GRI tumors. Time to local recurrence strongly correlated with the time to metastasis (R2 0.85, p < 0.001). GRI was a good discriminator of metastasis in patients with tumors larger than 5 cm and of malignancy grade IV. Our study suggests that clinical characteristics (e.g., GRI) of local recurrence rather than presence, per se, are important in predicting tumor behavior.