Objectives: To determine if radiological response to preoperative radiotherapy is related to oncologic outcome in patients with extremity soft tissue sarcomas (STS). Methods: 309 patients with extremity STS who underwent preoperative radiation and wide resection were identified from a prospective database. Pre-and post-radiation MRI scans were retrospectively reviewed. Radiological response was defined by the modified Response Evaluation Criteria in Solid Tumours (RECIST).Local recurrence-free (LRFS), metastasis-free (MFS) and overall survival (OS) were compared across response groups. Results: Tumour volume decreased in 106 patients (34.3%; PR- Partial Responders), remained stable in 97 (31.4%; SD- Stable Disease), increased in 106 (34.3%; PD- Progressive Disease). The PD group were older (p = 0.007), had more upper extremity (p = 0.03) and high grade tumours (p < 0.001). 81% of myxoid liposarcomas showed substantial decrease in size. There was no difference in initial tumour diameter (p = 0.5), type of surgery (p = 0.5), margin status (p = 0.4), or complications (p = 0.8) between the three groups. There were ten (3.2%) local recurrences with no differences between the three response groups (p = 0.06). Five-year MFS was 52.1% for the PD group versus 73.8 and 78.5% for the PR and SD groups respectively (p < 0.001). OS was similar (p < 0.001). Following multivariable analysis, worse MFS and OS were associated with higher grade, larger tumour size at diagnosis and tumour growth following preoperative radiation. Older age was also associated with worse OS. Conclusion: STS that enlarge according to RECIST criteria following preoperative radiotherapy identify a high risk group of patients with worse systemic outcomes but equivalent local control. Advances in knowledge: Post radiation therapy, STS enlargement may identify patients with potential for worse systemic outcomes but equivalent local control. Therefore, adjunct therapeutic approaches could be considered in these patients.
Histology-based Classification Predicts Pattern of Recurrence and Improves Risk Stratification in Primary Retroperitoneal Sarcoma