Surveillance MRI for the detection of locally recurrent Ewing sarcoma seems futile

PURPOSE: To determine the frequency of locally recurrent Ewing sarcoma on surveillance MRI and the outcome of these patients.MATERIALS AND METHODS: This retrospective single-center study included all patients with newly diagnosed Ewing sarcoma who underwent surveillance MRI of the primary tumor location after primary treatment between 1997 and 2016.RESULTS: Thirty-two patients underwent a total of 176 local surveillance MRI scans, yielding an average of 5.5 ± 4.4 MRI scans per patient. Follow-up time of surveillance MRI after completion of primary treatment ranged between 1 and 111 months. Surveillance MRI detected five (15.6%) locally recurrent Ewing sarcomas, at 2, 4, 6, 6, and 7 months after completion of primary treatment, of whom three also had simultaneous recurrent (metastatic) disease elsewhere. Two patients had recurrent metastatic disease without any signs of locally recurrent disease on surveillance MRI. All five patients with locally recurrent disease on surveillance MRI died, at 2, 4, 5, 8, and 9 months after local recurrence detection. Patients with locally recurrent disease had a significantly worse overall survival than patients without locally recurrent disease (log-rank test, P < 0.0001).CONCLUSIONS: A limited number of patients have locally recurrent Ewing sarcoma on surveillance MRI. These patients often have simultaneous recurrent (metastatic) disease elsewhere, and their outcome is poor. Moreover, some patients present without locally recurrent disease on MRI but disease recurrence elsewhere. Therefore, surveillance MRI currently seems to have little value and should be reconsidered, also given the costs and the repeated exposure of surviving patients to gadolinium-based contrast agents.