What does equivocal end-of-therapy imaging say about recurrence in pediatric sarcoma?

Amongst patients with Ewing sarcoma (EWS) or rhabdomyosarcoma (RMS) who received radiotherapy (RT) for local control, end-of-therapy imaging studies that showed equivocal findings did not indicate a higher risk of local recurrence than negative findings, according to a study.

“Posttherapy imaging studies can provide reassurance or induce anxiety regarding risk of recurrence for patients and their families,” the authors wrote. “In some cases, it is difficult to determine if imaging findings represent posttreatment changes or residual disease.”

Researchers analyzed posttherapy scans and identified negative imaging findings in 51 cases with a negative predictive value of 88% and positive imaging findings in 1 with a positive predictive value of 100%. There were equivocal findings in 16 cases; when these were categorized with negative results, the negative predictive value was 90%, and when they were categorized with positive results, the positive predictive value was 12%.

“These results may contribute to appropriate surveillance schedules and accurate counseling of patients with RMS and EWS who have received RT for local control,” the authors concluded.

Reference
McLean-Thomas L, Gao D, Trenbeath Z, et al. Equivocal end-of-therapy imaging findings do not predict a higher risk of local relapse after definitive radiotherapy in pediatric Ewing sarcoma and rhabdomyosarcoma. Pediatr Blood Cancer. 2023;e29989. doi: 10.1002/pbc.29989. Epub ahead of print. PMID: 36726177.