Undervaluation of Radiotherapy for Gross Desmoid Tumors: The Need for Absolute Volume Assessment

Background/Aim: To compare absolute volume (AV) assessment according to Response Evaluation Criteria in Solid Tumors (RECIST) for the response evaluation of desmoid tumors (DTs) treated with radiotherapy. Patients and Methods: Eighteen patients with DTs ≥3 cm in size were included. Results: The median follow-up duration was 78.0 months. Five patients achieved a complete response according to RECIST, seven reached a partial response (PR), and one eventually exhibited progression. The overall response rate was 61%, the median time to PR was 8.0 months. Six patients achieved stable disease, although three developed progressions. Of the six patients with a PR, the median change in maximum diameter was −46%, and the median change in maximum volume was −84%. Three patients could have been diagnosed with progression at least 6 months earlier if the AV increment was considered. Conclusion: An AV assessment is essential for an accurate response assessment of DTs and radiotherapy seems feasible as a first-line treatment for DTs.