Interobserver variability of clinical target volume delineation in soft-tissue sarcomas.

Purpose: The present observational study reports the results of a multi-institutional dummy-run designed to estimate the consistency of interobserver variability in clinical target volume delineation in two different cases of soft-tissue sarcomas in which postoperative and preoperative radiotherapy were prescribed, respectively. The purpose of this work was to quantify interobserver variability in routine clinical practice.

Patients And Methods: Two different cases of soft-tissues sarcomas were chosen: a case of postoperative and a case of preoperative radiation therapy. Participating centres were requested to delineate clinical target volumes according to their experience in both cases. Descriptive statistic was calculated for each variable (volume, diameters) separately for two cases. Box-whiskers plots were used for presentation of clinical target volume. A Shapiro-Wilk's test was performed to evaluate the departures from normality distribution for each variable. The comparison between relative variations of diameters was evaluated using the Student's t test.

Results: Several variations affecting both volumes and diameters were observed. Main variations were observed in the craniocaudal and laterolateral diameters. Each case showed similar dispersion, indicating a lack of reproducibility in volumes definition.

Conclusions: This observational study highlighted that, in the absence of specific instructions or guidelines, the interobserver variability can be significant both in postoperative and preoperative radiotherapy of soft-tissue sarcomas.