Prediction of survival in children with rhabdomyosarcoma after chemotherapy by three-dimensional radiology

  Objective  To evaluate the survival situations of children with rhabdomyosarcoma (RMS) after chemotherapy predicted by three-dimensional radiology.

  Methods  A total of 66 patients with RMS who received chemotherapy were retrospectively analyzed. Four methods were used to measure the tumor size on magnetic resonance or computed tomography images before and after chemotherapy. Maximal diameter was measured with Response Evaluation Criteria in Solid Tumors (1D-RECIST); multiplying the two maximal diameters was calculated with World Health Organization (2D-WHO); multiplying the three maximal diameters was calculated with European pediatric soft tissue sarcoma Study Group (3D-EpSSG); a software-assisted volume assessment was measured with the 3D-Osirix. Patients were classified as responders or non-responders based on the proposed thresholds for each method. Tumor response was compared with survival using Kaplan-Meier plots, the log-rank test, and Cox's regression.

  Results  Kaplan-Meier results showed that among the three methods, 5-year event free survival (5y-EFS) responders were longer than non-responders, and the difference of 3D-EpSSG evaluation between responder and non-responder was better than 1D-RECIST or 2D-WHO (P_1D-RECIST=0.018, P_2D-WHO=0.007, P_3D-EpSSG and P_3D-OsiriX < 0.001). In terms of 5y-EFS between the two groups, the adjusted hazard ratio of 1D-RECIST was 3.57 (P=0.016), 5.05 for 2D-WHO (P=0.004), 14.40 for 3D-EpSSG (P < 0.001), and 11.60 for 3D-Osirix (P < 0.001).

  Conclusion  Early tumor response is confirmed as a significant prognostic factor in RMS, and 3D-EpSSG and 3D-Osirix methods are superior to 1D-RECIST and 2D-WHO in predicting survival after chemotherapy for RMS.