Relative tumor burden predicts metastasis-free survival in pediatric osteosarcoma

Background To analyze the significance of relative tumor burden in pediatric osteosarcoma. Methods We retrospectively reviewed 241 patients with localized pediatric osteosarcoma and measured tumor size on MR images at presentation. Absolute tumor size parameters measured on MR images were converted to relative values by dividing body surface area. Both absolute and relative size parameters were analyzed for their correlation with metastasis‐free survival (MFS). Results The 5‐year MFS was 67.5 ± 3.1%, with median follow‐up of 72 months (range, 8–205 months). In addition to poor histologic response (RR 3.24; 95% CI: 1.99–5.28; P