Response Evaluation Criteria in Solid Tumors (RECIST) following neoadjuvant chemotherapy in osteosarcoma.

Background: In osteosarcoma, patient survival has not changed in over 30 years. Multiple phase II trials have been conducted in osteosarcoma using the Response Evaluation Criteria in Solid Tumors (RECIST) as a primary endpoint; however, none of these have revealed new treatment strategies. We investigated RECIST in newly diagnosed patients who received neoadjuvant chemotherapy proven to be beneficial. Methods: Patients treated from 1986 to 2011 for newly diagnosed osteosarcoma with paired tumor imaging before and after adequate neoadjuvant chemotherapy were included in this retrospective study. Two radiologists performed independent, blinded (to image timing) RECIST measurements of primary tumor and lung metastases at diagnosis and post-neoadjuvant chemotherapy. Association between RECIST and histological necrosis and outcome were assessed. Results: Seventy-four patients met inclusion criteria. Five-year overall survival and progression-free survival (PFS) were 77 +/- 7% and 61 +/- 8%, respectively. No patients had RECIST partial or complete response in the primary tumor. Sixty-four patients (86%) had stable disease, and 10 (14%) had progressive disease (PD). PD in the primary tumor was associated with significantly worse PFS in localized disease patients (P = 0.02). There was no association between RECIST in the primary tumor and necrosis. There were an insufficient number of patients with lung nodules >= 1 cm at diagnosis to evaluate RECIST in pulmonary metastases. Conclusions: PD by RECIST predicts poor outcome in localized disease patients. In bone lesions, chemotherapy proven to improve overall survival does not result in radiographic responses as measured by RECIST. Further investigation of RECIST in pulmonary metastatic disease in osteosarcoma is needed.