Abstract
BackgroundDiffusion-weighted imaging (DWI) has been described to correlate with tumoural necrosis in response to preoperative chemotherapy for osteosarcoma.ObjectiveTo assess the accuracy of DWI in evaluating the response to neoadjuvant chemotherapy at the mid-course treatment of long-bone osteosarcoma and in predicting survival.Materials and methodsWe conducted a prospective single-centre study over a continuous period of 11 years. Consecutive patients younger than 20 years treated with a neoadjuvant regimen for peripheral conventional osteosarcoma were eligible for inclusion. Magnetic resonance imaging (MRI) with DWI was performed at diagnosis, and mid- and end-course chemotherapy with mean apparent diffusion coefficients (ADC) calculated at each time point. A percentage less than or equal to 10% of the viable residual tissue at the histological analysis of the surgical specimen was defined as a good responder to chemotherapy. Survival comparisons were calculated using the Kaplan-Meier method. Uni- and multivariate analyses with ADC change were performed by Cox modelling. This is an expansion and update of our previous work.ResultsTwenty-six patients between the ages of 4.8 and 19.6 years were included, of whom 14 were good responders. At mid-course chemotherapy, good responders had significantly higher mean ADC values (P=0.046) and a higher increase in ADC (P=0.015) than poor responders. The ADC change from diagnosis to mid-course MRI did not appear to be a prognosticator of survival and did not impact survival rates of both groups.ConclusionDWI at mid-course preoperative chemotherapy for osteosarcoma should be considered to evaluate the degree of histological necrosis and to predict survival. The anticipation of a response to neoadjuvant treatment by DWI may have potential implications on preoperative management.
Highlights
Materials and methodsOsteosarcoma is the most common malignant bone tumour in adolescents and young adults [1]
A good response to neoadjuvant chemotherapy was defined as a surgical specimen section composed of 10% or less of viable tumoural cells, and a poor response as more than 10% of viable tumoural cells
We selected known risk factors reported in the literature, i.e. tumour volume, metastases at diagnosis, and poor histological response to neoadjuvant chemotherapy, as well as apparent diffusion coefficient (ADC) change from Magnetic resonance imaging (MRI)-1 to MRI-2, to test their prognostic potential for overall survival
Summary
Materials and methodsOsteosarcoma is the most common malignant bone tumour in adolescents and young adults [1]. The response to preoperative chemotherapy is a strong predictor of local recurrence and outcome, and impacts decisions regarding postoperative checmotherapy and further surgery [3, 4]. Postoperative histological analysis of the bone specimen remains the reference standard to determine the response to neoadjuvant chemotherapy [5,6,7]. Neoadjuvant regimen adjustment decisions have been based on visual interpretation of volume change during neoadjuvant chemotherapy. This does not provide reliable predictive values of tumour behaviour [8,9,10]. Diffusion-weighted imaging (DWI) has been described to correlate with tumoural necrosis in response to preoperative chemotherapy for osteosarcoma
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