Correlation Between Fluid–Fluid Levels on Initial MRI and the Response to Chemotherapy in Stage IIB Osteosarcoma

Abstract

The presence of fluid-fluid levels (FFLs) on osteosarcoma magnetic resonance imaging (MRI) is underestimated as a nonspecific finding; however, we hypothesized that FFL in conventional osteosarcoma may be indicative of chemoresistance. In 567 stage IIB osteosarcoma patients, we evaluated the following: the incidence of FFL and their correlation with other clinicopathological variables; tumor volume change after chemotherapy and survival according to the presence of FFL; and the relationship between survival and the extent of FFL. One hundred eight (19%) tumors showed FFL on initial MRI. FFL were correlated with proximal humeral location (P=0.017), osteolytic on plain radiographs (P<0.001), tumor enlargement after chemotherapy (P<0.001), and poor histological response (P=0.005). Large tumor (P<0.01), proximal tumor location (P=0.01), and presence of FFL (P<0.01) were independent predictors of poor survival. Compared to the extensive FFL (more than one third of the tumor), small foci of FFL (less than one third of the tumor) showed a high tendency for tumor enlargement after chemotherapy (P<0.001), poor histologic response (P=0.001), and worse survival (P<0.001). FFL on initial MRI could predict tumor progression after chemotherapy. Notably, tumors with small foci of FFL (less than one third of the tumor) have a high propensity for poor outcome. Patients with this finding should be considered for risk-adapted therapy.