Objective  To investigate the expression level of serum interleukin-33 (IL-33) and its correlation with pulmonary metastasis in children with primary osteosarcoma.

  Methods  A total of 126 children with osteosarcoma were selected asstudy subjects, they were divided into osteosarcoma pulmonary metastasis group (n=39) and osteosarcoma group (n=87) according to whether the children had pulmonary metastasis, and forty healthy children were selected as control group.The incidence of pulmonary metastasis in children with osteosarcoma was recorded and the differences in serum IL-33 levels among the three groups were compared.The risk factors of lung metastasis in children with osteosarcoma were analyzed and the clinical efficacy of IL-33 in the diagnosis of lung metastasis in osteosarcoma were evaluated.

  Results  The incidence of pulmonary metastasis in one hundred and twenty-six children with osteosarcoma was 30.95% (39/126).The expression level of serum IL-33 in lung metastatic osteosarcoma group was significantly higher than that in the control group and osteosarcoma group (P < 0.01). The expression level of serum IL-33 in the osteosarcoma group was significantly higher than that in the control group (P < 0.01).The expression level of serum IL-33 in children with osteosarcoma was closely related to tumor diameter, alkaline phosphatase (AKP) level, pathological stage and pulmonary involvement.Pathological stage (OR=8.478), serum IL-33 level (OR=5.223) and tumor diameter (OR=2.235) were all independent risk factors for pulmonary metastasis in children with osteosarcoma. The area under the curve (AUC) of serum IL-33 expression level in diagnosing pulmonary metastasis in children with osteosarcoma was 0.923 (95%CI ranging from 0.876 to 0.970). When the cut-off value of IL-33 was 120.47 ng/mL, the sensitivity and specificity were 82.10% and 86.20%, respectively.

  Conclusion  IL-33 may be as a serological marker of pulmonary metastasis in osteosarcoma children.