Dual Use of Skeletal Muscle Index and Body Mass Index Measured at the Time of Diagnosis Predicts Prognosis in Children With Malignant Solid Tumors: A Single-Center Retrospective Study.

Background: Sarcopenia, a progressive muscle-wasting disorder, is increasingly being recognized in childhood cancers. While skeletal muscle index (SMI) is commonly used to assess sarcopenia, we investigated the combined utility of SMI and body mass index (BMI) in predicting the prognosis of children with malignant solid tumors.

Methods: The BMI and SMI of 119 children with different types of malignant solid tumors were analyzed. Computed tomography and height at the time of diagnosis were used to determine the SMI. SMI and BMI were standardized using reference values. Cluster and survival time analyses were conducted to identify subpopulations.

Results: Cluster analysis performed using z-scores for SMI and BMI yielded four clusters: Cluster 1 had high z-scores for both indices; Cluster 2 had average z-scores for both indices; Cluster 3 had low z-scores for SMI and average z-scores for BMI; and Cluster 4 had low z-scores for both indices. Cluster classification was an independent prognostic factor for both event-free survival (hazard ratio 1.56; 95% confidence interval: 1.09-2.25) and overall survival (hazard ratio 1.70; 95% confidence interval: 1.10-2.64) after combining age and metastasis. Cluster 1 had low metastasis prevalence and a favorable prognosis, whereas Cluster 4 exhibited a poorer prognosis.

Conclusion: The potential prognoses of the four distinct patient clusters based on the z-scores for SMI and BMI at the time of diagnosis were determined. The dual use of SMI and BMI may facilitate the identification of children with malignant solid tumors who are at a high risk of poor outcomes.