Bone Metastases, Skeletal-related Events, and Survival Among Children With Cancer in Denmark

Bone metastases and skeletal-related events (SREs), including radiation therapy or surgery to bone, pathologic fracture, or spinal cord compression, among children have not been described in a population-based study. We examined the rate of bone metastasis, SREs, and survival in the Danish pediatric cancer population. We identified children below 18 years with a first-time diagnosis of cancer between January 1, 1994 and December 31, 2009 in the Danish Cancer Registry. From the Danish National Registry of Patients, we obtained bone metastasis and SRE diagnoses, and estimated incidence rates (IRs). We estimated 6-month, 1-year, and 5-year survival using Kaplan-Meier curves. Of 2652 children, 35 (1.3%) developed bone metastasis during a mean follow-up of 7.0 years (IR = 1.9 per 1000 person-years [95% confidence interval (CI), 1.4-2.6]). IRs were substantially higher among children with solid tumors than those with hematologic malignancies (IR = 3.2 [95% CI, 2.3-4.6] and IR = 0.48 [95% CI, 0.18-1.3]). Survival was poorer for children with bone metastasis than those without bone metastasis. Among children with bone metastasis, 67% experienced an SRE during a mean follow-up of 1.1 years, yielding an IR of 590 per 1000 person-years (95% CI, 381-915). Bone metastases are rare among children with cancer, but SREs are a common consequence.