Innovation in the management of soft tissue sarcomas in infants and young children: high-dose-rate brachytherapy.

PURPOSE

Conventional low-dose-rate (LDR) brachytherapy is effective in treating childhood sarcomas, but often not practical (due to the associated radiation hazards) in the young children who require continuous observation and sedation. Fractionated high-dose-rate brachytherapy (HDR) was used to deliver adequate tumoricidal radiation while preserving bone and organ growth in children.

MATERIALS AND METHODS

Twelve children with diverse sarcomas were treated with fractionated HDR. The median age at diagnosis was 18 months (range, 1 to 42). Nine patients had rhabdomyosarcoma and three had other soft tissue sarcoma (STS) variants. Ten patients had microscopic residual disease at the time of brachytherapy. All patients were treated with appropriate chemotherapy and surgery. HDR was delivered in 3-Gy fractions twice a day to a total dose of 36 Gy in 8 days. External-beam radiation therapy (EBRT) was avoided. Patients were monitored for a median of 61 months (range, 30 to 78).

RESULTS

One patient developed local recurrence and distant metastases to the lungs. The 6-year actuarial local control and overall survival rates were 91% and 81%, respectively. Brachytherapy-related morbidity occurred in 50% of patients. The morbidity was mild to moderate in 42% of patients and consisted primarily of acute skin and mucosal reaction. One patient experienced severe (grade III to IV) toxicity. Another child, treated to the tongue, had delayed dentition only in the teeth adjacent to the brachytherapy site. The other children have exhibited only minimal or none of the bone growth retardation expected with EBRT.

CONCLUSION

The combination of conservative surgery, chemotherapy, and exclusive HDR to postchemotherapy tumor volume with a modest margin, avoiding EBRT, provided disease control in carefully selected young children, while preserving bone growth and organ function. The short duration of therapy and small volume irradiated allowed chemotherapy to be resumed shortly after brachytherapy. The use of HDR challenges the present philosophy of radiotherapy treatment volume, which holds that the prechemotherapy tumor volume should be treated with an acceptable margin. Brachytherapy should be included in multicentric clinical trials in young children.