Intensity modulated radiation therapy (IMRT) is a feasible alternative for imaging children and adolescents, according to a retrospective analysis published Sept. 23 in Radiation Oncology.
According to Florian Sterzing, MD, and colleagues from the department of radiology at the University of Heidelberg in Germany, the study summarized the facility's experience of treating 31 children (mean age of 14.2 years) with IMRT between 1999 and 2008 in the departments of radiation oncology and anesthesiology.
The group of patients had 20 different tumor entities with Ewing’s sarcoma occurring in five patients, and juvenile nasopharyngeal fibroma, esthesioneuroblastoma and rhabdomyosarcoma occurring in three patients each. The authors also reviewed the available literature on technology, quality, toxicity, outcome and concerns of IMRT.
According to the authors, as a technique IMRT has provided “remarkable advances in target conformity, dose escalation in the target volume and sparing of neighboring organs at risk.” This has allowed physicians to irradiate patients with complex-shaped tumors in difficult locations, who previously could not be treated with conventional radiation methods.
But, while IMRT has been widely used for adults, it has been used with more caution with children. The reasons, the authors said, include concerns about increased fraction time, a need “for exact immobilization with tailor-made steep dose gradients present" and worries about inducing a secondary malignancy through changes in low dose spillage or integral dose.
In the 31 children treated, reported side effects included low-grade skin erytherna, mucositis, local alopecia, mild nausea and diarrhea, loss of taste and epistaxis. Pancytopenia occurred in four patients who also received chemotherapy.
One patient developed thoracic scoliosis two years following spine irradiation, one adolescent—also treated with chemotherapy—made claims of hypoaestesia in his right forearm two years after his upper thoracic wall was irradiated, and one girl developed enophthalmia after being irradiated for Ewing’s sarcoma of the orbit.
The authors reported that while their experience shows that IMRT could be applied “with only few low-grade acute toxicities and hardly any long-term side effects so far,” it should be noted that the follow period has been short as far as assessing any secondary malignancies that might occur in the study group.
They concluded that IMRT is a feasible method of radiotherapy for pediatric malignancies based on the experiences in their clinic. For the 31 patients in the analysis, it was decided that the benefit of increased tumor control probabilities and improved sparing of organs from radiation doses was greater than the calculated risk of late side effects from the treatment.
However, the authors warned, since “the risk of secondary cancer induction can only be estimated, IMRT for children should only be used with caution.”