Conventional Radiation Therapy vs Stereotactic Conformal Therapy

Jalali and colleagues and the patients who participated in this trial are to be commended for making an invaluable contribution to the literature concerning the understanding of radiation effects. In their prospective randomized clinical trial, Jalali and colleagues describe randomized pediatric and young adult patients with a rare group of low-grade and benign brain tumors to treatment with 1 of 2 radiation therapy techniques. The randomization was stratified for known prognostic factors, including tumor distance to the hypothalamic-pituitary-adrenal axis, pubertal status, baseline neurologic performance, and baseline hydrocephalus. Patients in one arm received standard-of-care conventional radiation therapy (ConvRT), and those in the other received stereotactic conformal therapy (SCRT). Patients in both arms received a radiation dose of 54 Gy (to convert to rad, multiply by 100) delivered in 30 fractions to the tumor target volume. With ConvRT, the target volume was defined on computed tomography (CT) images and patients were immobilized with a face mask; the target dose was delivered through 4 fields to the CT-defined target volume plus a 1- to 2-cm target volume expansion to account for uncertainties in imaging accuracy and possible variations in daily treatment setup. With the SCRT technique, the target was defined on fused CT and magnetic resonance (MR) images, the patient was immobilized with a stereotactic head frame, and the dose was delivered through 6 to 9 noncoplanar fields to the target volume plus a 2- to 3-mm expansion. The use of additional fields with a smaller target volume expansion in the SCRT technique resulted in a moderate-to-high dose volume that was much smaller than the moderate-to-high dose volumes on the ConvRT arm and conformed more precisely to the actual target volume, resulting in a significant reduction in the volume of normal, nontargeted brain tissue receiving moderate-to-high radiation doses. Baseline, interval, and 5-year neurocognitive tests were performed.

http://ift.tt/2qKqyGL