Kidney-sparing whole abdominal irradiation in Wilms tumor: Potential advantages of VMAT technique

To present a preliminary clinical experience and a dosimetric comparison of kidney-sparing volumetric modulated arc therapy (VMAT) with three-dimensional conformal radiotherapy (3D-CRT) for whole abdominal irradiation (WAI), in the setting of Wilms tumor (WT) treatment.

From a total of 20 consecutive WT cases treated with adjuvant irradiation, seven were submitted to WAI with VMAT. Renal function and survival rates were evaluated, and, for comparison purposes, similar VMAT and 3D-CRT treatment plans were performed for WAI patients, and differences were dosimetrically evaluated regarding doses to the remaining kidney and other organs at risk and the planning target volume (PTV).

After a median follow-up time of 40.8 months (35.3-52.2), no acute significant intestinal toxicity was observed, and median creatinine clearance was 110.1 and 103.3 mL/min/1.73 m², respectively, before treatment and at last follow-up for WAI patients (P = 0.128). For comparative plans, maximum and median doses were lower for the remaining kidney with VMAT than with 3D-CRT. VMAT was associated with better PTV coverage as compared with 3D-CRT, with superior results for all the evaluated parameters (D95, D2, V100%, V98%, V95%; P = 0.018).

The use of VMAT technique is associated with lower radiation doses to the remaining kidney and better coverage to the PTV than 3D-CRT technique for WAI, with preliminary clinical experience showing a favorable toxicity profile. Long-term results from prospective studies might prove the ability of VMAT to spare renal function in the setting of WT treatment.