Locoregional control using highly conformal flank target volumes and volumetric-modulated arc therapy in pediatric renal tumors: Results from the Dutch national cohort

Joeri Mul,Martine Van Grotel,Enrica Seravalli,Mirjam E Bosman,Harm Van Tinteren,Prakriti Roy,Raquel Dávila Fajardo,Godelieve A.M Tytgat,Annelies M.C Mavinkurve-Groothuis,Cornelis P Van De Ven,Marc H.W.A Wijnen,Ronald R De Krijger,Annemieke S Littooij,Marry M Van Den Heuvel-Eibrink,Geert O Janssens

doi:10.1016/j.radonc.2021.04.005

Joeri Mul, Martine Van Grotel + Show 13 more

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https://doi.org/10.1016/j.radonc.2021.04.005

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Abstract

Background and purposeIn pediatric renal tumors, conventional two opposing photon beams have been used to cover the postoperative flank target volume for decades. This single center study describes the locoregional outcome using highly conformal flank target volumes adjusted for postoperative changes and intra-fraction motion combined with Volumetric-Modulated Arc Therapy (VMAT). Materials and methodsBetween 01-2015 and 12-2019, 36/161 newly diagnosed patients with renal tumors underwent flank only irradiation (n = 30) or flank + whole lung irradiation (n = 6) using highly conformal target volumes in line with the SIOP-RTSG consensus statement. VMAT consisted of full-arc 10MV photon beams optimized for constraints of the organs at risk. In case of locoregional relapses, image co-registration and dose reconstruction was performed. Each relapse was classified as either ‘infield’ (V95%relapse: ≥99.0%), ‘marginal’ (V95%relapse: 20.0–98.9%) or ‘outfield’ (V95%relapse: 0–19.9%). ResultsAt a median follow-up from diagnosis of 3.1 years (range:0.4–5.7), the estimated 2-year Locoregional Control Rate, Disease-Free Interval and Overall Survival were 94%, 91% and 94%, respectively. Locoregional relapse was observed in two patients. One patient had a combined tumor bed and regional recurrence, classified as infield (V95%relapse: 100%) and outfield (V95%relapse: 1.2%). The second patient had a regional relapse in the inferior vena cava classified as marginal recurrence (V95%relapse: 93%). Relapses would not have been adequately covered by conventional beams. ConclusionsThis single center analysis provides encouraging evidence that excellent locoregional control can be obtained by using highly conformal flank target volumes with VMAT in pediatric renal tumors. The safety of this approach will be validated in a prospective multicenter study.

Highlights

Background and purposeIn pediatric renal tumors, conventional two opposing photon beams have been used to cover the postoperative flank target volume for decades
Children with a local stage II Wilms tumors (WT) with diffuse anaplastic histology, local stage III WT with Intermediate-/High-risk (IR/HR) histology, local stage I–III Malignant Rhabdoid Tumors of the Kidney (MRTK) or local stage II–III Clear Cell Sarcoma of the Kidney (CCSK), were irradiated by Volumetric-Modulated Arc Therapy (VMAT) on highly conformal flank volumes with dose prescriptions according to the SIOP-RTSG-2001 (EudraCT number 2007004591-39), the SIOP-RTSG-UMBRELLA-2016 (EudraCT number 2016 004180 39) or the European Rhabdoid Registry guideline (EU-RHAB version 2.0, 2010), and included in the current descriptive analysis (Supplementary Table 1)
The first relapsed patient, at primary diagnosis irradiated for a localized left-sided intermediate-risk stage III WT because of a positive resection margin, developed tumor recurrence at the ipsilat

Summary

Introduction

Conventional two opposing photon beams have been used to cover the postoperative flank target volume for decades. This single center study describes the locoregional outcome using highly conformal flank target volumes adjusted for postoperative changes and intra-fraction motion combined with Volumetric-Modulated Arc Therapy (VMAT). Conclusions: This single center analysis provides encouraging evidence that excellent locoregional control can be obtained by using highly conformal flank target volumes with VMAT in pediatric renal tumors. The safety of this approach will be validated in a prospective multicenter study.

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