Postoperative SBRT in the treatment of early-stage oropharyngeal and oral cavity cancers with high-risk margins: A dosimetric comparison of volumetric modulated arc therapy with or without non-coplanar arcs and acute toxicity outcomes from the STEREOPOSTOP GORTEC 2017-03 phase 2 trial.

Details

Serval ID
serval:BIB_DB540CCA7ED5
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Postoperative SBRT in the treatment of early-stage oropharyngeal and oral cavity cancers with high-risk margins: A dosimetric comparison of volumetric modulated arc therapy with or without non-coplanar arcs and acute toxicity outcomes from the STEREOPOSTOP GORTEC 2017-03 phase 2 trial.
Journal
Clinical and translational radiation oncology
Author(s)
Biau J., Lopez L., Thivat E., Casile M., Millardet C., Saroul N., Pham-Dang N., Molnar I., Bourhis J., Lapeyre M.
ISSN
2405-6308 (Electronic)
ISSN-L
2405-6308
Publication state
Published
Issued date
01/2023
Peer-reviewed
Oui
Volume
38
Pages
169-174
Language
english
Notes
Publication types: Journal Article
Publication Status: epublish
Abstract
The STEREO POSTOP GORTEC 2017-03 phase 2 trial (NCT03401840) evaluates postoperative stereotactic body radiotherapy (SBRT) in case of high-risk margins for pT1-T2/N0 oropharyngeal and oral cavity tumors. The present ancillary study aimed to compare the dosimetric impact of adding non-coplanar arcs to the volumetric modulated arc therapy (VMAT) technique and to evaluate acute toxicities on the first patients included in this trial.
Ten patients were included. Patients were treated with Novalis TX®. The total dose was 36 Gy (100 % isodose line) in 6 fractions, treated every other day. Two treatment plans were created for each patient: one plan using 2 coplanar arcs only (VMATc) and one plan using coplanar and 3 non-coplanar arcs (VMATc + nc). Acute toxicity was evaluated according to NCI CTCAE criteria V4.03.
Median age was 62 years. Localization of tumor was the mobile tongue for 6 patients, floor of mouth for 2, cheek for 1, and gingiva for 1. Six patients had pT2N0 tumors (AJCC 7th edition) and 4 had pT1N0. Mean CTV and PTV volumes were 36.4 and 56.1 cc respectively. Mean PTV coverage by the 36 Gy isodose was 98.2 % for both techniques (p = ns), with comparable conformity indexes (1.1 for VMATc vs 1.07 for VMATc + nc; p = 0.23). VMATc + nc had a significantly better gradient index (3.45 vs 2.97; p = 0.01), resulting in a significantly better sparing of most organs at risk. For example, mean Dmean to the oral cavity, lips, and homolateral parotid were respectively of 16.8 Gy, 11.1 Gy, and 10.4 Gy for VMATc vs 14.8 Gy (p = 0.005), 8.1 Gy (p = 0.001), 6.5 Gy (p = 0.04) for VMATc + nc. No grade ≥ 4 or higher acute toxicity was reported. The most common acute toxicity was grade ≥ 2 mucositis.
VMATc + nc had better dosimetric outcomes than VMATc and has become the standard technique for patients treated in the STEREO POSTOP GORTEC 2017-03 trial (NCT03401840) in our institution. Acute toxicity appears acceptable.
Keywords
Early stage, Head and neck cancers, Postoperative, Stereotactic body radiotherapy
Pubmed
Open Access
Yes
Create date
12/12/2022 11:19
Last modification date
04/01/2023 6:49
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