The dosimetric and clinical advantages of the GTV-CTV-PTV margins reduction by 6 mm in head and neck squamous cell carcinoma: Significant acute and late toxicity reduction

Abrahim Al-Mamgani, Rob Kessels, Tomas Janssen, Arash Navran, Suzanne van Beek, Casper Carbaat, Willem H. Schreuder, Jan-Jakob Sonke, Corrie A. M. Marijnen

Research output: Contribution to journalArticleAcademicpeer-review

9 Citations (Scopus)

Abstract

Purpose: We aim to identify the dosimetric and clinical impact of reducing the total GTV-CTV-PTV margins in head-and-neck squamous cell carcinoma (HNSCC) treated with definitive (chemo)radiation. Materials and methods: The acute and late toxicity and outcomes of 155 consecutive patients treated between February 2017 and March 2019 with GTV-CTV-PTV margins of 9 mm were compared to those of 155 consecutive patients treated with total margin of 15 mm margin, before April 2015. All patients were treated with VMAT with daily-image guidance using CBCT. Results: Reducing the GTV-CTV-PTV by 6 mm resulted in significant reduction of total irradiated volume (PTV-total) by a median of 28.1% and significant reduction of doses to all salivary glands (largest reduction ipsilateral parotid gland; median −9.6 Gy) and constrictor muscle (−6.1 Gy) with subsequent reduction of the incidence of overall acute grade 3 toxicity (47.7% for 9 mm and 66.5% for 15 mm groups, p = 0.001), grade 3 mucositis (18.1% vs. 35.5%, p < 0.001) and feeding tube-dependency at the end of treatment (24.5% vs. 40%, p = 0.005). The incidence of late grade ≥ 2 xerostomia and dysphagia were also significantly lower in the 9 mm group (31.7% vs. 58.6% p < 0.001, and 15.4% vs. 26.7%, p = 0.04). The 2-year rates of loco-regional control, disease-free and overall survival were 78.8% vs.75.8%, 70.9% vs. 64.4%, and 83.8% vs. 67.6%, (p > 0.05, all). Conclusion: Reduction of the total GTV-CTV-PTV margins from 15 to 9 mm in HNSCC significantly reduced the irradiated volumes and the dose to salivary glands and constrictor muscle with significant reduction of radiation-related toxicity. The loco-regional control rates of both groups were comparable.
Original languageEnglish
Pages (from-to)16-22
Number of pages7
JournalRadiotherapy and oncology
Volume168
DOIs
Publication statusPublished - 1 Mar 2022

Keywords

  • GTV-CTV-PTV margin reduction
  • HNSCC
  • Head and neck cancer
  • Locoregional control
  • Toxicity
  • VMAT

Cite this