18F-FDG-PET/CT-based treatment planning for definitive (chemo)radiotherapy in patients with head and neck squamous cell carcinoma improves regional control and survival

Sven van den Bosch; Patricia A H Doornaert; Tim Dijkema; Ellen M Zwijnenburg; Lia C G Verhoef; Bianca A W Hoeben; Nicolien Kasperts; Ernst J Smid; Chris H J Terhaard; Johannes H A M Kaanders

doi:10.1016/j.radonc.2019.07.025

¹⁸F-FDG-PET/CT-based treatment planning for definitive (chemo)radiotherapy in patients with head and neck squamous cell carcinoma improves regional control and survival

Radiother Oncol. 2020 Jan:142:107-114. doi: 10.1016/j.radonc.2019.07.025. Epub 2019 Aug 19.

Affiliations

¹ Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, The Netherlands. Electronic address: Sven.vandenBosch@radboudumc.nl.
² Department of Radiation Oncology, University Medical Center Utrecht, The Netherlands.
³ Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, The Netherlands.

PMID: 31439447
DOI: 10.1016/j.radonc.2019.07.025

Abstract

Background and purpose: Multimodality imaging including ¹⁸F-FDG-PET has improved the detection threshold of nodal metastases in head and neck squamous cell carcinoma (HNSCC). The aim of this retrospective analysis is to investigate the impact of FDG-PET/CT-based nodal target volume definition (FDG-PET/CT-based NTV) on radiotherapy outcomes, compared to conventional CT-based nodal target volume definition (CT-based NTV).

Materials and methods: Six-hundred-thirty-three patients treated for HNSCC with definitive (chemo)radiotherapy using IMRT/VMAT techniques between 2008 and 2017 were analyzed. FDG-PET/CT-based NTV was performed in 46% of the patients. The median follow-up was 31 months. Diagnostic imaging depicting the regional recurrence was co-registered with the initial CT-scan to reconstruct the exact site of the recurrence. Multivariate Cox regression analysis was performed to identify variables associated with radiotherapy outcome.

Results: FDG-PET/CT-based NTV improved control of disease in the CTV_{elective-nodal} (HR: 0.33, p = 0.026), overall regional control (HR: 0.62, p = 0.027) and overall survival (HR: 0.71, p = 0.033) compared to CT-based NTV. The risk for recurrence in the CTV_{elective-nodal} was increased in case of synchronous local recurrence of the primary tumor (HR: 12.4, p < 0.001).

Conclusion: FDG-PET/CT-based NTV significantly improved control of disease in the CTV_{elective-nodal}, overall regional control and overall survival compared to CT-based NTV. A significant proportion of CTV_{elective-nodal} recurrences are potentially new nodal manifestations from a synchronous local recurrent primary tumor. These results support the concept of target volume transformation and give an indication of the potential of FDG-PET to guide gradual radiotherapy dose de-escalation in elective neck treatment in HNSCC.

Keywords: Elective irradiation; FDG-PET; Head and neck cancer; Nodal target volume definition; Radiotherapy; Target volume transformation.

MeSH terms

Chemoradiotherapy
Female
Fluorodeoxyglucose F18*
Head and Neck Neoplasms / diagnostic imaging*
Head and Neck Neoplasms / drug therapy
Head and Neck Neoplasms / radiotherapy
Head and Neck Neoplasms / therapy*
Humans
Male
Middle Aged
Neoplasm Recurrence, Local / diagnostic imaging
Neoplasm Recurrence, Local / drug therapy
Neoplasm Recurrence, Local / radiotherapy
Neoplasm Recurrence, Local / therapy
Neoplasm Staging
Positron Emission Tomography Computed Tomography / methods
Proportional Hazards Models
Radiopharmaceuticals
Radiotherapy Planning, Computer-Assisted / methods*
Retrospective Studies
Squamous Cell Carcinoma of Head and Neck / diagnostic imaging*
Squamous Cell Carcinoma of Head and Neck / radiotherapy
Squamous Cell Carcinoma of Head and Neck / therapy*
Survival Rate

Substances

Radiopharmaceuticals
Fluorodeoxyglucose F18