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.

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 CTVelective-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 CTVelective-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 CTVelective-nodal, overall regional control and overall survival compared to CT-based NTV. A significant proportion of CTVelective-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