The tubarial salivary glands: A potential new organ at risk for radiotherapy

Matthijs H Valstar*, Bernadette S de Bakker, Roel J H M Steenbakkers, Kees H de Jong, Laura A Smit, Thomas J W Klein Nulent, Robert J J van Es, Ingrid Hofland, Bart de Keizer, Bas Jasperse, Alfons J M Balm, Arjen van der Schaaf, Johannes A Langendijk, Ludi E Smeele, Wouter V Vogel

*Corresponding author for this work

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Abstract

Introduction: The presence of previously unnoticed bilateral macroscopic salivary gland locations in the human nasopharynx was suspected after visualization by positron emission tomography/computed tomography with prostate-specific membrane antigen ligands (PSMA PET/CT). We aimed to elucidate the characteristics of this unknown entity and its potential clinical implications for radiotherapy.

Materials and methods: The presence and configuration of the PSMA-positive area was evaluated in a retrospective cohort of consecutively scanned patients with prostate or urethral gland cancer (n = 100). Morphological and histological characteristics were assessed in a human cadaver study (n = 2). The effect of radiotherapy (RT) on salivation and swallowing was retrospectively investigated using prospectively collected clinical data from a cohort of head-neck cancer patients (n = 723). With multivariable logistic regression analysis, the association between radiotherapy (RT) dose and xerostomia or dysphagia was evaluated.

Results: All 100 patients demonstrated a demarcated bilateral PSMA-positive area (average length 4 cm). Histology and 3D reconstruction confirmed the presence of PSMA-expressing, predominantly mucous glands with multiple draining ducts, predominantly near the torus tubarius. In the head-neck cancer patients, the mean RT dose to the gland area was significantly associated with physician-rated posttreatment xerostomia and dysphagia >= grade 2 at 12 months (0.019/gy, 95%CI 0.005-0.033, p =.007; 0.016/gy, 95%CI 0.001-0.031, p =.036). Follow-up at 24 months had similar results.

Conclusion: The human body contains a pair of previously overlooked and clinically relevant macroscopic salivary gland locations, for which we propose the name tubarial glands. Sparing these glands in patients receiving RT may provide an opportunity to improve their quality of life. (C) 2020 The Authors. Published by Elsevier B.V.

Original languageEnglish
Pages (from-to)292-298
Number of pages7
JournalRadiotherapy and Oncology
Volume154
Early online date22-Sep-2020
DOIs
Publication statusPublished - Jan-2021

Keywords

  • Tubarial glands
  • Salivary glands
  • Radiation toxicity
  • Radiotherapy
  • Head and neck cancer
  • PSMA PET/CT

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