Page 160 - New epidemiological and PSMA-expression based paradigms in salivary gland tumors

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Chapter 10
suggesting a dose-response relation. These findings support further exploration of PSMA PET/CT to guide and evaluate RT, with the ultimate aim to reduce salivary gland toxicity.
Chapter 9:
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 their potential clinical implications for radiotherapy.
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.
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 post- treatment 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.
In 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.
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In a letter-to-the-editor, we thank the authors of 9 letters for their constructive comments and thereby their contribution to the interpretation of the glandular structure as described in the tubarial gland paper and the clinical consequences of its presence. A first comment concerned the novelty of our report on clustered