Our body contains a pair of previously overlooked and clinically relevant nasopharyngeal salivary glands, according to new research led by the Netherlands Cancer Institute and the University of Amsterdam. Sparing these newly-identified glands, named the ‘tubarial glands,’ in patients receiving radiotherapy may provide an opportunity to improve their quality of life.
The human salivary gland system can be divided into two separate groups: major and minor glands.
The major salivary glands are parotid, submandibular, and sublingual glands. The minor glands are distributed in groups of hundreds in the upper aerodigestive tract mucosa.
These glands produce the saliva required for mastication, swallowing, digestion, tasting and dental hygiene.
“The recently introduced molecular imaging modality of positron emission tomography/computed tomography with radio-labeled ligands to the prostate-specific membrane antigen (PSMA1 PET/CT) can visualize salivary glands with high sensitivity and specificity,” said lead author Dr. Matthijs Valstar, an oral and maxillofacial surgeon in the Department of Head and Neck Oncology and Surgery at the Netherlands Cancer Institute and the Department of Oral and Maxillofacial Surgery at the University of Amsterdam, and his colleagues from the Netherlands.
“Surprisingly, we observed that PSMA PET/CT also depicted an unknown bilateral structure posterior in the nasopharynx, with ligand uptake similar to the known major salivary glands.”
“To our knowledge, this structure did not fit prior anatomical description.”
The researchers confirmed the presence of tubarial glands in PSMA PET/CT scans of 100 patients (99 male, one female; median age 69.5; range 53-84) and the tissue of two human bodies.
“The two new areas that lit up turned out to have other characteristics of salivary glands as well,” Dr. Valstar said.
“We call them tubarial glands, referring to their anatomical location.”
The scientists assume the physiological function of the tubarial glands is the moistening and lubrication of the nasopharynx and oropharynx.
“Radiation therapy can damage the salivary glands, which may lead to complications,” said senior author Dr. Wouter Vogel, a radiation therapist in the Department of Nuclear Medicine and the Department of Radiation Oncology at the Netherlands Cancer Institute.
“Patients may have trouble eating, swallowing, or speaking, which can be a real burden.”
“Radiation treatment of these new glands can also go hand in hand with these complications.”
The team analyzed the data of 723 patients who had undergone radiation treatment and found that the radiotherapy dose to this area was associated with complications (xerostomia and dysphagia).
This means that the discovery is not only surprising, but it could also be a benefit to cancer patients.
“For most patients, it should technically be possible to avoid delivering radiation to this newly-discovered location of the salivary gland system in the same way we try to spare known glands,” Dr. Vogel said.
“Our next step is to find out how we can best spare these new glands and in which patients.”
“If we can do this, patients may experience less side effects which will benefit their overall quality of life after treatment.”
The team’s paper was published online September 23, 2020 in the journal Radiotherapy and Oncology.
Matthijs H. Valstar et al. The tubarial salivary glands: A potential new organ at risk for radiotherapy. Radiotherapy and Oncology, published online September 23, 2020; doi: 10.1016/j.radonc.2020.09.034
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