A large team of cancer researchers in The Netherlands has made a surprising new discovery, finding a pair of previously unknown salivary glands. Nestled deep in the back of the nasopharynx, the discovery may help prevent damaging side effects from head and neck cancer radiotherapy.
The discovery arose out of a study investigating a relatively new method of medical imaging, called a PSMA PET/CT scan. This scan was originally developed to image patients with prostate cancer, however, the radio-labeled ligands designed to light up prostate cancer cells have also been found to effectively visualize salivary glands.
Oral surgeon Matthijs Valstar and radiation oncologist Wouter Vogel first noticed a pair of unexpected areas lighting up while examining PSMA PET/CT scans. The scans suggested these were salivary glands but the pair of researchers knew there were no known salivary glands in those particular areas of the head.
"People have three sets of large salivary glands, but not there," says Vogel. "As far as we knew, the only salivary or mucous glands in the nasopharynx are microscopically small, and up to 1,000 are evenly spread out throughout the mucosa. So, imagine our surprise when we found these."
A larger and more systematic investigation commenced, first looking at 100 historical PSMA PET/CT scans to confirm the consistent presence of these unknown glands. Two targeted autopsies were also conducted, validating the presence of the glands.
The final step in the study was understanding the function of these previously unidentified glands. The evidence suggested they were salivary glands, so medical records from 723 head and neck cancer patients were analyzed.
"Radiation therapy can damage the salivary glands, which may lead to complications," explains Vogel. "Patients may have trouble eating, swallowing, or speaking, which can be a real burden."
Knowing that radiation therapy can damage these glands, the researchers found the patients with the highest volume of salivary complications following treatment were the ones where the radiotherapy was most concentrated on the areas containing them. This finding helped confirm that these are indeed a pair of previously unknown salivary glands.
The researchers named the new organ tubarial glands, due to the glands’ predominant location over the torus tubarius.
One of the immediate outcomes from the discovery is the hope of reducing negative side effects from head and neck cancer radiotherapy. Vogel suggests this discovery helps explain why some people suffer significant damage to their salivary gland systems following radiation, and in some cases the damage could be mitigated by ensuring the radiation is more precisely targeted away from this particular spot.
"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," says Vogel. "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 new study was published in the journal Radiotherapy and Oncology.
Source: Netherlands Cancer Institute