The use of targeted irradiation is enabling researchers at the University Medical Center (UMC) Utrecht to spare salivary glands more effectively in patients with oropharyngeal cancer. This can prevent severe symptoms of dryness in the mouth, a frequent side effect of the treatment. Dr. Chris Terhaard, a radiotherapist at UMC Utrecht, reported this last weekend at a congress of the European Society for Radiotherapy and Oncology.
Researchers at UMC Utrecht applied a new irradiation technique called intensity-modulated radiotherapy (IMRT) in 102 patients with oropharyngeal cancer. This is an extremely precise, computer-controlled 3-D irradiation technique that causes less radiation damage to surrounding tissues than conventional radiotherapy. They were hoping to spare not only the parotid but also the submandibular salivary glands. Radiation damage to these glands can cause severe dry mouth symptoms that are associated with pain, ulceration, inflammation, mastication and swallowing problems.
The patients were examined again one year after radiotherapy. Analyses showed that it was possible to preserve the function of one of the two submandibular salivary glands in patients with small tumors of the throat. This resulted in greater saliva production in the salivary gland that was spared as well as reductions in the dry mouth symptoms, in comparison with patients in whom the submandibular gland had been subjected to a higher dose of radiation. The functioning of the parotid salivary glands did not have a significant effect on the symptoms.
“IMRT currently enables us to keep the radiation dose low enough in 50% of our patients so that saliva production is retained,” said Dr. Terhaard. “Although we are therefore increasingly able to retain the function of the submandibular gland after radiotherapy, it’s essential for the patients’ well-being that this percentage rises further in future.”
Tumours in the head and neck region are diagnosed in about 2,900 people in the Netherlands annually. They are often treated with radiotherapy, which can damage the mandibular and submandibular salivary glands permanently and often 70% of patients, this creates problems with eating, sleeping, speech, tooth loss and poorer oral hygiene. This can in turn result in weight loss, reduced quality of life and even social isolation. Complaints involving dryness of the mouth are difficult to treat, so preventing them is important.
This study is part of the doctoral research of Dr. Tim Dijkema, who received his PhD from the University of Utrecht on March 28, 2013 (supervisor: Professor M. van Vulpen). The research was partly funded by a grant from the Dutch Cancer Society. Dr. Terhaard presented the results on April 20 at the 2nd Forum of the European Society for Radiotherapy and Oncology (ESTRO) in Geneva, Switzerland.
Sparing of the salivary glands with IMRT in a patient with cancer of the right tonsillar region.
On the left, the planning CT-scan is shown with target volumes and normal tissues delineated.
In the centre and right, the dose distribution obtained with IMRT can be seen from above and front, respectively. In particular, the left parotid and submandibular gland are spared from high doses on this patient.