April 21, 2013
Head, Neck Cancer Patients May Find Cure For Dry Mouth With New Technique
redOrbit Staff & Wire Reports - Your Universe Online
Head and neck cancer patients who experience dry mouth after being treated with radiotherapy can have that symptom reduced if the radiation dose to a salivary gland on the opposite side of the tumor is minimized, researchers from the Netherlands claim in a new study.
Dr. Chris Terhaard, an associate professor and radiation oncologist at the University Medical Center (UMC-Utrecht) in The Netherlands, and colleagues discovered a correlation between radiation doses to what is known as the submandibular glands and their saliva output. Their findings were presented Saturday at the 2nd Forum of the European Society for Radiotherapy and Oncology (ESTRO).
Those glands, which are salivary glands located beneath the lower jaw on each side of the face, are primarily responsible for producing saliva while at rest or throughout the night. Based on their findings, Terhaard and his colleagues believe guidelines for recommended maximum doses for these regions of the mouth could be issued for use in clinical practice in order to benefit patients.
Individuals who have cancerous tumors in their mouth and throat are often treated with radiation, but such treatment can be hard on their salivary glands and result in a xerostomia, also known as dry mouth. Approximately 40 percent of all head and neck cancer patients suffer from long-term xerostomia, which can hamper their eating, sleeping, speech and oral hygiene. Attempts to treat the condition tend to be somewhat ineffective and extremely costly, leading the researchers to emphasize that prevention is the key to dealing with the disorder.
Terhaard and his colleagues recruited 50 patients with throat cancer that had neither migrated into the contralateral lymph nodes nor spread to other parts of the body. Each was treated with a special type of radiotherapy known as contralateral submandibular gland-sparing IMRT (intensity modulated radiotherapy), meaning the normally endangered saliva glands were exposed to far less radiation than usual.
“IMRT currently enables us to keep the radiation dose low enough in 50 percent of our patients so that saliva production is retained,” said Dr. Terhaard in a statement. “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.”
The 50 patients were then compared with a historical group of 52 patients who had received regular radiotherapy treatment for their conditions, which spared just the parotid glands that produce saliva during food consumption. After six weeks and one year´s time, the researchers measured saliva flow from both glands by stimulating saliva with citric acid placed on the tongue and collecting it in special cups. Each subject was also asked to complete a questionnaire subjectively describing their experience with dry mouth symptoms.
“We found that saliva flows from the contralateral submandibular glands were significantly higher at six weeks and at one year in patients who received a dose to the submandibular gland of less than 40 Gy, and this translated into fewer complaints of dry mouth,” Terhaard said. “Using the new technique, we managed to keep the dose under 40 Gy in 50 percent of the patients. Now we are looking for further improvements, since in 50 percent of the patients the dose to the submandibular glands was still too high.
“This is the largest detailed study to show the correlation between the dose to the submandibular gland and the measured output of the contralateral submandibular gland. It is the first study to show subjectively and objectively that when you reduce the dose to the submandibular gland, the patients have fewer severe complaints,” he added. “This leads to a guideline, which can be used in clinical practice, of the recommended maximum dose of 40 Gy for the submandibular gland. It also shows that with improved techniques, such as IMRT, you may better spare the submandibular gland, as well the parotid glands.”