A correlation between radiation doses to submandibular glands and the output saliva of those glands has been documented in the largest study to date on the topic, investigators reported at the 2nd Forum of the European Society for Radiotherapy and Oncology (ESTRO), held in Geneva, Switzerland, April 19-23, 2013.

A total of 50 persons with oropharyngeal cancer and no contralateral lymph node metastases underwent treatment with an optimized radiation technique using intensity-modulation radiotherapy (IMRT) with the intention to spare both parotid glands as well as the contralateral submandibular gland, which is the main source of saliva in resting conditions. This was accomplished by administering much lower radiation doses to the contralateral glands (less than 40 Gy) than is used with standard radiotherapy.

Saliva flow from the parotid and submandibular glands was measured at 6 weeks and at 1 year by applying citric acid to the patient’s tongue and collecting the resulting saliva in specially designed cups. The study participants also responded to a questionnaire addressing their subjective experience of dry mouth.

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The trial results were compared with data from a cohort of 52 patients who had received only parotid-gland-sparing IMRT. 

“We found that saliva flows from the contralateral submandibular glands were significantly higher at 6 weeks and at 1 year in patients who received a [radiation] dose to the submandibular gland of less than 40 Gy, and this translated into fewer complaints of dry mouth,” summarized radiation oncologist and study coinvestigator Dr. Chris Terhaard, of the University Medical Center Utrecht in Utrecht, the Netherlands, in an ESTRO statement. ONA