(ChemotherapyAdvisor) – Stem cells essential for regenerating the parotid gland are located primarily in its major ducts, which can easily be spared with current treatment modalities, significantly reducing complications in radiotherapy for head and neck cancer, investigators reported in announcing their discovery at the 31st conference of the European Society for Radiotherapy and Oncology (ESTRO31) in Barcelona, Spain, on May 10.

Currently, approximately 500,000 patients worldwide are treated with radiotherapy for head and neck cancer annually, and 40% suffer from side effects of dry-mouth syndrome related to parotid gland damage.

The study investigated the location of stem cells and the effects of radiotherapy to particular regions of the gland first in mouse and rat models, then in parotid and salivary gland tissue taken from patients undergoing a neck dissection for head and neck cancer. The hypothesis was tested by creating a mathematical model based on the treatment of 36 patients, estimates of expected parotid gland function depending on the dose to the stem cells.

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Results demonstrated that “dose to the cranio-ventral extension of the gland containing the major ducts was most predictive of saliva production.” The investigators found that this part of the gland could be spared during radiotherapy, and a dose reduction of approximately 50% “could be achieved without increasing the mean dose to the whole parotid gland or other critical structures in the head and neck region, and without compromising adequate target coverage.” Analysis of the patient cohort suggests parotid gland dysfunction will be prevented in all 36 patients.

The investigators noted that sparing the parotid gland during radiotherapy is relatively simple. “The stem cell region is on the side of the gland that is normally furthest away from the target area containing the tumor cells. Since only this area needs a high radiation dose, this distance makes avoiding the stem cell area easier than avoiding other parts of the gland,” they concluded.

Abstract (search for 0C-0167)