Parotid-gland Stem-cell Sparing Intensity-modulated Radiotherapy (SCS-IMRT)

Prevention of Radiation-induced Parotid Gland Dysfunction by Parotid-gland Stem-cell Sparing Intensity-modulated Radiotherapy(SCS-IMRT)

Rationale: Radiation-induced parotid gland dysfunction, often leading to xerostomia is the most-frequently occurring side-effect with a major impact on patient-reported quality of life after radiotherapy for head and neck cancer (HNC). Therefore, treatments for HNC are currently optimized to minimize the mean dose to the parotid glands. Though this resulted in a significant reduction of toxicity, 30%-40% of the patients still develop sustained parotid gland dysfunction and xerostomia. However, in animal studies the investigators found that the dose to the sub-volume of the gland containing the parotid gland stem cells is a better predictor for dysfunction than the mean dose to the whole gland. Subsequently, this finding was confirmed in a retrospective analysis in patients. Therefore, a reduction of dose specifically in this sub-volume of the parotid glands of patients is expected to further reduce the risk of parotid gland dysfunction and xerostomia. Objective: To test the hypothesis that parotid gland stem cell sparing intensity modulated radiotherapy in HNC patients reduces the risk of parotid gland dysfunction and xerostomia as compared to conventional parotid gland sparing intensity modulated radiotherapy. Study design: Double-blind prospective randomized trial (51 patients per arm). Study population: Patients treated for tumours in the head-and-neck region with curative radiotherapy, with or without the addition of chemotherapy or cetuximab. Intervention: Patients randomized into the experimental arm will receive a treatment in which the radiation dose to the parotid gland is re-distributed to minimize dose to the sub-volume containing the stem cells, while keeping the same mean dose to the parotid gland as a whole. Main study parameters/endpoints: Primary endpoint is parotid gland salivary secretion. Secondary endpoints are patient- and physician-rated xerostomia.

Stem-cell Sparing IMRT in which the mean dose to the stem cell containing region of the parotid gland is minimized

Inclusion Criteria: Squamous cell carcinoma originating from the mucosa of the head and neck area or nasopharyngeal carcinoma originating from the nasopharynx; The radiotherapy includes prophylactic or therapeutic irradiation of both sides of the neck (at least level II to IV); Age ≥ 18 years; WHO performance 0-2; To reduce the uncertainty in the assessment of relative flow after treatment, pre-treatment parotid gland saliva production stimulated with 5% citric acid should exceed >0.1 ml/min Exclusion Criteria: Postoperative radiotherapy; Previous radiotherapy of the head and neck region (re-irradiation); Unilateral radiotherapy; Primary salivary gland tumours

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