This study evaluates the possible benefits of a tasteless and sugar free chewing gum as a salivary stimulant for head and neck cancer patients treated with curative intended radiotherapy.

Radiation-induced xerostomia and hyposalivation are frequent side effects after completed treatment for oral and oropharyngeal cancers. This may induce eating and swallowing difficulties, compromised oral hygiene, pain in the mouth, or speech deficiencies. As a consequence, quality of life is often impaired for this group of patients even after completing treatment.

This study hypothesize that chewing gum can stimulate salivary flow from the residual functional salivary glands and thereby improving the patient's oral well-being.

Primary endpoint:

- To assess whether the difference between the unstimulated and stimulated salivary flow after a one-month period of using chewing gum will result in improved oral well-being.

Secondary endpoint:

• To assess if unstimulated and stimulated salivary flow differs between the two groups of patients
• To evaluate changes in quality of life with EORTC QLQ H&N-35 for patients using chewing gum
• To evaluate differences in quality of life with EORTC QLQ H&N-35 between the two groups of patients.

All patients who have received curative intended treatment for oral or oropharyngeal carcinomas at the Department of Oncology, Odense University Hospital, will be invited to participate in the study. If the eligibility criteria are met the patient will be randomized 2:1 to either the intervention arm with chewing gum or the control arm with standard oral care. The study intends to include 210 patients in total. Of these, 140 patients in the intervention arm and 70 in the control arm. Recruitment to the study was initiated in September 2016 and is expected to be completed in July 2018.

The duration of the study is one month from inclusion and randomization to final follow up. For all included patients, saliva samples are collected (unstimulated and stimulated sialometry) and the EORTC QLQ H&N-35 questionnaire and a xerostomia specific questionnaire are completed. The patients in the control arm are only introduced to chewing gum at the last follow up visit. In the intervention arm, all patients are instructed to use the chewing gum on a daily basis (preferably 5 times a day) and to make notes in a patient diary to document compliance.

Inclusion Criteria:

• Over 18 years of age
• Diagnosed with oral or oropharyngeal carcinoma
• Received curative intended radiation therapy (primary or postoperative), 60-66Gy including concurrent chemotherapy
• Within 6 to 60 months after radiation therapy
• Complains of xerostomia level 1 (according to Danish Head and Neck Cancer group)
• Written informed consent

Exclusion Criteria:

• Poor teeth condition or full set of dentures
• Recurrence of cancer or palliative treatment