Photobiomodulation Therapy Plus M-health in Head and Neck Cancer Patients: LAXER Study

Patients will be included in the study if they meet the following inclusion criteria: * men or women aged 18 years or older and were diagnosed with HNC. * chronic xerostomia. * received RT in the parotid, submandibular and/or sublingual salivary glands. * grade 3 oral dryness according to the Common Terminology Criteria for Adverse Events version 5.0 (CTCAE). * medical treatment completed and in complete remission. * received medical clearance for participation in this study. * at least one month passed since the end of RT to avoid the possible presence of oral mucositis and/or radiodermatitis, which limits adherence to treatment and maximum 36 months. * no history of drugs/devices/products (pilocarpine, cevimeline, amifostine, oral devices, humidifiers, or herbs) to prevent or treat xerostomia prior to study inclusion or no change in their use (no change in type or dose) for two months prior to study inclusion. * and able to access mobile applications or living with someone who has this ability. The exclusion criteria will be as follows: * patients with metastases. * a score \<60 on the Karnofsky Performance Status Scale. * contraindications to receiving PBM therapy (e.g., cardiac arrhythmias, pacemakers, photosensitivity, drugs with photosensitizing action, and pregnancy). * other comorbidities such as diabetes and polypharmacy. * and retraction of the declaration of consent.