Radiation induced xerostomia (RIX) represents a common debilitating side effect for (RT), adversely affecting oral health and hindering head and neck cancer (HNC) patients' quality of life (QOL). To date, managing (RIX) is mainly symptomatic, while the only FDA-approved preventive therapeutic agent is Amifostine, with associated systemic toxicities. Sialendoscopic management is a minimally invasive technique that can help in restoring ductal patency, decreasing inflammation and improving salivary flow. Laser Photobiomodulation (PBM) is a noninvasive approach that enhances salivary gland function by stimulating cellular activity, increasing blood flow and attenuating oxidative stress.

Aim: The present study aims to evaluate and compare the efficacy of sialendoscopic management and photobiomodulation in managing (RIX) in (HNC) patients.

Materials and Methods: A randomized clinical trial will be carried out on 42 (HNC) patients. Directly prior to the first (RT) session, Group I (n= 14 patients) will receive sialendoscopic management. Group II (n=14 patients) will receive (PBM) sessions. Group III (n= 14 patients) will receive basic oral care (BOC). Xerostomia will be evaluated at baseline, at 3 weeks and after 8 weeks from the end of (RT), clinically using Common Terminology Criteria for Adverse Events (CTCAE) v5.0 and objectively using unstimulated salivary flow. Quality of life will be assessed using Multidisciplinary Salivary Gland Society (MSGS) questionnaire. Salivary amylase will be assessed at baseline and after 8 weeks from the end of (RT).

Inclusion Criteria:

• Patients who are going to receive (IMRT) as a treatment of (HNC) either as postoperative (adjuvant) therapy or definitive therapy.
• Patients who are planned to receive (RT) with parotid mean dose bilaterally not exceeding 25 Gy.
• Males and females with an age not less than 18 years30

Exclusion Criteria:

• Patients suffering from uncontrolled systemic diseases (such as diabetes, hypertension, cardiovascular, liver or renal dysfunction).
• Patients with history of using drugs such as (pilocarpine ), oral humidifiers or herbs that prevent or treat xerostomia 2 months prior to study inclusion.
• Patients with findings of any physical or mental abnormality which would interfere with or be affected by the study procedure.
• Patients diagnosed with Sjögren's disease or other underlying systemic illness that is known to cause xerostomia.