Effectiveness of Photobiomodulation as a Treatment for Xerostomia in Patients with Head and Neck Cancer Undergoing...

Background: Radiotherapy-induced xerostomia is a prevalent and disabling complication in patients with head and neck cancer, leading to persistent oral pain, impaired salivary function, and substantial deterioration in quality of life. Photobiomodulation (PBM) has emerged as a supportive therapeutic strategy with potential anti-inflammatory, analgesic, and tissue-preserving effects; however, its clinical effectiveness remains incompletely defined. Methods: We conducted a systematic review and meta-analysis of randomized controlled trials evaluating PBM for the management of radiotherapy-induced xerostomia in adults with head and neck cancer. MEDLINE (PubMed), Embase, Scopus, and Web of Science were searched from inception to October 2025. Eligible studies assessed intraoral and/or extraoral PBM using predefined laser parameters and reported outcomes related to oral pain, salivary flow, or xerostomia-related quality of life. Risk of bias was assessed using the Cochrane RoB 2.0 tool. Random-effects meta-analyses were performed using the Paule-Mandel estimator. Certainty of evidence was appraised using the GRADE framework. Results: Seven randomized trials were included. PBM significantly reduced oral pain compared with control interventions (mean difference [MD] -0.76; 95% CI -1.33 to -0.20), with moderate heterogeneity. For stimulated and unstimulated salivary flow, pooled estimates favored PBM but did not reach statistical significance, and heterogeneity was considerable (I² > 90%). Substantial variability in laser wavelength, energy density, treatment frequency, anatomical targeting, and radiation exposure of salivary glands contributed to inconsistent effects across studies. The certainty of evidence was rated as moderate for pain reduction and low to very low for salivary flow outcomes. Conclusions: Photobiomodulation provides a clinically meaningful reduction in radiotherapy-related oral pain and may confer symptomatic benefit in xerostomia; however, its effect on salivary flow restoration remains uncertain. Standardized PBM protocols, improved methodological rigor, and adequately powered trials are required to clarify its role in supportive care for head and neck cancer patients.