Photobiomodulation for restoring salivary flow after radiotherapy in head and neck cancer: a randomised placebo-controlled trial.

BACKGROUND: Head and neck cancer (HNC) treatment modalities, especially radiotherapy (RT), often lead to salivary gland dysfunction, resulting in hyposalivation and xerostomia, which impair patients' quality of life. Photobiomodulation (PBM) therapy, a noninvasive approach using nonthermal red/near-infrared light, has shown promise in mitigating these side effects. This study evaluated the impact of PBM therapy on salivary flow, biochemical biomarkers, patient-reported outcome measures and mouth opening in patients with HNC suffering from chronic xerostomia after RT. METHODS: In a prospective, two-arm, randomised, placebo-controlled, double-blinded trial, 31 adult patients with HNC in complete remission and chronic xerostomia (> 3 months after RT) were enrolled. Participants were randomised (1:1) to receive either active PBM therapy or a sham intervention. The PBM protocol employs an 830 nm diode device applied intra- and extraorally over 24 sessions (twice weekly for 3 months) targeting the major salivary glands. The outcome measures assessed at baseline, 3 months (postintervention), and 6 months included the unstimulated salivary flow rate (SFR) by sialometry, total protein and IgA (sialochemistry), quality of life via European Organisation for Research and Treatment of Cancer (EORTC) questionnaires, severity of xerostomia, dysphagia, and mouth opening. Data were analysed using repeated measures analysis of covariance (ANCOVA) (adjusting for relevant covariates) and nonparametric tests, as appropriate. RESULTS: Compared with the placebo group, the PBM group presented a nearly significant increase in the SFR (0.22 ± 0.29 vs. 0.05 ± 0.15 ml/min, p = 0.051; effect size d = 0.75) after the intervention. A responder analysis revealed that five patients in the PBM group shifted from hyposalivation (SFR < 0.25 ml/min) to normal salivary flow, whereas no such change was observed in the placebo group (p = 0.048). Both groups reported similar levels of satisfaction and adherence, and no adverse events were recorded. CONCLUSIONS: PBM therapy demonstrated potential benefits in improving salivary flow among oncological patients with chronic RT-induced xerostomia, suggesting possible regenerative effects on the salivary glands. Despite the objective improvements in the SFR, changes in biochemical markers and the remaining outcome measures were less definitive in patients with HNC. Further studies with larger sample sizes are needed to confirm these preliminary findings and better delineate the clinical utility of this therapy. TRIAL REGISTRATION: This trial was registered on ClinicalTrials.gov (NCT05614843) and First Posted date [2022-11-14].