De La Hoz T.Q. et al. - Photobiomodulation and Xerostomia Following Head and Neck Radiation Therapy: A Systematic Review and Meta-Analysis

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In this meta-analysis of 7 randomized trials, photobiomodulation was associated with a reduction in oral pain among adults undergoing radiation therapy for head and neck cancer. With regard to salivary flow, the estimates point in the same direction but did not reach statistical significance.

What this study measured

Radiation-induced xerostomia is a common and debilitating complication in patients undergoing treatment for head and neck cancer. The authors sought to determine the clinical efficacy of photobiomodulation, which was used here as supportive care rather than as a cancer treatment.

This is a systematic review with a meta-analysis of randomized controlled trials conducted in adults. Four databases (MEDLINE via PubMed, Embase, Scopus, and Web of Science) were searched from their inception through October 2025. The included studies evaluated intraoral and/or extraoral photobiomodulation, using predefined laser parameters, and reported on oral pain, salivary flow, or quality of life related to xerostomia. The risk of bias was assessed using the Cochrane RoB 2.0 tool; data were pooled using a random-effects model (Paule-Mandel estimator); and the certainty of the evidence was assessed using the GRADE method.

Key Findings

Seven randomized trials were included. Compared with the comparison interventions, photobiomodulation significantly reduced oral pain, with moderate heterogeneity among the studies. For salivary flow—both stimulated and unstimulated—the pooled estimates favored photobiomodulation but did not reach statistical significance, with considerable heterogeneity.

Oral pain: mean difference -0.76 (95% CI -1.33 to -0.20), in favor of photobiomodulation.
Stimulated and unstimulated salivary flow: non-significant results.
Heterogeneity of salivary flow: I² greater than 90%.
Certitude of evidence (GRADE): moderate for pain; low to very low for salivary flow.

How photobiomodulation works for this indication

Photobiomodulation involves applying low-intensity light to tissues. The authors describe it as a supportive strategy with potential anti-inflammatory, analgesic, and tissue-protective effects. This study compares clinical outcomes and does not demonstrate any mechanism of action.

The protocols included varied widely. The authors cite differences in wavelength, energy density, frequency of sessions, targeted anatomical region, and exposure of the salivary glands to radiation. According to them, these variations contribute to inconsistent results across studies.

Limits You Should Know

The finding regarding salivary flow is not significant, and the very high heterogeneity (I² greater than 90%) precludes any conclusion. The certainty of the evidence is low to very low for these outcomes. The number of trials is limited (7), and the protocols vary widely. The abstract does not specify the total sample size or the pain measurement scale; therefore, these details are not reported here. The authors emphasize the need for standardized protocols, greater methodological rigor, and trials with sufficient statistical power.

What This Means in Practice

The authors conclude that photobiomodulation provides a clinically significant reduction in oral pain associated with radiation therapy and may offer benefits for symptoms of xerostomia. However, its effect on restoring saliva flow remains uncertain. Photobiomodulation is used here as a supportive treatment to improve oral comfort and is not intended to treat the cancer itself. It is not a substitute for oncological follow-up or prescribed treatments.

Frequently Asked Questions

Does photobiomodulation restore saliva production?

This has not been proven. In this meta-analysis, the estimates of salivary flow support the efficacy of photobiomodulation, but they are not statistically significant, and the certainty of the evidence is low to very low.

What effect was observed on oral pain?

The authors report a significant reduction in oral pain compared with the comparison interventions, with a mean difference of -0.76 (95% CI -1.33 to -0.20) and a certainty of evidence rated as moderate.

Is there a recommended standard protocol?

No. The parameters varied significantly from one study to another (wavelength, energy, frequency of sessions, targeted area). The authors call for standardized protocols and better-designed studies.

Reference

De La Hoz TQ, Peña YS, Ramírez FQ, Rivera-Lozada O, Barboza JJ. Effectiveness of Photobiomodulation as a Treatment for Xerostomia in Patients with Head and Neck Cancer Undergoing Radiotherapy: A Systematic Review and Meta-Analysis. Dent J (Basel), 2026. PMID 42782929. https://pubmed.ncbi.nlm.nih.gov/42782929/

This summary is provided for informational purposes only and does not constitute medical advice. Photobiomodulation is not a substitute for prescribed treatment. Consult a healthcare professional.