The main objective of this comprehensive systematic review was to establish if using low-level laser therapy (LLLT) prophylactically would reduce mucositis severity in adults and children undergoing cancer treatment or haematopoietic stem cell transplantation (HSCT).

The authors performed a very extensive search across six online databases; they also reviewed relevant conferences and went over references manually with no language restriction.

They included RCTs using LLLT as prophylaxis for oral mucositis until 2014.

The primary outcome was overall incidence of mucositis but also they evaluated its severity, duration and incidence of pain.

Two of the reviewers independently evaluated the studies using clear inclusion and exclusion criteria set a priori and the results were clearly reported. Agreement between reviewers was very high and it was practised during study inclusion.

Eighteen studies were included in the review and their quality was assessed based on the risk of bias using the Cochrane tool. Four studies were considered low risk of bias overall. Ten studies were included in the meta-analysis of the primary outcome.

The results presented as risk reduction (RR) for the presence or no of severe mucositis showed an overall beneficial effect when LLLT was used of 0.37 RR, 95% CI 0.20 to 0.67; p=0.001. Heterogeneity between studies was high. Statistically significant benefits were also evident for each of the secondary outcomes but incidence of pain.

The authors evaluated publication bias using a funnel plot. After adjusting for 'missing' studies, the effect, although reduced to RR 0.51, 95% CI 0.29 to 0.90, continues to show benefits.

Despite this promising result, no clear recommendation can be made because of the variability among studies concerning the laser characteristics, schedule, evaluation interval and assessment scale. Only one study included a paediatric population.

No patient centred outcomes were evaluated. Improvement of quality of life or personal preferences may be more important than any objective measurement on this patient population.