Long-term safety of photobiomodulation therapy for oral mucositis in hematopoietic cell transplantation patients: a 15-year retrospective study.

Photobiomodulation therapy (PBMT) has demonstrated efficacy in the prevention and treatment of oral mucositis (OM) in hematopoietic cell transplantation (HCT). However, based on the cell stimulation properties, its long-term safety has been questioned, mainly in relation to risk for secondary malignancies in the oral cavity. The aim of this study was to investigate if different PBMT protocols for OM control have association with immediate and late adverse effects in HCT patients. Data on autologous and allogeneic transplantation, conditioning regimen, PBMT protocols, and OM severity were retrospectively collected from medical and dental records. Presence of secondary malignancies in the oral cavity was surveyed during a 15-year follow-up. Impact of OM on overall survival was also analyzed. Different PBMT protocols for prevention and treatment of OM were recorded over the years. Severe OM (grades 3 and 4) was infrequently observed. When present, we observed a significant decrease of the overall survival. No immediate adverse effect and secondary malignancy was associated to PBMT. In conclusion, the PBMT protocols used in the study were considered safe. The low frequency of severe OM observed encourages the implementation of this technique, with a special emphasis on the dosimetry adjustments focused on the HCT context.