Variability of High-dose Melphalan Exposure on Oral Mucositis in Patients Undergoing Prophylactic Low-level Laser Therapy

The present study outlines the clinical impact and risk factors of oral mucositis in 79 patients with multiple myeloma following high-dose melphalan for autologous transplant. All patients underwent daily prophylactic low-level indium gallium aluminum phosphate diode laser therapy (660 nm, 15 mW, 3.75 J/cm, 10 s per point) from the beginning of the conditioning regimen up to day +2. Oral mucositis assessments were made daily until hospital discharge. For analysis, oral mucositis was divided into two groups according to severity: group 1, patients with oral mucositis grade <III (n = 71) and group 2, patients with oral mucositis grade ≥III (n = 8). Univariate logistic models were used to determine the risk factors. Patients in group 1 were found to have statistically fewer days of oral pain than those in group 2 (3.94 and 6.25 days, respectively, p = 0.014). Morphine was required in 75% of patients in group 2, versus 42.25% in group 1 (p = 0.06). Risk of severe oral mucositis was associated with higher serum creatinine levels (OR = 6.10; 95% CI 1.25-31.60; p = 0.02) and older age (OR = 1.21; 95% CI 1.05-1.47; p = 0.027). Severe oral mucositis was associated with worse clinical outcomes. Older patients and those with renal dysfunction previous autologous transplant had the greatest risk for severe oral mucositis despite prophylactic laser treatment. Our results highlight the importance of further research to define the dose, application time, and number of prophylactic laser sessions in those patients with the greatest risk for severe oral mucositis.