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Low‐power laser to prevent oral mucositis in autologous hematopoietic stem cell transplantation

To the Editor, Oral mucositis is a frequent complication of hematopoietic stem cell transplantation (HSCT) (1, 2). Low power laser (LPL) has been tested in the prophylaxis and treatment of oral mucositis with promising results (1, 3, 4). In this study, the prophylactic effect of LPL was tested in a double-blind randomized placebo-controlled trial. Adult patients undergoing autologous HSCT from January 2005 to July 2006 were eligible, provided they had integrity of the oral mucosa, and good oral hygiene and dental status on admission. The protocol was approved by the Institution Ethics Committee and patients signed an informed consent. Patients received LPL or placebo with daily applications from D-7 to D0. LPL was applied bilaterally in the following anatomic sites: posterior wall of the oropharynx; buccal mucosa; hard and soft palate; dorsal, ventral and lateral sides of the tongue; floor of the mouth; upper and lower labial mucosa; and vermillion border. A diode laser (Laser Solution Ltda, Niterói, Brazil) of 50 mW AsGaAl was applied emitting continuous light at 660 nm. Patients in the control group received the same form of treatment simulated by a light spot from a simple led. The dentist who applied the laser was not blind for randomization group. Evaluation was performed daily from D-2 until discharge by trained physicians, using the Tardieu’s scale (5). The primary endpoint was the number of days with oral mucositis grade zero and secondary endpoints were the proportion of patients with any grade of mucositis different from zero and the cumulative probability of developing mucositis. Routine prophylactic acyclovir was applied to all patients, but antifungal prophylaxis was not given routinely. Low power laser was given to 17 patients and 17 received placebo. The groups were comparable regarding baseline characteristics. The median duration of hospitalization of patients receiving LPL and placebo were similar (21 d, range 17–30 vs. 20 d, range 15–42, P = 0.52). Low power laser was well tolerated and no toxicity was recorded. There was a trend for a lower proportion of patients with fever of unknown origin in the laser group (35% vs. 65%, P = 0.09), suggesting that preventing mucositis may reduce the frequency of infection (6, 7). Oral mucositis was observed in eight patients in LPL group (47%) and 12 in the control group (71%, P = 0.16). The median number of days with oral mucositis grade zero (primary endpoint) was 14 in the laser group and eight in the placebo group (P = 0.01). There were no differences in the grade of oral mucositis between the two groups (P = 0.34). The cumulative probability to develop oral mucositis was 47% in the laser group and 69% in the placebo group (P = 0.27). Comparison of studies evaluating LPL in HSCT is difficult because of differences in the types of transplant, conditioning regimens, protocols of LPL application and evaluation of mucositis (1, 3, 4). Nevertheless, all studies showed a reduction in the duration and ⁄or severity of oral mucositis, suggesting that LPL should perhaps be incorporated into the general care of HSCT recipients. However, future studies need to evaluate different parameters of LPL application and the timing of intervention.