Cancer chemotherapy induced peripheral neuropathy not only significantly decreases the patients QOL but can also affect the therapeutic efficacy. Menthol is TRPM-8 agonist and is reported to have indicated some effects on neuropathic pain. The effects of menthol to cancer chemotherapy induced peripheral neuropathy were studied as the single-institutional phase II study.Method
1.35% menthol ointment was given to the subjects, who applied it twice daily. The hands and feet were studied, respectively, to evaluate by the numerical rating scale (NRS) on the first day, 4 weeks later and 8 weeks later of the study treatment. The evaluation by the peripheral neuropathy scale (PNS) was also conducted so that the detailed improvement of the dysfunction symptoms and neural symptoms could be evaluated.Results
As 2 of 29 registered cases did not satisfy the evaluation criteria, they were excluded. Therefore, 27 cases were studied for the evaluation. The compliance rate was 88.9%. According to the NRS analysis of the completion cases, the median value of the hands before the treatment was 4.3, which decreased to 4.1 after 4 weeks and to 3.6 after 8 weeks. As to the feet, the median value before the treatment was 5.4, which decreased to 4.9 after 4 weeks and to 4.4 after 8 weeks. Although the evaluation using PNS indicated one or more decrease in 19 of 24 cases, 5 of 24 cases indicated no improvement by either NRS or PNS.Conclusion
As a result of this experiment, the improvement ratio was 75%, which led to the conclusion that menthol is effective for peripheral neuropathic pain as supportive care. The discontinuation ratio due to adverse effects is as low as 11%, which were quickly improved upon discontinuation and the safety was confirmed; thus, it is considered to be effective to be used at clinical practice.