The validity of evaluations for chemotherapy-induced peripheral neuropathy (CIPN)

Abstract Background Chemotherapy-induced peripheral neuropathy (CIPN) is an important factor that renders the continuation of chemotherapy difficult. Prevention and treatment of CIPN are indispensable in improving patients’ quality of life and promoting the continuation of chemotherapy that may improve survival. Numbness and pain are currently evaluated using subjective methods such as the visual analogue scale (VAS). However, the assessment of pain can vary greatly depending on the mood and physical state of the patient at the time of assessment. In this stage, objective evaluation methods have not been used for evaluations of CIPN in clinical trials because they have not been established as quantified evaluation methods for CIPN yet. A method to quantify CIPN objectively and easily is necessary. The PainVision PS-2100 (PV) is an analytical instrument that was designed to quantitatively and objectively assess sense perception and nociception in patients. The advantage of PV is that it can evaluate pain in a relatively short time, as well as assess pain without causing further pain to patients. Methods We examined a total of 73 CIPN patients with metastatic CRC received chemotherapy between April 2014 and December 2015 by using VAS, the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group - Neurotoxicity (NTX), the Disk-Criminator™ test, the monofilament test and PV. And then, we evaluated the correlation between subjective and objective evaluation methods or correlation between PV and other objective evaluation methods for CIPN. Results The average VAS (hand), VAS (foot) and PV scores of CIPN were 18.4 (range: 0–100), 23.8 (range: 0–100) and 24.7 (range: 0–496), respectively. A strong positive correlation was found between VAS (hand) and VAS (foot) scores (r = 0.798). The VAS (hand), VAS (foot), NTX 2, NTX 4 and NTX 8 significantly correlated with PV. PV showed no correlation with a Disk-Criminator™ or the monofilament test used as an objective evaluation. Conclusions This is the 1st report regarding the correlation between PV and other objective evaluation methods in CIPN patients. The evaluation of CIPN is complicated because numerous factors are involved. And further research and effort are needed to improve objective evaluation of CIPN by PV. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.