Dorsal sural nerve conduction study as an early predictor for oxaliplatin-related neuropathy

Introduction: Peripheral neuropathy is one of the most common dose-limiting and disabling side-effect of oxaliplatin (OXA)-based chemotherapy; a gold standard in its assessment has not yet been established. A multicenter study was performed to define early neurophysiological markers that may help identify patients at risk of developing severe, OXA-induced peripheral neuropathy (OXAIPN). Being OXAIPN a length-dependent neuropathy, lower limb nerves are the best candidate to detect early predictors of nerve damage, since they are affected first; among them, dorsal sural nerve, whose normative values have been recently published, has already been demonstrated to be a good tool for the early diagnosis of other polyneuropathies, such as the ones related to diabetes mellitus. Moreover, it is a tool that could be easily and rapidly applied in the every-day-clinical practice. Methods: Two hundred colorectal cancer patients, scheduled to receive OXA-based chemotherapy, were prospectively followed, through the mean of the clinical Total Neuropathy Score (TNSc), oncological rating scales (NCI-CTCv3), and routine nerve conduction studies (NCS) with the additional monitoring of dorsal sural nerve. Evaluations were performed at baseline, at mid-treatment, and at the end of chemotherapy. Results: According to TNSc, 36 (18%) patients developed treatment emergent, grade 3 OXAIPN. Multivariate analysis showed that the >30% decrease in sensory nerve action potential amplitude from the baseline value in radial (OR: 41.4; CI 95%: 4.98-343.1; p=0.001) and dorsal sural nerves (OR: 24.96; CI 95%: 2.6-239.4; p=0.005) were independently associated with the risk of developing severe OXAIPN. Conclusion: High-grade OXA neurotoxicity can be predicted by neurophysiological alterations demonstrated at mid-treatment. Dorsal sural nerve NCS monitoring should be carefully performed longitudinally during OXA based regimen administration in order to detect patients at high risk of developing severe OXAIPN.