# Chemotherapy-induced polyneuropathy: diagnostic challenges and the potential of neurofilament as a biomarker for sensory disorders: the CONKO 023-ChemTox Trial

## TL;DR

This study explores chemotherapy-induced polyneuropathy and suggests neurofilament light chain could help diagnose it better.

## Contribution

The study identifies neurofilament light chain as a potential biomarker for detecting chemotherapy-induced polyneuropathy.

## Key findings

- 75% of patients experienced chemotherapy-induced polyneuropathy.
- Neurofilament light chain levels correlated with neuropathy severity (r = 0.385, p = 0.004).
- Patients with CNS cancer had elevated baseline neurofilament light chain levels.

## Abstract

Chemotherapy-induced polyneuropathy (CIPN) is a prevalent side effect impairing patients’ quality of life, often manifesting as dysesthesia or pain in extremities. To minimize therapy-related side effects as well as to improve quality of life, modern approaches grow increasingly more relevant. We conducted a longitudinal, prospective study to examine patients with lymphoma, leukemia, or gastrointestinal malignancies receiving continuous and temporary treatment up to five times over a 12- to 24-month period, beginning prior to chemotherapy. Assessments included comprehensive questionnaires, clinical neurological and electroneurographic examinations and measurements of neurofilament light chain (NFL). One hundred eight patients were enrolled with fifty-six patients having undergone all examinations both before and after chemotherapy. Data showed a significant rise of the mean Total Neuropathy Score (TNSr) after chemotherapy. Results revealed that approximately 75% of patients experienced CIPN. Continuous chemotherapy was associated with a steady increase in TNSr. Older patients, often with pre-existing and underdiagnosed neuropathy, were more frequently and more severely affected. According to medical records, where diagnostics were primarily based on patients’ subjective information, even moderate cases were frequently underdiagnosed. A moderate correlation was observed between the increase in NfL and changes in TNSr (r = 0.385, p = 0.004). Patients with cancer affecting the central nervous system (CNS) showed elevated baseline NFL levels. In contrast to non-responders, NFL decreased in patients who responded well to therapy. In conclusion, data underline the necessity of improved diagnostic accuracy of CIPN and support the potential of NFL as a biomarker for its detection. Further investigations should assess its potential in daily oncological routine.

Trial registration number: EA2/167/21 (date of registration: 12.08.2021).