<p>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 (<i>r</i> = 0.385, <i>p</i> = 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.</p><p><i>Trial registration number</i><i>: </i>EA2/167/21 (date of registration: 12.08.2021).</p>