AbstractThis prospective cohort study aimed to characterise the impact of oxaliplatin-based chemotherapy and its neurotoxic side effects (i.e., chemotherapy-induced neuropathy) on functional fall-risk and falls. Twenty chemotherapy-naïve participants (mean age, 59 years; 16 males) were consecutively included. A multimodal fall risk assessment was performed at four time points within 6 months. Polyneuropathy was assessed using the Neurologic Disability Scale; the fall risk was assessed by functional tests (Tinetti Test, Chair-Rising Test, and Timed up and Go Test). Patient-reported outcomes comprised the Hospitality Anxiety and Depression Scale (HADS), the Falls Efficacy Scale – International (FES-I) to assess the fear of falling, and the Physical Activity for the Elderly (PASE) questionnaire. Three falls occurred during the study. All fallen participants had a high fall risk-index (≥4 more risk factors) compared to only 30% of the non-fallen participants (p= 0.03) and suffered more frequently from pre-existing mild polyneuropathy (p= 0.049). Study discontinuation (n= 12) was associated with a higher rate of polypharmacy (p= 0.045), anxiety (HADS-A,p= 0.03), and specific fear of falling (FES-I,p= 0.025). In contrast, study completers (n= 8) reported an improvement in physical activity (PASE) (p= 0.018). In summary, pre-existing fall-risk factors impacted more falls than chemotherapy. A fall risk index offers a time-efficient screening option in an outpatient oncological setting.