Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting toxicity1 of several commonly used classes of chemotherapy drugs. Peripheral neuropathies have been shown to lead to pain, falls, difficulty in walking and performing activities of daily living in many different populations including the elderly, diabetics, and, caner patients. Based on previous data from other groups of patients with peripheral neuropathies, the central hypothesis of our study is that CIPN results in altered gait and balance, similar to what has been observed in elderly and diabetic populations with peripheral neuropathy. To test our hypothesis, we will first characterize the alterations in gait and balance that occur i breast and colorectal cancer patients during chemotherapy with paclitaxel and oxaliplatin agents. Specifically, we will evaluate (1) spatiotemporal gait parameters, including cadence, step length, and step width, and (2) balance parameters, including time-to-contact and 95% ellipse area, using each patient as his/her own control. Subsequently, we will compare the natural history of changes in gait and balance parameters with changes in CIPN status as measured by validated objective and patient-report instruments including the TNS, EORTC CIPN-20 and BPI that are in commonly used in CIPN research. The long-term goal of our research is to reduce the burden of CIPN on cancer patients' mobility and quality of life. The overall objective of this application is to quantify the natural history o functional deficits that occur due to chemotherapy with oxaliplatin and paclitaxel. Completion of this study will establish the feasibility of evaluating balance and gait parameters as predictors o CIPN. If successful, then this will be an easy to implement and objective assessment of CIPN for future assessment of effectiveness of interventions that help mitigate or perhaps even prevent CIPN in breast and colorectal cancer survivors.