11 were among the first to report a greater prevalence of functional limitations, including reduced mobility, among older female cancer survivors (<5 years post-diagnosis) compared to older women with no cancer history. Cancer

survivors were more likely to report that they were unable to do heavy household work (odds ratio (OR) = 1.47, 95%CI: 1.27, 1.69), walk one-half mile (OR = 1.31, 95%CI: 1.1, 1.54), or walk up and down stairs (OR = 1.34, 95%CI: 1.05, 1.72). Functional limitations may begin a cascade to disability, dependence, and death.12 In fact, slower 20-m walk speeds are associated with higher mortality (OR = 1.09, 95%CI: 1.02, 1.16) and faster progression to disability (OR = 1.25, 95%CI: 1.13, 1.35) among older cancer survivors.13 Cancer treatment Ivacaftor can alter physical functioning in ways that are similar to aging (i.e., weakness) but also in ways unique to treatment. Chemotherapy is associated with sarcopenia,14, 15, 16, 17 and 18 fatigue,19 and deconditioning.20 Regimens that contain neurotoxic agents also cause peripheral neuropathy21 and vestibulotoxicity22 and 23 that affect balance and mobility. Neuropathy and vestibulotoxicity in older adults are associated with poor balance, low mobility, and subsequent falls.24, 25 and 26 The relative contributions

of muscle weakness, neuropathy, and vestibular dysfunction to physical functioning in cancer survivors are not yet known, but approaches that strengthen muscles used in everyday movements Vemurafenib chemical structure and strengthen the damaged sensory systems

that contribute to instability during movement could be the best rehabilitation strategy for reversing functional declines caused by neurotoxic cancer treatment. Falls and disability share common risk factors (e.g., weakness, instability, and altered gait) that typically increase with age; and, like disability, falls are a significant concern for cancer survivors. Chen et al.27 reported an elevated risk of falls after women developed breast cancer compared to women never diagnosed with cancer (hazard ratio (HR) = 1.15, 95%CI: 1.06, 1.25), and others have observed fall rates in cancer survivors that are double those of cancer-free peers28 or community-dwelling also older adults.29 Cancer treatment itself and inactivity that often accompanies treatment can worsen age-related weakening. For cancer survivors treated with chemotherapies that are toxic to the nervous system, neuropathy and vestibular dysfunction (e.g., damage to the inner ear) are common side effects. In a single report of patients who received neurotoxic chemotherapies (n = 109), 20% experienced a fall during treatment and fallers had higher scores on self-report measures of neuropathy than non-fallers. 30 Using posturography tests that evaluate sensory inputs to balance control, breast cancer survivors with a history of falls have worse performance in conditions challenging vestibular input to balance control compared to survivors with no fall history.