Neuromodulation of Central Sensory Integration to Improve Postural Control

The objective is to evaluate if neuromodulation of the PFC can acutely improve sensory integration for balance performance in OTTBCS.

Sensory integration required for balance will be measured using the sensory organization test which includes six conditions in which visual and proprioceptive sensory cues are sequentially referenced (i.e. reduced) to stress available sensory information and sensory integration for postural control. Performance on the sensory organization test has been correlated with falls and successful response to balance perturbation.Balance performance will be evaluated by postural sway. Cognitive function will be assessed using the NIH toolbox with a focus on executive function. tDCS will be used to modify PFC excitability and measure its immediate after-effect on balance performance while performing the sensory organization test in OTTBCS. CIPN severity will be evaluated using measurements of distal proprioception.The study sample will be older breast cancer survivors (n=20) diagnosed and treated with taxane chemotherapy after the age of 60 years to avoid heterogeneity due to multiple cancer types, treatments, and sexes.

Eligibility Criteria:
Inclusion Criteria:

Inclusion criteria for breast cancer survivors:

* Women aged 60-85 years
* Breast cancer survivors, stages I-IIIc
* Completion of taxane chemotherapy treatment. Taxane combined with a history of anthracycline and/or cyclophosphamide is permitted. Active anti-estrogen therapy is permitted. Receiving platin based agents is permitted.
* Ability to walk without an assistive device
* Ability to speak and read English
* Without neurological disease, aside from chemotherapy induced peripheral neuropathy (CIPN) or chemotherapy related cognitive dysfunction (CRCD)
* No history of a second cancer
* Own a device with capability to sync the Fitbit

Exclusion criteria for cancer survivors:

* Inability to stand or walk unassisted for 60 seconds
* Hospitalization within the past three months due to acute illness or as the result of a musculoskeletal injury significantly affecting gait or balance
* Any unstable medical condition
* Diagnosis of a gait disorder, Parkinson's disease, Alzheimer's disease or dementia, multiple sclerosis, previous stroke or other neurodegenerative disorder. Cognitive status assessed via the Telephone Interview of Cognitive Status (mTICS). We will exclude those with marked dementia (score below 31).
* Chronic vertigo
* Myocardial infarction within the past six months
* History of platin chemotherapy
* History of immunotherapy
* Any history of brain or spine surgery, known hearing, visual, or vestibular impairment
* Active chemotherapy, radiation, or immunotherapy
* Contraindications to transcranial direct simulation (tDCS), including reported seizure within the past five years, active use of neuro-active drugs, metal objects anywhere in the body, self-reported presence of specific implanted medical devices (e.g., deep brain stimulator, medication infusion pump, cochlear implant, pacemaker, etc.), or the presence of any active dermatological condition, such as eczema, on the scalp.
* Currently taking anti-epileptic medication