Photobiomodulation for Cancer-Related Cognitive Impairment

Inclusion Criteria: * Adults ≥ 18 years * Previous diagnosis of stage I-III non-central nervous system solid tumor malignancy, Hodgkin, or Non-Hodgkin lymphoma * Completed cancer treatment (chemotherapy and/or radiation) more than 6 months ago but less than 5 years ago (Current concurrent endocrine therapy, anti-HER-2 therapy allowed, or other stable maintenance therapies (such as rituximab) will be allowed. * Self-reported cognitive complaints (score ≤ 54 on the Functional Assessment of Cancer Therapy-Cognition, Version 3, Perceived Cognitive Impairment subscale) * Written informed consent obtained from subject and ability for subject to comply with the requirements of the study. * Ability to read, write and understand either English OR Spanish. Exclusion Criteria: * Current pregnancy or nursing status * Current use of Photobiomodulation (PBM) (for any reason) * A lifetime history of any brain tumor or central nervous system metastasis * Previous use of intrathecal chemotherapy, chimeric antigen receptor treatment (CAR-T), or stem cell/marrow transplant * Known history of other neurological conditions involving impaired cognitive function (such as Alzheimer's Disease and related dementias, Parkinson's Disease, or Multiple Sclerosis).