>18 years of age Biopsy proven head and neck cancer No evidence of cancer at the time of study enrollment, between 12- and 60-month post-cancer treatment Chronic lymphedema (defined as lymphedema persisting for a minimum of 6 months) A minimum of 2 sites of external lymphedema At least 1 site with lymphedema of moderate severity as assessed using the HN-LEF Assessment Criteria Failed lymphedema therapy (defined as any of the following: incomplete response to therapy, progression of lymphedema after therapy, inability to perform effective self-care resulting in fluid re-accumulation; and inability to complete treatment due to systems barriers). In addition, patients must be able to understand English in order to complete questionnaires; and to provide informed consent.

Patients will be excluded if they have any of the following medical conditions that would prohibit the safe implementation of PBMT: Women of childbearing age and potential Acute cellulitis within the soft tissues in the head and neck region Chronic inflammatory diseases Venous thrombosis Carotid artery stenosis Requiring ongoing use of diuretics and corticosteroids Pre-existing skin rash, ulceration, open wound in the treatment area Active lymphedema or physical therapy (including hyperbaric oxygen or trental) Allergic and other systemic skin diseases