Personalized Ultrafractionated Stereotactic Adaptive Radiotherapy for Palliative Head and Neck Cancer Treatment (PULS-Pal)

Inclusion Criteria:

* \>= 18 years old
* Diagnosis of primary or recurrent, localized or metastatic (American Joint Committee on Cancer (AJCC) 8th Edition stages I-IV) head and neck cancer. In primary diagnosis cases, pathologic confirmation is required. In recurrent and/or metastatic diagnosis cases, pathologic confirmation is not required if not beneficial to the patient as standard of care, and diagnosis can be assumed based on clinical and/or radiographic evidence
* Ineligible for or declines standard of care definitive treatment(s), which will be documented in the patient's trial screening progress note in their electronic medical record by the treating physician
* Measurable disease within the head and/or neck clinically and/or on imaging studies (CT, PET, MRI) within 30 days from date of enrollment
* Patient maximum tumor(s) or tumor bed diameter must be less than 10cm
* In a woman of childbearing potential, a negative serum or urine pregnancy test within 1 week of treatment start must be documented. Women of childbearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; or abstinence) for duration of study participation and for up to 4 weeks following the study treatment
* Patients with a tracheostomy and/or a percutaneous endoscopic gastrostomy tube are eligible for inclusion

Exclusion Criteria:

* Pregnant or breast-feeding
* More than 1 prior radiation treatment course directed to the treatment area over the patient's lifetime. In patients who have received 1 prior radiation treatment course directed to the treatment area, that prior radiation treatment course must have concluded at least 6 months prior to trial enrollment
* Any comorbidity or condition which would limit full compliance with the protocol