The purpose of this study is to evaluate the tumor control and the side effects of using proton therapy for head and neck cancer that has come back.

Inclusion Criteria:

• Patient willing and able to provide written informed consent
• Age ≥18 years at the time of consent
• Pathologically confirmed diagnosis of a recurrent or a new primary head and neck cancer
• A history of prior radiation to the head and neck (>/= 40 Gy, in 2 Gy/fraction equivalent)
• The recurrent or the second primary tumor is unresectable, the patient elects against surgical resection; patients who underwent surgery who has indications for postoperative radiation therapy is also eligible
• Men and women of childbearing potential must be willing to consent to using effective contraception while on treatment and for at least 3 months after treatment Note: Patient with <6 months of life expectancy will be treated with palliative QUAD shot radiotherapy and those with > 6 months of life expectancy will be treated with conventionally fractionated full dose re-irradiation approach. Additional other factors determining which patients will be treated with Quad Shot therapy rather than full dose are if the patients have poor performance status, bulky or diffuse disease, significant medical co-morbidities, and significant metastatic disease burden.

Exclusion Criteria:

• Women who are pregnant or lactating
• Inability to comply with study and/or follow-up procedures
• <6 months between completion of prior RT and initiation of reirradiation using proton therapy