The purpose of this study is to demonstrate that adaptive radiotherapy (ART) in head and neck cancer patients are comparable to historical controls in head and neck patients undergoing standard intensity-modulated radiation therapy (IMRT) without ART.

Inclusion Criteria:

• Participants with pathologically confirmed cancers of paranasal sinuses, oropharynx, oral cavity, nasopharynx, larynx, hypopharynx, and unknown primary and will receive definitive radiation therapy with or without chemotherapy.
• Karnofsky performance status >= 70%
• Women of childbearing potential need to have a negative serum pregnancy test at the time of therapy
• Participants must have the ability to understand and the willingness to sign a written consent form

Exclusion Criteria:

• Female participants who are pregnant or breast feeding
• Participants who are not able to comply with study and/or follow up procedures
• Participants who have received induction chemotherapy before radiation treatment
• Participants who had prior head and neck radiation therapy
• Participants who are enrolled in a national/international cooperative group trials
• Patients with metastatic disease