This study is being done to answer the following question: Does stereotactic body radiation therapy (SBRT) provide better cancer control compared to standard radiation therapy (RT) for those with advanced head and neck cancer?

Stereotactic body radiation therapy, or SBRT, is a cancer treatment that more precisely delivers radiation to the tumour area with less radiation going to unaffected areas around the tumour. It uses fewer treatments of higher doses compared to standard radiation therapy. This study is being done to find out if this approach is better than the usual approach for advanced head and neck cancer. The usual approach is defined as care most people get for advanced head and neck cancer.