It sounds like a like a T4 Squamous cell carcinoma. It is not stage IV unless it has spread to other parts of the Body (although sometimes they call extensive Local diseasse stage IV A, I think this confuses patients AND clinicians) He need Combined Chemo radiation plus/minus surgery depending on response. He may require a neck dissection in any case, this should be done after the initial treatment. He will need dental work if needed and a temporary feeding tube to get him thru treatment. He should get a pretreatment PET / CT scan if available to r/o mets and synchronous primaries.
You need a Radiation Oncology Center with Modern equipment and a well trained staff in Western Methods of treatment. If you can afford it this would be worth the extra expense. Based on the data you present I think with aggressive treatment the potential cure could be about 15 to 20 percent higher