A recurrence in the original site so soon after treatment is very serious. I think that the doctors are trying to prepare you for the worst.

I wanted to address something that Gita said about "not receiving the full dose". What that means is his sister probably received 72 cGy of radiation, which is a full dose in itself. It is typically lethal for most cancers that will respond to radiation.

The maximum dose possible is about 82 cGy total and the additional fraction (around 9 cGy) is called a "boost". Depending on what stage her tumor was originally at (and other risk factors as well) would dictate whether she gets the boost or not. Getting the full 82 cGy has risks of its own and they prefer limiting the radiation if possible.

Many times they use the additional radiation (the boost) to irradiate areas other then the tumor site itself such as lymph nodes that may be suspicious. So the actual tumor site may indeed not receive any additional radiation.

Brett is correct about chemo, especially with head and neck cancers. Like Brett also stated, if he is not being seen at a comprehensive cancer center already, I would get a second opinion from them.

I am very sorry to hear about your fathers situation.