( welcome btw)

Okay - tongue tumors... It sounds like its oral tongue - inside his mouth - the standard treatment for this is actually surgery - then depending on the pathology and involvement - a follow up of 6-7 weeks of daily chemo radiation with weekends off.

In the event that it is too extensive to operate then they may give him longer chemoradiation. Radiation is hard. At his age it will be harder I suspect... He'll need a lot of support. I would get a second opinion at a cancer center if you haven't.

And the lump under his jaw is likely a node that's been invaded.

Hugs and we're here