Is there anyone out there who has had any experience with Re radiation?

My husband has stage iv cancer. Has had 3/4 of his tongue removed and a radical neck dissection in Feb 2009. That was followed by 7 weeks of radiation combined with 6 cycles of Cisplatin Chemo which ended in June 2009.

His cancer came back in August 2009. From Sept. 2009 to March 2010 he had Erbitux, Carbotaxol, plus 1 other drug chemo. He has a new cancer site below his thyroid.

Re radiation is now being considered. Does anyone have any experience with re radiation? What can be expected? What should I be asking my husband's doctors?