I'm very sorry to hear of your husband's diagnosis. I am not familiar with treatment of such large tumors, but maybe can give a little general information.
My wife was diagnosed Jan.1, 2006 with CC plus a tumor in the liver about 7 Cm.
She was on Gemzar plus Oxaliplatin for 10 months, and the tumor shrank to only 2.3 Cm 6 months after treatment started and was about the same 2 months later. She was being considered for resection of both it and the bile duct tumor, when suddenly the tumor began growing again very fast up to 8.5 Cm in Feb. 2007, ending chance of resection. I mention this only because this particular chemo combination worked very well for her with virtually no side effects during that time, although most people have a bad time with the oxaliplatin.
The next consideration was ChemoEmboliztion, and I noticed several postings about it under "Experiences". I don't know the maximum size tumor that can be treated with this method, but it didn't work for my wife because the doctors could not find any arteries feeding the tumor to inject the chemo into!
The tumor is now up to over 10 Cm, another Chemo was tried starting in June (Taxol and Carboplatin), but it beat her to the ground, caused considerable pain, and she had to be hospitalized on Sunday the 15th with infection due to extremely low white blood counts. She is out now, very weak, but recovering, and will not receive that chemo again! The next step is not sure, but except for the last 6 weeks, has felt good and enjoyed every day. Of course we pray a lot and are looking at supplements that may help.
We will be praying for you and your husband, as we do for others on the website. Above all, keep asking questions and checking all the alternatives. May God Bless You Both.