Your case sounds a lot like mine - solitary liver met that was gone from CT, PET and MRI after 6 treatments of Xeloda/oxaliplatin/Avastin - that was back in 2005 and I am still here. While I did have 1 lung recurrence, my liver has been clear since then.
My oncologist did not think I should I should pursue liver resection at that time. I decided to consult with a liver surgeon at Johns Hopkins - he said flat out that he would not operate at that time. In the Spring of 2006, I was evaluated for a clinical trial at NIH that involved liver RFA. I was turned down because they could find no evidence of any liver disease. The surgeon at NIH who was running the trial told me that were he still in private practice, he would not operate on me. So, one onc and 2 liver surgeons all agreed on not having surgery.
It is usually said that chemo alone cannot eliminate liver mets, but I am proof that it can (although it isn't the norm).
diag. Stage IV, 5/05, liver met
lap sigmoid colectomy, 6/05
6 cycles Xeloda/oxaliplatin/Avastin (NED after 2)
11/08 9x13mm right lower lobe lung nodule; removed via VATS 4/09
6 cycles Xeloda + Avastin
Avastin only 10/09-5/11
Still NED 06/18