The statistics that you may read are out of date. There have been advances in the treatment of Stage 4 colon cancer. Some liver tumors are operable, others are large but after chemo, can shrink enough to be removed, and some are located on or close to a blood vessel and non-operable. The liver is an organ that can regenerate itself, so if a lobe or section of a lobe is removed, after a few months the liver will grow back to its normal size. Mop-up chemo is usually used after a liver resection, to destroy any stray remaining cancer cells. There is also targeted radiation that can zap liver tumors not suitable for resection.
Statistically, in about 30% of Stage 4 liver resections, assuming there is no disease elsewhere in the body, removal of liver tumors can be curative.