What an awful decision you have to make and I don't believe there is one right answer. I guess if it was me I'd make my decision based first on what your mother has said in her more lucid days about end of life care when things look bleak. Absent that information I'd base the decision on what you'd want done if YOU were in the exact same situation. I know what I'd want but everyone is different.

Diagnosed in March 2011. Treatment ended May 28, 2011. Back of tongue cancer with one lymph node(stage 4). Feeding tube 5 - 2011, to 9 - 2011. Some saliva and taste. Eating most foods; meat, fish and dry foods not so well. Swallowing pretty normal otherwise. Doing well now. The future? Who knows.