Is it okay to skip one treatment??

Hi All! I haven't posted in a while, but I do try to read your messages daily, and you are all in my thoughts and prayers.

My Dad is taking FOLFOX, and he is half way through his treatment. He has totally lost his appetite, and is feeling very, very tired. I told him he should see if he could take a break, delay treatment a week or two. His Oncologist said that if all possible he shouldn't do that. Have any of you had similar experiences, or taken a small break?

Hugs to all~
Michele