Tracy, my dad (who is totally done and getting better every day) had fevers of up to 102. It was awful seeing him shudder when the fevers would break. It seems odd to say, but we took it as a good thing that there was nothing specific that the MD's isolated as causing the fever, this is a not an unusual thing during this treatment. After touching base with many of my oncology buddies, we have had discussions that just having cancer in general causes fevers and when tumors die, they release lots of icky substances that may increase basal temperature. These are only discussions and thoughts, so please don't apply this as fact to your fathers situation. I will say that with a little acetaminophen and Boat loads of hydration in the tube or via the iv, my dad's fevers were obliterated. Just keep thinking that your dad will likely turn around in a couple days--that's what I did and that's what happened. My dad spent a week in the hospital then another unexpected early stay. Those fluids can do a ton. Oh, also, I THINK (my feeling) is that going through all of this your body tends to be in a basic dehydrated state which also contributes to increased temperature. Take a deep breath and pray for your pops. My dad's rad was delayed as well.