I did start the chemo BEFORE the Whipple, as recommended and had to stop as I was practically comatose. Yes, I disregarded (hard to say I "went against" because I know my oncologist was sincere and had spent many years trying to make his patients well) his recommendation. I would say the oncologist supported my decision, though disagreed with it and said radiation was palliative, not a cure. Also, I had great support from my son and daughter who saw what the chemo did and wanted me to have as good a life as possible in my later years. I still see the oncologist every 3 months and he persists in suggesting chemo at every meeting, but accepts my decision.
I did not have radiation until a mass appeared in my mesentery, over a year after the Whipple. I found out then how much less radiation impacted my body. I now see both the oncologist (the chemo expert) and the radiologist every 3 months.