Marianne- We struggle with this a lot in my mom's treatments. I struggle with the balance between the treatment and the quality of life. Are we curing her or killing her? You always have the option to have a say in your own treatment plan. The risk of cutting down is that it could be less effective. Just make sure your dad is open with the doctor(s) about his side effects he is having. Cutting back may be the best option or maybe getting a second opinion is a value. I strongly believe that if your physician does not have "time" or interest in discussing all this with you and your dad then you can find a smart caring doctor out there who will. Ask your doctor about a drug named Tarceva...new in pancreatic cancer treatment. Mom is supposed to start next week. We are still researching the side effects and I have lots of questions for the doctor at the next visit.
Good luck and take care. May you find angels to support and guide you along your journey.