I think your dad has what my mom had, ampullary cancer. It took two visits to different oncologists for us to get this information. The nodule started in the small intestines and the junction of the biliary ducts and traveled to the pancrease and to the lymph nodes.
She had a terrbile time, just terrible. She had her operation on the 2nd of February 2009 and has continued to loose weight, but she is feeling much better, sleeps half the day, but can go to movies, out to eat and is actually taking a short trip to the coast.
When my mom was looking at chemotherapy, the second oncologist said she really needed to be treated for colon cancer and pancreatic cancer, which would make the drug of choice Full Fox...but your dad is younger, my mom is 79. So they would probably do a more aggressive treatment.
Did your dad loose his hair due tot he trauma of the operation by chance?
Yes, my mom is altered, lost 65Ibs since December and is not going to do chemo or radiation. As we call it, she has chosen life for her remaining time. She said she could not go through the nausea and not eating again.
Hope this helps.