I have an update, got some good news. The mass was detected before it became cancerous. Because of the location, they are going to do a Whipple procedure to remove it. This is a major surgery, but doctors at the Mayo clinic are experts, so we are optimistic. Thanks for the prayers.
Dad is scheduled for a CAT scan today. This is to determine if they can do the surgery using a less invasive technique, sort of like arthroscopically, with a series of small incisions. That would greatly speed up recovery. I guess they are also going to confirm that the mass isn't cancerous. Pending all this, surgery may be scheduled for late this week.