My dad had the same thing 8 years ago.

The symptoms starts real late when the lump on the Pancreas has push one side of his stomach giving him stomach discomfort such as gastric and nausea feeling.

For several weeks he visited the doc for med and thought it was a normal thing.

When he decided to visit the specialist when the symptoms arent going away. We found out in the xray there was a lump and hopefully it wasnt cancerous that will spread around the organ..

But it was already too late when the symptom is out.

cancer take years to develop just like you said.

One question. Is your dad a heavy smoker?

Mine was. 1-2 packs a day till the age of 58 which took him away