Cancer of the pancreas is a genetic disease which means that it is caused by changes (mutations) in DNA. These changes can be inherited or they can be acquired; the inherited changes explain why cancer of the pancreas runs in some families whereas the acquired changes can result from exposure to carcinogens and/or an immune system which is depressed in some way, rendering it less capable of killing cancerous cells once they develop.
Pancreatic malignancy has one of the highest mortality rates for cancer, being the fifth leading cause of cancer deaths in the United States. A full 80% of patients diagnosed with it die within a year.