How often do tumors on the pancreas end up being benign?

Not often: Most of them are malignant, especially if solid. And many cystic lesions are premalignant..

Lots are benign: Tumors of the pancreas are often benign, and often just cysts. It really takes a specialized team to be able to determine tumors/cysts are benign and can be followed without surgical removal and which require further evaluation and potentially surgical removal. CT scans, MRI scans, and endoscopic ultrasound are the most common tests to make this determination.