This can be done in a variety of ways.
This is where only the tumour and a small margin of surrounding tissue is removed. Essentially the tumour is 'shelled' out. Blood vessels supplying the tumour are cauterised with diathermy proximal to the tumour and clipped proximal to the pancreas. Once isolated it can be removed.
When lesions are too large, too numerous or too invasive to remove individually, parts of the pancreas may be removed (pancreatectomy) 'en bloc'. If the lesions lie in the body and tail, a distal pancreatectomy can be performed. This is where only the body and tail of the pancreas are removed.
Rarely, when the tumour is in the head of the pancreas and involving surrounding structures, a Whipple's procedure may be done.
Diagram of Whipple's procedure - click to enlarge
This is also known as a pancreaticoduodenectomy, where the gall bladder, common bile duct, duodenum, the head of the pancreas and the pylorus of the stomach are removed. The stomach, common hepatic ducts and the body and tail of the pancreas are joined independently on to the jejunum to restore continuity of the gut.