John A. Windsor - General, Pancreatobiliary, Gastro-oesophageal & Laparoscopic Surgeon
The pancreas is located deep in the body, behind the stomach, just anterior to the vertebral body. It is shaped a little bit like a fish – extending almost horizontally from the first part of the small bowel (duodenum) on the right to the hilum of the spleen on the left. It is about 15 cm long and less than 5 cm wide. The pancreas is composed of two types of glands. The exocrine pancreas makes up the majority of the gland. It makes pancreatic "juice” that is composed of enzymes that help to break down food you eat. The pancreatic juice is secreted into the pancreatic duct that joins the bile to empty the contents into the first part of the small intestine (duodenum). The endocrine pancreas is composed of clusters of cells called islets, that make hormones like insulin that help balance the amount of sugar in the blood.
Cancer can develop in both the exocrine and endocrine cells of the pancreas. Tumours formed by the exocrine cells are much more common. Not all of the tumours in the pancreas are malignant, some are benign. It is important to know whether a tumour is from the exocrine or endocrine part of the pancreas as it is treated in different ways, and has a different prognosis.
Exocrine tumours are the most common type of pancreas cancer. The majority arise within the glands of the exocrine pancreas and are called adenocarcinomas. A special type of cancer called ampullary cancer arises within the distal bile duct where it empties into the small intestine. This type of cancer often presents with jaundice, so is usually found at an earlier stage. Adenocarcinoma of the pancreas is typically an aggressive tumour with a poor outcome unless it can be completely removed. Treatment of exocrine cancer of the pancreas depends upon the stage of the cancer. Unfortunately most patients with adenocarcinoma of the pancreas present too late to be removed by surgery, and are managed palliatively. Even if curative resection is possible, only around one in five patients will be cured.
Endocrine tumours of the pancreas are rare. They are also known as islet cell tumours or neuroendocrine tumours (NET) and are divided into different types depending upon the hormones that they produce. Most endocrine pancreatic tumours are benign, but they can be malignant. Rarely, the pancreas is a site for secondaries (metastases) from cancers elsewhere. Some tumours can present as cysts. The majority are benign and can be safely watched.
Pancreatic resection refers to the removal of a portion of the pancreas. This operation is usually done to remove various types of liver tumours. The principal aim of performing pancreatic resection is to completely remove the tumour without leaving any tumour behind. The success of pancreatic resection depends upon the location, size and type of tumour.
Pancreatic resection is mainly performed to remove pancreatic cancer. Most patients who require pancreatic resection have a primary cancer that has arisen within the pancreas, usually adenocarcinoma. Less commonly tumours can arise from the endocrine pancreas. Sometimes it is not possible to determine whether the tumour is benign or malignant and resection is performed to remove the tumour and establish the diagnosis. Biopsy of the pancreas is not routinely recommended as it has the potential to cause bleeding and spread of the cancer.
There are two principal types of operations:
1. Removal of the head of the pancreas, the duodenum and bile ducts (including gallbladder) with or without the distal stomach – known as a pancreaticoduodenectomy or Whipple’s procedure. The Whipple operation is performed for cancer that is located in the head of the pancreas.
2. Removal of the body and or tail of the pancreas with or without the spleen – known as a distal pancreatectomy. It is performed for tumours that are located in the neck, body or tail of the pancreas. It is technically more straightforward than a Whipple, and can be performed either by an open operation or laparoscopically.