Types & Stages

Pancreatic Cancer: Types & Stages

The exocrine cells and endocrine cells of the pancreas form different types of tumors. It’s very important to distinguish between exocrine and endocrine cancers of the pancreas. They have distinct risk factors and causes, have different signs and symptoms, are diagnosed with different tests, are treated in different ways, and have different outlooks.

Exocrine pancreatic cancers

Exocrine cancers are by far the most common type of pancreas cancer. If you are told you have pancreatic cancer, it is most likely an exocrine pancreatic cancer.

Pancreatic adenocarcinoma:About 95% of cancers of the exocrine pancreas are adenocarcinomas. These cancers usually begin in the ducts of the pancreas. Less often, they develop from the cells that make the pancreatic enzymes, in which case they are called acinar cell carcinomas

Less common types of exocrine cancer:Other, less common exocrine cancers include adenosquamous carcinomas, squamous cell carcinomas, signet ring cell carcinomas, undifferentiated carcinomas, and undifferentiated carcinomas with giant cells.

Less common types of exocrine cancer:Other, less common exocrine cancers include adenosquamous carcinomas, squamous cell carcinomas, signet ring cell carcinomas, undifferentiated carcinomas, and undifferentiated carcinomas with giant cells.

Ampullary cancer (carcinoma of the ampulla of Vater):This cancer starts in the ampulla of Vater, which is where the bile duct and pancreatic duct come together and empty into the small intestine. Ampullary cancers aren’t technically pancreatic cancers, but they are included here because they are treated very similarly.

Ampullary cancers often block the bile duct while they are still small and have not spread far. This blockage causes bile to build up in the body, which leads to yellowing of the skin and eyes (jaundice). Because of this, these cancers are usually found earlier than most pancreatic cancers, and they usually have a better prognosis (outlook).

Pancreatic endocrine tumors (neuroendocrine tumors)

Tumors of the endocrine pancreas are uncommon, making up less than 5% of all pancreatic cancers. As a group, they are often called pancreatic neuroendocrine tumors (NETs) or islet cell tumors.

Pancreatic NETs can be benign (not cancer) or malignant (cancer). Benign and malignant tumors can look alike under a microscope, so it isn’t always clear if a pancreatic NET is cancer. Sometimes it only becomes clear that an NET is cancer when it spreads outside the pancreas.

There are many types of pancreatic NETs.

Functioning NETs:About half of pancreatic NETs make hormones that are released into the blood and cause symptoms. These are called functioning tumors. Each one is named for the type of hormone the tumor cells make.

  • Gastrinomascome from cells that make gastrin. About half of gastrinomas are cancers.
  • Insulinomascome from cells that make insulin. Most insulinomas are benign (not cancer).
  • Glucagonomascome from cells that make glucagon. Most glucagonomas are cancers.
  • Somatostatinomascome from cells that make somatostatin. Most somatostatinomas are cancers.
  • VIPomascome from cells that make vasoactive intestinal peptide (VIP). Most VIPomas are cancers.
  • PPomascome from cells that make pancreatic polypeptide. Most PPomas are cancers.

Most functioning NETs are gastrinomas or insulinomas. The other types are rare.

Non­functioning NETs:These tumors don’t make enough excess hormones to cause symptoms. They are more likely to be cancer than are functioning tumors. Because they don’t make excess hormones that cause symptoms, they can often grow quite large before they are found.

Carcinoid tumors: These NETs are much more common in other parts of the digestive system, although rarely they can start in the pancreas. These tumors often make serotonin (also called 5­HT) or its precursor, 5­HTP.

A staging system is a standard way for doctors to sum up how large a cancer is and how far it has spread. The system used most often to stage cancers of the pancreas is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:

  • T – describes the size of the main (primary) tumorand whether it has grown outside the pancreas and into nearby organs.
  • N – describes the spread to nearby (regional) lymph nodes, which are bean­sized collections of immune system cells to which cancers often spread first.
  • M –  indicates whether the cancer has metastasized(spread) to other organs of the body. (The most common sites of pancreatic cancer spread are the liver, lungs, and the peritoneum, which is the lining that covers the organs in the abdomen.)

Numbers or letters appear after T, N, and M to provide more details about each of these factors. Higher numbers mean the cancer is more advanced.

T categories

TX:The main tumor cannot be assessed.

T0:No evidence of a primary tumor. Tis:Carcinoma in situ (the tumor is confined to the top layers of pancreatic duct cells). (Very few pancreatic tumors are found at this stage.)

T1:The cancer has not grown outside the pancreas and is 2 centimeters (cm) (about ¾ inch) or less across.

T2:The cancer has not grown outside the pancreas but is larger than 2 cm across.

T3:The cancer has grown outside the pancreas into nearby surrounding structures but not into major blood vessels or nerves.

T4:The cancer has grown beyond the pancreas into nearby large blood vessels or nerves.

N categories

NX:Nearby (regional) lymph nodes cannot be assessed.

N0:The cancer has not spread to nearby lymph nodes.

N1:The cancer has spread to nearby lymph nodes.

M categories

M0:The cancer has not spread to distant lymph nodes (other than those near the pancreas) or to distant organs such as the liver, lungs, brain, etc.

M1:The cancer has spread to distant lymph nodes or to distant organs.

Stages of pancreatic cancer

Once the T, N, and M categories have been determined, this information is combined to assign an overall stage of 0, I, II, III, or IV (sometimes followed by a letter).

 Stage Stage grouping Stage description
0 Tis, N0, M0 The tumor is confined to the top layers of pancreatic duct cells and has not invaded deeper tissues. It has not spread outside of the pancreas. These tumors are sometimes referred to as pancreatic carcinoma in situ or pancreatic intraepithelial neoplasia III (PanIn III).
IA T1, N0, M0 The tumor is confined to the pancreas and is 2 cm across or smaller (T1). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0).
IB T2, N0, M0 The tumor is confined to the pancreas and is larger than 2 cm across (T2). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0).
IIA T3, N0, M0 The tumor is growing outside the pancreas but not into major blood vessels or nerves (T3). The cancer has not spread to nearby lymph nodes (N0) or distant sites (M0).
IIB T1­T3, N1, M0 The tumor is either confined to the pancreas or growing outside the pancreas but not into major blood vessels or nerves (T1­T3). The cancer has spread to nearby lymph nodes (N1) but not to distant sites (M0).
III T4, Any N, M0 The tumor is growing outside the pancreas and into nearby major blood vessels or nerves (T4). The cancer may or may not have spread to nearby lymph nodes (Any N). It has not spread to distant sites (M0).
IV Any T, Any N, M1 The cancer has spread to distant sites (M1)