What is the stage of a cancer?
The stage of a pancreatic cancer is the extent of the disease at the time of diagnosis. It is one of the most important factors in choosing treatment options and predicting a patient’s outlook. Pancreatic cancer is staged based on the results of exams, imaging tests, endoscopies, and biopsies, which are described in Tests for pancreatic cancer.
The American Joint Committee on Cancer (AJCC) TNM staging system
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) tumor and whether it has grown outside the pancreas and into nearby organs.
- N describes the spread to nearby (regional) lymph nodes, which are bean-sized 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.
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.
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.
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).
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).
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).
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).
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).
T1-T3, N1, M0
The tumor is either confined to the pancreas or growing outside the pancreas but not into major blood vessels or nerves (T1-T3). The cancer has spread to nearby lymph nodes (N1) but not to distant sites (M0).
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).
Any T, Any N, M1
The cancer has spread to distant sites (M1).
Other prognostic factors
Although not formally part of the TNM system, other factors are also important in determining a person’s prognosis (outlook).
The grade of the cancer (how abnormal the cells look under the microscope) uses a scale from G1 to G3 (or sometimes G1 to G4), with G1 cancers looking the most like normal cells and having the best outlook.
The details of grading are a little different for pancreatic neuroendocrine tumors (NETs), where measures of how many of the cells are in the process of dividing is an important part of grading. This is determined by counting mitoses (cells that have started to split into two new cells) under a microscope and with a Ki-67 test that recognizes cells that are almost ready to start splitting. Based on these tests, NETs are divided into 2 groups:
- Well-differentiated NETs (which includes low-grade [G1] and intermediate-grade [G2] tumors) have 20 or fewer mitoses and a Ki-67 index of 20% or lower.
- Poorly differentiated tumors (high-grade [G3] tumors) have more than 20 mitoses or a Ki-67 index of more than 20%. These are also called neuroendocrine carcinomas, and they often grow and spread quickly.
Extent of resection
For patients who have surgery, another important factor is the extent of the resection — whether or not all of the tumor is removed:
- R0: All of the cancer is thought to have been removed. (There are no visible or microscopic signs suggesting that cancer was left behind.)
- R1: All visible tumor was removed, but lab tests of the removed specimen show that some small areas of cancer were probably left behind.
- R2: Some visible tumor could not be removed.
Resectable versus unresectable pancreatic cancer
The AJCC staging system gives a detailed summary of how far the cancer has spread. But for treatment purposes, doctors use a simpler staging system, which divides cancers into groups based on whether or not they can be removed (resected) with surgery:
- Borderline resectable
- Unresectable (either locally advanced or metastatic)
These terms are used more often to describe exocrine pancreatic cancers than pancreatic neuroendocrine tumors.
If the cancer is only in the pancreas (or has spread just beyond it) and the surgeon believes the entire tumor can be removed, it is called resectable. (In general, this would include most stage IA, IB, and IIA cancers in the TNM system.)
It’s important to note that some cancers might appear to be resectable based on imaging tests such as CT scans, but once surgery is started it might become clear that not all of the cancer can be removed. If this happens, only a sample of the cancer may be removed to confirm the diagnosis (if a biopsy hasn’t been done already), and the rest of the planned operation will be stopped to help avoid the risk of major side effects.
This term is used to describe some cancers that might have just reached nearby blood vessels, but which the doctors feel might still be removed completely with surgery. This would include some stage III cancers in the TNM system.
These cancers can’t be removed entirely by surgery.
Locally advanced: If the cancer has not yet spread to distant organs but it still can’t be removed completely with surgery, it is called locally advanced. Often the reason the cancer can’t be removed is because it has grown into or surrounded nearby major blood vessels. (In general, this would include stage IIB and most III cancers in the TNM system.)
Surgery to try to remove these tumors would be very unlikely to be helpful and could still have major side effects. Some type of surgery might still be done, but it would be a less extensive operation with the goal of preventing or relieving symptoms or problems like a blocked bile duct or intestinal tract, instead of trying to cure the cancer.
Metastatic: If the cancer has spread to distant organs, it is called metastatic. These cancers can’t be removed completely. Surgery might still be done, but the goal would be to prevent or relieve symptoms, not to try to cure the cancer.
Last Revised: 04/05/2016