CHAPTER 6

Staging Cancer

PART 1 What Is Cancer Staging?

Cancer staging, that is, determining the extent and spread of cancer in the body, is used by doctors to plan treatment and to arrive at a prognosis (estimate of future course and outcome) for the disease. READ MORE

Staging involves gathering different types of information to get as clear a picture as possible of the cancer and how far it has progressed. Physical exams, imaging tests (such as MRIs, CT scans, X-rays, PET scans, and PET/CT scans) may all be used. A biopsy is needed to confirm a diagnosis of cancer, but it can also help to stage the disease. LESS

PART 2 Types of Staging

There are different types of staging:

Clinical staging is done when the cancer is diagnosed and before treatment. It is based on the physical exam, imaging tests, and, possibly, biopsy. Blood tests may be used for some cancers. This is the stage at which a course of treatment is decided upon.

Pathologic staging is performed after the patient has had surgery to remove the cancer or to determine the extent of cancer in the body. The surgery may show, for instance, that there is more cancer in the body than had been previously thought, and this will affect prognosis.

Restaging may be performed to determine the extent of the cancer if it recurs after treatment.

PART 3 Staging Systems: The TNM System

For most cancers, staging is done using the TNM system, developed by the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC).

In the TNM system:

T = extent of the primary tumor

N = extent of spread to lymph nodes

M = presence of metastasis

In the T category:

TX	Primary tumor cannot be evaluated
T0	No evidence of primary tumor
Tis	Carcinoma in situ (early cancer that has not spread to neighboring tissue)
T1–T4	Size and/or extent of the primary tumor

In the N category:

NX	Regional lymph nodes cannot be evaluated
NO	No regional lymph node involvement (no cancer found in the lymph nodes)
N1-N3	Involvement of regional lymph nodes (number and/or extent of spread)

In the M category:

MX	Distant metastasis cannot be evaluated
MO	No distant metastasis (cancer has not spread to other parts of the body)
M1	Distant metastasis (cancer has spread to distant parts of the body)

However, each type of cancer has its own classification system, so these designations don’t mean the same thing for every kind of cancer. LESS

PART 4 Stage Grouping

Once T, N, and M are determined, they are combined, and an overall stage of 0-IV is assigned.

Stage 0: Carcinoma in situ (early cancer that is present only in the layer of cells in which it began)

Stage I, Stage II, and Stage III: Higher numbers indicate more extensive disease, ie, greater tumor size, and/or spread of the cancer to nearby lymph nodes, and/or organs adjacent to the primary tumor

Stage IV: The cancer has spread to another organ

Sometimes these stages are subdivided (eg, IIIA and IIIB).

Criteria for stages differ for different types of cancer. For example, bladder cancer T3N0M0 would be termed Stage III; however, colon cancer T3N0M0 would be Stage II.

PART 5 Summary Staging

Many cancer registries, such as the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program (SEER), use summary staging for all types of cancer. Summary staging groups cancer cases into five main categories:

In situ: Early cancer that is present only in the layer of cells in which it began

Localized: Cancer that is limited to the organ in which it began, without evidence of spread

Regional: Cancer that has spread beyond the primary site to nearby lymph nodes or organs and tissues

Distant: Cancer that has spread from the primary site to distant organs or distant lymph nodes

Unknown: Cases for which there is not enough information to indicate a stage

PART 6 Other Staging Systems

Leukemia and cancers of the central nervous system are not staged using the TNM system. In leukemia, the cancer is assumed to have spread throughout the body via the circulatory system. Cancers of the central nervous system (the brain and spinal cord) can disrupt vital functions even before they spread, so their progress is not judged in the same way as other cancers. These cancers are classified according to their cell type and grade. READ MORE

Some physicians still use older staging systems, and certain organizations have developed their own staging systems for specific types of cancer. For instance, the Dukes system is an older staging system for colorectal cancer that is still in use. The International Federation of Gynecologists and Obstetricians (FIGO) has a staging system for cancers of the female reproductive organs. LESS

PART 7 A Cancer’s Stage Doesn’t Change

A somewhat difficult concept to grasp is that a cancer’s assigned stage doesn’t change, even if the cancer progresses or recurs. The cancer is always referred to by the stage it was designated as when it was first diagnosed. So if someone was diagnosed with Stage II colorectal cancer and it metastasized to the liver, it would be called Stage II colorectal cancer with metastasis in the liver. If the colorectal cancer had been treated but then recurred, it would be termed Stage II colorectal cancer with recurrent disease in the liver.

It’s important to know this, as survival statistics and treatment information are based on the stage when the cancer was first diagnosed.