What is a cancer stage?

Following a diagnosis of cancer, the most important step is to accurately determine the stage of cancer. Stage describes how far the cancer has spread. (Some cancers, such as leukemia, may not be staged.) Each stage of cancer may be treated differently. In order for you to begin evaluating and discussing treatment options with your healthcare team, you need to know the correct stage of your cancer.

There are many staging systems, but TNM is the most common. “T” refers to the size of the tumor, “N” to the number of lymph nodes involved, and “M” to metastasis. TNM staging measures the extent of the disease by evaluating these three aspects and assigning a stage, which is usually between 0-4. Generally, the lower the stage, the better the treatment prognosis (outcome).

* Stage 0 – precancer
* Stage 1 – small cancer found only in the organ where it started
* Stage 2 – larger cancer that may or may not have spread to the lymph nodes
* Stage 3 – larger cancer that is also in the lymph nodes
* Stage 4 – cancer in a different organ from where it started

How is prognosis determined?
The probable course and/or outcome of the cancer is called the prognosis. Identifying factors that indicate a better or worse prognosis may help you and your doctor plan your treatment. There are many factors that help determine your prognosis. Some of these include:

* Your age
* Your level of physical fitness
* Size of your cancer
* Stage of your cancer
* Aggressiveness of your cancer (cancer cells that are growing and dividing rapidly are considered more aggressive)
Your doctor will evaluate all possible factors to determine your prognosis.

Recently, the genetic make-up of cancer is being increasingly recognized as an important prognostic factor. For example, some genes have been associated with an aggressive course or tendency to recur. Identification of these in an early stage cancer may indicate a poor prognosis. Some research suggests that the genetic make-up of the cancer may be even more important for determining prognosis than the stage of the cancer.

How is cancer diagnosed?
Diagnosing cancer involves the use of a variety of tests that provide details about abnormal cells, which may have been detected through routine medical examinations, self-examination, or reported symptoms. More information about these cells must be gathered in order to identify them as malignant (cancerous) or non-malignant (non-cancerous), and if they are malignant, to determine how serious (aggressive) the particular cancer cells are. Aggressive cancers grow and spread more quickly than less-aggressive or “indolent” cancers. There are many types of tests specifically designed to evaluate cancer:

* A pathology report is based on observation of abnormal cells under a microscope.
* Diagnostic imaging involves visualization of abnormal masses using high tech machines that create images, such as x-rays, computed tomography (CT), positron emission test (PET), magnetic resonance imaging (MRI), and combined PET/CT.
* Blood tests measure substances in the blood that may indicate how advanced the cancer is or other problems related to the cancer.
* Tumor marker tests detect substances in blood, urine, or other tissues that occur in higher than normal levels with certain cancers.
* Special laboratory evaluation of DNA involves the identification of the genetic make-up—the DNA—of the abnormal cells.

For more information about diagnostic tests, visit the Testing Center.