Decoding the Stages of Cancer

When your physician diagnoses you with cancer, she then needs to determine the stage of your cancer. For patients, the numbers and letters that describe cancer can sound mysterious and scary. Here is a brief overview of cancer staging.

What is Cancer Staging?

Staging describes how advanced your disease is and whether it has spread beyond the initial tumor site. This helps your physician plan your treatment and identify potential identify clinical trials you might be eligible for. Staging also helps physicians communicate with each other by providing a common language for discussing cancer. The way oncologists stage cancer changes as we learn more about how cancers form and grow.

Common Staging Conventions

Physicians generally use the TNM system for staging. TNM describes the extent of the tumor (T), whether it's also present in regional (nearby) lymph nodes (N), and whether the cancer has metastasized (M), or spread. Each type of cancer has its own classification system, so the same TMN number and letter can describe two different cancers.

Your physician determines your TNM using the information he used to initially diagnose your cancer. Physical exams, imaging tests, blood and other laboratory tests, pathology reports, and surgical reports all provide a piece of the puzzle.

Using the TNM data, your physician assigns you cancer a staging number between 0 and IV.

Stage 0 is the least serious and means there are abnormal cells only in the layers of cells where the tumor developed. Stage IV cancer is one that has metastasized. The stage of cancer does not change even if the cancer progresses; it's based on the stage at time of diagnosis.

Other Ways to Classify Cancer

Tumor grade classifies cells based on how abnormal they look under a microscope and how quickly they are likely to grow. Physicians assign tumor grade values based on the type of cancer. Grades progress from grade 1, least aggressive and slow growing, to grade 4, fast growing and aggressive.

Physicians can also classify some cancers through genetics. Certain genes provide clues whether your cancer is likely to spread and what types of treatment will be most effective.

There are exceptions to the standard staging classifications. Brain and spinal cord cancers use cell type and tumor grade, although there is not one single staging system for these cancers. Blood and marrow cancers and some gynecological cancers don't use TNM, and childhood cancers have their own staging protocol.


Sources:
National Cancer Institute. "Detection: Staging." Web.
http://www.cancer.gov/cancertopics/factsheet/Detection/staging

National Cancer Institute. "Tumor Grade: Questions and Answers." Web. 19 May 2004.
http://www.cancer.gov/cancertopics/factsheet/detection/tumor-grade

West, Jack H. "What Lung Cancer Staging Doesn't Tell Us." Medscape Medical News." Web. 22 December 2010.
http://boards.medscape.com/forums?128@626.0LtfaDauGZ5@.2a057e35!comment=1

American Joint Committee on Cancer. "What is cancer staging." Web. 5 May 2010.
http://www.cancerstaging.org/mission/whatis.html

Lung Cancer.org. "Lung cancer staging."
http://www.lungcancer.org/reading/staging.php

Cancer.net. "Staging." Web. May 2010.
http://www.cancer.net/patient/All+About+Cancer/Treating+Cancer/Staging