The Stages of Cancer Explained
What is cancer staging? Cancer staging is the way doctors explain how much cancer is in a person’s body and where it is located. It also helps to explain if the cancer has spread and whether it is affecting other parts of the body.
What is the difference between clinical and pathological staging? Your doctor will use test results (clinical) and the tumor itself (pathological) to determine your overall stage.
Clinical staging is based on the results of all of your testing before surgery: physical exams, imaging tests (CT scans, x-rays, etc.) and tumor biopsies.
Pathological staging (sometimes called surgical staging) is based on what is learned about the cancer during the surgery.
What is the TNM staging system? The American Joint Committee on Cancer has established the TNM system to describe a cancer’s stage. Using diagnostic tests, imaging scans and biopsies, doctors can answer the following questions as part of the TNM system.
- T – Tumor – What is the size and location of the original (primary) tumor?
- N – Node – Has the cancer spread to nearby lymph nodes?
- M – Metastasis – Has cancer spread to distant parts of the body?
In the TNM system, each type of cancer is assigned a TNM letter or number value to describe the tumor, node and metastasis.
Once the TNM values have been determined, your doctor will assign an overall stage. The stages are written in Roman numerals I – IV. In stages I through IV, stage IV is the highest and the cancer is more advanced than the lower stages.
Stage 0 – Sometimes a cancer stage can be 0, which means carcinoma in situ, a cancer that is found in the very early stages, is only present in the original site and has not spread.
Stage I – Stage I is an early stage cancer that has not grown deeply into surrounding tissue or spread into lymph nodes.
Stage II and III – In general these stages indicate cancers that have grown into surrounding tissues and may have spread into the lymph nodes.
Stage IV – This is the most advanced stage of cancer. It has spread into surrounding organs or distant parts of the body. This is often referred to as metastatic cancer.
Not all cancers use the TNM system. This system is used to describe cancers that form solid tumors such as breast, colon and lung cancers. Other cancers such as blood cancers, childhood cancers and brain tumors use other staging systems.
If you have questions about your cancer stage, please ask your physician. For more answers to frequently asked questions, please visit our FAQ page. To learn more about staging, feel free to check out American Cancer Society’s Understanding Your Diagnosis.