Diagnosis and Staging of Colorectal Cancer



Photo courtesy of National Cancer Institute

Staging is an important part of diagnosis, treatment planning, and what the prognosis is (predictions of long-term survival).

Once the stage is established, it doesn’t change, although the cancer may recur (come back).

First you will have blood tests and diagnostic scans:

A computed tomography (CT) scan is an imaging method that uses x-rays to create pictures of cross-sections of the body.

A positron emission tomography (PET) scan is an imaging test that uses a radioactive substance called a tracer that creates 3-D images to look for disease in the body.

Blood tests will look for certain enzymes; diagnostic scans will show where the cancer is located. Your doctor will assign a clinical stage to your cancer based on these tests and scans, as well as your physical history and physical exam.

Surgery may be the next step. Doctors may want to conduct a biopsy to remove cells from the tumor and have a pathologist examine them to determine whether they appear normal (called cell differentiation.) This process will determine the pathologic stage. Tumors with a large number of highly abnormal cells are called high grade, and are considered to be more aggressive (they reproduce and spread faster) than cells in low grade tumors.

To complete the staging process, colorectal cancer is classified according to the TNM system (tumor, node, metastasis system) developed by the American Joint Committee on Cancer (AJCC).

T—for Tumor: How far the tumor extends from the inner lining of the colon or rectum through the layers of its walls.

N—for Nodes: Whether cancer cells are found in the lymph nodes by the colon.

M—for Metastasis: Whether cancer has spread beyond the colon and its adjacent tissues to organs like the lungs or liver.

Once doctors classify a tumor with the TNM system, an overall stage is assigned, ranging from stage 0 (no cancer was found) to stage IV (cancer spread to other organs beyond the colon or rectum.)

If you have stage II, III or IV cancer, you may receive an even further classification such as A, B or C. This helps your treatment team determine the best treatment for your particular diagnosis.

Click here to learn more about the TNM Classification System for Staging Colorectal Cancer.

Staging of Colon and Rectal Cancer

Stage TNM Classification
Stage 0 Tis, N0, M0
Stage I T1-T2, N0, M0
Stage IIA T3, N0, M0
Stage IIB T4a, N0, M0
Stage IIC T4b, N0, M0
Stage IIIA T1-T2, N1, M0T1, N2a, M0
Stage IIIB T3-T4a, N1, M0T2-T3, N2a, M0T1-T2, N2b, M0:
Stage IIIC. T4a, N2a, M0T3-T4a, N2b, M0T4b, N1-N2, M0
Stage IVA Any T, Any N, M1a
Stage IVB Any T, Any N, M1b

Getting an accurate diagnosis takes time. If you feel any uncertainty, get a second or even third opinion.

New patient? Download the Personal Info & Medical History worksheet & carry it to all of your appointments. It will keep this information in one place.

Content medically-reviewed by members of the Fight Colorectal Cancer Medical Advisory Board, February 2014

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