Your cancer stage is one of the first pieces of information you’ll need to know once you’re diagnosed. This will determine your treatment plan.


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You may have a desire to begin treatment immediately. First, however, you’ll need to learn more about your cancer and how to treat it. This is important because your specific colon cancer or rectal cancer diagnosis will determine the treatment that’s best for you. 

Here are some steps for what to do after a colorectal cancer diagnosis.

Your Guide in the Fight

Have you or a loved on been diagnosed with stage III or stage IV colorectal cancer? Download our free resource, Your Guide in the Fight.

How Colorectal Cancer is Diagnosed

If you are experiencing symptoms of colon or rectal cancer, or if a colorectal cancer screening test has come back with abnormal results, you will receive additional testing to learn more about what is going on and to understand if there is cancer present. The tests that may be done include biopsies, scans, blood tests, colonoscopy, and others. After test results are received, your doctor will review these results with you.

Staging Colorectal Cancer

After someone is diagnosed with colorectal cancer, the next step is staging. Staging helps doctors understand if the cancer has spread, and if so, how far. Knowing this allows your doctor to make the best recommendation for treatment options tailored specifically to your stage.

Staging Step 1: Radiology Exams

First, blood tests will look for certain enzymes. You will also receive a physical exam and diagnostic scans to show where the cancer is located. This may include a computed tomography or CT Scan, which uses X-rays to create pictures of your body’s cross-sections. You could also expect a positron emission tomography or PET scan, which uses a radioactive substance called a tracer that creates 3-D images of your body. This is helpful for spotting diseases like cancer. Finally, a magnetic resonance imaging or MRI scan makes detailed pictures inside your body through the use of powerful magnets, radio waves, and a computer.

Visit Radiology Info for information about your radiology exam.

Staging Step 2: Surgery and Biomarkers

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. This process is called cell differentiation.

You’ll also want to have your tumor tested for biomarkers. Biomarkers play a key role in developing individualized treatment plans after a colorectal cancer diagnosis. Understanding your tumor type may help you experience fewer side effects and improved health during treatment. Currently, known biomarkers that impact colorectal cancer patients are:

More information about biomarkers and their implications.

Staging Step 3: How a Stage is Determined

Your cancer is then classified according to the Tumor, Node, Metastasis or TNM system, developed by the American Joint Committee on Cancer (AJCC).

  • Tumor: how far the tumor extends from the inner lining of the colon or rectum through the layers of its walls
  • Nodes: whether cancer cells are found in the lymph nodes by the colon
  • Metastasis: whether cancer has spread beyond the colon and its adjacent tissues to organs, like the lungs or liver

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

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 a Second Opinion

If you or your medical team have any uncertainty about your diagnosis or treatment choices, get a second opinion — or even a third opinion. A second opinion can help you feel confident that you have received an accurate diagnosis and stage. You might get an opinion from a doctor who has a specialty in a different area of cancer treatment, providing you with a different perspective. Finally, getting a second opinion can help you identify the best treatment approach and give you confidence in moving forward with treatment decisions.

Next Steps: Establishing a Treatment Plan

A colorectal cancer diagnosis can be incredibly stressful – no matter what stage. Take time to talk to your doctor before you decide which treatment option is best for you. Some treatment options include:

  • Surgery 
  • Targeted Therapy 
  • Radiation Therapy
  • Chemotherapy
  • Immunotherapy
  • End-of-Life Care

Once you receive a colon cancer or rectal cancer diagnosis, start gathering people on your treatment team. In addition to your oncologist and surgeon, seek professionals to help you manage mental health and other practical issues. It’s a good idea to include palliative care as well, regardless of your cancer stage. If you haven’t already been connected to a social worker or nurse navigator, make sure you do so as early as possible.

What’s Next?

At Fight Colorectal Cancer, our team is here for current, past, and future survivors and loved ones. If this is you, you’re not alone. We want you to meet others from all over the U.S. who share the same goal.