Let's Talk About Colorectal Cancer Stages
If you've been diagnosed with this disease, your path forward will depend largely on how far along the cancer is. Learn more about the different stages, and how it affects the types of treatments you may receive.by Lisa Davis Health Writer
If you’ve received a colorectal cancer diagnosis, the first order of business for your doctor is to figure out what stage it is—in other words, determining if the cancer has spread to other parts of your body and, if so, where and to what extent. That information will allow your medical team to determine the best approach to your care, so you can feel better, faster, and lower the odds of cancer coming back. Read on for more info on the various stages of colon cancer.
Our Pro Panel
We went to some of the nation's top experts in colorectal cancer to bring you the most up-to-date information possible.
Leonid Cherkassky, M.D.
Assistant Professor of Oncology
Roswell Park Comprehensive Cancer Center
Gautam Mankaney, M.D.
Eduardo Vilar-Sanchez, M.D., Ph.D.
Associate Professor of Clinical Cancer Prevention
The University of Texas MD Anderson Cancer Center
Colon cancer spreads in three ways. The tumor can grow through the wall of the colon and into nearby tissue. Cancer cells can travel via your bloodstream to another part of the body. They can also get into the lymph system—the body’s lesser-known second circulatory system.
When colon cancer is staged, it’s given a number, from 0 through IV; the lower the number, the less the cancer has spread. In addition, letters are used to subdivide the stages—so there’s a stage IIA, IIB, and IIC. The earlier in the alphabet the letter, the less advanced the cancer.
Statistically, people with stage I cancer have a 90% chance of living for at least another five years. If you've been diagnosed with stage IV cancer, your odds of living another five years drop to 14%. Remember, these are averages; how your body responds to treatment is unique to you.
For some people, CEA testing can be used to help monitor the effectiveness of treatment. It’s most useful in people whose levels of CEA are elevated before treatment and fall when they go into remission. In these cases, CEA monitoring can act as an early-warning system for cancer recurrence.
What Is Colorectal Cancer, Again?
Colorectal cancer—often used interchangeably with colon cancer—is a disease that begins in either your colon or rectum, which together make up your large intestine.
It’s highly treatable if caught early, yet it kills more people than breast or prostate cancer, largely because most people don’t know they have it until the cancer is pretty advanced.
When it comes to who gets it and why, there’s good news and bad news. On the positive front, colorectal cancer is less common—and less deadly—than it used to be, especially among the group traditionally at highest risk, adults 50 and older.
On the not-so-great side of things, colorectal cancer rates are climbing in younger ages: A 30-year-old today faces a higher risk of both colon and rectal cancer than a Baby Boomer did at the same age, possibly because the disease is linked to obesity, and obesity rates are going up.
If you receive a colorectal cancer diagnosis, your doctor will also want to determine how advanced the cancer is, known as its stage, in order to provide the best treatment.
What Are the Stages of Colon Cancer?
The basic idea behind the stages of colorectal cancer is simple: Every case can be categorized as being in one of five stages, from stage 0 to stage IV. To determine where exactly your cancer belongs along that spectrum, your doctor will use the TNM system (shorthand for tumor, nodes, and metastasis) to look at three factors:
How far the tumor has penetrated the lining of the colon
Whether the cancer has spread to nearby lymph nodes
Whether the cancer has metastasized (spread) to distant organs
Based on those variables, your cancer will be diagnosed as being one of these five stages:
Stage 0: This very early cancer or pre-cancer affects the innermost layer of the intestine.
Stage I: Cancer is in the inner layers of the colon but has not spread.
Stage II: Cancer has spread through the muscle wall of the colon. It may be found outside the colon but has not spread to the lymph nodes.
Stage III: Cancer has spread outside the colon and is found in the lymph nodes.
Stage IV: Cancer has spread to other organs in your body.
Tests for Colorectal Cancer Stages
Staging tests can be done two ways. The first is by examining tissue that is cut out during an operation to remove the cancer—that’s called surgical staging. Surgical staging is considered the most accurate method.
Doctors can also stage the cancer clinically by using information gathered before surgery from physical exams, biopsies, and imaging tests. Clinical staging can provide important information. For instance, it can help doctors decide whether a patient might need chemotherapy before surgery in order to shrink the tumor. In some cases, that can make the operation more effective and less debilitating.
Tests used to stage colon cancer include:
Carcinoembryonic antigen (CEA) assay: CEA is a protein normally found in very low levels in healthy adults, but tumor cells sometimes make the protein. A CEA test won’t definitively show if you have cancer, because not all cancers produce CEA, but it can be a useful indicator. CEA tests are also used to determine treatment effectiveness (higher CEA levels before, lower after).
Chest X-ray: This standard imaging exam can be used to look for evidence that colon cancer has spread to the lungs.
Computed tomography (CT) scan: In this imaging test, specialized equipment takes a series of X-ray pictures of an area of the body from different angles, and then uses a computer to assemble those “slices” into a cross-sectional view of an organ or structure.
Lymph node biopsy: In this procedure, all or part of a lymph node is removed, either during surgery or with a method called fine-needle aspiration. A pathologist examines the tissue under a microscope to see if cancer cells are present.
Magnetic resonance imaging (MRI): In this imaging test, powerful magnets and radiofrequency waves are used to produce detailed pictures. MRI is particularly useful for imaging soft tissues of the body. You may have an injection of a contrast agent called gadolinium to increase the definition of the image.
Positron emission tomography (PET) scan: In this imaging test, a small amount of radioactive glucose (sugar) is injected into a vein and then tracked in the body by a special scanner. Because cancer cells are more metabolically active than healthy cells, they take up more of the radioactive glucose and show up more brightly in the image. A PET scan may be used to identify cancer that has spread to other parts of the body.
Surgical biopsy: During an operation to remove the tumor, a pathologist will assess the tissue under a microscope and determine how far the cancer has spread.
In addition to doing some or all of these tests, your team of doctors will probably also run a blood test to get a complete blood count (CBC). Your blood will be checked for several things, including number of red blood cells, white blood cells, and platelets, which can be used as a baseline for any future changes.
How Accurate Is a Colorectal Cancer Stage Diagnosis?
While the 0-IV stages seem pretty clear on paper, in reality, staging isn’t so simple.
A cancer that has reached just one lymph node is less advanced than one that has reached six, for instance, even though both are considered stage III.
There are also many different ways that T, N, and M factors can combine, producing many different sub-stages. For instance, a cancer might be described as stage IIA, IIB, or IIC, or be given a similar subdivision of stage III or IV if the disease is more advanced.
Once you receive a staging report of your cancer, it’s best to discuss it with your care team. They can give you a detailed explanation of what your stage means, so you can plan the best treatment going forward.
Understanding Colorectal Cancer Grading
In addition to determining your cancer stage, your doctor may grade it as well. This is done by inspecting the cancer cells in a lab to see how similar they look to healthy cells.
When tissue is healthy, a look under the microscope reveals it to be organized, with cells grouping together into structures. If cancer cells look similar to healthy ones, the mass is called a low-grade tumor and a cancer grading report refers to it as “well-differentiated.”
In contrast, high-grade cancers are poorly differentiated, lacking the organization seen with healthy cells. High-grade cancer cells tend to grow faster, which can cause color cancer to spread more rapidly; typically, the lower the grade of tumor, the better the prognosis. These are the ways your cancer may be graded:
GX: The tumor grade cannot be identified.
G1: The cells are more like healthy cells (called well-differentiated).
G2: The cells are somewhat like healthy cells (called moderately differentiated).
G3: The cells look less like healthy cells (called poorly differentiated).
G4: The cells do not look like healthy cells (called undifferentiated).
It’s good to remember that as useful as these categories and designations are, they are still just guidelines to helping you and your doctor determine the best treatment plan. You may feel equally unwell with a stage II diagnosis as a stage IV, and it’s possible that your high-grade tumor is more operable than a low-grade one.
The most important thing is to continue working with your medical team and provide regular feedback on how you’re feeling and any symptoms of colorectal cancer you may be having. Together, you will figure out a treatment strategy that puts you back on the road to wellness.
- Colon Cancer Staging: National Cancer Institute. (n.d.) “Colon Cancer Treatment (PDQ)—Patient Version.” cancer.gov/types/colorectal/patient/colon-treatment-pdq#_93
- Colon Cancer Staging: American Cancer Society. (2018). “Colorectal Cancer Stages.” cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/staged.html
- Colon Cancer Staging: Memorial Sloan Kettering Cancer Center. (n.d.) “Stages of Colon Cancer.” mskcc.org/cancer-care/types/colon/diagnosis/stages
- Colon Cancer Grading: American Society for Clinical Oncology. (2019). “Colorectal Cancer: Stages.” cancer.net/cancer-types/colorectal-cancer/stages
- Carcinoembryonic Antigen (CEA) Test: U.S. National Library of Medicine: MedlinePlus. (n.d.) “CEA Test.” medlineplus.gov/lab-tests/cea-test/