Colon Cancer Stages - What You Need To Know From Diagnosis To Treatment

Colon cancer often referred to as colorectal cancer, is a type of cancer that begins in the colon - the part of the intestine just before the rectum. Since both colon and rectum cancers share many similarities, including diagnosis, treatment, and survivability, they often get grouped and discussed together.

When a person has colon cancer, it is usually caused by polyps that form on the inner lining of the colon. Not all polyps are cancerous, but sometimes abnormal cells cause polyps to become cancerous over time. When this occurs, your doctor will likely biopsy the abnormal cells or polyps, and if cancer is detected, a diagnosis will follow.

If you or someone you know is diagnosed with colon cancer, your doctor will want to determine whether cancer has spread and at what rate it's spreading. This process, called staging, allows your doctor to create an individualized treatment plan that will attempt to eliminate cancer from your body. It will also help them to determine the survivability of your specific diagnosis.

Depending on the stage, colon cancer survival rates¹ in the United States range from 14% to 91% five years after the initial diagnosis. As with most types of cancer, early detection is key, and survival rates are much higher when caught and treated early.

Colon cancer tests

Luckily, several tests can detect colon cancer very early. Doctors routinely screen² adults for colon cancer at regular check-ups, even when there are no symptoms. This can help your doctor to detect and diagnose colon cancer at an early and very treatable stage.

Your doctor can perform several tests, but colonoscopies are usually the method of choice for most doctors in the United States.

Here are the most common tests that doctors can perform to detect cancerous cells or polyps in the colon:

Fecal Immunochemical Testing (FIT) 

This particular test is non-invasive, and patients can perform the test in the privacy of their own homes. It's especially convenient because it can be done without needing to fast beforehand. Your doctor will simply give you a testing kit to use at home. Once you've provided a stool sample in the kit, you return the kit to your doctor, and it will be tested in a lab for cancerous cells. If any are detected, you'll need to get a colonoscopy.

Guaiac-Based Fecal Occult Blood Test (gFOBT)

Much like the FIT, patients use a testing kit at home and collect a stool sample that they then bring to their doctor. Since some medications and foods interfere with the gFOBT, there are a few restrictions that you may need to follow and several foods that you may need to avoid before doing the test. If cancerous cells are detected, you'll need to get a colonoscopy.

Colonoscopy

A doctor uses a flexible tube with a camera attached to see inside the entire colon and rectum. This procedure requires some prep, and you'll need to follow a few procedures in the days before your exam. Some of these procedures include fasting and drinking a liquid to completely empty your bowels so the doctor can get a good picture of the lining of your colon.

If your doctor finds abnormal cells or polyps, they'll likely take a biopsy for further testing, and if cancer is detected, the next step is to stage your particular disease.

How is colon cancer staged?

Staging is a process that helps doctors to determine how much cancer has spread. Once your doctor has staged your particular diagnosis, they'll be able to create the most effective treatment plan.

Doctors often use the TNM staging system, created by the American Joint Committee on Cancer³. With this system, they're able to effectively establish the best treatment plan for your disease.

TNM staging system

When determining the stage of your disease, your doctor will consider the following three factors:

1. Tumor (T): How big is the original tumor? Has it grown into the lining of the colon or spread anywhere else? 

2. Nodes (N): Has cancer spread to nearby lymph nodes? If the answer is yes, how many lymph nodes are affected?

3. Metastases (M): Has the disease spread to lymph nodes in other organs? How far has cancer spread throughout the body?

Colon cancer stages can range from zero to four, and each stage is further divided into levels A, B, and C.

Low-grade or high-grade classification

While staging your particular disease, your doctor will also want to determine whether it is low-grade⁴ or high-grade.

With this process, a pathologist will carefully look at your cancer cells under a microscope. If the cells look like normal cells, the cancer is most likely low-grade, meaning it is probably spreading and growing very slowly. On the other hand, high-grade cancer is usually very aggressive and needs to be treated quickly and effectively.

In most cases, the low-grade colon cancer survival rate is much higher than that of high-grade colon cancer.

Your doctor will use this classification to determine how aggressively they'll treat your disease and whether they can wait to begin a treatment plan.

Colon cancer stages

There are five different stages of colon cancer, starting at zero, the most treatable diagnosis, and topping out at four, the most advanced stage. Once your doctor has staged your disease, they'll sit down with you to discuss your particular treatment plan and your official prognosis.

Here's an in-depth look at each stage, along with the common treatment plans that doctors prescribe:

Stage 0 colon cancer

This is the earliest stage of colon cancer, and it's very treatable. Stage 0 colon cancer occurs when abnormal cells are found inside the inner walls of your colon, and it's detected very early. In this stage, the cells have not yet spread beyond the colon’s mucosa (inner lining), and chemotherapy and radiation therapy are often unnecessary.

According to the American Cancer Society⁵, this stage is considered localized, and the five-year survival rate is very promising, at around 91%.

Stage I colon cancer

Stage I colon cancer is also considered an early detection, and it is very treatable. In this stage, the tumor has grown through the lining of the colon. Because it has not spread beyond the colon wall or rectum, and no lymph nodes have been affected, this stage is still considered localized, and the five-year survival rate is still around 91%.

Stage II colon cancer

Stage II colon cancer is divided into three sub-stages, A, B, and C, based on how much it has spread into the lining of the colon. Cancer has not yet spread to any surrounding lymph nodes or organs in this stage, and survivability is still very high. Often, the best course of treatment for stage II colon cancer is surgery.

Stage 2A

• Cancer has spread to the serosa or outer layers of the colon.

• It has not yet spread all the way through the serosa.

• Cancer has not spread to nearby lymph nodes or organs.

Stage 2B

• Cancer has grown through the serosa.

• Cancer has reached the lining of the abdomen, called the visceral peritoneum.

• It has not yet spread to surrounding lymph nodes.

Stage 2C

• Cancer has spread all the way through the serosa.

• It has begun to grow into nearby organs, like the bladder or prostate.

• Cancer is still not present in lymph nodes.

Stage III colon cancer

Stage III colon cancer is divided into three sub-stages, ranging from A to C. In this stage, cancer has spread through the mucosa, the inner walls of the colon, and into the submucosa, which is the colon’s inner lining. In some cases, it has also spread into the muscle layers. Stage III colon cancer also means that the disease has begun to spread into nearby lymph nodes.

In many cases of stage III colon cancer, chemotherapy is recommended as a treatment plan.

The sub-stage of your diagnosis is determined by how much cancer has spread and the number of lymph nodes affected.

Stage 3A

• Cancer has spread through the colon’s inner lining and into the muscle layers of the intestine. 

• It has spread to nearby lymph nodes.

• Cancer has not yet spread to other parts of the body.

Stage 3B

• Cancer has spread into the visceral peritoneum or the outer layers of the colon.

• It has spread to surrounding lymph nodes or areas of fat near the lymph nodes.

• Cancer has not spread to other parts of the body.

Stage 3C

• Cancer has spread into the outer wall of the colon to the abdominal lining.

• Cancer has spread to four or more lymph nodes.

• It has not yet spread to other parts of the body.

Stage IV Colon Cancer

Stage IV colon cancer is the most advanced stage of colon cancer, and it often means that cancer has spread beyond the wall of the colon. That means nearby lymph nodes are affected, and cancer has spread to other organs like the lungs, bladder, or liver.

This stage can be divided into three sub-stages, and treatment plans often include chemotherapy and radiation therapy.

Stage 4A

• Cancer has spread to one distant part of the body, like the lungs or an ovary, or a distant set of lymph nodes.

• Nearby lymph nodes have been affected.

Stage 4B

• Cancer has spread to more than one distant part of the body, like the liver, lungs, or a set of lymph nodes.

• It has not yet spread to distant parts of the peritoneum, the lining of the abdominal cavity.

Stage 4C

• Cancer has spread to distant parts of the peritoneum (abdominal lining). 

• Cancer may have also spread to distant organs and/or lymph nodes.

Survival rates

Doctors heavily rely on the staging system to determine survival rates for patients five years after their diagnosis. According to the American Cancer Society⁶, the five-year survival rate of colon cancer is around 63%.

Although your stage and classification will help your doctor determine your prognosis, they are certainly not the only factors. Every individual is different, and statistics can only determine so much. Some other important and very individualized factors include:

• Your age at the time of diagnosis

• How well you respond to treatment

• The type of treatment that is prescribed

• Whether your cancer returns

• Your overall health at the time of diagnosis

• Your gender (females have been proven⁷ to have higher survival rates)

Treatment

Each stage of colon cancer requires its own unique treatment plan based on how much cancer has spread and how aggressively it is spreading. Your doctor will determine the best treatment plan for you, and they'll likely use the staging system to help them.

Here are the most common treatment plans used for each stage of colon cancer.

Stages 0 and I: The cancer is still localized, and surgery is usually all that is needed. No chemotherapy or radiation therapy is necessary.

Stage II: Surgery is usually recommended to remove the cancerous areas and any affected lymph nodes. Sometimes, chemotherapy is needed, especially if your cancer is high-grade or aggressive. 

Stage III: Your doctor will recommend surgery to remove the cancerous portions of your colon and any lymph nodes that are affected. Chemotherapy is often recommended with stage III colon cancer to ensure that they get every cancerous cell.

Stage IV: Surgery will be necessary to remove the infected sections of your colon and any lymph nodes that are affected as well as any other places where cancer has spread. Chemotherapy and radiation therapy will likely be prescribed to destroy cancer cells, and in some cases, immunotherapy will be recommended by your doctor as well.

Learn more about the different colon cancer treatment types and their potential side effects.