Everything You Always Wanted To Know About The Stages Of Colon Cancer

Overview

Colorectal cancer, also known as colon cancer,  occurs when there is abnormal cell growth in the colon — your large intestine or bowel — or the rectum, which connects the colon to the anus.

These cells — called polyps — may not morph into cancer at all and instead just hang out in your colon without causing any trouble. The problem is that there's no way to determine which polyps will become cancerous. 

Doctors and other health care professionals urge screening for colon cancer because when it's caught early, this type of cancer has a relatively high survival rate — over 90%, according to the American Cancer Society.¹

When colon cancer spreads or metastasizes, it typically goes to the kidneys and liver, but it occasionally reaches into the bones as well. The ACS (the American Cancer Society) reports five-year survival rates at 14% once it has spread, so early detection is truly critical for surviving this type of cancer. 

The National Cancer Institute reports that recent research has found that some malignant colon tumors spread early in their development, meaning that the genetic material is already there in the tumor and will metastasize (or spread to other parts of the body).²

This research also indicates that once the cancer develops, there is a two-year window for it to metastasize.

This process of cancer cells spreading to other parts of the body happens at a snail's pace — roughly ten years between the cancer cells starting to grow and the onset of symptoms. This is another reason not to delay getting a baseline colonoscopy and following up every ten years, as any pre-cancerous or benign polyps can be removed before they have a chance to cause trouble.

Americans have almost a 25% chance of developing colon cancer during their lifetimes, so it's important for you to understand more about the risks, diagnoses, stages, and treatments of the disease.³

How common is colon and rectal cancer?

Colorectal cancer is the third most common cancer in the US, outside skin cancer. In real numbers, the ACS estimates over 150,000 new cases in 2022. This number represents a drop in the past forty years, as more people are getting screened and changing their risk factors. 

What's changed is that more younger people are getting diagnosed. There’s been a 2% increase in people under 50 every year between 2012 and 2016.⁴

What are the stages of colon cancer?

Colon cancer is defined by stages, although there are variations within the individual stages. The lower the stage number, the more contained the cancer.

The colon has four layers of tissue, and the polyps (or finger-like growths) develop in the innermost layer. As they grow, they expand outward until a cancerous tumor bursts through the walls of the outer layer so it can spread.

Stage 0

At this stage, the polyps are still contained in the innermost layer, the mucosa.

Stage 1

When the polyps grow into the next layer, the submucosa, they’re still encapsulated — they’ve not spread into the next layer or the lymph nodes.

Stage 2

In this stage, the disease is separated into levels of severity. The tumor has grown past the mucosa and the submucosa and into a muscular layer called the muscularis propria.

• Stage 2A: The cancer has not spread to lymph nodes or surrounding tissue but has reached the outer layer of the colon.

• Stage 2B: The tumor has moved through the outer layer and into the layer of muscle that keeps the abdominal organs in place (called the visceral peritoneum).

• Stage 2C: The lymph nodes are still unaffected, but the tumor has expanded outward from the colon to other organs near the bowel.

Stage 3

This stage is also defined in one of three levels. The primary difference between stage 2 and stage 3 is that here, the cancer has spread to the lymph nodes.

• Stage 3A: Nearby lymph nodes are impacted, but more distant organs and lymph nodes are not.

• Stage 3B: Two situations fall into this stage.

• The tumor has grown out of the colon and invaded other organs and at least one lymph node.

• The tumor itself is still contained in the walls of the colon, but the cancer has invaded four or more nearby lymph nodes.

• Stage 3C: The cancer has moved out of the four layers of the colon and is detected in four or more lymph nodes — but not in distant areas.

Stage 4

This stage also has four levels of classification, but each indicates the cancer has spread outside the colon.

• Stage 4A: The cancer has spread to one distant site — lymph nodes, lungs, or liver

• Stage 4B: The cancer has spread to at least two distant sites but has not reached the inside of the abdomen.

• Stage 4C: The inside of the abdomen has cancer cells.

The chances of colon cancer spreading are directly related to how early the original disease was detected and treated — early diagnosis reduces the possibility of it spreading to other parts of the body.

If colon cancer is going to spread to the lungs, it will likely happen within two years of the initial diagnosis. Spreading to the liver typically occurs within one year, and up to three years after diagnosis, according to research published by Swedish surgeons in 2018.⁵

Symptoms of colon cancer

The early signs of colon cancer are subtle and easy to blame on bowel issues. These symptoms are easy to ignore, which is why many people aren’t diagnosed until the late stages. Early detection through screenings is certainly the best way to find cancer cells. These signs are definite indicators that there is a problem.

Blood in your stool is the most common sign, but others are also common. If you have a combination of any of these, it's time to see your doctor:

• Frequent constipation or diarrhea, or change in the consistency of the stool

• Persistent need to "go" or a feeling that your bowel doesn't completely empty

• Abdominal pain — cramps or gas that don't go away

• Fatigue or weakness

• Weight loss for no reason

• An accompanying loss of appetite is an indicator that the cancer has advanced.

Symptoms of cancer spreading to the liver and lungs 

Additional symptoms may present if the cancer has spread to the liver and lungs.

Here are the signs of liver cancer:

• Pain or discomfort on your right side

• Feeling sick

• Loss of appetite and weight

• Swollen abdomen

• Itchy skin, or yellowing skin or eyes (jaundice)

If cancer has spread to the lungs, the symptoms are also hard to ignore:

• A persistent cough that worsens at night

• Chronic chest infections

• Shortness of breath

• Coughing up blood

Signs of colorectal cancer that you should get checked out

For most people, the appearance of blood in the stool is the first sign of colon cancer. Most people don't take this sign seriously, mistaking cancer symptoms for something simple like hemorrhoids.

However, delaying a diagnosis of bowel cancer and treatment worsens the disease and your risk of survival. If at any time you have any of the symptoms listed above, you should schedule an appointment with your doctor as soon as possible.

Diagnosis

If your doctor suspects colon cancer, they will schedule a series of tests to determine if you have the disease, confirm a diagnosis, and then plan the best course of treatment.

Tests to confirm colon cancer

Since colon cancer has so many stages and levels of severity, expect a full battery of tests when you go in. All these tests will likely occur over a series of weeks — as results are confirmed, they will lead to the next round until your care team is satisfied they understand both the cancer and the optimal treatment protocol.

• Physical exam: Expect a full physical and health history, including checking for lumps and other unusual signs of other forms of cancer.

• Rectal exam: The doctor will examine the rectum internally to check for any abnormalities.

• Fecal blood test: This test looks for any blood in the stool itself. The sample is sent away to check for cancerous cells. You won't get those results for several days.

• Colonoscopy: A diagnostic colonoscopy will confirm the presence of tumors in the colon and rectum.

Blood tests

Your physician will order a panel of blood tests that will further narrow down the extent of the disease.

• Complete blood count (CBC): This test gives a complete overview of all the cell types in your blood. Anemia is one thing they're looking for; some colon cancer patients become anemic if the tumor is bleeding.

• Liver enzymes: The test will include a check of your liver function to determine if the cancer has already spread to the liver and is damaging your liver.

• Tumor markers: It's common for colon cancer cells to create substances — tumor markers — that show up in blood tests as carcinoembryonic antigen (or CEA) cells.

Screening for colorectal cancer

The best way to detect colorectal cancer is to start screening early — age 45 is the benchmark in the US and every ten years after. A colonoscopy is a method that provides the best results, although lately, thousands of low-to-moderate-risk people are testing at home with fecal samples.

Colon cancer rarely develops suddenly. If you have been ignoring symptoms and are diagnosed, then you may well think that it has happened in a hurry. The reality is that when you screen regularly and follow up with your physician if there are any abnormalities, colon cancer is hardly ever a surprise.

Colonoscopy

Patients undergoing a colonoscopy typically do so with a general anesthetic, in the doctor's office, or in an outpatient clinic. A video camera is attached to the end of a long, flexible, lighted tube inserted into the rectum and threaded up through the colon while you are asleep under a general anesthetic. 

If the doctor sees anything unusual, they can send a specialty instrument up through the tube to remove anything that looks suspicious for a biopsy.

A colonoscope already has the instruments built in to remove suspicious tissue, so this is easy for the doctor to do at the same time as a colonoscopy.

Treatment

Colon cancer has a wide range of treatment options. The stage of the cancer is the primary factor in developing treatment protocols — the earlier the stage, the less invasive the treatment. 

The primary factor here is whether the cancer cells are confined to the inner walls of the colon or if they have invaded lymph nodes or other areas of the body. Another consideration is whether the cancer cells have made a hole in the colon or if they have created a blockage in the passage. The type of treatment will also depend on whether this is a recurrence of an earlier cancer.

Treatment can range from single surgery to remove cancerous polyps to surgery plus courses of chemotherapy, radiation, or immunotherapy.

Risk factors

There are some risk factors for bowel cancer. If you have any of these, you should have regular screenings:

• Family history — Having first-degree relatives (parent, sibling) who have had bowel cancer increases your risk of getting bowel cancer.

• Personal history — If you've already had cancer of the colon, rectum, or ovaries, or you have a history of high-risk polyps or chronic ulcerative colitis, your risk of colon cancer is increased.

• Inherited genes that increase the risk of familial adenomatous polyposis or Lynch syndrome, which increases your risk of bowel cancer⁶

• Being of African-American heritage increases your risk of bowel cancer.

Luckily, as with some other cancers, there are several risk factors you can control. Obesity, smoking cigarettes, and having more than three alcoholic drinks per day can heighten your risk of colon cancer. Changing these lifestyle factors can help reduce your risk of developing bowel cancer.

The lowdown

There's no way to sugarcoat the fact that colorectal cancer can be a deadly disease. But with preventative screenings, quick response to any symptoms, and consideration of your individual risk factors, you can improve your odds of a full life if you develop this type of cancer.