Colorectal Cancer Is the 2nd Most Common Cause of US Cancer Deaths: Here Are Colon Cancer Symptoms, Treatment, and Prevention

Here's what to know about colon cancer symptoms and treatment, as well as how to prevent colorectal cancer with diet, exercise, and recommended cancer screenings, like colonoscopies.

What is colorectal cancer?

Katie Couric shared with The Healthy @ Reader’s Digest how losing her husband in 1998 to colorectal cancer when he was 42 years old has made her a “little neurotic” about her own health, especially when it comes to cancer screenings. One reason for the anxiety? Couric’s late husband had no noticeable symptoms, so by the time doctors discovered his cancer it was stage 4 and incurable.

Sadly, this isn’t unusual, says Fola May, MD, a gastroenterologist and associate professor of medicine, David Geffen School of Medicine at UCLA and the director of Fight Colorectal Cancer

“The scary part is that most colorectal cancers cause no symptoms in the early stages, so it’s often not discovered until it’s become quite advanced and has a much higher mortality rate,” she says. “This is why everyone needs to know their risk factors for colorectal cancer and get screened early, regardless of symptoms.”

Couric has been so passionate about it that she’s made a mission of increasing awareness about these cancers to encourage people to get screened—in fact, in 2000, Couric underwent a colonoscopy on national morning TV. 

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So what is colorectal cancer, exactly?

Colorectal cancer is cancer found in the colon or rectum, the parts of your digestive system responsible for processing and eliminating waste products from your body.

This cancer generally starts as a small growth on the lining of the colon or rectum called a polyp, which “looks like a pimple,” says Dr. May. Over time, some polyps can become cancerous and grow into tumors. If left untreated, these tumors can spread to other parts of the body.

There’s some encouraging news about colorectal cancer: Rates of this often-preventable cancer are going down overall. With better detection due to screenings with colonoscopies and other tests, as well as lifestyle changes that reduce the risk of this cancer, the incidence rate of new cases has declined by one percent each year between 2011 and 2019. 

Still, in the US, colorectal cancer is the second-leading cause of cancer-related deaths in men and women combined, according to the American Cancer Society. In 2023, it’s expected that about 106,970 people will be newly diagnosed and that 52,550 people will die of colorectal cancer—a heartbreaking number, Dr. May says, as colorectal cancer is very treatable and has a survival rate of over 90% when it’s caught early.

And even though the incidence—the number of new cases in a given time period—is declining overall, it’s actually rising in younger adults. In people younger than age 50, rates have been increasing by one percent to two percent a year since the mid-1990s, according to the ACA.

Exactly what’s responsible for the rise—perhaps it’s related to a change in the gut microbiome, a more sedentary lifestyle, diet, or inflammation—isn’t yet known, say Milena Gould Suarez, MD, a gastroenterologist and associate professor at Baylor College of Medicine in Houston.

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What causes colorectal cancer?

To understand colorectal cancer, it helps to know that these cancers form in the large intestine, either in the colon, the longest portion of this muscular tube, or the rectum, the final 15 centimeters or 6 inches. In this part of the body, cells turn over rather quickly. This fast cell division can lead to DNA mistakes that can lead to cancer.

“The lining of the intestine gets exchanged by the body on an almost weekly basis,” says colorectal surgeon David Liska, MD, director of the Center for Young-Onset Colorectal Cancer and director of the Weiss Center at Cleveland Clinic in Cleveland. “And because there is so much turnover, cells in the intestine are dividing constantly.”

While cells divide, mutations can sneak in. Eventually, these mutated cells can form into a polyp, which is a growth from a mucous membrane. In this case, the growth is located in the lining of the colon or rectum.

Usually, these are benign, but if it’s not detected and removed, a polyp can grow into cancer.

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Polyps are common

About 30% to 50% of people over age 50 will have polyps, says Dr. Suarez.

Only a small portion—maybe 10%, she says—progress to cancer. The fortunate news is that these polyps can take 10 to even 20 years to grow and develop into cancer. One polyp is not the same as another, and some are more likely or less likely to grow into cancer.

Here are the three types of polyps:

  • Adenomatous polyps: These are considered pre-cancerous, as they can sometimes become cancer. Your doctor may let you know if within this type you have a tubular, villous, or tubulovillous polyp, which are the different growth patterns of the polyp.
  • Hyperplastic polyp and inflammatory polyp: These are common, but usually not cancerous. If yours is rather large, your doctor may recommend getting a colonoscopy more often than the standard once-per-decade.
  • Sessile serrated polyps and traditional serrated adenomas: These have a higher risk of being cancerous. Sessile are broad and flat polyps, while serrated have a “saw-tooth” appearance.

Risk factors for colorectal cancer

The chance of getting colorectal cancer in your lifetime is one in 23 for men and one in 26 for women. However, your risk will vary based on your genetics, lifestyle, and other risk factors. Some of these risk factors are under your control, while others aren’t—but no matter where you fall, it’s important to keep colorectal cancer front of mind and take the steps to live a healthy lifestyle to reduce your risk.

About five percent to 10% of colorectal cancers are due to hereditary factors.

These are general risk factors for colorectal cancer:

  • Age
  • Family history
  • Inherited disorders, such as Lynch syndrome, that increases risk of some cancers
  • History of cancer
  • Having inflammatory bowel disease (IBD)
  • A family history of colorectal cancer
  • Obesity
  • Smoking and alcohol use
  • Lack of exercise
  • Eating a lot of red and processed meats

How to prevent colorectal cancer

When it comes to colorectal cancer prevention, screening with the appropriate tests is the best thing you can do—and you do have more options than just a colonoscopy, says Dr. May. (More on that later.) Screening tests are particularly effective at catching colorectal cancer at an early stage, increasing the likelihood of successful treatment.

However, certain daily habits—in particular, regular exercise, eating fruits and veggies, and avoiding smoking and alcohol—are known to help prevent colorectal cancer. With the increase in rates in younger adults, it’s even more important to double down on the healthy everyday habits that keep your bowel—and body—in good shape.

Experts recommend that you:

  • Get regular, daily exercise
  • Eat a diet packed with high-fiber fruits, vegetables (especially leafy greens), and whole grains
  • Maintain a healthy weight, as overweight and obesity is linked to a higher risk
  • Avoid smoking
  • Avoid alcohol, but if you do drink, limit it to no more than two drinks a day for men and one drink per day for women
  • Avoid sugar-sweetened beverages, like soda
  • Avoid or limit processed meat
  • Limit processed foods with preservatives

When to get colorectal cancer screening

Colorectal cancer screening saves lives. That’s why it’s so important to get the recommended tests. “Colorectal cancer is largely preventable with screening,” Dr. Suarez says.

In 2018 the American Cancer Society updated their recommendations to advise that all adults age 45 and over with an average risk for colorectal cancer get screened. In 2021, the American College of Gastroenterology also updated their guidelines to recommend that adults at average risk start screenings at age 45.

“However, if you have a family history of colorectal cancer you should start screenings at age 40, or 10 years earlier than the youngest age one of your near relatives was diagnosed,” adds Dr. May.

Currently, the U.S. Preventive Services Task Force suggests screening for adults ages 50 to 75. (They generally stop screening for colorectal cancers between 75 and 80 years old, as by that point they’re not likely to cause death and the risks of colonoscopies go up, says Dr. May.)

It’s important to talk to your doctor about your personal risk, and the specific recommendations for when you should start screening as they can help you assess your personal risk factors.

Everyone should follow their doctor’s guidance and the recommended screening intervals—regardless of your perceived risk. “You don’t have to have symptoms of colorectal cancer, and you don’t necessarily have to have a family history,” Dr. Suarez says.

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Types of screening tests

There are a few types of tests you can get to screen for colorectal cancer, according to the Task Force.

Stool tests

There are several types of stool tests, which are at-home colon cancer tests that involve collecting a stool sample with a small brush or stick. You then send the sample to a lab for analysis.

  • The guaiac-based fecal occult blood test (gFOBT) uses a chemical called guaiac to look for blood in the stool. It’s done each year.
  • The fecal immunochemical test (FIT) uses antibodies to detect blood in the stool. It’s also done once a year.
  • The FIT-DNA test, or stool DNA test, is the FIT along with a test that looks for altered DNA in the stool. For this test, you send away an entire bowel movement to a lab to look for cancer cells. It’s repeated every three years.

Colonoscopy

This test looks at the entire colon and rectum. During a colonoscopy, a long, flexible tube is inserted into the rectum while you are mildly sedated. During a colonoscopy, a doctor can find and remove polyps before they become cancerous. A colonoscopy can also find cancerous polyps at an early stage where they are more treatable, resulting in a better prognosis.

A doctor uses a camera at the end of the tube to look for polyps or any problems. They can remove anything suspicious or take samples of questionable growths. This test is typically performed every 10 years. ( Here are the best colonoscopy prep tips from doctors.)

Flexible sigmoidoscopy

Similar to a colonoscopy, this test uses a long, thin, flexible tube. It allows your doctor to look for polyps or cancer inside your rectum and lower third of your colon. It’s not as popular as other tests, like a colonoscopy, that show the entire colon.

This test is usually done every five years, or every 10 years if you have a FIT every year.

CT colonography

Also known as a virtual colonoscopy, this CT test uses X-rays to create computer images of the entire colon for the doctor to check for issues. The test is typically performed every five years.

Symptoms of colorectal cancer

Colorectal cancer often causes no symptoms at all—especially during the early stages, which is what makes it so concerning, says Dr. May. However, there are some signs and symptoms of colon cancer.

Keep in mind that these symptoms could be due to other causes completely unrelated to cancer. (For example, blood in your stool can also be caused by a benign condition like hemorrhoids, although you should always get symptoms checked out):

  • Blood in your stool or bleeding from the rectum (you might also see blood in the toilet)
  • Change in bowel habits, especially new diarrhea or constipation that lasts more than one week
  • Unexplained fatigue or weakness
  • Anemia or low iron
  • Unintentional weight loss
  • Cramps in the lower stomach and low back pain
  • Bloating
  • “Pencil shaped” stool (very thin and narrow)

During the later stages of colorectal cancer (stage 3 or 4), cancer could potentially spread to other nearby organs and cause the following symptoms:

  • Breathing difficulty
  • Blurry vision
  • Bone fractures
  • Chronic headaches
  • Jaundice
  • Hand and feet swelling

Stages of colorectal cancer

If you are diagnosed with colon or rectal cancer, your doctor will tell you the stage of your cancer, which is an indication of the severity of the cancer, including whether or not the cancer has spread, or where it has spread to.

Colorectal cancers are given a stage of 0 to 4:

  • Stage 0: This may be considered a “precancer,” as it’s in a very early stage that has not grown beyond the mucous layer in the colon.
  • Stage 1: The cancer has grown through the mucous membrane but has not spread to lymph nodes.
  • Stage 2: It’s deep in the colon or rectum, and may or may not have grown into nearby organs or tissues. It has not spread to lymph nodes.
  • Stage 3: It has spread into nearby lymph nodes or tissues.
  • Stage 4: The cancer has spread to one or more organs, the peritoneum, or distant lymph nodes.

Treatment and prognosis

Your doctor will talk to you about your treatment options depending on the stage of colon cancer and your personal health history. Surgery is the most common treatment for colorectal cancer.

However, chemotherapy or radiation may be used before and/or after surgery. You may receive immunotherapy, which is a type of drug that helps your immune system fight cancer. Another option may be targeted therapy, which uses drugs to target specific cancer cells.

If you can’t have surgery, your doctor may talk to you about radiofrequency ablation (a procedure that uses a probe with tiny electrodes) or cryosurgery (which destroys cancerous tissue by freezing).

When detected early, the five-year survival rate is 90%, notes the American Society of Clinical Oncology. Even if cancer has advanced to spread to nearby organs or tissues, the survival rate is 71%.

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Additional writing and reporting by Charlotte Hilton Andersen.

Sources
American Cancer Society: “All About Colorectal Cancer” Fola May, MD, a gastroenterologist and associate professor of medicine, David Geffen School of Medicine at UCLA and the director of Fight Colorectal Cancer.