All About Colorectal Cancer Screening

Rebekah Kuschmider
Rebekah Kuschmider
February 6, 2024
min read
Medically reviewed by:
Trager Hintze, PharmD
All About Colorectal Cancer Screening

What Is Colorectal Cancer?

Colorectal cancer is cancer that occurs anywhere in the colon or rectum. Together, the colon and rectum make up the large intestine. The colon is a muscular tube, about 5 feet in length that ends with the rectum, which is about 6 inches long. After food passes through the small intestine, it moves to the colon, which absorbs any remaining water and salt. The remaining waste material becomes feces. The rectum holds feces until it can be eliminated through the anus [1].

Colorectal cancer usually starts as a polyp or abnormal growth inside the wall of the colon. Polyps can be harmless, but some can become malignant over time. It usually takes years for a polyp to go from being benign to becoming cancerous [1].

Most cases of colorectal cancer are adenocarcinomas. These are cancers that form in cells in the walls of the colon that make mucus. In rare cases, other types of cancer can develop in the colon and rectum, including carcinoid tumors, gastrointestinal stromal tumors (GISTs), lymphomas, or sarcomas [1].

Who Can Get Colorectal Cancer?

Anyone can get colon cancer, but some factors increase the risk of the condition. Age is one factor; colorectal cancer is most common in people over age 50 [2].  

Racial and ethnic background can influence your overall risk. In the United States, the highest rates of colorectal cancer occur among American Indian, Alaska Native, and African American populations. Those of Ashkenazi Jewish descent have a higher risk than other groups. They have one of the highest colorectal cancer risks of any ethnic group in the world [2].

Other risk factors include [3]:

  • History of colorectal cancer or polyps
  • History of inflammatory bowel diseases
  • Family history of colon cancer
  • Diabetes
  • Radiation therapy for past cancer

Certain lifestyle factors also increase the risk of developing colon cancer, including [3]:

  • Low-fiber, high-fat diet.
  • Lack of regular exercise
  • Obesity
  • Smoking
  • Excessive alcohol consumption. Drinking too much alcohol can increase the risk of colon cancer.

Symptoms of Colorectal Cancer

In the early stages, colorectal cancer may not cause any symptoms. Noticeable symptoms may include [3]:

  • Changes in bowel habits, such as more frequent diarrhea or constipation.
  • Rectal bleeding or blood in the stool.
  • Ongoing discomfort in the belly area
  • Feeling like the bowel doesn't fully empty after a bowel movement.
  • Weakness or tiredness
  • Unexplained weight loss

Colorectal cancer can be treated. Treatments are most effective in the early stages of the disease, which is why doctors recommend routine screenings to detect colorectal cancer.

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Colorectal Cancer Screening

The American Cancer Society recommends that people at average risk of colorectal cancer start regular screenings at age 45 [4].

There are different types of screenings for colorectal cancer. Some should be performed annually, while others are only necessary every 5 to 10 years. Your doctor can help you determine which type of test to choose [5]:

  • Imaging Tests: Screening procedures like the colonoscopy are highly effective at detecting cancer. Your doctor will be able to identify areas of concern and take biopsies for further testing. In addition, these tests allow doctors to remove benign polyps before they can develop into cancer. The procedure requires significant preparation to empty the bowel, and it must be performed under anesthesia.
  • Stool Sample Tests: Stool testing is far less complicated than imaging tests and can be performed at home. You can get a colon cancer home test kit known as an Immunological Fecal Occult Blood (iFOB) test to collect a stool sample. The sample is sent to a lab to test for the presence of blood. Blood in stool can be a sign of colorectal cancer or precancerous polyps. A positive stool test does not mean you have cancer, but it is an indication that you should get a colonoscopy as a follow-up test.  

The ACS suggests the following frequency for different tests [4]:

  • Fecal occult blood testing every year
  • Multi-targeted stool DNA test (mt-sDNA) every three years
  • Colonoscopy every ten years
  • CT colonography (virtual colonoscopy) every five years
  • Flexible sigmoidoscopy (FSIG) every five years

People with higher risk factors may need to start colorectal cancer screening before age 45, be screened more often, and/or get specific tests.

Why Choose an At-Home Colon Cancer Test?

For people who do not have an elevated risk of colorectal cancer, home testing is an alternative to colonoscopy. Fecal occult blood test kits are effective, easy to use, and less stressful than other types of tests.

According to the Colorectal Cancer Alliance, the benefits of fecal immunochemical tests (FIT) include [6]:

  • Ease of use
  • Done at home on your schedule
  • No need to change diets or medicines before the test
  • No prep solutions to drink
  • Inexpensive and covered by most insurance plans

If an at-home colon cancer test shows the presence of blood, it doesn't automatically mean a diagnosis of colorectal cancer. Blood from other conditions, such as hemorrhoids, can trigger a positive result from a stool test kit [7]. A positive test means you should follow up with your doctor. You will probably need to get an imaging test to determine whether there are polyps or cancerous growths in your colon.

How To Decide on a Colorectal Cancer Screening Plan

Your doctor can help you assess your risk and advise you on which test is right for you. The Diagnox iFOB test is an easy, reliable option for a colon cancer home test kit. The test kit comes with everything you need to collect a sample in the privacy of your home, including easy-to-read instructions. Results are sent to you and your doctor.

Choosing a safe, reliable colorectal cancer screening method is one of the best ways to protect your health. Talk to your doctor to learn more.

  1. American Cancer Society Staff, "What Is Colorectal Cancer?" American Cancer Society. [Accessed January 8, 2024.]
  2. American Cancer Society Staff, "Colorectal Cancer Risk Factors," American Cancer Society. [Accessed January 8, 2024]
  3. Mayo Clinic Staff, "Colon Cancer," Mayo Clinic. [Accessed January 8, 2024]
  4. American Cancer Society Staff, 'American Cancer Society Guideline for Colorectal Cancer Screening," American Cancer Society. [Accessed January 8, 2024]
  5. American Cancer Society Staff, "Colorectal Cancer Screening Tests," American Cancer Society. [Accessed January 8, 2024]
  6. Colorectal Cancer Alliance Staff, "Fecal immunochemical test," Colorectal Cancer Alliance. [Accessed January 8, 2024]
  7. N. H. Kim, J. H. Park, D. I. Park, C. I. Sohn, K. Choi, and Y. S. Jung “Are Hemorrhoids Associated with False-Positive Fecal Immunochemical Test Results?” Yonsei Medical Journal, vol. 58, 1 (2017): 150-157.

About the Author
Rebekah Kuschmider

Rebekah has been writing about culture, health, and politics since 2010. She has a masters degree in Arts Policy and Administration from The Ohio State University. Her work has been seen at WebMD, The Candidly, MedicineNet, YourTango, Ravishly, Babble, Scary Mommy, Salon, Role Reboot, The Good Men Project, SheSaid, Huffington Post, and Mamamia. She is a former cohost of the weekly podcast The More Perfect Union. Rebekah lives in Maryland with her husband, two kids, and a dog who sheds a lot.

About the Reviewer
This blog was
Medically reviewed by:
Trager Hintze, PharmD

Trager Hintze is a clinical assistant professor and emergency medicine clinical pharmacist located in College Station, Texas. He has a bachelor's degree in biology as well as a Doctor of Pharmacy degree. He balances teaching at Texas A&M University College of Pharmacy and practicing emergency medicine at St. Joseph Regional Health Hospital.

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