About Colorectal Cancer

A clinician holdes and endocscope
What Is Colorectal Cancer?

Colorectal cancer is the kind that begins in the colon or rectum. These cancers are also called colon cancer or rectal cancer, depending on where the cancer starts. Although many colorectal cancers can be prevented with regular colonoscopy screenings, it remains the third leading cause of cancer deaths in the U.S. among the general population.1

Illustation of the anatomy of the colon as well as what colon cancer looks like in the body
This image from the Mayo Clinic illustrates the anatomy of the colon as well as what colon cancer looks like in the body as seen during colonoscopy.

The average lifetime risk for colorectal cancer is approximately 5 percent, but for adults with cystic fibrosis, this risk is 5–10 times higher and warrants screening 5 years earlier, at 40 years of age.

Meanwhile, those who receive a solid organ transplant are 20 times more likely to develop colorectal cancer and often need to begin screening even earlier —  age 30, depending on when the transplant occurs.  

Watch the animation above to learn more about colorectal cancer in CF and how early screening can help reduce your risk.

How Does Colorectal Cancer Form in the Body?

Most colorectal cancers start as a polyp — a small, abnormal growth of tissue that can develop on the inner lining of the colon or rectum. Most polyps are harmless (benign), but a certain kind of polyp, known as an adenoma, can become cancerous over time.

There are two general types of colon polyps:

  • Hyperplastic polyps and inflammatory polyps: common polyps that do not generally develop into cancer.
  • Adenomatous polyps: polyps that are considered pre-cancerous because they are more likely to develop into cancer.

It can take many years for a polyp to develop into cancer, but once the cancer forms, it can grow into the wall of the colon or rectum. When cancer cells are in the wall, they can then spread to surrounding tissues and, eventually, other parts of the body. The further the cancer spreads, the more difficult it is to treat.


In general, people with CF will experience many of the same symptoms of colorectal cancer as the general population, including:

  • Blood in the stool.
  • Abdominal pain that gets worse over time.
  • Weight loss.
  • Anemia.
  • Abrupt changes in prior bowel habits (i.e., new or persistent constipation or diarrhea).

At the same time, however, many people report experiencing no symptoms before receiving a colorectal cancer diagnosis, which is why it is sometimes called the “silent cancer.” That is why screening is incredibly important.

Although the Cystic Fibrosis Foundation’s Colorectal Cancer Screening Clinical Care Guidelines recommend that people with CF begin screening at age 40, symptoms can be an indicator to begin screening even earlier. If you think you are experiencing colorectal cancer symptoms, talk to a member of your CF care team.

"Before I was diagnosed, I found blood in my stool one time and then, months later, had two days of stomachaches despite regularly taking my enzymes. At the time, however, I didn’t know about my increased risk for colorectal cancer and attributed it to CF-related digestion issues. I wish I had said something to my CF doctor about these small symptoms earlier when the cancer was still in its most curable stages." — Christine Borland, who had CF and colon cancer
What's My Risk?

The risk for colorectal cancer in adults with cystic fibrosis is 5–10 times greater than the general population. In addition, polyps are thought to develop earlier and progress into cancer more quickly in people with cystic fibrosis.

This risk is even higher (about 20 times) for people with CF who've had solid organ transplantation like a lung transplant. People who have had a transplant are at an increased risk for cancer in general because the medications they must take to prevent rejection work by weakening the immune system.

Why Are People With CF at an Increased Risk?

We don't know for certain why people with CF have an increased risk of developing colorectal cancer, but it is thought to be associated with the cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation. Additional research is being conducted to understand how mechanisms in the bodies of people with CF put them at an increased risk for developing colorectal cancer and, in turn, how to better treat it. Researchers recognize that there is still more to learn and have identified some of those questions in the section titled “Unanswered Questions” in the Colorectal Cancer Screening Guidelines.

What Can I Do?

An effective way to prevent and treat colorectal cancer is to have regular screenings called colonoscopies.

A colonoscopy allows the gastroenterologist or colonoscopist to identify and remove polyps before they can develop into cancer. Colonoscopies can also help find the cancer in its earliest (and most treatable) stages.

What Is a Colonoscopy?

A colonoscopy is a procedure that uses a long, flexible tube about the width of a finger. This tube is attached to a video camera to view your colon and rectum. If there is anything that looks abnormal, the gastroenterologist or colonoscopist can pass small surgical tools through the tube to take tissue samples for analysis and remove any polyps.

The goal of a colonoscopy is to identify and remove as many polyps as possible.

Watch Mark B. Pochapin, MD, FACG, director of the Division of Gastroenterology at New York University Langone Medical Center, narrate a tour of a patient's colon during a colonoscopy where he discovers and removes a pre-cancerous polyp.

"Knowing that people with CF have a higher risk of colon cancer can seem daunting. We already deal with so much and face enough challenges trying to balance daily life with our health. As someone who has had 10–12 colonoscopies in the last decade, they still slightly stress me out. But, I know I need to have them done so that I can be sure I don't develop cancer. Plus, I'm finally equipped with the knowledge of what to expect and how to get the best results.” — Amy Braid, an adult with CF, from the CF Community Blog

Why Should I Get a Colonoscopy to Screen for Colorectal Cancer?

Colonoscopy is the only method that has been studied as an effective screening test for people with cystic fibrosis. Unlike other screening procedures, a colonoscopy can detect and remove polyps, which is one of the main reasons why it is the recommended screening procedure for other high-risk groups, such as those with Lynch syndrome.

"If your endoscopist finds any polyps, he or she will remove them during the procedure. This eliminates the need to return a second time.” — Amy Braid, an adult with CF, from the CF Community Blog

What About At-Home Testing?

At-home colorectal cancer screening, through such products as Cologuard, has become popular in recent years. Although less invasive than a colonoscopy, screening methods like fecal immunochemical testing (FIT) are not recommended for people with CF because there is a lack of CF-specific evidence to support the method's effectiveness. If you are interested in stool-based testing, it is important that you discuss this with your CF care team before proceeding with the procedure.

Research is being done to learn more about these tests in people with CF. 

Did you know?

According to Fight Colorectal Cancer, 60% of colorectal cancer deaths could be prevented with screening. Fight Colorectal Cancer shows how effective screening can prevent colorectal cancer.

When Should I Get Screened?

Due to the increased risk of developing colorectal cancer, people with CF are generally recommended to begin screening at age 40, 5 years earlier than for the general population.

In general, adults with CF age 40 or older should be screened for colorectal cancer every five years unless they have other symptoms or have had a positive screen in the past.

If you've had a colonoscopy and your physician found adenomatous (pre-cancerous) polyps, you will likely need to come back to get screened every 3 years.

"If your body is telling you something, go and get screened. Be your own vociferous advocate. I had zero symptoms until stage four, so please talk to your doctor about getting screened before 40." — Anna Payne, adult with CF, from the CF Community Blog

What If I've Had an Organ Transplant?

Because there is an increased risk of developing cancers post-transplant, organ transplant recipients — such as people who have received a lung transplant — should generally start screening for colorectal cancer at age 30.

If you are older than 30 when you receive your transplant, it is recommended that you start screening within two years of transplantation (unless you've had a negative colonoscopy within the past five years — which may be part of the workup depending on where you received your transplant).

Coordinating My Care

A colonoscopy is a medical procedure, which means there are important aspects to consider when you have cystic fibrosis. For example, CF-specific factors, such as lung function, level of cough, and mucus production, can all impact your screening decisions — particularly when it comes to the type of level of pre-exam sedation you receive.

For this reason, it is important to discuss the timing and appropriateness of screening with your CF care team. Together, you can assess your individual cancer risk and how other medical needs may impact your screening decisions.

Some questions you can ask your care team before a colonoscopy include:

  1. Am I healthy enough to undergo this exam? (For example, general anesthesia for elective procedures such as a screening colonoscopy may not be recommended for people with CF who have lowered lung function.)
  2. How should we approach the sedation for the procedure? (Factors such as emotional wellness, the use of opiate pain medication, and reduced lung function may warrant a different or deeper level of pre-exam sedation.)
  3. Should we meet with a gastroenterologist to discuss my screening plan? (As specialists in digestive conditions, a gastroenterologist may be able to provide greater detail for questions about screening or sedation.)
  4. Is there anything we can do to help ease my anxiety leading up to the procedure?
  5. What if I have CF-related diabetes or hypoglycemia? How might these factors change how I prepare for the exam?
Use this handout to guide your discussion with your endoscopist and CF care team to prepare for a successful colonoscopy.

Working With Your Colonoscopist and CF Care Team

Although the colonoscopy itself will be performed by a gastroenterologist or colonoscopist who is a clinical specialist outside of your CF care team, let your CF team know if you are planning to have a colonoscopy and encourage open communication with the physician performing your colonoscopy. Working closely with your care team and the specialist will help you coordinate your care by addressing your individual CF-specific needs.

Unlike the typical preparation for a colonoscopy, the bowel preparation for people with CF is more intensive than for the general population. People with CF tend to have thick, sticky intestinal mucus that makes it more difficult to clean out their colons. That's why it's important to carefully review the steps of a CF-specific bowel preparation with your CF care team so that your colonoscopy can be effectively performed the first time it is attempted.

Colonoscopy is generally a low-risk procedure, but there is always a small chance of bleeding and injury, such as colonic perforation, infection, and missed lesions.

"I typically say to my patients, 'There is no perfect test for colon cancer, and even with good preparation, some lesions can be missed. Colonoscopy is the best test currently available to look for and remove colonic polyps, and to identify potential cancers.'” — James Abraham, MD, a CF gastroenterologist, University of Minnesota

Although the benefits of colorectal cancer screening typically outweigh the risks, it is important to discuss colonoscopy screening with your CF care team and colonoscopist to ensure that colonoscopy is the right screening choice for you.

What Research Is Being Done?

The CF Foundation supports research focused on discovering why people with CF face increased colorectal cancer risk as well as ways to provide caregivers and people with CF more information about colorectal cancer. Researchers recognize that there is still more to learn and have identified some of those questions in the section titled “Unanswered Questions” in the Colorectal Cancer Screening Guidelines.

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Adult Care | Aging with CF | CF Related Health Conditions
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