About Colorectal Cancer

The risk for colorectal cancer in adults with cystic fibrosis is 5-10 times greater compared to the general population, and even higher for people with CF who receive a solid organ transplant like a lung transplant. Find out how early screening can help reduce your risk.

What Is Colorectal Cancer?

Colorectal cancer is a cancer 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.

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 10 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 -- at the age of 30, depending on when the transplant occurs.

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.

The two general types of colon polyps are:

  • 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.

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.


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

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

Although the Cystic Fibrosis Foundation’s Colorectal Cancer Screening Clinical Care Guidelines recommend that people with CF start getting screened 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, an adult with CF, who was diagnosed with colon cancer

What’s My Risk?

The risk for colorectal cancer in adults with cystic fibrosis is 5-10 times greater compared to the general population.

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

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.

What Can I Do?

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

According to the 2017 statistic from Fight Colorectal Cancer, 60 percent of cancer deaths could be prevented with screening.

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

When Should I Get Screened?

Polyps are thought to develop earlier and progress into cancer more quickly in people with cystic fibrosis, which is why screening for colorectal cancer is generally recommended to start at age 40, 10 years earlier than for the general population.

Colonoscopy is a medical procedure, which means there are important aspects to consider when you have CF. For example, the procedure can be performed under sedation or general anesthesia, which may carry some risks.

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, they may be able to provide greater detail to 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 procedure?
In general, adults with CF aged 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 for screening every three years.

What If I've Had an Organ Transplant?

Due to the increased risk of developing cancers post-transplant, organ transplant recipients -- such as people who have received a lung transplant -- should generally start getting screened 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 for transplant depending on the institution).

What Is a Colonoscopy?

Colonoscopy uses a long, flexible tube that is 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, M.D., 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.

Why Colonoscopy?

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.

Although less invasive, 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 their effectiveness. If you are interested in stool-based testing, it is important that you discuss this with your CF care team first.

Working With Your CF Care Team

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.

If the colon is not properly cleaned out, the physician performing the colonoscopy may not be able to identify polyps and may even require you to repeat the exam. This is 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.

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.

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 and level of pre-exam sedation you receive. It is important that all providers involved in your care communicate and work together prior to your colonoscopy so that you can make decisions about the level of sedation and other key factors.

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 a 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, M.D., CF Gastroenterologist (adult), 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.