Updated on July 30, 2024.
If you follow health news, you may have read about a European study published in The New England Journal of Medicine in October 2022 that looked at people’s willingness to get colonoscopies to screen for colorectal cancer. While only 42 percent of patients in the study who were invited to receive colonoscopies actually had the screening test done, the findings led many headlines to mistakenly cast doubt on the effectiveness of colonoscopy.
Are you wondering whether getting a colonoscopy is worth it? If so, the message from health experts in the United States is clear: Colonoscopies work and they are as important as ever for reducing the risk of colorectal cancer and the risk of dying from the disease.
“It’s hard to know the value of a screening test when the majority of people in the study didn’t get it done,” said William Dahut, MD, Chief Scientific Officer at the American Cancer Society, in a statement. “However, study patients who did undergo a colonoscopy had a 31 percent decrease in the risk of colorectal cancer as compared to those who were not screened. This result points to the value of continued screening.”
Karen Knudsen, PhD, Chief Executive Officer at the American Cancer Society, also invoked U.S. guidelines that advise that colorectal screening should begin at age 45: “There’s no reason to change that direction. Recommended cancer screenings should be a routine part of good health.”
What the guidelines recommend
Based on a systematic review of available research, the U.S. Preventive Services Task Force (USPSTF) updated its guidelines in May 2021 for colorectal cancer screening to recommend that adults at average risk should begin screening at age 45. (The previous USPSTF guidelines advised that screenings start at age 50.) The guidance follows a similar recommendation made by the American Cancer Society (ACS) in May 2018.
These guidelines reflect the power of routine screening to help catch cases of colorectal cancer early, when they are most treatable.
Colorectal cancer is the second leading cause of cancer deaths in the United States, according to the U.S. National Cancer Institute. The American Cancer Society (ACS) estimates that 106,180 new cases of colon cancer and 44,850 new cases of rectal cancer will be diagnosed in 2022. The organization also estimates that there will be 52,580 deaths due to colorectal cancer in 2022.
Why 45 is the current screening recommendation
While the overall colorectal cancer death rate is dropping, the current recommended screening age is due in large part to an increased incidence rate of colorectal cancer among younger people. Between the years of 2000-2002 and 2014-2016, the incidence of colorectal cancer in adults aged 40 to 49 rose by nearly 15 percent.
Meanwhile, according to the USPSTF, 26 percent of eligible adults in the U.S. had never been screened for colorectal cancer as of 2016. In 2018, 31 percent of Americans were not up to date with their screening.
The type of colorectal cancer screening people choose to have should be based on personal preference and availability. Regular screenings should continue through 75 years of age, as long as the person is in good health and has a life expectancy of more than 10 years.
Adults between 76 and 85 years old should make an informed decision with their healthcare provider (HCP) about whether to continue screenings based on life expectancy, current health, prior screening results, and personal preference. Colorectal cancer screenings are not recommended over the age of 85.
Colorectal cancer on the rise among younger adults
The reasons for the increase in colorectal cancer diagnoses in younger adults are not clear. Even though the incidence rate of colon cancer was still higher among adults aged 50 to 54, the ACS, in its guideline update published in CA: A Cancer Journal for Clinicians, indicated that it could be due to increased screenings among that age group. The incidence rate for adults 45 to 49 may be just as high, the group noted, since people in that cohort have been less likely to be screened.
The ACS also pointed to research that found that adults born around 1990 have twice the risk of colon cancer and four times the risk of rectal cancer compared with adults born around 1950, who have the lowest risk.
Some research suggests that unhealthy diets—in particular, those high in processed meat and fat and low in fruits and vegetables—may be contributing to increasing rates of early-onset colorectal cancer. Rising rates of obesity and sedentary lifestyles may also be factors.
What are the recommended screening options?
The guidelines do not preference one screening method over another, but rather highlight several types of colorectal cancer screening tests. Three of those screening methods are at-home tests in which stool samples are collected and sent away for analysis. Two of these at-home tests are recommended yearly, while a multi-targeted stool DNA test should be done every 1 to 3 years.
Other screening options include CT (virtual) colonoscopy or flexible sigmoidoscopy, either of which are recommended every five years.
On July 29, the U.S. Food and Drug Administration (FDA) approved a blood test for colorectal cancer screening. The Shield test, which is made by Guardant Health, is available by prescription for adults ages 45 and older who are at average risk for the disease. The test, which will reportedly cost $895, is also expected to be covered by Medicare. It works by finding the DNA that cancerous tumors release into the bloodstream.
Guardant Health recommends that the Shield test be taken every three years, but experts have not yet made a formal recommendation on how often this blood test should be repeated.
The Shield test is a less invasive screening option, but it is not a replacement for colonoscopy, which remains the gold standard for colorectal cancer detection.
Here’s why: It is more likely to find cancer at a later stage, when it is more difficult to treat.
In clinical trials, the blood test correctly detected colorectal cancer in 83 percent of people confirmed to have the disease. These people had not yet developed symptoms. But it has more limited detection of precancerous growths and early stage colorectal cancers. Studies show it found only 55 to 65 percent of stage 1 cancers and missed up to 87 percent of advanced precancerous lesions, which can be found and removed during colonoscopy.
In trials, the Shield blood test also had a false positive rate of about 10 percent. Anyone who tests positive—including false positives—would still need to undergo a follow up colonoscopy to confirm their result. In fact, any positive non-colonoscopy tests should be followed up with a colonoscopy.
Getting a colonoscopy every 10 years remains the option that is preferred by many experts.
Should you be screened at age 45?
“It is certainly true that the incidence of cancer at younger ages is increasing, so it might make some sense to screen earlier,” says Keith Roach, MD, associate professor in clinical medicine in the division of general medicine at Weill Cornell Medical College and New York Presbyterian Hospital.
The guidelines from the USPSTF and ACS can also serve as a good reminder to make a screening appointment. “The COVID-19 pandemic has kept many people from seeing their doctors, so many people might now actually be overdue for their screening colonoscopy,” Dr. Roach adds.
People at a higher risk of developing colorectal cancer should discuss earlier screening, regardless of their age. Risk factors include family and personal history of colorectal cancer or polyps, a personal history of inflammatory bowel disease, a family history of rare inherited syndromes linked to colon cancer, or experience with radiation to the abdomen to treat a previous cancer.
African Americans, Ashkenazi Jews, Native Americans, and Native Alaskans also have higher colorectal cancer risks.
If you are 45 or older and at average risk for colorectal cancer, discuss the benefits and drawbacks of screening with your HCP to help you make a decision that is right for you.
