Some prep options are smaller volume, some are in pill form, some are flavored and a little bit gentler—there are new ways to tailor the prep for your preferences.
Audrey H. Calderwood, MD, MSColorectal cancer is largely preventable through screening. Yet, rates of diagnoses and cancer-related deaths are rising in younger adults.
“Some of the thinking around early-onset colon cancer is that it's related to birth cohort effect, meaning the way people have grown up and the environment,” says Dartmouth Health gastroenterologist and colorectal cancer researcher Audrey H. Calderwood, MD, MS. “Theories include obesity, diabetes, sedentary lifestyle, more highly processed foods—things like that.”
In 2021, the U.S. Preventive Services Task Force lowered the recommended screening age from 50 to 45. Calderwood says it will take time to get the word out about the change and also about options for screening.
Options for screening
There are several approved and effective methods for colorectal cancer screening, including at-home stool-based testing, of which there are two main types. “Fecal immunochemical testing or ‘FIT’ is done at home once a year. You use a kit to send a small sample of stool back to a lab right here at Dartmouth. If it's negative, meaning no findings of hidden blood, the test can be repeated in another year,” explains Calderwood.
There’s also a multi-target stool DNA test known by the proprietary name, Cologuard. “You collect a whole stool and mail it back. The test looks for hidden blood as well as tumor markers shed in the stool. If that's negative, you repeat it in three years.” If either test is positive, colonoscopy is needed to figure out why.
Calderwood notes Cologuard is better at detecting polyps, which are small growths on the lining of the colon, of which a small percentage may become cancerous over time if not removed. But she also notes there are more false positives with Cologuard, “meaning more people need to come for colonoscopy after doing Cologuard vs. after FIT, only to be told they're normal,” she says. “But Cologuard is also every three years vs. FIT which is every year. So you have to decide which is better for you.”
Why not colonoscopy?
Colonoscopy remains the most commonly performed GI procedure for all indications. While it is the most informative, it is also a more invasive procedure, requiring preparation that includes some diet and medication changes as well as drinking a bowel purgative. And while it is does not cause lasting pain, most people require sedation to minimize discomfort during the procedure.
In addition to a lack of awareness about new screening recommendations and other access barriers, Calderwood notes “prep hesitancy” as a big reason why people may not want colonoscopy. “We did a study looking at what patients age 60 and up, thought were the most difficult parts of colonoscopy. Half the people said the prep.” More recently, she has researched and co-authored two American College of Gastroenterology presentations and a recent “Guide to Bowel Preparation” on this topic.
Calderwood notes that no other method of cancer screening, for example, breast, cervical and lung cancer, involves drinking a prep, sedation, taking the day off or needing someone to drive you home, all of which could be barriers to getting screened. “People also talk to their friends and hear things like ‘The prep is terrible.’ That can lead to a lot of built-up anxiety before they even have their own experience,” she says.
The prep isn’t as bad as it used to be
In an effort to address prep hesitancy, some of the preps have gotten more tolerable. “Some prep options are smaller volume, some are in pill form, some are flavored and a little bit gentler—there are new ways to tailor the prep for your preferences,” says Calderwood. “But the intended effect—to clear out the bowels—is still the same.”
The other good news is the death rate from colorectal cancer has been dropping in older adults for several decades, thanks to screening. Calderwood’s own research focuses on this special population to better understand which screening options and frequency result in the best outcomes.
“In people who have a history of colon polyps, we're learning that some of these smaller polyps or adenomas are much lower risk for colorectal cancer than we thought,” she says. As a result, in the last fifteen years, the amount of time between follow-up for people with polyps has increased. “We used to have people with polyps come back every five years indefinitely. Now, if there are one or two small adenomas, they can wait seven to ten years. It's likely that the next guideline will say a full ten years is ok.”
Calderwood credits the changes to large population-level data from groups in the U.S. and in other countries. “Over time, they’ve looked at long-term risk of colorectal cancer incidence and mortality in people who have one or two small polyps. Compared to people with what we call advanced or “high-risk” polyps, the group with one to two small polyps was really at similar risk of colon cancer and colon cancer death as people without any polyps.”
Knowing that a certain group’s risk of colorectal cancer is much lower than initially perceived opens doors to other forms of monitoring besides colonoscopy. “Perhaps FIT or Cologuard could be used by people who have a history of polyps instead of saying, as we do in the U.S. right now, that it can only be colonoscopy,” she says.
Calderwood is leading a multi-year clinical trial called COOP to help inform such guidelines. The trial is for people aged 65 to 82 with a history of low-risk polyps. Study participants are randomly assigned to either get annual at-home stool test with FIT or a one-time colonoscopy for monitoring polyps. “We're looking at their outcomes of colorectal cancer as well as how they feel about the testing, including trust and satisfaction with testing and their level of cancer worry,” she says.
Calderwood’s team chose adults 65 and older to study because they have an increased risk of complications from colonoscopy compared to younger adults. They may also have other comorbidities that can shift the risk-to-benefit balance of ongoing colonoscopy. “Our hope is that if FIT is effective, then we could offer it as another method for monitoring among people with small polyps. Also, if there is a long wait to get a colonoscopy, they could do FIT at home instead of waiting.”
Future directions
Most recently, last year, the FDA approved two blood tests for the detection of colorectal cancer. “They detect late-stage cancer, but not early-stage cancer or advanced polyps as well as FIT or Cologuard,” says Calderwood. “The blood tests shouldn't be a substitute for current screening methods. But hopefully, over time, if the technology improves and test performance increases, blood tests might be a good option for the 30-40% of people in the U.S. who would otherwise not get any colorectal cancer screening.”
To find out if you are eligible for colorectal cancer screening and discuss options, talk with your primary care doctor.
If you are interested in learning more about or joining the COOP Study, email coopstudy@hitchcock.org.