Single flexible sigmoidoscopy screening for colorectal cancer confers long-term benefits
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The protective effect of a single flexible sigmoidoscopy screening in older adults was maintained for up 15 years against colorectal cancer incidence and for up to 19 years against mortality, according to a randomized controlled trial.
Current guidelines recommend “repeated flexible sigmoidoscopy screening,” Carlo Senore, MD, MSc, of the Piedmont Region Cancer Prevention Center and the S. Giovanni Battista University Hospital of Turin, Italy, and colleagues wrote in Annals of Internal Medicine. These latest findings, which align with those from other trials, suggest the need to revise those recommendations, they said.
In the SCORE trial, Senore and colleagues randomly assigned 34,272 adults aged 55 to 64 years in a 1:1 ratio to receive flexible sigmoidoscopy screening or usual care. Although all participants had expressed an interest in flexible sigmoidoscopy screening, 7,138 patients in the flexible sigmoidoscopy cohort did not attend their screening appointment and another 87 did not have the procedure done for other reasons, narrowing it down to 9,911 patients in that cohort who had data available for analysis. All trial participants were followed for a median of 15.4 years for colorectal cancer (CRC) incidence and 18.8 years for CRC mortality.
According to the researchers, CRC incidence dropped 19% (rate ratio = 0.81; 95% CI, 0.71-0.93) in an intention-to-treat (ITT) analysis that compared the intervention with the control group and by 33% (rate ratio = 0.67; 95% CI, 0.56-0.81) in a per protocol (PP) analysis, which compared participants who were screened in the intervention group with controls. In addition, death from CRC was reduced by 22% (rate ratio = 0.78; 95% CI, 0.61-0.98) in the ITT analysis and by 39% (rate ratio = 0.61; 95% CI, 0.44 -0.84) in the PP analysis. The incidence of CRC was significantly reduced among both men and women who received flexible sigmoidoscopy, but the risk for death was only significantly reduced in men (ITT rate ratio = 0.73; 95% CI, 0.54 -0.97), not in women (ITT rate ratio = 0.9, 95% CI, 0.59 -1.37).
“The benefit-to-harm ratio of this strategy would be improved when adopting a once-in-a-lifetime approach because of the substantial reduction in the burden associated with screening as well as the reduction in health care costs,” the researchers wrote.
In a related editorial, Michael Bretthauer, MD, PhD, from the University of Oslo and University of Tromsø in Norway, and colleagues mentioned that when endoscopic screening was first discussed in the early 1990s, “colonoscopy was regarded as too invasive, too resource demanding, and too burdensome on patients to be seriously considered as a screening test.”
The findings from the Italian trial bring an end to a “remarkable, 3-decades long era in colorectal cancer screening,” they said.
References
Bretthauer M, et al. Ann Intern Med. 2021;doi:10.7326/M21-3770.
Senore C, et al. Ann Intern Med. 2021;doi:10.7326/M21-0977.
Perspective
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Robert A. Smith, PhD
There are different ways to screen for colorectal cancer, and they all differ in their complexities, costs, strengths, limitations, parts of the colon tested and patient preferences.
However, it is reasonable for physicians to tell patients that if he or she gets any one of the recommended tests and they do it faithfully over the course of their life during the period that they are recommended to undergo screening, and if they adhere to the recommendations faithfully, they have a very good chance of colorectal cancer or precancerous lesions being detected early. The same holds true even if they switch testing procedures during their lifetime.
The American Cancer Society recommends that doctors should offer average-risk patients ages 45 to 75 years the option of a stool test or a direct visualization test (colonoscopy, sigmoidoscopy, or CT-colonography) based on their personal preferences. Individuals with some risk factors (eg, a personal history of adenomatous polyps or colorectal cancer, a family history of adenomatous polyps or colorectal cancer diagnosed in a relative before the age of 60 years, a personal history of inflammatory bowel disease, a confirmed or suspected hereditary colorectal cancer syndrome, or a history of abdominal or pelvic radiation for a previous cancer should discuss these conditions with their doctor, but in most instances will be recommended to be screened for colorectal cancer only with colonoscopy, and may also be advised to begin screening before age 45 years, especially if an affected family member was diagnosed with colorectal cancer at a very young age.
Those patients who are aged 45 years with no family history can safely choose any of the six recommended options for colorectal cancer that are covered by most health plans.
People differ in their preferences for colorectal cancer screening tests, which is why the American Cancer Society recommends that patients be given a choice. Personal preferences may also be influenced by an individual’s circumstances. Getting a colonoscopy usually requires a day away from work, and an individual who would face difficulty getting a day off could reasonably be screened with one of the several stool test options, which should be done at home. Although adverse events during colonoscopy are rare, patients who are aged 65 years and older are among those who are more vulnerable to adverse events during colonoscopy. If they have had normal colonoscopies all their life, these patients could reasonably switch to a stool test, which can be completed at home and then shipped to the laboratory for interpretation. If their test is normal, they simply would repeat it the following year. If it is abnormal, then they must get a colonoscopy.
Although a flexible sigmoidoscopy only examines about half of the colon, the American Cancer Society leaves the flexible sigmoidoscopy on its list of recommended screening tests because it is effective at reducing deaths from colorectal cancer; identification of abnormalities within the reach of the scope can lead to the recommendation for a full colonoscopy, and there are some places where a sigmoidoscopy may be the only direct visual screening test available to a patient without driving a long distance from their home. Here in the United States, our country is made up not only of high-population urban areas, but also rural and frontier areas where it may very well be that somebody is very good at doing flexible sigmoidoscopy.
To borrow from Sydney Winawer, MD, Dr Sc (Hon), FASGE, MACG, AGAF, the former chief of the gastroenterology-nutrition service and chair of the cancer prevention and cancer control program at Memorial Sloan Kettering Cancer Institute and a former professor of medicine at Weill Cornell Medical College, the best test is the one a patient gets regularly and that is done well. We have the opportunity to prevent colorectal cancer and to prevent people from dying from it. The fact that we still have such a significant burden of colorectal cancer is discouraging to all of us who work in this field because the majority of newly diagnosed cases and deaths are due to a screening test having not been done, not done regularly, not followed up on when it came back positive, and in rarer instances, not being properly done. Regular colorectal screening saves lives. Let us make it a priority.
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