First Guideline to Say Colon Cancer Screening Is Not for All

Should Be Based on Individual Risk

Nick Mulcahy

October 02, 2019

For the first time, a guideline recommends that screening for colorectal cancer should not be routinely recommended for all adults aged 50 to 79 years, but instead should be limited to individuals with an elevated level of risk.

The new guideline, from an international panel of experts, goes against the grain. At present, many countries recommend routine screening for all older individuals, and recently some groups have even lowered the starting age to 45 years.

The new guidelines were published online October 2 in BMJ.

Screening should be recommended for adults with a cumulative cancer risk of 3% or more in the next 15 years, the point at which the balance between benefits and harms favors screening, say the authors, led by Lise Helsingen, MD, Clinical Effectiveness Research Group, University of Oslo in Norway

Screening is not recommended when cumulative risk is below 3%.

Risk calculation (over 15 years) can be made using the free online QCancer calculator, advises the panel. "The optimal choice for each person requires shared decision-making," Helsingen commented in an email to Medscape Medical News.

A risk-based approach is "increasingly regarded as the most appropriate way to discuss cancer screening" and is already used with patients in prostate and lung cancer screening, writes Philippe Autier, PhD, International Prevention Research Institute, Lyon, France, in an accompanying editorial.

The National Comprehensive Cancer Network (NCCN) said the new guide does not change their screening recommendation.

"At this time, NCCN continues to endorse screening for colorectal cancer in average risk individuals age 50-75," said Dawn Provenzale, MD, Duke Cancer Institute, Durham, North Carolina, in an email to Medscape Medical News. She is chair of the NCCN Guidelines Panel for Colorectal Cancer Screening.

Provenzale said that the NCCN "will continue to monitor" the risk-based, personalized approach to colorectal cancer screening.

The new guideline is based on research that includes a systematic review of screening trials — including new data from three randomized trials of one-time sigmoidoscopy.

Results from those three trials, recently published after 15 to 17 years follow-up, are what spurred the new guideline, which is part of the BMJ's "Rapid Recommendations" initiative. The journal aims to "accelerate" the creation of guidelines based on new evidence.

"It can take years for new research evidence to filter into new treatment guidelines," the BMJ states on its website.

Duke's Provenzale acknowledged that her NCCN panel has yet to review the sigmoidoscopy trials data but plans to do so at their next meeting, to be held November/December 2019.

The NCCN's chief executive officer, Robert Carlson, MD, countered the idea that Rapid Recommendations are the only fast-moving guideline entity.

"When scientifically significant and practice changing information emerges between the planned yearly [NCCN guideline] updates. . . , NCCN initiates a process to develop interim updates of the involved guideline(s) . . . within 2 weeks of released knowledge," he told Medscape Medical News in an email.

Consideration of Risk Factors

The new recommendations apply to men and women with no prior screening, no symptoms of colorectal cancer, and a life expectancy of at least 15 years.

In the new guide, individual cumulative risk is computed using sex, age, body mass index, physical activity, familial history, and presence of disease predisposing to colorectal cancer. Gender as a risk factor came under new scrutiny as two of the three above-mentioned sigmoidoscopy trials reported a reduction in colorectal cancer mortality and incidence with sigmoidoscopy screening in men, but only a small or no reduction in women (Holme et al [Ann Intern Med. 2018;168:775-82] and Senore and Arrigoni [Lancet Gastroenterol Hepatol. 2019;4:192-93]).

Most colorectal cancer screening guidelines recommend screening for everyone age 50 and over, regardless of individual risk. At this age, the cumulative risk of developing bowel cancer over the next 15 years ranges from 1% to 7% for "most people" considered in the new guideline, say the authors.

Screening Options

The new guideline looked at evidence and made recommendations on screening for four screening options: fecal immunochemical test (FIT) every year, FIT every 2 years, one-time sigmoidoscopy, or one-time colonoscopy.

For individuals with an estimated 15-year risk above 3%, the panel suggests screening with any of the four above approaches.

Because of the absence of randomized trials on FIT and colonoscopy screening, the guideline panel also used results of microsimulation models in their analysis and recommendations.

Overall, there was "substantial uncertainty" regarding the 15-year benefits and harms of screening. All four screening options resulted in similar colorectal cancer mortality reductions, the authors said.

However, FIT every 2 years "may have little or no effect" on cancer incidence over 15 years, but FIT every year, as well as sigmoidoscopy and colonoscopy, may reduce cancer incidence, they comment.

The magnitude of the benefits is dependent on the individual risk, they add.

Serious gastrointestinal and cardiovascular adverse events caused by screening are "rare," the authors note.

The guideline authors and the editorialist agree that the recommendations to screen are based on "weak" evidence. "We cannot give strong recommendations for screening," summarized Helsingen.

In his editorial, Autier points out that a personalized approach is in "sharp contrast" with traditional approaches to colorectal cancer screening. He says that institutions typically give the message everyone should get screened and that not doing so endangers one's health.

"What matters is the uptake, and, to maximize uptake, messages tend to overstate benefits of screening and to downplay any undesirable consequences," Autier writes.

A personalized approach has multiple benefits, says Autier. For example, prioritizing higher risk individuals is likely to optimize screening effectiveness.

The colorectal cancer screening panel emphasized that everyone invited to screening should be able to accept or decline the invitation based on the benefits and harms they might personally expect from screening.

The new panel was assembled by the MAGIC group, a nonprofit guidelines initiative, in collaboration with BMJ. Panel members included patients, clinicians, content experts and methodologists. The international group hailed from Norway, the United States, Switzerland, Canada, Saudi Arabia, the United Kingdom, and the Netherlands. Other Rapid Recommendations have included prostate cancer screening, corticosteroids for sore throat, and oxygen therapy for acute illness.

Helsingen, Autier, Carlson, and Provenzale have disclosed no relevant financial relationships.

BMJ. Published online October 2, 2019. Full text, Editorial

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