Doctors Debate: Should the Screening Age for Colonoscopy Be Reduced in Average-Risk Patients?

Uri Ladabaum, MD

Uri Ladabaum, MD

David S. Weinberg, MD, MSc

David S. Weinberg, MD, MSc

The incidence of colorectal cancer (CRC) is rising among people who are below 50 years of age, the colonoscopy screening age as recommended by the United States Preventive Service Task Force of the National Cancer Institute.¹Investigators have also noticed that the incidence of CRC is decreasing in adults over the age of 50, which may be related to screening.²To date, there is no research that can explain the rise which has led physicians to deliberation on whether the recommended screening age for colonoscopies should be lowered or left as is. During a debate at the 2020 Gastrointestinal Cancers Symposium, Uri Ladabaum, MD, and David S. Weinberg, MD, MSc, presented their stances on the topic.

The Recommended Age for Colonoscopy Screening Should Be Lowered

Ladabaum, director of the Gastrointestinal Cancer Prevention Program and head of the Clinical Service of the Division of Gastroenterology and Hepatology at Stanford University School of Medicine, holds that the screening age for average-risk adults should be lowered to 45 years of age because of the apparent disease burden; the role of modeling, which is a predictor of how screening should be performed; and the expectation that the performance of screening in patients under the age of 50 will be comparable with what has been seen in those aged 50 and older. This argument was supported by the 2018 update to guidelines from the American Cancer Society (ACS) which lowered the recommended age for screening in average-risk individuals from 50 to 45 years.³

The ACS also recommends that average-risk adults in good health have CRC screening through age 75, with individuals between 75 and 85 years being screened according to their overall health, prior screening history, and personal preferences. Those aged 85 years and older should no longer be screened for colorectal cancer. The ACS notes that there are multiple forms of screening which include stool-based tests, as well as more structural examinations like a colonoscopy.³

The research around the incidence of CRC also supported Ladabaum’s argument. In a study by Rebecca L. Siegel, MPH, and colleagues, long-term data were collected from 2008 to 2012 in individuals diagnosed with CRC across 5 continents, with the investigators noting that the incidence of CRC was increasing in adults under the age of 50 who lived in high-income countries. Decreasing rates were observed in low-income countries and in older adults aged 50 and older.²

In anticipation of Weinberg’s criticisms of his stance, Ladabaum answered questions about the magnitude of the problem, lead-time bias, limitations with modeling, and cost-effectiveness.

Having made a case for lowering the colonoscopy standard screening age, Ladabaum did not discount that challenges still exist in determining individual risk and deciding what action to take once the risk is found.

“One of the big issues is whether we can do it all. Can we do a better job at screening older people as well as beginning screening at age 45,” Ladabaum toldTargeted Oncologyin an interview.

Another challenge Ladabaum identified was that there is an unmet medical need for individuals under the age of 45 who do not get screening for CRC unless they are determined to be at high risk, which is based on factors like family history and certain comorbidities.

“Even if we lower the screening age to 45, we are not solving the problem of early onset CRC. We are not reaching people under age 45, and there’s also the issue of doing the appropriate work up when people present with symptoms. We need to distinguish [the differences] in screening of people who do not have symptoms and people who do have symptoms. If young people show up with rectal bleeding, we can’t just [assume] it’s hemorrhoids. We need to look at which patients might be showing early signs of CRC,” Ladabaum added.

The Recommended Age for Colonoscopy Screening Should Not be Lowered

Weinberg, chair of the Department of Medicine and chief of the Section of Gastroenterology at the Fox Chase Cancer Center, held that the colonoscopy screening age should not be lowered in average-risk patients. He began his presentation by highlighting the few areas where he and Ladabaum agree. Weinberg accepts that the incidence of CRC is rising in patients under the age of 50, but he noted that the risk is a relative risk and the absolute risk only impacts about 1.3% of people in their 40s and younger. Additionally, he thinks it’s important that the risk factors—which include being male, having a family history of CRC, and personal history of inflammatory bowel disease—be cited as contributors to the rise in the incidence of CRC rather than the mere lack of screening.

Reanalyzing the data in the Siegel paper that Ladabaum mentioned, Weinberg found that although the incidence of CRC was increasing in younger adults, the mortality rate stayed the same and these trends continued even as the amount of CRC screenings increased. He noted that a recommendation for decreasing the colonoscopy screening age based on this study was “textbook lead-time bias.” Also, he finds the core principle of colonoscopy screening to be a more informed viewpoint for determining the appropriate age to begin screening average-risk adults. His main point in this part of his presentation was that screening for CRC lowers the risk of CRC-related mortality, but the test is a risk in itself, which accounts for roughly 7 per 100,000 deaths.

“The data supporting lowering the screening age is intriguing, but based on what we know now, as opposed to what we’ve modeled, it seems premature to lower the colonoscopy screening age. This is mainly because there is no unanimity from amongst the various guidelines recommending what the screening age should be,” Weinberg toldTargeted Oncologyin an interview.

As anticipated, Weinberg also discussed the limitation of models during his presentation. He argued that models will never be more relevant than randomized clinical trials, stating “models help inform decisions, but they don’t define the standard of care. No one would vaccinate a population based on a model. Evidence-based medicine can’t be forgotten. It protects us, all of us, from all sorts of interventions that may be well-sounding and well-intended but,

when studied appropriately, are found to be ineffective or, in some cases, harmful. Why should screening for young people be any different?”

In terms of the challenges associated with determining which patients are at risk, Weinberg agrees with Ladabaum, but he discounts that the issue is related to the screening age for colonoscopies. According to the same guidelines that Ladabaum used to support his stance (ACS guidelines), patients who are determined to be at a higher risk for CRC should be screened every 1 or 2 years, regardless of their age.

“If a patient has rectal bleeding and they’re 25 years old, most physicians would suggest that they get a sigmoidoscopy, not a colonoscopy. The question that we don’t yet have an answer to is, if you have a healthy population of 45-year-old [patients], how many sigmoidoscopies or colonoscopies would you have to do to prevent one case of CRC?”

Weinberg finishes by stating that the main purpose of screening is to prevent mortalities, not the disease itself, and based on the current research, lowering the colonoscopy screening age does not prevent mortality from CRC.

References

1. Colorectal Cancer: Screening. U.S. Preventive Services Task Force website. Published June 2016. https://bit.ly/36X0H3z. Accessed February 4, 2020.
2. Siegel R, Torre LA, Soerjomataram I, et al. Global patterns and trends in colorectal cancer incidence in young adults.Gut. 2019;68 (12). DOI: http://dx.doi.org/10.1136/gutjnl-2019-319511.
3. Screening for colon and rectal cancer in average‐risk adults. American Cancer Society website. Published May 30, 2018. https://bit.ly/2UynccN. Accessed February 4, 2020.