CRC Screening: Right Patient, Right Test, Right Time

It has been three and a half years since the US Preventive Services Task Force (USPSTF) lowered the age to start colorectal cancer (CRC) screening from 50 to 45. As I mentioned in a previous commentary, two major medical groups — the American Academy of Family Physicians and the American College of Physicians — felt that the evidence was insufficient to support this change. 

Did doctors adjust their screening practices? A recent study suggests that they have. Comparing CRC screening rates in more than 10 million adults aged 45-49 during the 20 months preceding and 20 months following the USPSTF recommendation, researchers found significant increases during the latter time period, with the greatest increases among persons of high socioeconomic status or living in metropolitan areas.

Another study addressed concerns that younger adults may be less likely to follow up on positive screening results or more likely to have false positives on a fecal immunochemical test (FIT). Patients aged 45-49 years were slightly less likely to have a positive FIT result than 50-year-olds, but they had similar rates of colonoscopy completion and similar percentages of abnormal findings on colonoscopy.

Although the sensitivity and specificity of FIT varies quite a bit across different test brands, its overall effectiveness at reducing colorectal cancer deaths is well established. In 2024, the Food and Drug Administration approved three new screening options: a blood-based screening test (Shield), a next-generation multitarget stool DNA test (Cologuard Plus), and a multitarget stool RNA test (ColoSense) with similar performance characteristics as Cologuard Plus. The latter two tests will become available early next year.

This profusion of noninvasive options for CRC screening will challenge those tasked with developing the next iteration of the USPSTF recommendations. Not only must future guidelines establish what evidence threshold is sufficient to recommend a new screening strategy, but they also will need to consider the population-level consequences of relative utilization of different tests. For example, a cost-effectiveness analysis found that more CRC deaths would occur if people who would have otherwise accepted colonoscopy or fecal tests chose to be screened with Shield instead; however, this negative outcome could be offset if for every three of these test substitutions, two other people chose Shield who would otherwise have not been screened at all.

In the meantime, it is important for primary care clinicians to be familiar with evidence-based intervals for CRC screening tests and test eligibility criteria. A troubling study of patients who completed a multitarget stool DNA test in a Midwestern health system in 2021 found that more than one in five had the test ordered inappropriately, based on USPSTF guidelines. Reasons for inappropriate testing included having had a colonoscopy within the past 10 years, a family history of CRC, symptoms suggestive of possible CRC, age younger than 45, and a prior diagnosis of colonic adenomas. 

Just as a medication works best when the patient takes it as prescribed, a CRC screening test is most likely to yield more benefit than harm when it’s provided to the right patient at the right time.

Dr. Lin is Associate Director, Family Medicine Residency Program, at Lancaster General Hospital in Pennsylvania. He reported no relevant conflicts of interest.

A version of this article first appeared on Medscape.com.

It has been three and a half years since the US Preventive Services Task Force (USPSTF) lowered the age to start colorectal cancer (CRC) screening from 50 to 45. As I mentioned in a previous commentary, two major medical groups — the American Academy of Family Physicians and the American College of Physicians — felt that the evidence was insufficient to support this change. 

Did doctors adjust their screening practices? A recent study suggests that they have. Comparing CRC screening rates in more than 10 million adults aged 45-49 during the 20 months preceding and 20 months following the USPSTF recommendation, researchers found significant increases during the latter time period, with the greatest increases among persons of high socioeconomic status or living in metropolitan areas.

Another study addressed concerns that younger adults may be less likely to follow up on positive screening results or more likely to have false positives on a fecal immunochemical test (FIT). Patients aged 45-49 years were slightly less likely to have a positive FIT result than 50-year-olds, but they had similar rates of colonoscopy completion and similar percentages of abnormal findings on colonoscopy.

Although the sensitivity and specificity of FIT varies quite a bit across different test brands, its overall effectiveness at reducing colorectal cancer deaths is well established. In 2024, the Food and Drug Administration approved three new screening options: a blood-based screening test (Shield), a next-generation multitarget stool DNA test (Cologuard Plus), and a multitarget stool RNA test (ColoSense) with similar performance characteristics as Cologuard Plus. The latter two tests will become available early next year.

This profusion of noninvasive options for CRC screening will challenge those tasked with developing the next iteration of the USPSTF recommendations. Not only must future guidelines establish what evidence threshold is sufficient to recommend a new screening strategy, but they also will need to consider the population-level consequences of relative utilization of different tests. For example, a cost-effectiveness analysis found that more CRC deaths would occur if people who would have otherwise accepted colonoscopy or fecal tests chose to be screened with Shield instead; however, this negative outcome could be offset if for every three of these test substitutions, two other people chose Shield who would otherwise have not been screened at all.

In the meantime, it is important for primary care clinicians to be familiar with evidence-based intervals for CRC screening tests and test eligibility criteria. A troubling study of patients who completed a multitarget stool DNA test in a Midwestern health system in 2021 found that more than one in five had the test ordered inappropriately, based on USPSTF guidelines. Reasons for inappropriate testing included having had a colonoscopy within the past 10 years, a family history of CRC, symptoms suggestive of possible CRC, age younger than 45, and a prior diagnosis of colonic adenomas. 

Just as a medication works best when the patient takes it as prescribed, a CRC screening test is most likely to yield more benefit than harm when it’s provided to the right patient at the right time.

Dr. Lin is Associate Director, Family Medicine Residency Program, at Lancaster General Hospital in Pennsylvania. He reported no relevant conflicts of interest.

A version of this article first appeared on Medscape.com.

It has been three and a half years since the US Preventive Services Task Force (USPSTF) lowered the age to start colorectal cancer (CRC) screening from 50 to 45. As I mentioned in a previous commentary, two major medical groups — the American Academy of Family Physicians and the American College of Physicians — felt that the evidence was insufficient to support this change. 

Did doctors adjust their screening practices? A recent study suggests that they have. Comparing CRC screening rates in more than 10 million adults aged 45-49 during the 20 months preceding and 20 months following the USPSTF recommendation, researchers found significant increases during the latter time period, with the greatest increases among persons of high socioeconomic status or living in metropolitan areas.

Another study addressed concerns that younger adults may be less likely to follow up on positive screening results or more likely to have false positives on a fecal immunochemical test (FIT). Patients aged 45-49 years were slightly less likely to have a positive FIT result than 50-year-olds, but they had similar rates of colonoscopy completion and similar percentages of abnormal findings on colonoscopy.

Although the sensitivity and specificity of FIT varies quite a bit across different test brands, its overall effectiveness at reducing colorectal cancer deaths is well established. In 2024, the Food and Drug Administration approved three new screening options: a blood-based screening test (Shield), a next-generation multitarget stool DNA test (Cologuard Plus), and a multitarget stool RNA test (ColoSense) with similar performance characteristics as Cologuard Plus. The latter two tests will become available early next year.

This profusion of noninvasive options for CRC screening will challenge those tasked with developing the next iteration of the USPSTF recommendations. Not only must future guidelines establish what evidence threshold is sufficient to recommend a new screening strategy, but they also will need to consider the population-level consequences of relative utilization of different tests. For example, a cost-effectiveness analysis found that more CRC deaths would occur if people who would have otherwise accepted colonoscopy or fecal tests chose to be screened with Shield instead; however, this negative outcome could be offset if for every three of these test substitutions, two other people chose Shield who would otherwise have not been screened at all.

In the meantime, it is important for primary care clinicians to be familiar with evidence-based intervals for CRC screening tests and test eligibility criteria. A troubling study of patients who completed a multitarget stool DNA test in a Midwestern health system in 2021 found that more than one in five had the test ordered inappropriately, based on USPSTF guidelines. Reasons for inappropriate testing included having had a colonoscopy within the past 10 years, a family history of CRC, symptoms suggestive of possible CRC, age younger than 45, and a prior diagnosis of colonic adenomas. 

Just as a medication works best when the patient takes it as prescribed, a CRC screening test is most likely to yield more benefit than harm when it’s provided to the right patient at the right time.

Dr. Lin is Associate Director, Family Medicine Residency Program, at Lancaster General Hospital in Pennsylvania. He reported no relevant conflicts of interest.

A version of this article first appeared on Medscape.com.