Low Prevalence of Screen-Detected Colorectal Cancer in an Average-Risk Population: The New Normal

Evaluating New Non-invasive Screening Tests for Colorectal Cancer: An In-Depth International Perspective-Introduction to a Special Issue of Digestive Diseases and Sciences

Colorectal cancer (CRC) is a global disease accounting for nearly one in 10 cancer cases and deaths which can be reduced through CRC screening. In 2023 the World Endoscopy Organization (WEO) set forth twelve newly stated principles whereby new non-invasive CRC screening tests could be efficiently evaluated by a rigorous phased comparative approach. The complexities of evaluating new and evolving CRC screening tests and the necessity for a "one size does not fit all" approach was stressed. This special issue of Digestive Diseases and Sciences expands on this document and provides in-depth discussions of several of the issues raised during its development from a global perspective.

The Utility of Multitarget Stool DNA Testing in Community-Based Clinical Practice

INTRODUCTION

Multitarget stool DNA (MT-sDNA) tests (i.e., Cologuard) serve as screening tests for colorectal cancer (CRC) and are recommended by the US Preventive Services Task Force every 1-3 years. In this study, in a primary care setting, our aim was to evaluate the diagnostic performance of MT-sDNA testing and colonoscopy findings after a positive MT-sDNA testing result.

METHODS

This was a retrospective cohort study of electronic health record data including all patients who underwent MT-sDNA tests (Cologuard; Exact Sciences, Madison, WI) at 35 network primary care facilities from Winter of 2019 to Spring of 2023. Patients who were at high risk and had a prior colonoscopy or prior negative MT-sDNA test result were excluded. Assessment of pathology was as previously described, including for advanced adenomas and CRC.

RESULTS

Among the 5,827 patients for whom MT-sDNA testing was ordered, 3,119 patients completed the test; 482 (15%) had a positive MT-sDNA test, most of whom were women, had an average age of 65 years, and were predominantly White (Supplemental Figure 1, Table 1). Among these 482 patients, 277 (57%) had a follow-up screening colonoscopy, with 253 patients having complete colonoscopy data. Ten patients (4%) had CRC, 61 (24%) had advanced adenomas, and 184 patients (73%) had neither. The sigmoid colon was the most common site for CRC, with 8 of 10 patients having tumor, node, metastasis stage ≥1 CRC.

DISCUSSION

The rate of colon cancer detection (10/5,827 [0.2%] patients for whom it was ordered and 10/3,119 [0.3%] who completed the test) was lower than expected in a screening cohort. Most patients who completed MT-sDNA testing had a false-positive result for advanced adenomas or CRC (73%). Together, these findings raise questions about the effectiveness of screening based on MT-sDNA testing in an average risk population.

Risk Factors for Serrated Polyps: Results From a Large, Multicenter Colonoscopy-Based Study

INTRODUCTION

Risk factors for serrated polyps (SPs) are not well understood.

METHODS

Multivariable analyses of data from a multicenter colonoscopy-based study estimated odds ratios for having either a sessile serrated lesion or traditional serrated adenoma according to participant characteristics.

RESULTS

Six thousand seventy-eighty participants were included in the analyses (565 with either a sessile serrated lesion or traditional serrated adenoma). White race was associated with a higher risk of SPs compared with Black race (adjusted odds ratio 4.64, 95% confidence interval 1.89-11.41). Obesity and current smoking were also associated with a higher risk of SPs.

DISCUSSION

White race, smoking, and obesity are risk factors for precancerous SPs.

Comparative Performance of Common Fecal Immunochemical Tests : A Cross-Sectional Study

BACKGROUND

Despite widespread use of fecal immunochemical tests (FITs) for colorectal cancer (CRC) screening, data to guide test selection are limited.

OBJECTIVE

To compare the performance characteristics of 5 commonly used FITs, using colonoscopy as the reference standard.

DESIGN

Cross-sectional study. (ClinicalTrials.gov: NCT03264898).

SETTING

Three U.S. academic medical centers and affiliated endoscopy units.

PARTICIPANTS

Patients aged 50 to 85 years undergoing screening or surveillance colonoscopy.

INTERVENTION

Participants completed 5 different FITs before their colonoscopy, including 4 qualitative tests (Hemoccult ICT, Hemosure iFOB, OC-Light S FIT, QuickVue iFOB) and 1 quantitative test (OC-Auto FIT, which was run at the manufacturer's threshold for positivity of >100 ng/mL).

MEASUREMENTS

The primary outcome was test performance (sensitivity and specificity) for each of the 5 FITs for advanced colorectal neoplasia (ACN), defined as advanced polyps or CRC. Positivity rates, positive and negative predictive values, and rates of unevaluable tests were compared. Multivariable models were used to identify factors affecting sensitivity.

RESULTS

A total of 3761 participants were enrolled, with a mean age of 62.1 years (SD, 7.8); 63.2% of participants were female, 5.7% were Black, 86.4% were White, and 28.7% were Hispanic. There were 320 participants with ACN (8.5%), including 9 with CRC (0.2%). The test positivity rate varied 4-fold (3.9% to 16.4%) across FITs. Rates of unevaluable FITs ranged from 0.2% to 2.5%. The sensitivity for ACN varied from 10.1% to 36.7%, and specificity varied from 85.5% to 96.6%. Differences in sensitivity between FITs were all statistically significantly different except between Hemosure iFOB and QuickVue iFOB, and specificity differences were all statistically significantly different from one another. In addition to FIT brand, distal location of ACN was also associated with higher FIT sensitivity.

LIMITATION

The study did not assess the programmatic sensitivity of annual FIT.

CONCLUSION

Although considered a single class, FITs have varying test performance for detecting ACN and should not be considered interchangeable.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Colorectal cancer screening: A review of current knowledge and progress in research

Colorectal cancer (CRC) is one of the most prevalent malignancies worldwide, being the third most commonly diagnosed malignancy and the second leading cause of cancer-related deaths globally. Despite the progress in screening, early diagnosis, and treatment, approximately 20%-25% of CRC patients still present with metastatic disease at the time of their initial diagnosis. Furthermore, the burden of disease is still expected to increase, especially in individuals younger than 50 years old, among whom early-onset CRC incidence has been increasing. Screening and early detection are pivotal to improve CRC-related outcomes. It is well established that CRC screening not only reduces incidence, but also decreases deaths from CRC. Diverse screening strategies have proven effective in decreasing both CRC incidence and mortality, though variations in efficacy have been reported across the literature. However, uncertainties persist regarding the optimal screening method, age intervals and periodicity. Moreover, adherence to CRC screening remains globally low. In recent years, emerging technologies, notably artificial intelligence, and non-invasive biomarkers, have been developed to overcome these barriers. However, controversy exists over the actual impact of some of the new discoveries on CRC-related outcomes and how to effectively integrate them into daily practice. In this review, we aim to cover the current evidence surrounding CRC screening. We will further critically assess novel approaches under investigation, in an effort to differentiate promising innovations from mere novelties.

Diagnostic accuracy of risk assessment and fecal immunochemical test in colorectal cancer screening: Results from a population-based program and meta-analysis

BACKGROUND

Fecal immunochemical test (FIT) is a commonly used initial test for colorectal cancer (CRC) screening. Parallel use of FIT with risk assessment (RA) could improve the detection of non-bleeding lesions, but at the expense of compromising sensitivity. In this study, we evaluated the accuracy of FIT and/or RA in the Shanghai CRC screening program, and systematically reviewed the relevant evaluations worldwide.

METHODS

RA and 2-specimen FIT were used in parallel in the Shanghai screening program, followed by a colonoscopy among those with positive results. Sensitivity, specificity, detection rate of CRC, positive predictive value (PPV), and other measures with their 95% confident intervals were calculated for each type of tests and several assumed combined tests. We further searched PubMed, Embase, Web of Science, and Cochrane Library for relevant studies published in English up to January 5, 2022.

RESULTS

By the end of 2019, a total of 1,901,360 participants of the screening program completed 3,045,108 tests, with 1,901,360 first-time tests and 1,143,748 subsequent tests. Parallel use of RA and 2-specimen FIT achieved a sensitivity of 0.78 (0.77-0.80), a specificity of 0.78 (0.78-0.78), PPV of 0.89% (0.86-0.92), and a detection rate of 1.99 (1.93-2.05) for CRC per 1000 among participants enrolled in the first screening round, and performed similarly among those who participated for several times. A meta-analysis of 103 published observational studies demonstrated a higher sensitivity [0.76 (0.36, 0.94)] but a much lower specificity [0.59 (0.28, 0.85)] of parallel use of RA and FIT for detecting CRC in average-risk populations than in our subjects. One-specimen FIT, the most commonly used initial test, had a pooled specificity comparable to the Shanghai screening program (0.92 vs. 0.91), but a much higher pooled sensitivity (0.76 vs. 0.57).

CONCLUSION

Our results indicate the limitation of FIT only as an initial screening test for CRC in Chinese populations, and highlight the higher sensitivity of parallel use of RA and FIT. Attempts should be made to optimize RA to improve effectiveness of screening in the populations.

Colorectal Cancer Risk Is Impacted by Sex and Type of Surgery After Bariatric Surgery

PURPOSE

Sex differences exist in the associations between obesity and the risk of colorectal cancer (CRC). However, limited data exist on how sex affects CRC risk after bariatric surgery.

MATERIALS AND METHODS

This retrospective cohort study used the 2012-2020 MarketScan database. We employed a propensity-score-matched analysis and precise coding to define CRC in this nationwide US study. Adjusted hazards ratio (HR) assessed CRC risk ≥ 6 months. In a restricted analysis, logistic regression with adjusted odds ratios (OR) examined CRC risk ≥ 3 years.

RESULTS

Our sample included 327,734 controls with severe obesity and 88,630 patients with Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (VSG). The odds of cessation of diabetes mellitus medications, a surrogate for diabetes remission, were higher post-surgery vs. controls, especially in RYGB and males. In females, CRC risk decreased post-RYGB compared to controls (HR = 0.40, 95%CI: 0.18-0.87, p = 0.02). However, VSG was not associated with lower CRC risk in females. Paradoxically, in males compared to controls, CRC risk trended toward an almost significant increase, especially after 3 years or more from surgery (OR = 2.18, 95%CI: 0.97-4.89, p = 0.06). Males had a higher risk of CRC, particularly rectosigmoid cancer, than females after bariatric surgery (HR = 2.69, 95% CI: 1.35-5.38, p < 0.001). Furthermore, diabetes remission was not associated with a lower CRC risk post-surgery.

CONCLUSION

Our data suggest an increased risk of CRC in males compared to females after bariatric surgery. Compared to controls, there was a decrease in CRC risk in females' post-RYGB but not VSG. Mechanistic studies are needed to explain these differences.