Strongly Divergent Impact of Adherence Patterns on Efficacy of Colorectal Cancer Screening: The Need to Refine Adherence Statistics

Longitudinal screening adherence in the Australian National Bowel Cancer Screening Program from 2006 to 2022

OBJECTIVE

Australia's National Bowel Cancer Screening Program (NBCSP) offers two-yearly screening to 50-74-year-olds for the prevention and early detection of colorectal cancer (CRC). Internationally, detailed reporting of participation across multiple screening rounds - also known as longitudinal adherence - is becoming more common, but remains limited in Australia. We described the longitudinal screening adherence of individuals by age and sex invited to the NBCSP at least once, and quantified longitudinal adherence among individuals who received four NBCSP invitations.

METHODS

We obtained aggregate national data for individuals who received at least one NBCSP invitation between 1 August 2006 and 31 March 2022. We described screening adherence patterns including longitudinal adherence among individuals who received four invitations, and evaluated prior longitudinal adherence and adherence at most recent invitation as predictors of future participation.

RESULTS

Over the study period, 8.5 million individuals were invited to screen in the NBCSP; 51.9% of these individuals screened at least once. Of the >2.5 million individuals who received four invitations, 23.3% consistently screened, 38.3% never screened, and 38.3% inconsistently screened. The longitudinal adherence at the fourth invitation round for individuals who previously returned none, one, two, or three of their previous three invitations was 9.5%, 37.4%, 70.1% and 88.8%, respectively. Both longitudinal adherence and adherence at the most recent invitation were significant predictors of future participation.

CONCLUSION

Our study is the first detailed report of longitudinal adherence to the NBCSP in >2 screening rounds. These insights into long-term behaviours can inform planning for interventions to improve screening participation.

Longitudinal adherence to annual colorectal cancer screening among Black persons living in the United States enrolled in a community-based randomized trial

BACKGROUND

This study examined repeat colorectal cancer screening rates at 12 and 24 months as part of a randomized intervention trial among Black persons living in the United States and factors associated with screening adherence.

METHODS

Participants completed a survey assessing demographics and Preventive Health Model (PHM) factors (e.g., self efficacy, susceptibility) and received either a culturally targeted photonovella plus free fecal immunochemical test (FIT) kits (intervention group) or a standard educational brochure plus free FIT kits (comparison group). FIT return was assessed at 6, 12, and 24 months. Descriptive statistics summarized patterns of repeat screening. Logistic regression models assessed FIT uptake overtime, and demographic and PHM factors associated with screening adherence.

RESULTS

Participants (N = 330) were U.S.-born (93%), non-Hispanic (97%), and male (52%). Initial FIT uptake within 6 months of enrollment was 86.6%, and subsequently dropped to 54.5% at 12 months and 36.6% at 24 months. Higher FIT return rates were observed for the brochure group at 24 months (51.5% vs 33.3% photonovella, p = .023). Multiple patterns of FIT kit return were observed: 37% completed FIT at all three time points (full adherence), 22% completed two of three (partial adherence), 29% completed one of three (partial adherence), and 12% did not return any FIT kits (complete nonadherence). Predictors of full adherence were higher levels of education and self-efficacy.

CONCLUSIONS

Full adherence to repeat screening was suboptimal. Most participants had partial adherence (one or two of three) to annual FIT screening. Future studies should focus on strategies to support repeat FIT screening.

Making colonoscopy-based screening more efficient: A "gateopener" approach

Screening colonoscopy for early detection and prevention of colorectal cancer (CRC) is mostly used inefficiently. Here, we assessed the potential of an innovative approach to colonoscopy-based screening, by use of a single, low threshold fecal immunochemical test (FIT) as a "gateopener" for screening colonoscopy. Using COSIMO, a validated simulation model, we modeled scenarios including either direct invitation to screening colonoscopy or an alternative approach involving mailing a single ("gateopener") FIT along with an invitation to colonoscopy contingent on a FIT value above a low threshold yielding a 50% positivity rate (ie, every other pretest will be positive). Under plausible assumptions on screening offer adherence, we found that such "gateopener screening" (use of screening colonoscopy contingent on a positive, low threshold gateopener FIT) approximately doubled cancer detection rates vs conventional screening. In those spared from screening colonoscopy due to a negative gateopener FIT pretest, numbers needed to screen were 10-times higher vs those for individuals with a positive FIT, peaking in >2000 and >3800 (hypothetically) needed colonoscopies to detect one case of cancer in men and women, respectively. Gateopener screening resulted in 42%-51% and 59%-65% more prevented CRC cases and deaths, respectively. In summary, by directing colonoscopy capacities to those most likely to benefit, offering screening colonoscopy contingent on a "gateopener" low-threshold FIT would substantially enhance efficiency of colonoscopy screening.

Guidance for setting international standards on reporting longitudinal adherence to stool-based colorectal cancer screening

Longitudinal adherence to colorectal cancer (CRC) screening is reported using different summarizing measures, which hampers international comparison. We provide evidence to guide recommendations on which longitudinal adherence measure to report. Using adherence data over four stool-based CRC screening rounds in three countries, we calculated six summarizing adherence measures; adherence over all rounds, adherence per round, rescreening, full programme adherence (yes/no), regularity (never/inconsistent/consistent screenees) and number of times participated. For each measure, we calculated the accuracy in capturing the observed adherence patterns. Using the ASCCA model, we predicted screening effectiveness when using summarizing measures as model input versus the observed adherence patterns. Adherence over all rounds in the Italian, Spanish and Dutch cohorts was 64.9%, 42.8% and 61.5%, respectively, and the proportion of consistent screenees was 50.9%, 26.3% and 45.7%. Number of times participated and regularity were most accurate and resulted in similar model-predicted screening effectiveness as simulating the observed adherence patterns of Italy, Spain and the Netherlands (mortality reductions: 24.4%, 16.9% and 23.5%). Adherence over all rounds and adherence per round were least accurate. Screening effectiveness was overestimated when using adherence over all rounds (mortality reductions: 26.8%, 19.4% and 25.7%) and adherence per round (mortality reductions: 26.8%, 19.5% and 25.9%). To conclude, number of times participated and regularity were most accurate and resulted in similar model-predicted screening effectiveness as using the observed adherence patterns. However they require longitudinal data. To facilitate international comparison of CRC screening programme performance, consensus on an accurate adherence measure to report should be reached.

Impact of demographic changes and screening colonoscopy on long-term projection of incident colorectal cancer cases in Germany: A modelling study

Background

Demographic aging is expected to increase the number of colorectal cancer (CRC) cases in many countries. Screening for CRC can substantially reduce the disease burden but its use has remained rather limited in Germany. We aimed to quantify the expected impact of demographic aging on the future CRC burden and the potential to reduce that burden by increased use of screening colonoscopy offers in Germany.

Methods

We obtained sex- and age-specific data on colonoscopy use from AOK, the biggest health insurance provider in Germany, and combined these with the projected demographic development and current CRC incidence rates. We estimated the number of new CRC cases until 2060, assuming screening colonoscopy use to be constant or to increase to between 1·5 and 3 times the current levels.

Findings

Ten-year screening colonoscopy utilization rates were low (<20% in both sexes in all age groups). Assuming no change in screening colonoscopy use, the overall annual caseload was predicted to increase from approximately 62,000 cases in 2020 to more than 70,000 cases by the year 2040 and more than 75,000 cases by 2050. To avoid increasing case numbers, an increase of screening colonoscopy use to more than 3 times current levels would be needed.

Interpretation

At current levels of screening use, the strong effects of the demographic aging imply that the CRC caseload will significantly increase in the decades to come. CRC screening efforts will need to be substantially increased to even maintain the current level of incident cases.

Funding

German Federal Ministry of Education and Research (grant 01GL1712).

Model based evaluation of long-term efficacy of existing and alternative colorectal cancer screening offers: A case study for Germany

For individuals willing to minimize their lifetime risk of colorectal cancer (CRC), the most effective screening approach remains unclear. Here, we sought to compare the long-term performance of existing and alternative CRC screening offers in a case study for Germany. Applying the perspective of a perfectly adhering man or woman at average risk, we used COSIMO, a validated Markov-based multistate model, to simulate the effects of current CRC screening offers in Germany. These include age- and sex-dependent offers for fecal immunochemical testing (FIT) or screening colonoscopy, which may be used twice starting at age 50 in men and age 55 in women. For comparison, we modeled screening colonoscopies at ages 50, 60 and 70, screening colonoscopies at ages 50 and 60, followed by biennial FITs and conventional FIT-based strategies at varying intervals. We found that the highest reductions in lifetime risks of developing (76%-84%) and dying from CRC (82%-90%) were achieved by three colonoscopies, followed by annual FIT screening and strategies combining both modalities. In men, additional screening from age 70 onwards reduced the risk of dying from CRC by another 9% units and resulted in 32 to 39 additional life-years-gained per 1000 individuals. Among women, three colonoscopies outperformed current screening offers in all outcomes, at little risk of screening-related complications. In summary, several FIT- and colonoscopy-based offers yield comparably high CRC risk reductions, including approaches combining both modalities. German screening offers may be optimized by lowering the eligibility age for screening colonoscopy for women, along with additional offers for the elderly.