Use of epidemiological analyses in development of colorectal cancer clinical practice guidelines in the Czech Republic

Statistical methods for measuring trends in colorectal cancer incidence in registries: A systematic review

Background

Monitoring cancer trends in a population is essential for tracking the disease’s burden, allocating resources, and informing public health policies. This review describes variations in commonly employed methods to estimate colorectal cancer (CRC) incidence trends.

Methods

We performed a systematic literature search in four databases to identify population-based studies reporting CRC incidence trends, published between January 2010 and May 2020. We extracted and described data on methods to estimate trends and assess model validity, and the software used.

Results

This review included 145 articles based on studies conducted in five continents. The majority (93%) presented visual summaries of trends combined with absolute, relative, or annual change estimates. Fourteen (10%) articles exclusively calculated the relative change in incidence over a given time interval, presented as the percentage of change in rates. Joinpoint regression analysis was the most commonly used method for assessing incidence trends (n= 65, 45%), providing estimates of the annual percentage change (APC) in rates. Nineteen (13%) studies performed Poisson regression and 18 (12%) linear regression analysis. Age-period-cohort modeling- a type of generalized linear models- was conducted in 18 (12%) studies. Thirty-nine (37%) of the studies modeling incidence trends (n=104, 72%) indicated the method used to evaluate model fitness. The joinpoint program (52%) was the statistical software most commonly used.

Conclusion

This review identified variation in the calculation of CRC incidence trends and inadequate reporting of model fit statistics. Our findings highlight the need for increasing clarity and transparency in reporting methods to facilitate interpretation, reproduction, and comparison with findings from previous studies.

A systematic review of methods to estimate colorectal cancer incidence using population-based cancer registries

Background

Epidemiological studies of incidence play an essential role in quantifying disease burden, resource planning, and informing public health policies. A variety of measures for estimating cancer incidence have been used. Appropriate reporting of incidence calculations is essential to enable clear interpretation. This review uses colorectal cancer (CRC) as an exemplar to summarize and describe variation in commonly employed incidence measures and evaluate the quality of reporting incidence methods.

Methods

We searched four databases for CRC incidence studies published between January 2010 and May 2020. Two independent reviewers screened all titles and abstracts. Eligible studies were population-based cancer registry studies evaluating CRC incidence. We extracted data on study characteristics and author-defined criteria for assessing the quality of reporting incidence. We used descriptive statistics to summarize the information.

Results

This review retrieved 165 relevant articles. The age-standardized incidence rate (ASR) (80%) was the most commonly reported incidence measure, and the 2000 U.S. standard population the most commonly used reference population (39%). Slightly more than half (54%) of the studies reported CRC incidence stratified by anatomical site. The quality of reporting incidence methods was suboptimal. Of all included studies: 45 (27%) failed to report the classification system used to define CRC; 63 (38%) did not report CRC codes; and only 20 (12%) documented excluding certain CRC cases from the numerator. Concerning the denominator estimation: 61% of studies failed to state the source of population data; 24 (15%) indicated census years; 10 (6%) reported the method used to estimate yearly population counts; and only 5 (3%) explicitly explained the population size estimation procedure to calculate the overall average incidence rate. Thirty-three (20%) studies reported the confidence interval for incidence, and only 7 (4%) documented methods for dealing with missing data.

Conclusion

This review identified variations in incidence calculation and inadequate reporting of methods. We outlined recommendations to optimize incidence estimation and reporting practices. There is a need to establish clear guidelines for incidence reporting to facilitate assessment of the validity and interpretation of reported incidence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01632-7.

Which bacterial toxins are worthy of validation as markers in colorectal cancer screening? A critical review

Appropriate screening of early asymptomatic cases can reduce the disease burden and mortality rate of sporadic colorectal cancer (CRC) significantly. Currently, fecal occult blood testing (FOBT) is able to detect up to 80% of asymptomatic cases in the population aged 50+. Therefore, there is still a demand for new screening tests that would complement FOBT, mainly by detecting at least a part of the FOBT-negative CRC and adenoma cases, or possibly by identifying person at increased risk of sporadic CRC in order to offer them tailored follow-up. Among the potential markers studied, our knowledge has advanced at most in toxigenic gram-negative bacteria. In this review, we assess their potential critically and recommend those best suited for prospective evaluation of their true ability to increase the sensitivity of FOBT when combined during general population screening. In our opinion, colibactin and Bacteroides fragilis toxin are the best candidates, possibly complemented by the cytotoxic necrotizing factor (CNF).

The experience with colorectal cancer screening in the Czech Republic: the detection at earlier stages and improved clinical outcomes

OBJECTIVES

Colorectal cancer (CRC) remains a major health burden. Although screening is recommended and considered beneficial, further data on its positive effects are needed for worldwide implementation.

STUDY DESIGN

The aim of our national multicentre prospective observational study was to reveal and document clinicopathological differences in CRC diagnosed by screening and presented by disease symptoms as well as assess the efficiency of the screening programme in the Czech Republic.

METHODS

Between March 2013 and September 2015, a total of 265 patients were enrolled in 12 gastroenterology centres across the Czech Republic. Patients were divided into screening and symptomatic groups and compared for pathology status and clinical characteristics. Screening was defined as a primary screening colonoscopy or a colonoscopy after a positive faecal occult blood test in an average-risk population.

RESULTS

The distribution of CRC stages was significantly (statistically and clinically) favourable in the screening group (predominance of stages 0, I and II) compared with the non-screening group (P < 0.001). The presence of distant and local metastases was significantly less frequent in the screening group than in the symptomatic group (P < 0.001). Patients in the screening group had a higher probability of radical surgery (R0) than those diagnosed based on symptoms (P < 0.001). Systemic palliative treatment was indicated in two patients in the screening group compared with 23 patients in the non-screening group (P = 0.018).

CONCLUSION

CRC diagnosed by screening disclosed less advanced clinicopathological characteristics and results in patients with a higher probability of radical surgery (R0) than diagnoses established based on symptoms, with subsequent management differing accordingly between both groups. These results advocate the implementation of a suitable worldwide screening programme.