The cumulative risk of false-positive fecal occult blood test after 10 years of colorectal cancer screening

Eliciting preferences for cancer screening tests: Comparison of a discrete choice experiment and the threshold technique

OBJECTIVE

To compare results of three preference elicitation methods for a cancer screening test.

METHODS

Participants (undergraduate students) completed a discrete choice experiment (DCE) and a threshold technique (TT) task. Accuracy (false positives, false negatives), benefits (lives saved), and cost for a cancer screening test were used as attributes in the DCE and branching logic for the TT. Participants were also asked a direct elicitation question regarding a hypothetical screening test for breast (women) or prostate (men) cancer without mortality benefit. Correlations assessed the relationship between DCE and TT thresholds. Thresholds were standardized and ranked for both methods to compare. A logistic regression used the thresholds to predict results of the direct elicitation.

RESULTS

DCE and TT estimates were not meaningfully correlated (max ρ = 0.17). Participant rankings of attributes matched only 20% of the time (58/292). Neither method predicted preference for being screened (ps > 0.21).

CONCLUSIONS

The DCE and TT yielded different preference estimates (and rank orderings) for the same participant. Neither method predicted patients' desires for a screening test.

PRACTICE IMPLICATIONS

Clinicians, patients, policy makers, and researchers should be aware that patient preference results may be sensitive to the method of eliciting preferences.

AI and Clinical Decision Making: The Limitations and Risks of Computational Reductionism in Bowel Cancer Screening

Advances in artificial intelligence in healthcare are frequently promoted as ‘solutions’ to improve the accuracy, safety, and quality of clinical decisions, treatments, and care. Despite some diagnostic success, however, AI systems rely on forms of reductive reasoning and computational determinism that embed problematic assumptions about clinical decision-making and clinical practice. Clinician autonomy, experience, and judgement are reduced to inputs and outputs framed as binary or multi-class classification problems benchmarked against a clinician’s capacity to identify or predict disease states. This paper examines this reductive reasoning in AI systems for colorectal cancer (CRC) to highlight their limitations and risks: (1) in AI systems themselves due to inherent biases in (a) retrospective training datasets and (b) embedded assumptions in underlying AI architectures and algorithms; (2) in the problematic and limited evaluations being conducted on AI systems prior to system integration in clinical practice; and (3) in marginalising socio-technical factors in the context-dependent interactions between clinicians, their patients, and the broader health system. The paper argues that to optimise benefits from AI systems and to avoid negative unintended consequences for clinical decision-making and patient care, there is a need for more nuanced and balanced approaches to AI system deployment and evaluation in CRC.

Colorectal Cancer Screening: An Updated Modeling Study for the US Preventive Services Task Force

Importance

The US Preventive Services Task Force (USPSTF) is updating its 2016 colorectal cancer screening recommendations.

Objective

To provide updated model-based estimates of the benefits, burden, and harms of colorectal cancer screening strategies and to identify strategies that may provide an efficient balance of life-years gained (LYG) from screening and colonoscopy burden to inform the USPSTF.

Design, Setting, and Participants

Comparative modeling study using 3 microsimulation models of colorectal cancer screening in a hypothetical cohort of 40-year-old US individuals at average risk of colorectal cancer.

Exposures

Screening from ages 45, 50, or 55 years to ages 70, 75, 80, or 85 years with fecal immunochemical testing (FIT), multitarget stool DNA testing, flexible sigmoidoscopy alone or with FIT, computed tomography colonography, or colonoscopy. All persons with an abnormal noncolonoscopy screening test result were assumed to undergo follow-up colonoscopy. Screening intervals varied by test. Full adherence with all procedures was assumed.

Main Outcome and Measures

Estimated LYG relative to no screening (benefit), lifetime number of colonoscopies (burden), number of complications from screening (harms), and balance of incremental burden and benefit (efficiency ratios). Efficient strategies were those estimated to require fewer additional colonoscopies per additional LYG relative to other strategies.

Results

Estimated LYG from screening strategies ranged from 171 to 381 per 1000 40-year-olds. Lifetime colonoscopy burden ranged from 624 to 6817 per 1000 individuals, and screening complications ranged from 5 to 22 per 1000 individuals. Among the 49 strategies that were efficient options with all 3 models, 41 specified screening beginning at age 45. No single age to end screening was predominant among the efficient strategies, although the additional LYG from continuing screening after age 75 were generally small. With the exception of a 5-year interval for computed tomography colonography, no screening interval predominated among the efficient strategies for each modality. Among the strategies highlighted in the 2016 USPSTF recommendation, lowering the age to begin screening from 50 to 45 years was estimated to result in 22 to 27 additional LYG, 161 to 784 additional colonoscopies, and 0.1 to 2 additional complications per 1000 persons (ranges are across screening strategies, based on mean estimates across models). Assuming full adherence, screening outcomes and efficient strategies were similar by sex and race and across 3 scenarios for population risk of colorectal cancer.

Conclusions and Relevance

This microsimulation modeling analysis suggests that screening for colorectal cancer with stool tests, endoscopic tests, or computed tomography colonography starting at age 45 years provides an efficient balance of colonoscopy burden and life-years gained.

Colorectal cancer screening programme: is the French faecal immunological test (FIT) threshold optimal?

BACKGROUND

In France, the colorectal cancer organised screening programme uses the faecal immunological test. A positive test ⩾30 μg Hb/g of stool leads to a colonoscopy for identification of potential colorectal lesions. Cut-off values vary from 20 to 47 μg Hb/g of stool in Western countries. We herein question this threshold's relevance in a French population and perform a retrospective observational study using the Parisian database between 1 April 2015 and 31 December 2018.

METHODS

Rates of participation, numbers of positive faecal immunological test (FIT), detection rates and positive predictive values for advanced adenomas and/or colorectal cancer were determined. Mean positivity values for colorectal lesions were calculated.

RESULTS

In our population, there were 4.1% positive tests and 67.6% colonoscopy results available with final reports. Positive predictive value for advanced adenomas and colorectal cancer were 30% [95% confidence interval (CI) 29.8-30.3] and 7.4% (95% CI 7.35-7.52), respectively. The mean positivity value for all positive tests in our population was 101.7 µg Hb/g of stool (95% CI 85-118.3). There were 1136 normal colonoscopies (21.4%) with a mean positivity value of 88.6 μg Hb/g of stool. Following a negative test in a first screening campaign, 40.8% of patients in our population performed a second test with a positivity rate of 1.3% and with the encounter of 81 colorectal cancers. The risk of having a positive test during the second screening campaign and finding advanced colorectal lesions significantly increased (all p < 0.001) when comparing negative FIT results ranging between 15 and 29 μg Hb/g of stool to 0 and 14 μg Hb/g of stool from the previous campaign.

CONCLUSION

Using the current positivity threshold, some patients were considered negative with a delay in colorectal cancer diagnosis, suggesting the threshold could be lowered. Also, the mean positivity value for normal colonoscopies was high, raising the question of upper gastrointestinal bleeding.

Surrogate markers of mucosal healing in inflammatory bowel disease: A systematic review

BACKGROUND

Mucosal healing (MH) has emerged as a key therapeutic target in inflammatory bowel disease (IBD), and achievement of this goal is documented by endoscopy with biopsy. However, colonoscopy is burdensome and invasive, and substitution with an accurate noninvasive biomarker is desirable.

AIM

To summarize published data regarding the performance of noninvasive biomarkers in assessing MH in IBD patients.

METHODS

We conducted a systematic review of studies that reported the performance of biomarkers in diagnosing MH in patients with IBD. The main outcome measure was to review the diagnostic accuracy of serum and fecal markers that showed promising utility in assessing MH.

RESULTS

We screened 1301 articles, retrieved 46 manuscripts and included 23 articles for full-text analysis. The majority of the included manuscripts referred to fecal markers (12/23), followed by circulatory markers (8/23); only 3/23 of the included manuscripts investigated combined markers (serum and/or fecal markers). Fecal calprotectin (FC) was the most investigated fecal marker for assessing MH. In ulcerative colitis, for cutoff levels ranging between 58 mcg/g and 490 mcg/g, the sensitivity was 89.7%-100% and the specificity was 62%-93.3%. For Crohn’s disease, the cutoff levels of FC ranged from 71 mcg/g to 918 mcg/g (sensitivity 50%-95.9% and specificity 52.3%-100%). The best performance for a serum marker was observed for the endoscopic healing index, which showed a comparable accuracy to the measurement of FC and a higher accuracy than the measurement of serum C-reactive protein.

CONCLUSION

Several promising biomarkers of MH are emerging but cannot yet substitute for endoscopy with biopsy due to issues with reproducibility and standardization.

Cancer Screening in Older Adults: Individualized Decision-Making and Communication Strategies

Cancer screening decisions in older adults can be complex due to the unclear cancer-specific mortality benefits of screening and several known harms including false positives, overdiagnosis, and procedural complications from downstream diagnostic interventions. In this review, we provide a framework for individualized cancer screening decisions among older adults, involving accounting for overall health and life expectancy, individual values, and the risks and benefits of specific cancer screening tests. We then discuss strategies for effective communication of recommendations during clinical visits that are considered more effective, easy to understand, and acceptable by older adults and clinicians.

Development of Surface-Enhanced Raman Scattering (SERS)-Based Surface-Corrugated Nanopillars for Biomolecular Detection of Colorectal Cancer

In this paper, a nanobiosensor with surface-enhanced Raman scattering (SERS) capability is introduced for highly sensitive miRNA detection in colorectal cancer. This sensor was designed and fabricated by employing a nanoshielding mechanism from nanopolystyrene beads to resist reactive ion etching and allow anisotropic electrochemical etching, producing high-aspect-ratio, surface-corrugated nanopillars (SiNPs) on a silicon wafer to create extensive hot spots along the nanopillars for improved SERS signals. SERS enhancements were correlated with nanorange roughness, indicating that hot spots along the pillars were the crucial factor to improve the SERS effect. We achieved the detection capability of a trace amount of R6G (10-8 M), and the SERS signal enhancement factor (EF) was close to 1.0 × 107 on surface-corrugated gold SiNPs. miRNA samples were also demonstrated on this sensor with good sensitivity and specificity. The target molecule miR-21-Cy5 was easily monitored through Raman spectrum variation with a PCR-comparable concentration at around 100 pM with clear nucleotide-specific Raman signals, which is also suitable for biomolecule sensing.

Effectiveness of Interventions to Increase Colorectal Cancer Screening Among American Indians and Alaska Natives

INTRODUCTION

Screening rates for colorectal cancer are low in many American Indian and Alaska Native (AI/AN) communities. Direct mailing of a fecal immunochemical test (FIT) kit can address patient and structural barriers to screening. Our objective was to determine if such an evidence-based intervention could increase colorectal cancer screening among AI/AN populations.

METHODS

We recruited study participants from 3 tribally operated health care facilities and randomly assigned them to 1 of 3 study groups: 1) usual care, 2) mailing of FIT kits, and 3) mailing of FIT kits plus follow-up outreach by telephone and/or home visit from an American Indian Community Health Representative (CHR).

RESULTS

Among participants who received usual care, 6.4% returned completed FIT kits. Among participants who were mailed FIT kits without outreach, 16.9% returned the kits - a significant increase over usual care (P < .01). Among participants who received mailed FIT kits plus CHR outreach, 18.8% returned kits, which was also a significant increase over usual care (P < .01) but not a significant increase compared with the mailed FIT kit-only group (P = .44). Of 165 participants who returned FIT kits during the study, 39 (23.6%) had a positive result and were referred for colonoscopy of which 23 (59.0%) completed the colonoscopy. Twelve participants who completed a colonoscopy had polyps, and 1 was diagnosed with colorectal cancer.

CONCLUSION

Direct mailing of FIT kits to eligible community members may be a useful, population-based strategy to increase colorectal cancer screening among AI/AN people.

Stool-Based Tests for Colorectal Cancer Screening: Performance Benchmarks Lead to High Expected Efficacy

PURPOSE OF REVIEW

Participation goals for colorectal cancer (CRC) screening in the USA have not been met. Non-invasive screening strategies may improve CRC screening participation. We highlight recent literature on stool-based screening performance and expectations for emerging non-invasive screening tests.

RECENT FINDINGS

Stool-based CRC screening detects screen-relevant colorectal neoplasia and outperforms a currently available plasma assay. Though modestly sensitive for CRC, adherence to annual fecal immunochemical testing (FIT) is sub-optimal. Multi-target stool DNA (MT-sDNA) has greater adherence, superior sensitivity for screen-relevant lesions (including those in the proximal colon and sessile serrated architecture), and equivalent specificity to FIT over a 3-year period. Stool-based CRC screening tests are anticipated to reduce the incidence and mortality of CRC through detection of early-stage cancers and high-risk polyps. These endpoints in performance will need to be met by emerging blood sample-based tests in order have meaningful impact in clinical practice.

The cumulative false-positive rate in colorectal cancer screening: a Markov analysis

BACKGROUND

Faecal occult blood testing is widely used in colorectal cancer screening. However, there is little empirical long-term evidence on the accumulation of false-positive test results over several screening rounds. We aimed to systematically explore and quantify the cumulative false-positive rate for various scenarios of colorectal cancer screening.

METHODS

Using a Markov analysis, we estimated the lifetime cumulative number of false-positive test results (cumFP) per 100 000 50-year-old persons. We varied the screening interval and the specificity of a single screening test and the starting age of screening.

RESULTS

For a test with a specificity of 98% used from 50 to 74 years, the cumFP at age 74 was 26 260 (1-year interval), 15 102 (2-year interval), and 10 819 (3-year interval), respectively. For a test with a specificity of, respectively, 95 and 92% used at a 2-year interval, the cumFP at age 74 was 2.2 times and 3.0 times higher as compared to a test with a specificity of 98%. The cumFP at age 74 was 18% lower for screening persons aged 54-74 years vs. 50-74 years.

CONCLUSION

Our findings quantitatively illustrate the large variation of the cumFP in colorectal cancer screening between screening strategies, which is relevant to informed decision making and adequate resource planning.

Factors Associated With Colonoscopy Compliance Based on Health Belief Model in a Community-Based Colorectal Cancer Screening Program Shanghai, China

Screening can help early detection of colorectal cancer (CRC) in the general population. However, colonoscopy compliance in screening program is low in China. The study aimed to identify factors associated with colonoscopy compliance based on Health Belief Model (HBM). An investigation was conducted in Huangpu District, Shanghai in 2015. High-risk individuals of CRC received an in-person interview with physicians to fill out a questionnaire. The questionnaires assessing predictors of colonoscopy compliance were collected, and status of colonoscopy participation was determined. Univariate and multiple logistic regression analyses were conducted. Among 2,568 high-risk population (20.68%), 531 subjects underwent colonoscopy. Participants with both risk assessment and fecal immunochemical test positive were most likely to undergo colonoscopy. Based on HBM, colonoscopy compliance was positively associated with higher perceived severity (odds ratio [OR] = 1.05, 95% confidence interval [CI] = [1.00, 1.10]). Higher perceived barriers (OR = 0.97, 95% CI = [0.94, 0.99]), without prior colonoscopy (OR = 0.35, 95% CI = [0.26, 0.47]), not knowing anyone who underwent colonoscopy before (OR = 0.74, 95% CI = [0.58, 0.96]), without health-care provider recommendation on colonoscopy (OR = 0.58, 95% CI = [0.44, 0.77]), and without psychosocial support from someone for colonoscopy (OR = 0.27, 95% CI = [0.21, 0.35]) were shown to be associated with colonoscopy noncompliance. The colonoscopy compliance was low in this CRC screening program in Shanghai, China. The influencing factors were positive results in primary screening, perceived severity, perceived barriers, personal or others' experiences in colonoscopy, health-care provider recommendation, and psychosocial supports. Effective education campaign and facilitated communication between health-care providers and high-risk population were suggested in the future interventions.

False-Positive Results in a Population-Based Colorectal Screening Program: Cumulative Risk from 2000 to 2017 with Biennial Screening

BACKGROUND

The aim of this study was to estimate the cumulative risk of a false-positive (FP) result in a fecal occult blood test (FOBT) through 7 screening rounds and to identify its associated factors in a population-based colorectal cancer screening program.

METHODS

Retrospective cohort study, which included participants ages 50 to 69 years of a colorectal cancer screening program in Catalonia, Spain. During this period, 2 FOBTs were used (guaiac and immunochemical). A discrete-time survival model was performed to identify risk factors of receiving a positive FOBT with no high-risk adenoma or colorectal cancer in the follow-up colonoscopy. We estimated the probability of having at least 1 FP over 7 screening rounds.

RESULTS

During the period of 2000 to 2017, the cumulative FP risk was 16.3% (IC_95%: 14.6%-18.3%), adjusted by age, sex, and type of test. The median number of screens was 2. Participants who began screening at age 50 years had a 7.3% [95% confidence interval (CI), 6.35-8.51] and a 12.4% (95% CI, 11.00-13.94) probability of an FP with 4 screening rounds of guaiac-based test and immunochemical test, respectively. Age, the fecal immunochemical test, first screening, and number of personal screens were factors associated with an FP result among screenees.

CONCLUSIONS

The cumulative risk of an FP in colorectal screening using FOBT seems acceptable as the colonoscopy, with its high accuracy, lengthens the time until additional colorectal screening is required, while complication rates remain low.

IMPACT

It is useful to determine the cumulative FP risk in cancer screening for both advising individuals and for health resources planning.

Implications of false-positive results for future cancer screenings

BACKGROUND

False-positive cancer screening results may affect a patient's willingness to obtain future screening.

METHODS

The authors conducted logistic regression analysis of 450,484 person-years of electronic medical records (2006-2015) in 92,405 individuals aged 50 to 75 years. Exposures were false-positive breast, prostate, or colorectal cancer screening test results (repeat breast imaging or negative breast biopsy ≤3 months after screening mammography, repeat prostate-specific antigen [PSA] test ≤3 months after PSA test result ≥4.0 ng/mL or negative prostate biopsy ≤3 months after any PSA result, or negative colonoscopy [without biopsy/polypectomy] ≤6 months after a positive fecal occult blood test). Outcomes were up-to-date status with breast or colorectal cancer screening. Covariates included prior screening history, clinical information (eg, family history, obesity, and smoking status), comorbidity, and demographics.

RESULTS

Women were more likely to be up to date with breast cancer screening if they previously had false-positive mammography findings (adjusted odds ratio [AOR], 1.43 [95% confidence interval, 1.34-1.51] without breast biopsy and AOR, 2.02 [95% confidence interval, 1.56-2.62] with breast biopsy; both P<.001). The same women were more likely to be up to date with colorectal cancer screening (AOR range, 1.25-1.47 depending on breast biopsy; both P<.001). Men who previously had false-positive PSA testing were more likely to be up to date with colorectal cancer screening (AOR, 1.22 [P = .039] without prostate imaging/biopsy and AOR, 1.60 [P = .028] with imaging/biopsy). Results were stronger for individuals with more false-positive results (all P≤.005). However, women with previous false-positive colorectal cancer fecal occult blood test screening results were found to be less likely to be up to date with breast cancer screening (AOR, 0.73; P<.001).

CONCLUSIONS

Patients who previously had a false-positive breast or prostate cancer screening test were more likely to engage in future screening. Cancer 2018;124:2390-8. © 2018 American Cancer Society.

Long-term Follow-up of Patients Having False-Positive Multitarget Stool DNA Tests after Negative Screening Colonoscopy: The LONG-HAUL Cohort Study

Background: Studies of colorectal cancer screening by multitarget stool DNA (MT-sDNA) show false-positive (FP) rates of 7% to 13%. It is unclear whether FP patients are at increased long-term risk of adverse outcomes.Methods: We compared subsequent clinical events among patients with apparent FP MT-sDNA with those in patients reported as true negative (TN). This was a retrospective cohort study of participants in pre-FDA approval MT-sDNA studies having nonadvanced or negative baseline colonoscopy findings from a single referral center. Per-protocol and calibrated cutoffs defined FP and TN groups. From the time of stool collection, we measured differences between FP and TN groups in time to death, subsequent cancer diagnosis, and onset of alarm symptoms.Results: Of 1,050 eligible patients, only 6 were lost to follow-up. Median age was 65.6 years [interquartile range (IQR), 56.8-72.3]; 54% were female. Median follow-up time was 4 years (IQR, 3.5-5.3). Eight aerodigestive (lung and gastrointestinal tract) cancers occurred. FP status by calibrated, but not per-protocol, cutoffs was associated with subsequent aerodigestive cancer; however, cumulative incidence did not exceed SEER expectations from the general population. By any cutoff method, FP status was not associated with mortality or alarm symptoms.Conclusions: Although FP status was associated with long-term aerodigestive cancers, new cases were not temporally related and did not exceed incidence estimates from general population.Impact: These observations do not justify aggressive follow-up evaluation for patients with FP MT-sDNA at this time. Larger studies are needed to confirm these early findings. Cancer Epidemiol Biomarkers Prev; 26(4); 614-21. ©2016 AACR.

[Current principles in the screening, diagnosis, and therapy of colorectal cancer]

The data available in the literature on the prevalence of colorectal cancer (CRC), its risk factors and genetic aspects are analyzed. Basic screening tests and their diagnostic value are described. The paper indicates the importance of methods (colonoscopy, occult blood feces analysis, fecal immunochemical test, determination of molecular genetic profile of fecal enterocytes) for the early primary diagnosis of colonic epithelial tumors and techniques (echography, computed tomography, magnetic resonance imaging, positron emission tomography) that are required to specify clinical TNM staging and enable one to choose an optimal treatment policy for CRC patients owing to the estimation of tumor volume and to the diagnosis of reginal and distant metastases. It also shows that new screening methods based on the detection of molecular markers for early (premorphological) tumor stages are promising. The role of primary CRC prevention aimed at molding and maintaining a healthy lifestyle in the population is demonstrated.

Cancer Models and Real-world Data: Better Together

Decision-analytic models are increasingly used to inform health policy decisions. These models synthesize available data on disease burden and intervention effectiveness to project estimates of the long-term consequences of care, which are often absent when clinical or policy decisions must be made. While models have been influential in informing US cancer screening guidelines under ideal conditions, incorporating detailed data on real-world screening practice has been limited given the complexity of screening processes and behaviors throughout diverse health delivery systems in the United States. We describe the synergies that exist between decision-analytic models and health care utilization data that are increasingly accessible through research networks that assemble data from the growing number of electronic medical record systems. In particular, we present opportunities to enrich cancer screening models by grounding analyses in real-world data with the goals of projecting the harms and benefits of current screening practices, evaluating the value of existing and new technologies, and identifying the weakest links in the cancer screening process where efforts for improvement may be most productively focused. We highlight the example of the National Cancer Institute-funded consortium Population-based Research Optimizing Screening through Personalized Regimens (PROSPR), a collaboration to harmonize and analyze screening process and outcomes data on breast, colorectal, and cervical cancers across seven research centers. The pairing of models with such data can create more robust models to not only better inform policy but also inform health care systems about best approaches to improve the provision of cancer screening in the United States.

Social network effects of nonlifesaving early-stage breast cancer detection on mammography rates

OBJECTIVES

We estimated the effect of anecdotes of early-stage, screen-detected cancer for which screening was not lifesaving on the demand for mammography.

METHODS

We constructed an agent-based model of mammography decisions, in which 10 000 agents that represent women aged 40 to 100 years were linked together on a social network, which was parameterized with a survey of 716 women conducted through the RAND American Life Panel. Our model represents a population in equilibrium, with demographics reflecting the current US population based on the most recent available census data.

RESULTS

The aggregate effect of women learning about 1 category of cancers-those that would be detected but would not be lethal in the absence of screening-was a 13.8 percentage point increase in annual screening rates.

CONCLUSIONS

Anecdotes of detection of early-stage cancers relayed through social networks may substantially increase demand for a screening test even when the detection through screening was nonlifesaving.

High expression of ROR2 in cancer cell correlates with unfavorable prognosis in colorectal cancer

The receptor tyrosine kinase-like orphan receptor 2 (ROR2) is a transmembrane protein that belongs to a conserved family of tyrosine kinase receptors involved in several functional processes. ROR2 is overexpressed in various types of solid tumors; however, the expression of ROR2, as well as its functional and prognostic significance has yet to be evaluated in colorectal cancer (CRC). In this study, one-step quantitative reverse transcription-polymerase chain reaction and immunohistochemical analysis using tissue microarrays were used to evaluate ROR2 expression in CRC and to investigate the association between ROR2 expression and patient prognosis. We observed that the expression of ROR2 mRNA and protein was significantly higher in CRC specimens compared with normal, tumor-adjacent tissues (both p<0.05). Cytoplasmic ROR2 expression was related to TNM stage (p=0.041) and lymph node metastasis (N) (p=0.015). Kaplan-Meier and multivariate analyses suggested that high cytoplasmic ROR2 expression (p=0.001), poor tumor differentiation (p=0.001), and advanced TNM stage (p=0.001) and high preoperative CEA level (p<0.001) were significantly associated with unfavorable survival of CRC patients. These results suggest that ROR2 expression is correlated with malignant attributes of CRC and may serve as an indicator for poor prognosis in patients with CRC.

Ethical issues in colorectal cancer screening

In many countries, colorectal cancer screening is currently an established population screening program due to the evidence on its reduction of colorectal cancer mortality. There is general consensus that colorectal cancer screening meets the screening criteria as proposed by Wilson and Jungner. However, as for all population screening programs, colorectal cancer screening also has disadvantages and thereby entails ethical issues. There are the general issues concerning the introduction of screening programs (e.g. medicalization, overdiagnosis and overtreatment, information provision to screenees), evaluation of cancer screening programs (e.g. lead time and length bias), chosen screening method (e.g. false-positive and false-negative test results, reduction of all-cause mortality, choice between different screening methods). The different colorectal cancer screening methods and the ethical issues concerning colorectal cancer screening will be discussed in this review.