Evaluation of a risk index for advanced proximal neoplasia of the colon

New scoring systems for predicting advanced proximal neoplasia in asymptomatic adults with or without knowing distal colorectal findings: a prospective, cross-sectional study

BACKGROUND

Models estimating risk for advanced proximal colorectal neoplasia (APN) may be used to select colorectal cancer (CRC) screening test, either prior to knowing distal colorectal findings or afterward. Current models have only fair discrimination and nearly all require knowing distal findings.

OBJECTIVE

Derive and test risk prediction models for APN with and without distal findings.

SETTING

Selected endoscopy centers within central Indiana, USA.

PARTICIPANTS

Average-risk persons undergoing first-time screening colonoscopy.

INTERVENTIONS

Demographics, personal and family medical history, lifestyle factors and physical measures were linked to the most advanced finding in proximal and distal colorectal segments. For both models, logistic regression identified factors independently associated with APN on a derivation set. Based on equation coefficients, points were assigned to each factor, and risk for APN was examined for each score. Scores with comparable risks were collapsed into risk categories. Both models and their scoring systems were tested on the validation set.

MAIN OUTCOME

APN, defined as any adenoma or sessile serrated lesion ≥1 cm, one with villous histology or high-grade dysplasia, or CRC proximal to the descending colon.

RESULTS

Among 3025 subjects in the derivation set (mean age 57.3 ± 6.5 years; 52% women), APN prevalence was 4.5%; 2859 (94.5%) had complete data on risk factors. Independently associated with APN were age, sex, cigarette smoking, cohabitation status, metabolic syndrome, non-steroidal anti-inflammatory drug use and physical activity. This model (without distal findings) was well-calibrated (P = 0.62) and had good discrimination (c-statistic = 0.73). In low-, intermediate- and high-risk groups that comprised 21, 58 and 21% of the sample, respectively, APN risks were 1.47% (95% CI, 0.67-2.77%), 3.09% (CI, 2.31-4.04%) and 11.6% (CI, 9.10-14.4%), respectively (P < 0.0001), with no proximal CRCs in the low-risk group and 2 in the intermediate-risk group. When tested in the validation set of 1455, the model retained good metrics (calibration P = 0.85; c-statistic = 0.83), with APN risks in low- (22%), intermediate- (56%) and high-risk (22%) subgroups of 0.62% (CI, 0.08-2.23%) 2.20% (CI, 1.31-3.46%) and 13.0% (CI, 9.50-17.2%), respectively (P < 0.0001). There were no proximal CRCs in the low-risk group, and two in the intermediate-risk group. The model with distal findings performed comparably, with validation set metrics of 0.18 for calibration, 0.76 for discrimination and APN risk (% sample) in low-, intermediate-, and high-risk groups of 1.1 (69%), 8.3 (22%) and 22.3% (9%).

CONCLUSION

These models stratify large proportions of average-risk persons into clinically meaningful risk groups, and could improve screening efficiency, particularly for noncolonoscopy-based programs.

Development and Validation of the Asia-Pacific Proximal Colon Neoplasia Risk Score

BACKGROUND & AIMS

Patients found to be at high risk of advanced proximal neoplasia (APN) after flexible sigmoidoscopy screening should be considered for colonoscopy examination. We developed and validated a scoring system to identify persons at risk for APN.

METHODS

We collected data from 7954 asymptomatic subjects (age, 50-75 y) who received screening colonoscopy examinations at 14 sites in Asia. We randomly assigned 5303 subjects to the derivation cohort and the remaining 2651 to the validation cohort. We collected data from the derivation cohort on age, sex, family history of colorectal cancer, smoking, drinking, body mass index, medical conditions, and use of nonsteroidal anti-inflammatory drugs or aspirin. Associations between the colonoscopic findings of APN and each risk factor were examined using the Pearson χ² test, and we assigned each participant a risk score (0-15), with scores of 0 to 3 as average risk and scores of 4 or higher as high risk. The scoring system was tested in the validation cohort. We used the Cochran-Armitage test of trend to compare the prevalence of APN among subjects in each group.

RESULTS

In the validation cohort, 79.5% of patients were classified as average risk and 20.5% were classified as high risk. The prevalence of APN in the average-risk group was 1.9% and in the high-risk group was 9.4% (adjusted relative risk, 5.08; 95% CI, 3.38-7.62; P < .001). The score included age (61-70 y, 3; ≥70 y, 4), smoking habits (current/past, 2), family history of colorectal cancer (present in a first-degree relative, 2), and the presence of neoplasia in the distal colorectum (nonadvanced adenoma 5-9 mm, 2; advanced neoplasia, 7). The c-statistic of the score was 0.74 (95% CI, 0.68-0.79), and for distal findings alone was 0.67 (95% CI, 0.60-0.74). The Hosmer-Lemeshow goodness-of-fit test statistic was greater than 0.05, indicating the reliability of the validation set. The number needed to refer was 11 (95% CI, 10-13), and the number needed to screen was 15 (95% CI, 12-17).

CONCLUSIONS

We developed and validated a scoring system to identify persons at risk for APN. Screening participants who undergo flexible sigmoidoscopy screening with a score of 4 points or higher should undergo colonoscopy evaluation.

Capability of four sigmoidoscopy-based screening strategies to predict proximal neoplasia in an asymptomatic Chinese population

BACKGROUND AND AIM

A proper colonoscopy referral criterion is essential for flexible sigmoidoscopy-based colorectal cancer screening. We aimed to compare the predictive capability of four existing criteria to detect proximal neoplasia (PN) and advanced proximal neoplasia (APN) in a Chinese population.

METHODS

Asymptomatic Chinese participants aged 50-75 years, who received screening colonoscopy, were consecutively recruited. The four criteria included (i) UK flexible sigmoidoscopy; (ii) Italian Screening for COlon REctum; (iii) NORwegian Colorectal Cancer Prevention trial; and (iv) US clinical index. The sensitivity, specificity, positive/negative predictive value, and the number of subjects needed to screen (NNS)/refer (NNR) to detect one APN/PN were examined. The area under receiver operating characteristic curve was evaluated.

RESULTS

Among 5833 subjects, 749 (12.8%) and 151 (2.6%) cases were found to have PN and APN, respectively. US criteria achieved the highest sensitivity for PN (49%) and APN (66%), while UK criteria attained the highest specificity (93%) for PN/APN. The lowest NNS was required by US criteria for PN (16 vs 19-38) and APN (58 vs 69-86), while the lowest NNR was required by UK criteria for PN (3.2 vs 4.0-4.8) and APN (7 vs 10-16). The receiver operating characteristic of all four criteria was 0.57-0.61 for PN and 0.68-0.70 for APN.

CONCLUSIONS

Among all the four criteria, US criteria had the highest sensitivity and lowest NNS, while UK criteria achieved the highest specificity and lowest NNR. Their limited discriminatory capability highlighted the need for a new score to predict PN/APN in Chinese populations.

Quality Metrics of a Fecal Immunochemical Test-Based Colorectal Cancer Screening Program in Korea

Background/Aims

Knowledge regarding the quality metrics of fecal immunochemical test (FIT)-based colorectal cancer screening programs is limited. The aim of this study was to investigate the performance and quality metrics of a FIT-based screening program.

Methods

In our screening program, asymptomatic subjects aged ≥50 years underwent an annual FIT, and subjects with positive FIT results underwent a subsequent colonoscopy. The performance of the FIT and colonoscopy was analyzed in individuals with a positive FIT who completed the program between 2009 and 2015 at a university hospital.

Results

Among the 51,439 screened participants, 75.1% completed the FIT. The positive rate was 1.1%, and the colonoscopy completion rate in these patients was 68.6%. The positive predictive values of cancer and advanced neoplasia were 5.5% and 19.1%, respectively. The adenoma detection rate in the patients who underwent colonoscopy after a positive FIT was 48.2% (60.0% for men and 33.6% for women). The group with the highest tertile quantitative FIT level showed a significantly higher detection rate of advanced neoplasia than the group with the lowest tertile (odds ratio, 2.6; 95% confidence interval, 1.4 to 5.1; p<0.001).

Conclusions

The quality metrics used in the United States and Europe may be directly introduced to other countries, including Korea. However, the optimal quality metrics should be established in each country.

Colorectal Cancer Screening: The Role of Psychological, Social and Background Factors in Decision-making Process

Since ColoRectal Cancer (CRC) remains the third cause of cancer death in the world, a better understanding of the reasons underlying poor adherence to and delay in undergoing CRC screening programs is important. CRC screening decision-making process can be conceptualized as the relationship between intention and behavior and needs to be investigated including the impact on patients' decision of a broad range of psychological factors and personal predisposition as fear of a positive screening test, poor understanding of the procedure, psychological distress, anxiety, anticipation of pain, feelings of embarrassment and vulnerability. Also socioeconomic, ethnic and sociological influences, and organizational barriers have been identified as factors influencing CRC screening adherence. Decision-making process can finally be influenced by the healthcare background in which the intervention is promoted and screening programs are carried out. However, there is still a gap on the scientific knowledge about the influences of diverse elements on screening adherence and this deserves further investigations in order to carry out more focused and effective prevention programs.

The Association between Distal Findings and Proximal Colorectal Neoplasia: A Systematic Review and Meta-Analysis

OBJECTIVES

Whether screening participants with distal hyperplastic polyps (HPs) detected by flexible sigmoidoscopy (FS) should be followed by subsequent colonoscopy is controversial. We evaluated the association between distal HPs and proximal neoplasia (PN)/advanced proximal neoplasia (APN) in asymptomatic, average-risk patients.

METHODS

We searched Ovid Medline, EMBASE, and the Cochrane Library from inception to 30 June 2016 and included all screening studies that examined the relationship between different distal findings and PN/APN. Data were independently extracted by two reviewers with disagreements resolved by a third reviewer. We pooled absolute risks and odds ratios (ORs) with a random effects meta-analysis. Seven subgroup analyses were performed according to study characteristics. Heterogeneity was characterized with the I² statistics.

RESULTS

We analyzed 28 studies (104,961 subjects). When compared with normal distal findings, distal HP was not associated with PN (OR=1.16, 95% confidence interval (CI)=0.89-1.51, P=0.14, I²=40%) or APN (OR=1.09, 95% CI=0.87-1.36, P=0.39, I²=5%), while subjects with distal non-advanced or advanced adenoma had higher odds of PN/APN. Higher odds of PN/APN were observed for more severe distal lesions. Weaker association between distal and proximal findings was noticed in studies with higher quality, larger sample size, population-based design, and more stringent endoscopy quality-control measures. The Egger's regression tests showed all P>0.05.

CONCLUSIONS

Distal HP is not associated with PN/APN in asymptomatic screening population when compared with normal distal findings. Hence, the presence of distal HP alone detected by FS does not automatically indicate colonoscopy referral for all screening participants, as other risk factors of PN/APN should be considered.

Power of screening tests for colorectal cancer enhanced by high levels of M2-PK in addition to FOBT

Colorectal cancer (CRC) is a multistep process that involves adenoma-carcinoma sequence. CRC can be prevented by routine screening, which can detect precancerous lesions. The aim of this study is to clarify whether faecal occult blood test (i-FOBT), tumor M2 pyruvate kinase (t-M2-PK), and endocannabinoid system molecules (cannabinoid receptors type 1-CB1, type 2-CB2, and fatty acid amide hydrolase-FAAH) might represent better diagnostic tools, alone or in combination, for an early diagnosis of CRC. An immunochemical FOB test (i-FOBT) and quantitative ELISA stool test for t-M2-PK were performed in 127 consecutive patients during a 12 month period. Endocannabinoid system molecules and t-M2-PK expression were detected by immunostaining in healthy tissues and normal mucosa surrounding adenomatous and cancerous colon lesions. i-FOBT and t-M2-PK combination leads to a better diagnostic accuracy for pre-neoplastic and neoplastic colon lesions. T-M2-PK quantification in stool samples and in biopsy samples (immunostaining) correlates with tumourigenesis stages. CB1 and CB2 are well expressed in healthy tissues, and their expression decreases in the presence of advanced stages of carcinogenesis and disappears in CRC. FAAH signal is well expressed in normal mucosa and low-risk adenoma, and increased in high-risk adenoma and carcinoma adjacent tissues. This study shows that high levels of t-M2-PK in addition to FOBT enhance the power of a CRC screening test. Endocannabinoid system molecule expression correlates with colon carcinogenesis stages. Developing future faecal tests for their quantification must be undertaken to obtain a more accurate early non-invasive diagnosis for CRC.

How to improve colon cancer screening rates

Colorectal carcinoma is a common cause of death throughout the world and may be prevented by routine control, which can detect precancerous neoplasms and early cancers before they undergo malignant transformation or metastasis. Three strategies may improve colon cancer screening rates: convince the population about the importance of undergoing a screening test; achieve higher efficacy in standard screening tests and make them more available to the community and develop new more sensitive and efficacious screening methods and make them available as routine tests. In this light, the present study seeks to review these three means through which to increase colon cancer screening rates.

Evaluation of a clinical risk index for advanced colorectal neoplasia among a North American population of screening age

Background

A clinical risk index employing age, sex, family history of colorectal cancer (CRC), smoking history and body mass index (BMI) may be useful for prioritizing screening with colonoscopy. The aim of this study was to conduct an external evaluation of a previously published risk index for advanced neoplasia (AN) in a large, well-characterized cohort.

Methods

Five thousand one hundred thirty-seven asymptomatic persons aged 50 to 74 (54.9 % women) with a mean age (SD) of 58.3 (6.2) years were recruited for the study from a teaching hospital and colorectal cancer screening centre between 2003 and 2011. All participants underwent a complete screening colonoscopy and removal of all polyps. AN was defined as cancer or a tubular adenoma, traditional serrated adenoma (TSA), or sessile serrated adenoma (SSA) with villous characteristics (≥25% villous component), and/or high-grade dysplasia and/or diameter ≥10 mm. Risk scores for each participant were summed to derive an overall score (0–8). The c-statistic was used to measure discriminating ability of the risk index.

Results

The prevalence of AN in the study cohort was 6.8 %. The likelihood of detecting AN increased from 3.6 to 13.1 % for those with a risk score of 1 to 6 respectively. The c-statistic for the multivariable logistic model in our cohort was 0.64 (95 % CI = 0.61–067) indicating modest overlap between risk scores.

Conclusions

The risk index for AN using age, sex, family history, smoking history and BMI was found to be of limited discriminating ability upon external validation. The index requires further refinement to better predict AN in average risk persons of screening age.