The relationship between distal and proximal colonic neoplasia: a meta-analysis

Findings in the distal and proximal colon in colonoscopy screening after positive FIT and related pre-procedure factors

BACKGROUND

Colonoscopy is the gold standard method for the early diagnosis and prevention of colorectal cancer (CRC). Screening programs include immune determination of blood in feces. Regardless of the method used, proximal colon lesions appear to be detected less frequently.

OBJECTIVE

Analyze the characteristics of proximal and distal lesions and possible predisposing factors.

METHODS

A cross-sectional study was performed of 692 patients from the CRC screening program with FIT ≥ 100ngHb/ml (October 2017 - October 2018). The right colon was examined twice as patients were participating in a randomized clinical trial to re-evaluate the right colon by forward-viewing endoscope or proximal retroflexion. The adenoma detection rate (ADR), advanced neoplasia (AN) and CRC in the proximal and distal colon, the histological and morphological characteristics in each section were analyzed.

RESULTS

52.9% of the patients were male, with a mean age of 59.5 years (SD: 7.6). 1490 polyps were found and the ADR was 57.7% (distal 42% and proximal 37%). Detection rates were 45.8% for AN, 40.9% for advanced adenomas, 5.2% for advanced SSL and CRC was diagnosed in 4.8% of patients. Males had more AN than females. The mean age of patients with AN was significantly higher. AN were associated with smoking and alcohol consumption (p=0.0001). Globally, FIT levels were higher in patients with AN (p=0.003). Sixty-six per cent of cancers were distally located and 61.3% of CRC were diagnosed in the early stages.

CONCLUSIONS

In an average-risk asymptomatic population undergoing colonoscopy after positive FIT, AN were more common in the distal colon in males, older patients, smokers and those with alcohol intake.

Global Prevalence of Colorectal Neoplasia: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

Most colorectal cancers (CRC) arise from colorectal adenomas, yet there is not enough information on global prevalence to inform health care policy. We examined the prevalence of any type of adenomas, advanced adenomas (AADs), and CRC according to age, sex, ethnicity, geographic regions, and anatomic location (proximal vs distal).

METHODS

MEDLINE and Embase were searched from their inception through May 1, 2018, to identify population-based, observational studies that reported the prevalence of colorectal neoplasia. Studies on participants 15 years or older, with a sample size of 500 persons or more, were included. Metaprop (College Station, TX) was used to model within-study variability by binomial distribution and Freeman-Tukey Double Arcsine Transformation to stabilize the variances. The prevalence figures were presented by proportions and their 95% CIs using random-effects models.

RESULTS

Our meta-analysis included 70 studies involving 637,414 individuals. The overall prevalence rates of adenoma (23.9%; 95% CI, 22.2%-25.8%), AAD (4.6%; 95% CI, 3.8%-5.5%), and CRC (0.4%, 95% CI, 0.3%-0.5%) were calculated. Subgroup analysis indicated that prevalence values (adenomas, AADs, and CRCs) were higher among men (29.7%, 6.5%, and 0.8%, respectively) than women (19.3%, 3.8% and 0.4%, respectively), among older adults (25.9%, 5.2%, and 0.6%, respectively) than younger adults (14.6%, 1.6%, and 0.1%, respectively), among Caucasians (23.7%, 6.6%, and 0.5%, respectively) than other ethnicities, in European countries (25.9%, 8.4%, and 0.8%, respectively) than other countries, and among patients with proximal (25.9%, 5.3%, and 0.1%, respectively) vs distal neoplasia.

CONCLUSIONS

In a systematic review and meta-analysis, we found a high prevalence of colorectal neoplasia among some populations. This indicates a need to expand CRC screening programs for these groups. The pooled prevalence estimates can be used as quality indicators for established CRC screening programs.

Synchronous pathologic findings in patients with colorectal cancer and preoperative incomplete colonoscopy

BACKGROUND AND PURPOSE

Guidelines recommend perioperative complete colonoscopy in patients with colorectal cancer (CRC) to reduce the risk of metachronous carcinoma. Our aim was to verify these recommendations by examining the residual colon of patients with incomplete preoperative colonoscopy.

PATIENTS AND METHODS

This retrospective analysis included patients with the initial diagnosis of CRC and preoperative incomplete or no colonoscopy. Postoperative colonoscopies were investigated to identify synchronous lesions.

RESULTS

In two-thirds of the patients, synchronous lesions could be detected. In 78% of the cases, the lesion was located proximal of the endpoint of the initial colonoscopy and therefore undiscovered. Two-thirds of the synchronous lesions were adenomata.

CONCLUSIONS

Complete perioperative colonoscopy in patients with CRC should be performed to reduce the rate of metachronous carcinoma. Postoperative completion of preoperative insufficiently colonoscoped patients is recommended.

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.

An algorithm to predict advanced proximal colorectal neoplasia in Chinese asymptomatic population

This study aims to develop and validate a new algorithm that incorporates distal colonoscopic findings to predict advanced proximal neoplasia (APN) in a Chinese asymptomatic population. We collected age, gender, and colonoscopic findings from a prospectively performed colonoscopy study between 2013 and 2015 in a large hospital-based endoscopy unit in Shanghai, China. Eligible subjects were allocated to a derivation group (n = 3,889) and validation group (n = 1,944) by random sampling. A new index for APN and its cut-off level were evaluated from the derivation cohort by binary logistic regression. The model performance was tested in the validation cohort using area under the curve (AUC). Age, gender, and distal finding were found to be independent predictors of APN in the derivation cohort (p < 0.001). Subjects were categorized into Average Risk (AR) and High Risk (HR) based on a cut-off score of 2. The AUC of the derivation and validation cohorts were 0.801 (0.754-0.847) and 0.722 (0.649-0.794), respectively. In the validation cohort, those in the HR group had a 3.57 fold higher risk of APN when compared with the AR group (P < 0.001), requiring 18 (95% CI = 12-28) follow-up colonoscopies to detect 1 APN. This new clinical index is useful to stratify APN risk in Chinese population.

Association of distal hyperplastic polyps and proximal neoplastic lesions: a prospective study of 5613 subjects

BACKGROUND AND AIMS

Current evidence of whether distal hyperplastic polyps (HPs) are markers of proximal neoplasia (PN) is mixed. We evaluated the association between distal neoplasia and synchronous PN in asymptomatic subjects.

METHODS

We recruited 5819 Chinese asymptomatic screening participants 50 to 70 years of age who underwent colonoscopy in Hong Kong from 2008 to 2014, of whom 206 subjects with distal advanced neoplasia or cancer were excluded. The association between distal pathology (tubular adenomas [TAs], HPs, no polyps) and proximal pathology (PN, proximal advanced neoplasia [PAN]) was assessed by multivariate regression models, overall and stratified by the Asia Pacific Colorectal Screening scoring system (scores of 4-7, high risk; scores of 0-3, lower risk).

RESULTS

The prevalence of PN in the no distal polyps group, distal HPs group, and distal TAs group was 14.8%, 19.3%, and 29.4%, respectively. The corresponding prevalence of PAN was 1.8%, 3.2%, and 3.5%. Participants with distal HPs did not have significantly higher odds of PN (adjusted odds ratio [AOR] 1.24; 95% confidence interval [CI], 0.97-1.59; P = .089), and their association with PAN was marginally significant (AOR 1.77; 95% CI, 1.00-3.13; P = .052), except in lower risk subjects for whom the odds of PAN were marginally higher in the distal HPs group than the no distal polyps group (AOR 1.97; 95% CI, 1.01-3.85; P = .048). Overall, the distal polyps group had significantly lower odds of PN than the distal TAs group (AOR 0.55; 95% CI, 0.40-0.76; P < .001). The increased risk of PN and PAN among those with distal HPs was modest.

CONCLUSIONS

A direct association between distal HPs and PN is lacking, and this implies a need for a multivariate assessment of the risk of PAN. Recommending colonoscopy for every patient with distal HPs detected by screening sigmoidoscopy is not supported by this study.

Factors related to advanced colorectal neoplasm at the Policlínico Peruano Japonés

BACKGROUND

Identifying persons at high risk for advanced colorectal neoplasia can aid in the prevention of colon cancer. Previous studies have shown that some patients can present with proximal advanced neoplasia with no distal findings.

AIMS

To determine the factors related to advanced neoplasia and advanced proximal colorectal neoplasia in a Latin American population.

MATERIAL AND METHODS

A prospective, cross-sectional, observational, analytic study was conducted. It included patients that underwent colonoscopy at the Policlínico Peruano Japonés within the time frame of January and July 2012. Advanced neoplasia was defined as the presence of lesions ≥ 10mm with a villous component, high-grade dysplasia, or carcinoma. The splenic flexure was the limit between the proximal and distal colon.

RESULTS

A total of 846 patients were included in the study. Advanced neoplasia was detected in 108 patients (12.8%) and advanced proximal neoplasia in 55 patients (6.7%), 42 (76.4%) of whom had no neoplasia in the distal colon. Factors related to advanced neoplasia found in the multivariate analysis were age, at the intervals of 50-59 (p=0.019), 60-69 (p=0.016), and ≥ 70 years (0.002) and male sex (p=0.003). In the evaluation of advanced proximal neoplasia, the multivariate analysis identified the 60-69 year age interval (p=0.039) and advanced distal neoplasia (p=0.028) as factors related to advanced proximal disease. The ROC curve established the age cut-off point at 60 years for initially performing colonoscopy, rather than sigmoidoscopy.

CONCLUSIONS

Age and sex are related to advanced neoplasia, whereas age and advanced distal neoplasia are related to advanced proximal neoplasia.

Colorectal Cancer Screening

Colorectal cancer (CRC) is a leading cause of cancer morbidity and mortality in the Western world. Advances in surgical and medical management have led to improved outcomes; however, the prognosis of CRC is often poor when detected at a symptomatic stage. Most cases of CRC develop over years from removable well-defined precursor lesions, and asymptomatic, curable disease may be detected by convenient noninvasive tests. These features make CRC a suitable candidate for screening, and several options are available. This article outlines the evidence for established CRC screening tests along with a discussion on newer tests and ongoing research.

Advanced proximal neoplasia of the colon in average-risk adults

BACKGROUND

Estimating risk for advanced proximal neoplasia (APN) based on distal colon findings can help identify asymptomatic persons who should undergo examination of the proximal colon after flexible sigmoidoscopy (FS) screening.

OBJECTIVE

We aimed to determine the risk of APN by most advanced distal finding among an average-risk screening population.

DESIGN

Prospective, cross-sectional study.

SETTING

Teaching hospital and colorectal cancer screening center.

PATIENTS

A total of 4651 asymptomatic persons at average risk for colorectal cancer aged 50 to 74 years (54.4% women [n = 2529] with a mean [± standard deviation] age of 58.4 ± 6.2 years).

INTERVENTIONS

All participants underwent a complete colonoscopy, including endoscopic removal of all polyps.

MAIN OUTCOME MEASUREMENTS

We explored associations between several risk factors and APN. Logistic regression was used to identify independent predictors of APN.

RESULTS

A total of 142 persons (3.1%) had APN, of whom 85 (1.8%) had isolated APN (with no distal findings). APN was associated with older age, a BMI >27 kg/m(2), smoking, distal advanced adenoma and/or cancer, and distal non-advanced tubular adenoma. Those with a distal advanced neoplasm were more than twice as likely to have APN compared with those without distal lesions.

LIMITATIONS

Distal findings used to estimate risk of APN were derived from colonoscopy rather than FS itself.

CONCLUSION

In persons at average risk for colorectal cancer, the prevalence of isolated APN was low (1.8%). Use of distal findings to predict APN may not be the most effective strategy. However, incorporating factors such as age (>65 years), sex, BMI (>27 kg/m(2)), and smoking status, in addition to distal findings, should be considered for tailoring colonoscopy recommendations. Further evaluation of risk stratification approaches in other asymptomatic screening populations is warranted.

Current status of screening for colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer morbidity and mortality. A well-defined precursor lesion (adenoma) and a long preclinical course make CRC a candidate for screening. This paper reviews the current evidence for the most important tests that are widely used or under development for population-based screening.

MATERIAL AND METHODS

In this narrative review, we scrutinized all papers we have been aware of, and carried out searches in PubMed and Cochrane library for relevant literature.

RESULTS

Two screening methods have been shown to reduce CRC mortality in randomised trials: repetitive faecal occult blood testing (FOBT) reduces CRC mortality by 16%; once-only flexible sigmoidoscopy (FS) by 28%. FS screening also reduces CRC incidence (by 18%), FOBT does not. Colonoscopy screening has a potentially larger effect on CRC incidence and mortality, but randomised trials are lacking. New screening methods are on the horizon but need to be tested in large clinical trials before implementation in population screening.

CONCLUSIONS

FS screening reduces CRC incidence and CRC mortality by removal of adenomas; FOBT reduces CRC mortality by early detection of cancer. Several other tests are available, but none has been evaluated in randomised trials. Screening strategies differ considerably across countries.