Clinicopathological features of colorectal polyps: evaluation of the 'predict, resect and discard' strategies

White spots around colorectal tumors are cancer-related findings and may aid endoscopic diagnosis: a prospective study in Japan

BACKGROUND/AIMS

During endoscopy, white spots (WS) are sometimes observed around benign or malignant colorectal tumors; however, few reports have investigated WS, and their significance remains unknown. Therefore, we investigated the significance of WS from clinical and pathological viewpoints and evaluated its usefulness in endoscopic diagnosis.

METHODS

Clinical data of patients with lesions diagnosed as epithelial tumors from January 1, 2019, to December 31, 2020, were analyzed (n=3,869). We also performed a clinicopathological analysis of adenomas or carcinomas treated with endoscopic resection (n=759). Subsequently, detailed pathological observations of the WS were performed.

RESULTS

The positivity rates for WS were 9.3% (3,869 lesions including advanced cancer and non-adenoma/carcinoma) and 25% (759 lesions limited to adenoma and early carcinoma). Analysis of 759 lesions showed that the WS-positive lesion group had a higher proportion of cancer cases and larger tumor diameters than the WS-negative group. Multiple logistic analysis revealed the following three statistically significant risk factors for carcinogenesis: positive WS, flat lesions, and tumor diameter ≥5 mm. Pathological analysis revealed that WS were macrophages that phagocytosed fat and mucus and were white primarily because of fat.

CONCLUSIONS

WS are cancer-related findings and can become a new criterion for endoscopic resection in the future.

Colorectal cancer and advanced adenoma characteristics according to causative mismatch repair gene variant in Japanese colorectal surveillance for Lynch syndrome

BACKGROUND

The optimal interval of colonoscopy (CS) surveillance in cases with Lynch syndrome (LS), and stratification according to the causative mismatch repair gene mutation, has received much attention. To verify a feasible and effective CS surveillance strategy, we investigated the colorectal cancer (CRC) incidence at different intervals and the characteristics of precancerous colorectal lesions of LS cases.

METHODS

This retrospective multicenter study was conducted in Japan. CRCs and advanced adenomas (AAs) in 316 LS cases with germline pathogenic variants (path_) were analyzed according to the data of 1,756 registered CS.

RESULTS

The mean time interval for advanced CRCs (ACs) detected via CS surveillance was 28.7 months (95% confidence interval: 13.8-43.5). The rate of AC detection within (2.1%) and beyond 2 years (8.7%) differed significantly (p = 0.0003). AAs accounted for 43%, 46%, and 41% of lesions < 10 mm in size in the MLH1-, MSH2-, and MSH6-groups, respectively. The lifetime incidence of metachronous CRCs requiring intestinal resection for path_MLH1, path_MSH2, and path_MSH6 cases was 34%, 23%, and 14% in these cases, respectively. The cumulative CRC incidence showed a trend towards a 10-year delay for path_MSH6 cases as compared with that for path_MLH1 and path_MSH2 cases.

CONCLUSIONS

In cases with path_MLH1, path_MSH2, and path_MSH6, maintaining an appropriate CS surveillance interval of within 2 years is advisable to detect of the colorectal lesion amenable to endoscopic treatment. path_MSH6 cases could be stratified with path_MLH1 and MSH2 cases in terms of risk of metachronous CRC and age of onset.

Evaluation of a new method, "non-injection resection using bipolar soft coagulation mode (NIRBS)", for colonic adenomatous lesions

BACKGROUND/AIMS

Endoscopic resection of all colorectal adenomatous lesions with a low complication rate, simplicity, and negative residuals is challenging. Hence, we developed a new method called "non-injection resection using bipolar soft coagulation mode (NIRBS)" method, adapted for colorectal lesions. In addition, we evaluated the effectiveness of this method.

METHODS

We performed NIRBS throughout a 12-month period for all colorectal lesions which snare resection was acceptable without cancerous lesions infiltrating deeper than the submucosal layer.

RESULTS

A total of 746 resected lesions were included in the study, with a 4.5 mm mean size (range, 1-35 mm). The major pathological breakdowns were as follows: 64.3% (480/746) were adenomas, and 5.0% (37/746) were intraepithelial adenocarcinomas (Tis lesions). No residuals were observed in any of the 37 Tis lesions (mean size, 15.3 mm). Adverse events included bleeding (0.4%) but no perforation.

CONCLUSIONS

NIRBS allowed the resection of multiple lesions with simplicity because of the non-injection and without perforating due to the minimal burn effect of the bipolar snare set in the soft coagulation mode. Therefore, NIRBS can be used to resect adenomatous lesions easily, including Tis lesions, from small to large lesions without leaving residuals.

Complete endoscopic removal rate of detected colorectal polyps in a real world out-patient practical setting

OBJECTIVES

Colonoscopy with adenomatous polypectomy reduces the incidence and mortality of colorectal cancer. We introduced a strategy of removing all neoplastic polyps in single-session out-patient colonoscopy using cold polypectomy. We aimed to investigate the achievement of single-session complete removal rate of detected colorectal polyps in clinical practice.

MATERIALS AND METHODS

This retrospective study included colonoscopy-scheduled 40-79-year-old outpatients, with at least one colorectal neoplasm, between January 2015 and December 2016. Exclusion criteria were: colorectal neoplasms 21 mm or larger in size; pre-examination for colorectal surgery or endoscopic submucosal dissection; colonoscopy performed by health check program; ongoing antithrombotic treatment; inflammatory bowel disease; familial adenomatous polyposis. We defined 'clean colon' as the removal of all detected neoplastic polyps in a single-session colonoscopy. We evaluated clean colon rate, factors relating to clean colon failure and complications.

RESULTS

We evaluated 2527 patients (mean age 68 years; 799 women) with 8203 colorectal polyps (7675 adenomas, 423 serrated lesions, 105 Tis and T1 cancers). In 1-4 mm polyps, cold snare polypectomy (CSP; 51.8%) and cold forceps polypectomy (CFP; 45.8%) were applied. Clean colon rates were 95.1% per patient and 97.1% per lesion. The significant factors denoting clean colon failure were inadequate bowel preparation, ≥5 lesions, and the most advanced estimated histology of adenocarcinoma, on multivariate analyses. Post-polypectomy bleeding requiring endoscopic hemostasis occurred in five patients (0.2%) who had undergone endoscopic mucosal resection (EMR) or hot snare polypectomy (HSP). Perforation occurred in one patient (0.04%) with EMR.

CONCLUSIONS

The clean colon rates were satisfactory in single-session out-patient colonoscopy using cold polypectomy.

Comparison of Linked Color Imaging and White Light Imaging Colonoscopy for Detection of Colorectal Adenoma Requiring Endoscopic Treatment: A Single-Center Randomized Controlled Trial

BACKGROUND

Linked color imaging (LCI) improves detection of colorectal neoplastic lesions during colonoscopy. However, polyps <5 mm in diameter often do not require resection, and the benefits of LCI are unclear for detection of colorectal polyps ≥5 mm that are indicated for endoscopic resection in clinical practice. This randomized controlled trial compared rates of detection of adenoma polyps, stratified by size, for LCI and white light imaging (WLI).

METHODS

We compared ADR (5 mm-) and PDR (5 mm-), which were defined as the proportion of patients with at least one adenoma or polyp with a diameter of 5 mm or larger in the LCI and WLI groups. Moreover, we estimated ADR and PDR for diameters between 5 and 10 mm (ADR (5-9 mm), PDR (5-9 mm) ) and for diameters larger than 10 mm (ADR (10 mm-), PDR (10 mm-) ).

RESULTS

Data from 594 patients (LCI, n=305; WLI, n=289) were analyzed. ADR (5 mm-) and PDR (5 mm-) were significantly higher in the LCI group than in the WLI group (ADR (5 mm-): P=0.016, PDR (5 mm-): P=0.020). In the assessment of adenoma and polyp size, ADR (5-9 mm) and PDR (5-9 mm) were significantly higher in the LCI group than in the WLI group, although no significant differences were seen in ADR (10 mm-) and PDR (10 mm-) between these groups.

CONCLUSIONS

Polyps ≥5 mm, which are indicated for endoscopic treatment, were more easily visualized with LCI mode than with WLI mode. The improvement in detection rate was obvious for polyps <10 mm, which are easier to miss.

Metformin combined with endoscopic therapy in patients with familial polyposis associated with carcinoma: A case report

RATIONALE

Familial adenomatous polyposis (FAP) is an autosomal dominant genetic disease, with a very high cancer rate. At present, endoscopic resection of polyps ≥ 1 cm is often chosen for patients with non-cancerous polyps who are unwilling to undergo surgery, and regular review is conducted. Once the polyps are pathologically confirmed to be cancerous, surgical resection of the diseased large intestine is generally recommended, but surgery often leads to a series of complications. So what do you do with cancer patients who don't want surgery?

PATIENT CONCERNS

A 19-year-old woman presented with intermittent hematochezia with abdominal pain. A colonoscopy revealed hundreds of intestinal polyps.

DIAGNOSES

The patient had a family history of FAP, and there were hundreds of polyps in the intestine. The pathology was adenomatous, and some polyps became cancerous, which met the diagnostic criteria of FAP.

INTERVENTIONS

Endoscopic examination was arranged for the patient, the resection of intestinal polyps ≥ 1 cm was given priority, and other polyps were removed as far as possible. After that, metformin 500 mg orally was given twice a day, and endoscopic follow-up was conducted every 6 months. During each endoscopic follow-up, intestinal polyps ≥ 1 cm were preferred to be removed, and other polyps were removed as far as possible.

OUTCOMES

The patient's abdominal pain and blood in the stool disappeared after endoscopic treatment. Cancerous polyps were found at the second and third follow-up visits, but the patient always refused surgical treatment. After 4 years of follow-up, polyp load was significantly reduced, abdominal pain and bloody stool symptoms did not appear again, and imaging examination showed no tumor recurrence and metastasis.

LESSONS

Endoscopic polyp resection is an important method to treat the clinical symptoms of FAP. Metformin combined with endoscopic therapy is a good alternative for patients with familial polyposis who do not want surgery. When the polyp is cancerous and the polyp is radically resected by the endoscope, if the patient refuses additional surgery, oral metformin combined with endoscopic follow-up can be considered.

Resection depth and layer of underwater versus conventional endoscopic mucosal resection of intermediate-sized colorectal polyps: A pilot study

Background and study aims  Curability of colorectal tumors is associated with resection depth and layer in endoscopic resection. Underwater endoscopic mucosal resection (UEMR) has not undergone sufficient histopathological evaluation. We conducted a pilot study to compare the effectiveness, including resection depth and layer, of UEMR and conventional endoscopic mucosal resection (CEMR). Patients and methods  This study was a single-center, retrospective study. Patients with colorectal lesions were treated by UEMR or CEMR between January 2018 and March 2020. Eligible patients were selected from included patients in a 1:1 ratio using propensity score matching. We compared the resection depth and layer and treatment results between the UEMR and CEMR groups. Results  We evaluated 55 patients undergoing UEMR and 291 patients undergoing CEMR. Using propensity score matching, we analyzed 54 lesions in each group. The proportion of specimens containing submucosal tissue was 100 % in both groups. The median thickness of the submucosal tissue was significantly greater in the CEMR group than in the UEMR group [1235 µm (95 % confidence interval [CI], 1020-1530 µm) vs. 950 µm (95 % CI, 830-1090 µm), respectively]. However, vertical margins were negative in all lesions in both groups. Conclusions  Our findings suggest that the median thickness of submucosal tissue in the UEMR group was about 1,000 μm. Even though the resection depth achieved with UEMR was more superficial than that achieved with CEMR, UEMR may be a treatment option, especially for colorectal lesions ≤ 20 mm in diameter without suspicious findings of submucosal deeply invasive cancer.

Resection depth for small colorectal polyps comparing cold snare polypectomy, hot snare polypectomy and underwater endoscopic mucosal resection

Background and study aims  Small colorectal polyps are removed by various methods, including cold snare polypectomy (CSP), hot snare polypectomy (HSP), and underwater endoscopic mucosal resection (UEMR), but the indications for using these methods are unclear. We retrospectively assessed the efficacy of CSP, HSP, and UEMR for small polyps, focusing on the depth of the resected specimens. Patients and methods  Outpatients with non-pedunculated small polyps (endoscopically diagnosed as 6 to 9 mm), resected by two endoscopists between July 2019 and September 2020, were enrolled. We histologically evaluated the specimens resected via CSP, HSP, and UEMR. The main outcome was the containment rate of the muscularis mucosa (MM) and submucosa (SM) tissues. Results  Forty polyps resected via CSP (n = 14), HSP (n = 12), or UEMR (n = 14) were enrolled after excluding 13 polyps with resection depths that were difficult to determine. The rates of specimens containing MM and SM tissue differed significantly (57 % and 29 % for CSP, 92 % and 83 % for HSP, and 100 % and 100 % for UEMR, respectively ( P  = 0.005 for MM and P  < 0.001 for SM tissue). Multiple logistic regression analysis showed UEMR was an independent factor relating to the containment of SM tissue. The thickness of SM tissue by CSP, HSP, and UEMR were 52 μm, 623 μm, and 1119 μm, respectively ( P  < 0.001). The thickness by CSP was significantly less than those by HSP and UEMR ( P  < 0.001, Bonferroni correction). Conclusions  UEMR could be the best method to contain SM tissue without injection. Further studies are needed to evaluate the indication of UEMR for small polyps.

Depth of the cutting plane with underwater and conventional endoscopic mucosal resection: Post-hoc analysis of a randomized study

BACKGROUND AND AIM

A multicenter randomized controlled trial reported a better R0 resection rate for intermediate-sized (10-20 mm) colorectal polyps with underwater endoscopic mucosal resection (UEMR) than conventional endoscopic mucosal resection (CEMR). To clarify whether UEMR removes enough submucosal tissue in the removal of unpredictable invasive cancers, we investigated the cutting plane depth with UEMR versus CEMR.

METHODS

This was a post-hoc analysis of a randomized controlled trial in which 210 intermediate-sized colorectal polyps were removed in five Japanese hospitals. One pathologist and two gastroenterologists independently reviewed all resected specimens and measured the cutting plane depth. The cutting plane depth was evaluated as (i) maximum depth of submucosal layer and (ii) mean depth of submucosal layer, calculated using a virtual pathology system.

RESULTS

We identified 168 appropriate specimens for the evaluation of the cutting plane depth, resected by UEMR (n = 88) and CEMR (n = 80). The median resection depth was not significantly different between UEMR and CEMR specimens, regardless of the measurement method ([i] 1317 vs 1290 μm, P = 0.52; [ii] 619 vs 545 μm, P = 0.32). All specimens in the UEMR and CEMR groups contained substantial submucosa and no muscularis propria.

CONCLUSIONS

The cutting plane depth with UEMR was comparable with that with CEMR. UEMR can be a viable alternative method that adequately resects the submucosal layer for the histopathological assessment of unpredictable submucosal invasive cancers.

Influence of early colorectal cancer component on the positive margins after endoscopic resection: a retrospective study

Background

Endoscopic treatment methods for early colorectal cancer (ECRC) mainly depend on the size and morphology. It is unclear whether different endoscopic resection methods could achieve curative resection for ECRC confined in the mucosa. The study was designed to compare the rate of positive vertical margin (VM) of ECRC with advanced adenomas (AAs) including adenoma > 1 cm, villous adenoma, high-grade intraepithelial neoplasia/dysplasia stratified by different endoscopic resection methods.

Methods

Rate of positive VM for 489 ECRCs including Intramucosal (pTis) and superficial submucosal invasion (pT1) carcinomas were compared with those of 753 AAs stratified by different endoscopic resection methods using Chi-squared test. Multivariate logistic model was performed to investigate the risk factors of positive VM for different endoscopic resection methods.

Results

The pTis ECRC exhibited a similar rate of positive VM as that of AAs for en bloc hot snare polypectomy (HSP, 0% Vs. 0.85%, P = 0.617), endoscopic mucosal resection (EMR, 0.81% vs. 0.25%, P = 0.375) and endoscopic submucosal dissection (ESD, 1.82% Vs. 1.02%, P = 0.659). The pTis carcinoma was not found to be a risk factor for positive VM by en bloc EMR (P = 0.349) or ESD (P = 0.368). The en bloc resection achieved for pT1a carcinomas exhibited similar to positive VM achieved through ESD (2.06% Vs. 1.02%, P = 1.000) for AAs. Nonetheless, EMR resulted in higher risk of positive VM (5.41% Vs. 0.25%, P < 0.001) for pT1a carcinomas as compared to AAs. The pT1a invasion was identified as a risk factor for positive VM in polyps with en bloc EMR (odds ratio = 23.90, P = 0.005) but not ESD (OR = 2.96, P = 0.396).

Conclusion

Collectively, the pTis carcinoma was not found to be a risk factor for positive VM resected by en bloc HSP, EMR or ESD. Additionally, ESD may be preferred over EMR for pT1a carcinomas with lower rate of positive VM.

Safety and efficacy of cold versus hot snare polypectomy including colorectal polyps ≥1 cm in size

Cold snare polypectomy (CSP; polypectomy without electrocautery) has spread rapidly worldwide during the past decade in what has been called "Cold Revolution". We performed a PubMed literature search for studies investigating CSP outcomes for colorectal polyps. Five randomized controlled trials (RCTs) assessed the complete resection rates (CRRs). The CRRs were similar regardless of the presence or absence of electrocautery, and the efficacy of submucosal injection for better CRRs is still controversial. Eight RCTs assessed the adverse events. The incidence of intraprocedural bleeding with cold procedures was comparable to or higher than that of hot procedures. The incidences of delayed bleeding were comparable to or lower with cold procedures, especially in patients taking anticoagulants. Fifteen studies have been reported on CSP for large (≥1 cm) colorectal polyps (10 retrospective studies, four prospective single-arm studies, and one prospective RCT). These studies reported that the safe cold procedures (a low intra- and post-procedural bleeding rate without perforation) could be implemented for lesions ≥1 cm. However, considering the incision depth of CSP and the local recurrence rate based on the current evidence, only large sessile serrated lesions (SSLs) can be candidates for cold procedures, and large adenomas should not be candidates for this procedure. Based on the current evidence, CSP seems to be the appropriate standard procedure for sub-centimeter colorectal low-grade adenomas due to its safety and simplicity. Thus, large SSLs can be candidates for cold procedures; however, careful inspection and further prospective studies are warranted to confirm the procedure's clinical relevance.

Medical needs related to the endoscopic technology and colonoscopy for colorectal cancer diagnosis

Background

The high incidence and mortality rate of colorectal cancer require new technologies to improve its early diagnosis. This study aims at extracting the medical needs related to the endoscopic technology and the colonoscopy procedure currently used for colorectal cancer diagnosis, essential for designing these demanded technologies.

Methods

Semi-structured interviews and an online survey were used.

Results

Six endoscopists were interviewed and 103 were surveyed, obtaining the demanded needs that can be divided into: a) clinical needs, for better polyp detection and classification (especially flat polyps), location, size, margins and penetration depth; b) computer-aided diagnosis (CAD) system needs, for additional visual information supporting polyp characterization and diagnosis; and c) operational/physical needs, related to limitations of image quality, colon lighting, flexibility of the endoscope tip, and even poor bowel preparation.

Conclusions

This study shows some undertaken initiatives to meet the detected medical needs and challenges to be solved. The great potential of advanced optical technologies suggests their use for a better polyp detection and classification since they provide additional functional and structural information than the currently used image enhancement technologies. The inspection of remaining tissue of diminutive polyps (< 5 mm) should be addressed to reduce recurrence rates. Few progresses have been made in estimating the infiltration depth. Detection and classification methods should be combined into one CAD system, providing visual aids over polyps for detection and displaying a Kudo-based diagnosis suggestion to assist the endoscopist on real-time decision making. Estimated size and location of polyps should also be provided. Endoscopes with 360° vision are still a challenge not met by the mechanical and optical systems developed to improve the colon inspection. Patients and healthcare providers should be trained to improve the patient’s bowel preparation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08190-z.

Chemoprevention with low-dose aspirin, mesalazine, or both in patients with familial adenomatous polyposis without previous colectomy (J-FAPP Study IV): a multicentre, double-blind, randomised, two-by-two factorial design trial

BACKGROUND

The only established treatment for preventing colorectal cancer in patients with familial adenomatous polyposis (FAP) is colectomy, which greatly reduces patient quality of life. Thus, an alternative method is warranted. In this trial, we aimed to clarify the individual and joint effects of low-dose aspirin and mesalazine on the recurrence of colorectal polyps in Japanese patients with FAP.

METHODS

This was a randomised, double-blind, placebo-controlled, multicentre trial with a two-by-two factorial design done in 11 centres in Japan. Eligible patients were aged 16-70 years and had a history of more than 100 adenomatous polyps in the large intestine, without a history of colectomy. Before the study, patients underwent endoscopic removal of all colorectal polyps of at least 5·0 mm in diameter. Randomisation was done with a minimisation method with a random component to balance the groups with respect to the adjustment factors of sex, age (<30 years vs ≥30 years), or smoking status at the time of entry. Patients and researchers were masked to the treatment group. There were four groups: aspirin (100 mg per day) plus mesalazine (2 g per day), aspirin (100 mg per day) plus mesalazine placebo, aspirin placebo plus mesalazine (2 g per day), or aspirin placebo plus mesalazine placebo. Treatment was continued until 1 week before 8 month colonoscopy. The primary endpoint was the incidence of colorectal polyps of at least 5·0 mm at 8 months and was assessed in the intention-to-treat population. Safety was assessed in the ITT population. We also did a per-protocol analysis including only patients who took at least 70% of the allocated study drug. This trial is registered with the UMIN Clinical Trials Registry, number UMIN000018736, and is complete.

FINDINGS

Between Sept 25, 2015, and March 13, 2017, 104 patients were randomly assigned to receive either aspirin or aspirin placebo (n=52) or mesalazine or mesalazine placebo (n=52). Two patients withdrew from the aspirin plus mesalazine placebo group. 26 (50%) of 52 patients who received no aspirin had colorectal polyps of at least 5·0 mm at 8 months, as did 15 (30%) of the 50 patients who received any aspirin, 21 (42%) of the 50 patients who received no mesalazine, and 20 (38%) of the 52 patients who received any mesalazine. The adjusted odds ratio for polyp recurrence was 0·37 (95% CI 0·16-0·86) in the patients who received any aspirin and 0·87 (95% CI 0·38-2·00) in any who received mesalazine. The most common adverse events were grade 1-2 upper gastrointestinal symptoms in three (12%) of 26 patients who received aspirin plus mesalazine, one (4%) of 24 patients who received aspirin plus mesalazine placebo, and one (4%) of 26 patients who received mesalazine plus aspirin placebo. There was one grade 4 event in the mesalazine plus aspirin placebo group, but not related to the treatment.

INTERPRETATION

Low-dose aspirin safely suppressed the recurrence of colorectal polyps larger than 5·0 mm in patients with FAP. These results suggest an effect of low-dose aspirin for FAP and could be an alternative method for preventing colorectal cancer in FAP.

FUNDING

Japan Agency for Medical Research and Development.

Association between the chronic use of gastric acid suppressants and high-risk colorectal polyps

Background and Aim

Although gastric acid suppressants such as proton pump inhibitors (PPIs) and histamine‐2 receptor antagonists (H2RAs) are considered safe, the consequences of hypochlorhydria and hypergastrinemia caused by chronic use are unclear. This study aimed to investigate the association between the chronic use of gastric acid suppressants and high‐risk colorectal polyps, focusing on polyp size.

Methods

A population‐based, nested case–control study was conducted using data from the Japanese Diagnosis Procedure Combination database between 2014 and 2019. Cumulative PPI or H2RA use prior to polypectomy was evaluated during the study period. Endoscopic polypectomy was categorized as polypectomy <2 cm, polypectomy ≥2 cm, and endoscopic submucosal dissection. Baseline characteristics were compared between the high‐risk (≥2 cm polyps or polyps treated by endoscopic submucosal dissection) and low‐risk (<2 cm polyps) endoscopic polypectomy groups. We calculated adjusted odds ratios (ORs) using multivariable logistic regression analysis.

Results

Of 27 694 patients who underwent endoscopic polypectomy, 2518 were treated with PPIs or H2RAs for >1 year prior to polypectomy. After adjusting for age, gender, and other confounders, a higher prevalence of high‐risk colorectal polyps was noted with PPI (OR: 2.67; 95% confidence interval: 2.37–3.01) and H2RA (OR: 1.86; 95% confidence interval: 1.52–2.26) use. Longer PPI or H2RA use was associated with increased risks of high‐risk colorectal polyps (P for trend <0.001). The highest OR (3.17) was observed among patients who received PPIs for ≥3 years.

Conclusion

Chronic use of PPIs and H2RAs may be associated with high‐risk colorectal polyps. Requirements for long‐term gastric acid suppressant use should be reevaluated.

Higher risk of advanced histology in adenoma less than 10 mm in fecal immunochemical test screening: Implication for management

BACKGROUND AND AIM

Whether diminutive or small adenomas detected by fecal immunochemical tests (FITs) are associated with a higher risk of advanced histology remains unknown. We investigated the prevalence of advanced histology in diminutive and small adenomas detected by FIT and compared with that detected by colonoscopy screening.

METHODS

We prospectively compared 1860 FIT-positive patients (FIT-positive cohort) and 6691 average-risk patients (screening colonoscopy cohort). Both groups underwent colonoscopies and were shown to have neoplastic lesions. The prevalence of advanced histology was determined, as was the associations with size and FIT positivity.

RESULTS

We analyzed 3920 neoplastic lesions from the FIT-positive cohort and 9789 neoplastic lesions from the screening colonoscopy cohort. Eighty (4.3%) diminutive lesions in FIT-positive cohort had advanced histology but without any invasive cancer. Twenty-one patients in the FIT-positive cohort and 49 in the screening colonoscopy cohort with diminutive adenomas displayed advanced histology (3.5% vs 1.2%; adjusted odds ratio [aOR] = 2.99, 95% confidence interval [CI]: 1.77-5.06). Sixteen patients in the FIT-positive cohort (2.7%) with diminutive adenomas might have changed the surveillance interval if a resect-and-discard strategy was applied, with a higher likelihood compared with the screening colonoscopy cohort (aOR = 2.76, 95% CI: 1.53-4.99).

CONCLUSIONS

Fecal immunochemical test screening detected more diminutive and small adenomas with advanced histology compared with colonoscopy screening. Its impact on current management of diminutive polyp is limited.

Serrated polyps of the colon and rectum: Remove or not?

In recent years, the serrated neoplasia pathway where serrated polyps arise as a colorectal cancer has gained considerable attention as a new carcinogenic pathway. Colorectal serrated polyps are histopathologically classified into hyperplastic polyps (HPs), sessile serrated lesions, and traditional serrated adenomas; in the serrated neoplasia pathway, the latter two are considered to be premalignant. In western countries, all colorectal polyps, including serrated polyps, apart from diminutive rectosigmoid HPs are removed. However, in Asian countries, the treatment strategy for colorectal serrated polyps has remained unestablished. Therefore, in this review, we described the clinicopathological features of colorectal serrated polyps and proposed to remove HPs and sessile serrated lesions ≥ 6 mm in size, and traditional serrated adenomas of any size.

Association of second surveillance colonoscopy findings with index and first surveillance colonoscopy results

OBJECTIVE

Although there have been established guidelines for first surveillance colonoscopy (FSC) after a polypectomy, there is no consensus on performing a second surveillance colonoscopy (SSC), especially in Asian countries. This study aimed to investigate the association of SSC findings with index total colonoscopy (TCS) and FSC results.

METHODS

This was a single-center retrospective cohort study involving 1928 consecutive Japanese patients who had received three or more colonoscopies. High-risk colonoscopic findings were defined as advanced adenoma (≥10 mm in size, with a villous histology or high-grade dysplasia) or more than three adenomas, whereas low-risk findings were defined as one to two non-advanced adenomas. On the basis of index TCS results, the patients were divided into three groups: no adenomas (NA) (n = 888), low-risk (LR) (n = 476), and high-risk (HR) (n = 564) groups, respectively.

RESULTS

In the NA group, the rate of high-risk findings on SSC was significantly higher in patients with high-risk or low-risk findings on FSC than in those with no adenoma (7.7% and 7.9% vs 2.2%, P < 0.05). Patients in the LR and HR groups with high-risk findings on FSC had a significantly higher risk on SSC than those with low-risk findings or no adenoma on FSC (LR group: 28.6%, 9.4%, and 5.9%, respectively, P < 0.01; HR group: 34.5%, 18.8%, and 7.9%, respectively, P < 0.01).

CONCLUSIONS

Index TCS and especially FSC findings were predictive of SSC results. The study results may be useful for determining appropriate intervals for surveillance colonoscopy in Asian countries.

Efficacy of autofluorescence imaging for flat neoplasm detection: a multicenter randomized controlled trial (A-FLAT trial)

BACKGROUND AND AIMS

Colorectal flat (nonpolypoid) lesions can be overlooked during colonoscopy. This study evaluated the efficacy of updated autofluorescence imaging (AFI) for detecting colorectal flat neoplasms.

METHODS

This was a prospective, multicenter, randomized controlled trial in 9 Japanese tertiary institutions. Patients undergoing colonoscopy because of positive fecal immunochemical tests, surveillance after polypectomy, or investigation of minor symptoms were enrolled and randomly assigned to either the white-light imaging (WLI) or the AFI group. Primary outcome measurement was number of flat neoplasms per patient.

RESULTS

From November 2015 to June 2017, 817 patients were enrolled. After excluding 15 patients, 802 were finally analyzed (404, WLI; 398, AFI). Patients' backgrounds (sex, age, indication of colonoscopy, experience of endoscopists) and quality of colonoscopy (bowel preparation, sedative use, cecal insertion rate, insertion and withdrawal time) were not different between groups. Number of flat neoplasms in each patient was significantly higher in the AFI than in the WLI group (.87 [95% confidence interval [CI], .78-.97] vs .53 [95% CI, .46-.61]), whereas overall and polypoid neoplasm detection was not significantly different between the groups (1.33 [95% CI, 1.22-1.45] vs 1.14 [95% CI, 1.03-1.24], .46 [95% CI, .40-.53] vs .60 [95% CI, .53-.68]). Flat neoplasms were more frequently detected in the right-sided colon with AFI (.61 [95% CI, .54-.70] vs .30 [95% CI, .25-.36]) but not in the left-sided colon and rectum (.26 [95% CI, .21-.32] vs .23 [95% CI, .19-.28]).

CONCLUSIONS

Updated AFI improves the detection of flat colorectal neoplasms in the right-sided colon compared with WLI. (Clinical trial registration number: UMIN000019355.).

Resection depth and layer of cold snare polypectomy versus endoscopic mucosal resection

BACKGROUND

Cold snare polypectomy (CSP) has not undergone sufficient histopathological evaluation. This study aimed to clarify the histopathological features of CSP specimens, including resection depth and layer, as compared with endoscopic mucosal resection (EMR).

METHODS

Polyps were recruited retrospectively. Sessile, semi-pedunculated, and 0-IIa polyps of ≤ 9 mm were selected by propensity score matching and classified as either a complete resection or one with an unevaluable/positive (X/+) margin. Resection depth and layer were estimated and the risk factors for an X/+ margin were evaluated.

RESULTS

A total of 1072 polyps were enrolled. After matching, 184 polyp pairs were selected. An X/+ margin was seen in 105/184 (57%) vs. 70/184 (38%) CSP vs. EMR specimens (p < 0.001): specimen damage was 53/184 (29%) vs. 30/184 (16%) (p < 0.01) and vertical margin (VM) X/+ was 11/184 (6%) vs. 2/184 (1%) (p < 0.05). Among 193 completely resected specimens, resection depth from the muscularis mucosae in CSP vs. EMR was 76 vs. 338 µm (p < 0.001) and resection layer was the submucosa in 7/79 (9%) vs. 105/114 (92%) (p < 0.001). In multivariate analysis, CSP was a risk factor for procedure-associated VMX/+ [odds ratio (OR) 6.80, 95% confidence interval (CI) 1.33-34.69, p < 0.05]. Sessile serrated adenoma/polyp (SSA/P) was a risk factor for VMX/+ margin in CSP specimens (OR 58.36, 95% CI 7.45-456.96, p < 0.001).

CONCLUSIONS

SSA/P and colorectal cancer may not be suitable for CSP adoption.

Colorectal polyps located across a fold are difficult to resect completely using endoscopic mucosal resection: A propensity score analysis

Background

Incomplete polyp resection during colorectal endoscopic mucosal resection (EMR) might contribute to the development of interval cancer.

Objective

This retrospective study aimed to determine the incidence of incomplete polyp resection during EMR of colorectal polyps located across a fold compared with that of colorectal polyps located between folds.

Methods

In total, 262 patients with 262 lesions that were ≥10 mm in diameter and treated with conventional EMR were enrolled. The main outcome was the incidence of incomplete polyp resections. Propensity score matching and inverse probability of treatment weighting (IPTW) were performed to reduce the effects of selection bias.

Results

Fifty-seven lesions (21.8%) were incompletely resected. After propensity score matching, the lesions located across a fold were at higher risk of incomplete resection than those between folds (26/68, 38.2% vs 7/68, 10.3%; odds ratio (OR): 3.71; 95% confidence interval (CI): 1.61-8.56; p < 0.01). These findings persisted after adjusting for the differences at baseline using the IPTW method (OR: 3.63; 95% CI: 1.72-7.63; p = 0.001).

Conclusions

There is an increased risk of an incomplete polyp resection for a colorectal polyp that is located across a fold compared with that for a polyp that is located between folds.

Clinical and endoscopic evaluations of sessile serrated adenoma/polyps with cytological dysplasia

BACKGROUND AND AIM

Although sessile serrated adenoma/polyps (SSA/Ps) are considered to be premalignant lesions and rapidly progress to carcinomas after they develop cytological dysplasia (CD), a treatment strategy for SSA/Ps in Asian countries is still being debated and has not yet been established. The present study aimed to propose a treatment strategy for SSA/Ps.

METHODS

Histopathological data of patients, who underwent colonoscopy at our center between January 2011 and December 2016, were reviewed. Data of patients with ≥ 1 SSA/P were retrieved, and clinicopathological characteristics were retrospectively analyzed.

RESULTS

A total of 281 patients with 326 SSA/Ps, including 258 patients who had 300 SSA/Ps without CD (SSA/Ps-CD[-]) and 23 patients who had 26 SSA/Ps with CD (SSA/Ps-CD[+]), were evaluated in this study. Although SSA/Ps-CD(+) were often found in older female patients and in the proximal colon, there were no significant differences between SSA/Ps-CD(-) and SSA/Ps-CD(+). Endoscopic morphological findings, such as large or small nodules on the surface and partial protrusion of the lesions, were significantly more common in SSA/Ps-CD(+) than in SSA/Ps-CD(-). Although the diagnostic ability of nodule/protrusion in lesions to predict CD within SSA/Ps was very high with an accuracy of 93.9% and a negative predictive value of 95.4%, sensitivity was low at 46.2%. SSA/Ps-CD(+) were significantly larger than SSA/Ps-CD(-), and the rate of CD within SSA/Ps significantly increased with lesion size (≤ 5 mm, 0%; 6-9 mm, 6.0%; ≥ 10 mm, 13.6%).

CONCLUSION

The study proposes removing all SSA/Ps ≥ 6 mm in order to remove high-risk SSA/Ps-CD(+), with high sensitivity.

Width and depth of resection for small colorectal polyps: hot versus cold snare polypectomy

BACKGROUND AND AIMS

Curability is associated with resection width and depth in polypectomy. We evaluated the resection width and depth achieved with hot snare polypectomy (HSP) and cold snare polypectomy (CSP) for small colorectal polyps.

METHODS

In this single-center, prospective, randomized controlled study, patients with rectal or rectosigmoid polyps ≤10 mm in diameter were treated with HSP or CSP. Resection width was evaluated as mucosal defect size, measured immediately postprocedure and 1 day later. Resection depth was histologically evaluated using obtained specimens.

RESULTS

Fifty-two patients were enrolled. Mean lesion size was 5.6 mm with HSP (n = 27) and 5.8 mm with CSP (n = 25). Mean mucosal defect diameter immediately after HSP and CSP was 5.1 mm and 7.5 mm, respectively (P < .001). The diameter 1 day after the procedure increased by 29% (95% confidence interval [CI], 17%-41%) with HSP and decreased by 25% (95% CI, 18%-32%) with CSP (P < .001). Muscularis mucosa was obtained similarly with HSP and CSP (96% [95% CI, 82%-99%] vs 92% [95% CI, 75%-98%]; P = .603). Submucosal tissue was obtained significantly more frequently with HSP than with CSP (81% [95% CI, 63%-92%] vs 24% [95% CI, 11%-43%]; P < .001).

CONCLUSIONS

The resection width immediately after CSP was larger than that after HSP but was significantly smaller at day 1 after resection. Although the resection depth after CSP was more superficial, muscularis mucosa was obtained in most specimens. Thus, CSP has sufficient resection width and depth to enable complete polyp resection and potentially has a superior safety profile than HSP.

Computed Tomography Colonography Phantom: Construction, Validation and Literature Review

Background

Several dedicated computed tomography (CT) colonography phantoms have been described previously.

Objectives

To compare their pros and cons and describe the construction of a dedicated phantom that can be easily manufactured.

Materials and Methods

We found 15 different phantom designs by literature search and compared their advantages and disadvantages based on their description and images. We tested various materials for density and mechanical properties and constructed a phantom from polypropylene pipes (30 mm and 50 mm in diameter, 52 cm in length). Haustral folds were created by heat shaping and 39 intermediate sessile polyps with a target size of 6-10 mm and two flat lesions were created from silicone. Nine polyps were attached to a fold. The model was placed in a 30-cm barrel filled with water to simulate attenuation of human body. Attenuation of polyps was compared to intermediate polyps found in patients.

Results

None of the earlier colonic phantoms found in the literature incorporated all the properties that would ensure both reproducibility and validity of the model (including a rigid wall, density of the wall and polyps similar to human colon, at least two levels of distension and durability). In the present phantom, the average size of sessile polyps was 8.6 ± 0.9 mm and their density was 53 ± 24 HU. We found no significant difference in polyp density between simulated polyps in the phantom and polyps in human subjects (P = 0.70). All polyps, with the exception of one flat lesion, were detected by computer aided detection.

Conclusion

We constructed and validated a CT colonography phantom with correct density allowing performance of reproducible experiments.

Development of a Novel Scoring System for Predicting the Risk of Colorectal Neoplasia: A Retrospective Study

OBJECTIVE

The purpose of this study was to develop a novel scoring system to screen subjects who have a high risk for colorectal neoplasia.

STUDY DESIGN AND SETTING

We retrospectively analyzed 1061 subjects undergoing total colonoscopy (TCS) for the first time at Gihoku Kosei Hospital. The characteristics and habits of the subjects were analyzed using a multivariate logistic regression analysis. The risk score was established according to each odds ratio of the individual risk factors, and the correlations between the sum of the risk scores and the prevalence of colorectal neoplasia for each individual were evaluated.

RESULTS

Age 45-59 (risk score: 2 points) and ≥60 (3 points), male gender (1 point), and habitual alcohol consumption ≥21g daily (1 point) were extracted as the significant risk factors for colorectal neoplasia. When the risk groups were determined by summing up these risk scores, the prevalence rates of colorectal neoplasia were 8.8% for the low risk group (0-2 points), 30.5% for the low-moderate risk group (3 points), 39.1% for the high-moderate risk group (4 points), and 57.6% for the high risk group (5 points). In comparison with the low risk group, the odds ratio of the low-moderate risk, the high-moderate risk, and the high risk groups were 4.6, 6.7, and 14.1 folds, respectively.

CONCLUSION

Our scoring system, which linearly correlates with the prevalence rate of colorectal neoplasia, may be an effective tool for screening the subjects who have a high risk for colorectal neoplasia. These subjects, therefore, should be recommended to undergo TCS.

Advances in the removal of diminutive colorectal polyps

Diminutive polyps (<5 mm in diameter) represent the majority of polyps found during colonoscopy; about a half of them are adenomatous, with low risk of advanced neoplasia. Recent studies have demonstrated that cold polypectomy should be considered the recommended approach for resecting diminutive polyps and that cold snaring may be superior to cold forceps biopsy, at least for polyps of 4-5 mm. Recently, electronic chromoendoscopy has been applied to characterization of diminutive polyps to discriminate adenomatous from nonadenomatous lesions. Optical diagnosis of polyp histology could potentially exert huge cost savings by the 'resect and discard' strategy for diminutive polyps and 'leaving-in' for diminutive hyperplastic polyps in the recto-sigmoid colon. These policies represent the mainstay for adopting endoscopy-directed post-polypectomy surveillance strategies, endorsed by both American and European Endoscopy Societies. Accuracy of both histology and surveillance intervals predictions from academic centers have been encouraging, although the same performance has not been replicated in community practices.

Usefulness of narrow-band imaging with dual-focus magnification for differential diagnosis of small colorectal polyps

BACKGROUND

Many authors have already reported the usefulness of narrow-band imaging (NBI) for the differential diagnosis of non-neoplastic and neoplastic colorectal lesions. However, it is not clear whether magnification is required for differential diagnosis. The aim of this prospective study was to clarify the clinical usefulness of a newly developed NBI system with a dual focus function (dual-focus NBI) compared with conventional white-light imaging (WLI) and NBI without magnification for distinguishing between non-neoplastic and neoplastic lesions.

PATIENTS AND METHODS

Thirty-seven consecutive patients who underwent screening colonoscopy with the novel system between July and December 2013 were analyzed. Patients with polyps >10 mm and those with polyps previously evaluated by histologic examination or colonoscopy were excluded. Lesions were diagnosed in real time with WLI, NBI without magnification, and dual-focus NBI, and then excised endoscopically. Each diagnosis was compared to that in the final histopathology reports. The primary endpoint was the diagnostic accuracy and the confidence level assigned to each modality by the endoscopists. The secondary endpoint was the differentiation ability according to the size of the lesion (≤5 and 6-10 mm).

RESULTS

In all, 100 lesions including 76 adenomatous polyps and 24 hyperplastic polyps were analyzed in 37 patients. The overall diagnostic accuracy, sensitivity, and specificity for differentiating adenomatous from hyperplastic polyps were 87.0, 89.5, and 79.2 % for WLI, 93.0, 94.7, and 87.5 % for NBI without magnification, and 94.0, 96.1, and 87.5 % for dual-focus NBI, respectively. The level of confidence was significantly different between dual-focus NBI and WLI and NBI without magnification for diminutive (≤5 mm) lesions (p < 0.001 and p < 0.01).

CONCLUSION

Dual-focus NBI is especially useful for differential diagnosis of diminutive colorectal lesions.

Current status and future perspectives of endoscopic diagnosis and treatment of diminutive colorectal polyps

During colonoscopy, small and diminutive colorectal polyps are commonly encountered. It is estimated that at least one adenomatous polyp is detected in almost half of all patients undergoing screening colonoscopy. In contrast, the 'predict, resect, and discard' strategy for diminutive and small colorectal polyps is a current topic especially in Western countries. 'Is this an acceptable policy in Japan?' Herein, we report the results of a questionnaire survey with regard to the management of diminutive colorectal polyps, including the thoughts of Japanese endoscopists regarding the 'predict, resect, and discard' strategy. At the moment, we propose that this strategy should be used by skilled endoscopists only.

Colorectal polyps and polyposis syndromes

A polyp is defined as any mass protruding into the lumen of a hollow viscus. Colorectal polyps may be classified by their macroscopic appearance as sessile (flat, arising directly from the mucosal layer) or pedunculated (extending from the mucosa through a fibrovascular stalk). Colorectal polyps may also be histologically classified as neoplastic or as non-neoplastic (hyperplastic, hamartomatous, or inflammatory). The neoplastic polyps are of primary importance because they harbor a malignant potential, which represents a stage in the development of colorectal cancer. For this reason, it is essential to identify these polyps at a sufficiently early stage, when a simple outpatient procedure to remove them can interrupt the development of colorectal cancer and prevent disease and death. When invasive carcinoma arises in a polyp, careful consideration must be given to ensuring the adequacy of treatment. Although most neoplastic polyps do not evolve into cancer, it is well accepted that the majority of colorectal carcinomas evolve from adenomatous polyps; the sequence of events leading to this transformation is referred to as the adenoma-to-carcinoma sequence.

The presence of a systemic process that promotes the development of multiple gastro-intestinal polyps is termed ‘polyposis’. Hereditary gastro-intestinal polyposis syndromes account for approximately 1% of all cases of colorectal cancer and are associated with a broad spectrum of extra-colonic tumors. Early detection and accurate classification of these syndromes are essential, in order to initiate a surveillance program for the early detection of cancer. Several polyposis syndromes have been described, each having its own genetic basis and characteristic polyp distribution, clinical presentation, and malignancy risk.

Diagnostic modalities and treatment options for neoplastic polyps—as well as the most prevalent polyposis syndromes—are reviewed below.