Colorectal lateral spreading tumor subtypes: clinicopathology and outcome of endoscopic submucosal dissection

Endoscopic submucosal dissection versus endoscopic mucosal resection for laterally spreading rectal tumours

AIM

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are the two main techniques used for endoscopic resection of superficial rectal tumours. The aim of this study was to compare the outcomes of ESD and EMR in treating superficial rectal tumours.

METHOD

A retrospective observational study was conducted at two French centres including all patients treated with ESD or EMR for superficial rectal tumours. The primary outcome was the rate of local recurrence at the first follow-up endoscopy after endoscopic resection. Secondary outcomes included the curative resection rate, procedure duration, length of hospital stay, complication rates and the need for additional surgery.

RESULTS

A total of 254 patients were included, 159 treated with ESD and 95 treated with EMR. The local recurrence rate at the first follow-up endoscopy was 8.6% and was significantly lower in the ESD group than in the EMR group (4.3% vs. 16.9%; p = 0.005). The rates of en bloc and histologically complete resections were higher in the ESD group (88.1% vs. 42.7% and 85.5% vs. 38.9%, respectively; p < 0.001), while the curative resection rate was 90.6% in the EMR group and 92.5% in the ESD group (p = 0.59). Mostly due to poor histoprognostical criteria, 6.0% of patients underwent additional surgery (6.3% vs. 5.2% in the ESD vs. EMR group, respectively; p = 0.73).

CONCLUSION

ESD demonstrated higher rates of en bloc, R0 resection than EMR, translating into significantly lower rates of local recurrence at the first follow-up endoscopy.

Integrated Analysis Identifies Novel Fusion Transcripts in Laterally Spreading Tumors Suggestive of Distinct Etiology Than Colorectal Cancers

BACKGROUND

Laterally spreading tumors (LSTs) of the colon and rectum are a class of abnormality which spreads laterally and appears ulcerated. They are a subclass of colorectal cancer (CRCs) with higher invasive potential than CRCs. Moreover, the etiology of LST still remains obscure.

METHODS

This study aimed to identify unique fusion transcript(s) in LSTs and evaluate their role in LST development and progression. RNA-Seq data for LST samples from the EMBL-EBI database were used to identify fusion transcripts. An integrated approach using Gene Ontology, pathway analysis, hub gene, and co-expression network analysis functionally characterized fusion transcripts to shed light upon the etiology of LSTs.

RESULT

We identified 48 unique fusion genes in LSTs. GO terms were enriched in mRNA metabolic (p ≤ 2.06E-06), mRNA stabilization (p ≤ 1.60E-05), in cytosol (1.20E-05), RBP (p ≤ 2.30E-04), and RNA binding activity (p ≤ 3.51E-08) processes. Pathway analysis revealed an inflammatory phenotype of LSTs suggesting a distinct etiology than CRCs as pathways were enriched in salmonella infection (p ≤ 4.41 e-03), proteoglycans in cancer (p ≤ 1.18 e-02), and insulin signaling (p ≤ 2.13 e-02). Our exclusion and inclusion criteria and hub gene analysis finally identified 9 hub genes. Co-expression analysis of hub genes identified the most significant transcription factors (NELFE, MYC, TAF1, MAX) and kinases (MAPK14, CSNK2A1, CDK1, MAPK1) which were implicated in various cancer pathways. Furthermore, an overall survival analysis of hub genes was performed. Our predefined criterion resulted in the enrichment of NPM1-PTMA (NPM1: p ≤ 0.005) and HIST1H2BO-YBX1 (YBX1: p ≤ 0.02) fusion transcripts, significantly associated with the patient's overall survival.

CONCLUSION

Our systematic analysis resulted in novel fusion genes in LSTs suggesting a different etiology than CRCs. Fusion transcripts were observed more frequently in non-granular LSTs suggestive of genetically more unstable than granular LST. We hypothesize that NPM1-PTMA and HIST1H2BO-YBX1 could be implicated in LST development and progression and may also serve as a prognostic or diagnostic biomarker in future for better management of LSTs.

Colorectal Endoscopic Submucosal Dissection: An Update on Best Practice

Endoscopic submucosal dissection (ESD) is a method of en-bloc resection of neoplastic colorectal lesions which is less invasive compared to surgical resection. Lesion stratification, architecture recognition and estimation of depth of invasion are crucial for patient selection. Expert endoscopists have integrated a variety of classification systems including Paris, lateral spreading tumor (LST), narrow band imaging (NBI), international colorectal endoscopic (NICE) and Japanese NBI expert team (JNET) in their day-to-day practice to enhance lesion detection accuracy. Major societies recommend ESD for LST-non granular (NG), Kudo-VI type, large depressed and protruded colonic lesions with shallow submucosal invasion. Chance of submucosal invasion enhances with increased depth as well as tumor location and size. In comparison to endoscopic mucosal resection (EMR), ESD has a lowerl recurrence rate and higher curative resection rate, making it superior for larger colonic lesions management. Major complications such as bleeding and perforation could be seen in up to 11% and 16% of patients, respectively. In major Western countries, performing ESD is challenging due to limited number of expert providers, lack of insurance coverage, and unique patient characteristics such as higher BMI and higher percentage of previously manipulated lesions.

Risk factors associated with clinical outcomes of endoscopic mucosal resection for colorectal laterally spreading tumors: A Honam Association for the Study of Intestinal Diseases (HASID) multicenter study

BACKGROUND/AIMS

Colorectal laterally spreading tumors (LSTs) are large and superficial neoplasms. Most are adenomatous lesions. Endoscopic mucosal resection (EMR) is a standard technique of removing precursor colorectal lesions. The aim of the present study was to assess the factors associated with the clinical outcomes of EMR for LSTs.

MATERIALS AND METHODS

A total of 275 patients with LSTs who underwent EMR were enrolled in the study. The clinical outcomes of the patients were analyzed by retrospectively reviewing their medical records.

RESULTS

The en bloc resection and R0 resection rates were 86.9% and 80.4%, respectively. The bleeding and perforation rates were 7.6% and 0.4%, respectively. The frequency of high-grade dysplasia and adenocarcinoma histology was significantly higher, and the procedure time was significantly longer in LSTs >20 mm than in those ≤20 mm. The R0 resection rate was significantly higher in LSTs ≤20 mm than in those >20 mm. The frequency of piecemeal resection was significantly higher in LSTs with an adenomatous and cancerous pit pattern than in those with a non-neoplastic pit pattern. The frequency of piecemeal resection was significantly higher in LSTs with adenocarcinoma than in those with low-grade dysplasia. Multivariate analysis revealed that adenomatous pit pattern, high-grade dysplasia, or adenocarcinoma was a significant independent risk factor of LSTs for piecemeal resection after EMR.

CONCLUSION

EMR is useful for treating ≤20 mm LSTs with regard to curative resection and procedure time. LSTs with an adenomatous pit pattern, high-grade dysplasia, or adenocarcinoma are significant independent risk factors for piecemeal resection after EMR.

ASGE review of adverse events in colonoscopy

Colonoscopy is the most commonly performed endoscopic procedure and overall is considered a low-risk procedure. However, adverse events (AEs) related to this routinely performed procedure for screening, diagnostic, or therapeutic purposes are an important clinical consideration. The purpose of this document from the American Society for Gastrointestinal Endoscopy's Standards of Practice Committee is to provide an update on estimates of AEs related to colonoscopy in an evidence-based fashion. A systematic review and meta-analysis of population-based studies was conducted for the 3 most common and important serious AEs (bleeding, perforation, and mortality). In addition, this document includes an updated systematic review and meta-analysis of serious AEs (bleeding and perforation) related to EMR and endoscopic submucosal dissection for large colon polyps. Finally, a narrative review of other colonoscopy-related serious AEs and those related to specific colonic interventions is included.

Long-term prognosis after treatment for T1 carcinoma of laterally spreading tumors: a multicenter retrospective study

PURPOSE

Long-term prognosis of T1 laterally spreading tumors (LSTs) after treatment have not been clarified. This study compared clinicopathological characteristics and long-term prognosis of T1 LSTs.

METHODS

We retrospectively assessed 169 patients with 169 T1 LSTs between January 1992 and December 2008 by ten hospitals. Patients who did not meet the Japanese Society for Cancer of the Colon and Rectum (JSCCR) 2016 guidelines for the treatment of colorectal carcinoma (CRC) criteria were defined as non-endoscopically curable. The number of non-endoscopically curable patients with LST-granular/ nodular mixed (LST-G-M) was 61, that with LST-non-granular/ flat elevated (LST-NG-FE) was 23, and that with LST-non-granular/ pseudo depressed (LST-NG-PD) was 23. Clinicopathological variables and long-term prognosis were analyzed.

RESULTS

For overall patients, tumor size, number of non-endoscopically curable cases, and rate of submucosal invasion depth ≥ 1000 μm for the LST-G-M group were significantly higher than those in the other groups. For non-endoscopically curable patients, the tumor size for those with LST-G-M was significantly larger than those in the other groups. The rate of submucosal invasion width ≥ 4000 μm and type B/C muscularis mucosae with LST-G-M was higher than that with LST-NG-FE. All recurrences occurred in non-endoscopically curable patients with LST-G-M. Five-year overall and disease-free survivals for non-endoscopically curable patients with LST-G-M were significantly shorter than those for patients with non-endoscopically curable LST-NG-FE and PD.

CONCLUSIONS

Our data supported adequacy of the JSCCR guidelines for the treatment of CRC criteria for endoscopically curable patients after T1 LSTs treatment. Patients with T1 LST-G-M should be followed up more carefully.

Clinical outcomes of endoscopic submucosal dissection for laterally spreading tumors involving the dentate line

OBJECTIVE

Endoscopic submucosal dissection (ESD) for laterally spreading tumors (LST) involving the dentate line (LST-DL) is challenging because of the specific anatomical features of the anorectum. This study aimed to evaluate the efficacy and safety of ESD for LST-DL.

METHODS

Consecutive patients with LST-DL who had undergone ESD at our hospital between January 2010 and December 2015 were retrospectively enrolled in this study. Rates of en bloc resection, R0 resection, and complications, pathological characteristics, and tumor recurrence were analyzed and compared with those of LST in the rectum not involving the dentate line (LST-NDL).

RESULTS

Altogether 49 patients with LST-DL (median age 63 years; 39 women; median lesion size 57 mm; median follow-up period of 24 months) and 96 patients with LST-NDL (median age 67 years; 31 women; median lesion size 47 mm; median follow-up period of 31 months) were enrolled. En bloc resection (93.9% [46/49] vs 94.8% [91/96]) and en bloc R0 resection rates (83.7% [41/49] vs 88.5% [85/96]), respectively, for LST-DL and LST-NDL, with no significant differences. However, ESD for LST-DL had a longer procedure time (77 min vs 54 min, P = 0.02), a greater postprocedural perianal pain rate (28.6% vs 0%, P < 0.001), and more anal strictures (4.1% vs 0%, P = 0.04). The complication rates of perforation, bleeding and fever, recurrence rate, and pathological characteristics did not differ between the two groups.

CONCLUSIONS

ESD is a safe and effective therapeutic modality for LST-DL. However, this procedure should be performed by experienced endoscopists and the difficulty needs to be fully considered.

Management of colorectal laterally spreading tumors: a systematic review and meta-analysis

Objective and study aims  To evaluate the efficacy and safety of different endoscopic resection techniques for laterally spreading colorectal tumors (LST). Methods  Relevant studies were identified in three electronic databases (PubMed, ISI and Cochrane Central Register). We considered all clinical studies in which colorectal LST were treated with endoscopic resection (endoscopic mucosal resection [EMR] and/or endoscopic submucosal dissection [ESD]) and/or transanal minimally invasive surgery (TEMS). Rates of en-bloc/piecemeal resection, complete endoscopic resection, R0 resection, curative resection, adverse events (AEs) or recurrence, were extracted. Study quality was assessed with the Newcastle-Ottawa Scale and a meta-analysis was performed using a random-effects model. Results  Forty-nine studies were included. Complete resection was similar between techniques (EMR 99.5 % [95 % CI 98.6 %-100 %] vs. ESD 97.9 % [95 % CI 96.1 - 99.2 %]), being curative in 1685/1895 (13 studies, pooled curative resection 90 %, 95 % CI 86.6 - 92.9 %, I ²  = 79 %) with non-significantly higher curative resection rates with ESD (93.6 %, 95 % CI 91.3 - 95.5 %, vs. 84 % 95 % CI 78.1 - 89.3 % with EMR). ESD was also associated with a significantly higher perforation risk (pooled incidence 5.9 %, 95 % CI 4.3 - 7.9 %, vs. EMR 1.2 %, 95 % CI 0.5 - 2.3 %) while bleeding was significantly more frequent with EMR (9.6 %, 95 % CI 6.5 - 13.2 %; vs. ESD 2.8 %, 95 % CI 1.9 - 4.0 %). Procedure-related mortality was 0.1 %. Recurrence occurred in 5.5 %, more often with EMR (12.6 %, 95 % CI 9.1 - 16.6 % vs. ESD 1.1 %, 95 % CI 0.3 - 2.5 %), with most amenable to successful endoscopic treatment (87.7 %, 95 % CI 81.1 - 93.1 %). Surgery was limited to 2.7 % of the lesions, 0.5 % due to AEs. No data of TEMS were available for LST. Conclusions  EMR and ESD are both effective and safe and are associated with a very low risk of procedure related mortality.

Clinical outcomes of endoscopic resection for colorectal laterally spreading tumors with advanced histology

BACKGROUND

Colorectal laterally spreading tumors (LSTs) are large, flat neoplasms that are usually treated using different endoscopic techniques based on their morphology, size, and histology. The aim of this study was to evaluate the clinical outcomes of LSTs with advanced histology treated by endoscopic resection.

METHODS

A total of 246 LSTs with advanced histology [i.e., high-grade dysplasia (HGD) and adenocarcinoma (AC)] treated by endoscopic resection [i.e., endoscopic mucosal resection (EMR), EMR-precutting (EMR-P), and endoscopic submucosal dissection (ESD)] were enrolled. Clinicopathological characteristics were collected by review of patient's medical records.

RESULTS

The en bloc resection and R0 resection rates were 75.6% and 85.0%, respectively. The bleeding and perforation rates were 10.2% and 2.4%, respectively. The frequency of cancerous pit pattern and bleeding was significantly higher in LSTs with AC than in LSTs with HGD. The R0 resection rate in LSTs with HGD was significantly higher than that in LSTs with AC. The frequency of cancerous pit patterns in LST cases with submucosal AC was significantly higher than those with intramucosal AC. The mean size of the LSTs was significantly larger in ESD group than in EMR or EMR-P groups. The frequencies of nodular mixed subtype, cancerous pit patterns, and en bloc resection rates were significantly higher in the ESD group than in the EMR or EMR-P groups. However, the frequency of perforation was significantly higher in EMR-P group than in EMR or ESD groups.

CONCLUSIONS

These results indicate that ESD is a more acceptable treatment approach for resection of colorectal LSTs of larger size, with nodular mixed subtype, having a cancerous pit pattern or AC, using either en bloc or curative resection methods, compared to EMR or EMR-P procedures.

Clinicopathological feature and treatment outcome of patients with colorectal laterally spreading tumors treated by endoscopic submucosal dissection

BACKGROUND/AIMS

Endoscopic submucosal dissection (ESD) is an advanced technique that can be used to treat precancerous and early colorectal neoplasms by facilitating en bloc resection regardless of tumor size. In our study, we investigated the clinicopathological feature and the treatment outcome of patients with colorectal laterally spreading tumors (LSTs) that were treated by ESD.

METHODS

The study enrolled all of 210 patients with colorectal LSTs who underwent ESD. Clinical outcomes were analyzed by retrospectively reviewing medical records.

RESULTS

A cancerous pit pattern (Vi/Vn) was more common in pseudo-depressed (PD) subtype than in flat elevated (FE) subtype. The incidence of adenocarcinoma in the PD subtype and nodular mixed (NM) subtypes was significantly higher than in the homogenous (HG) subtype and FE subtype. The en bloc and R0 resection rates were 89.0% and 85.7%, respectively. The bleeding and perforation rates were 5.2% and 1.9%, respectively. The mean procedure time was much longer in the PD subtype than in the FE subtype. The en bloc resection rate was significantly higher in the NM subtype than in the HG subtype. However, there were no statistically significant differences in mean procedure time, en bloc resection rate, R0 resection rate, bleeding rate, or perforation rate between LST-granular and LST-nongranular types.

CONCLUSIONS

These results indicate that ESD is acceptable for treating colorectal LSTs concerning en bloc resection, curative resection, and risk of complications. Careful consideration is required for complete resection of the PD subtype and NM subtype because of their higher malignant potential.

Risk factors for procedure-related complications after endoscopic resection of colorectal laterally spreading tumors

Colorectal laterally spreading tumors (LSTs) are large and flat elevated neoplasms with diameters of at least 10 mm. Endoscopic resection of LSTs, with their large size and broad base, is difficult and dangerous compared with the resection of polypoid neoplasms. This study aimed to determine the risk factors for procedure-related complications including bleeding and perforation after endoscopic resection of LSTs.Patients with colorectal LST undergoing endoscopic resection at 5 university hospitals in Honam Province of South Korea were enrolled, and their records about patients, lesions, and procedure parameters associated with the occurrence of complications were reviewed retrospectively. Logistic regression analysis was performed to identify risk factors for complications.The frequency of comorbidities in bleeding group was significantly higher than in the no bleeding group. The frequency of bleeding was significantly higher in lesions with adenocarcinoma than in lesions with low or high-grade dysplasia. The frequency of bleeding was significantly higher in piecemeal resection than in en bloc resection. The frequency of perforation was significantly higher in endoscopic mucosal resection-precutting (EMR-P) than in endoscopic mucosal resection (EMR) or endoscopic submucosal dissection. The mean procedure duration was significantly longer in the perforation group than in the no perforation group. On multivariate analysis, patient comorbidity and histologic grade of the lesion were significant independent risk factors for bleeding, whereas EMR-P was a significant independent risk factor for perforation after endoscopic resection.This study demonstrated that patient comorbidity and histologic grade of lesion were significant independent risk factors for bleeding, and EMR-P was a significant independent risk factor for perforation after endoscopic resection of colorectal LSTs.

Comparing outcomes for endoscopic submucosal dissection between Eastern and Western countries: A systematic review and meta-analysis

AIM

To compare endoscopic submucosal dissection (ESD) outcomes between Eastern and Western countries.

METHODS

A systematic review and meta-analysis was performed using PubMed, MEDLINE, Web of Science, CINAHL and EBM reviews to identify studies published between 1990 and February 2016. The primary outcome was the efficacy of ESD based on information about either curative resection, en bloc or R0 resection rates. Secondary outcomes were complication rates, local recurrence rates and procedure times.

RESULTS

Overall, 238 publications including 84318 patients and 89512 gastrointestinal lesions resected using ESD were identified. 90% of the identified studies reporting ESD on 87296 lesions were conducted in Eastern countries and 10% of the identified studies reporting ESD outcomes in 2216 lesions were from Western countries. Meta-analyses showed higher pooled percentage of curative, en bloc, and R0 resection in the Eastern studies; 82% (CI: 81%-84%), 95% (CI: 94%-96%) and 89% (CI: 88%-91%) compared to Western studies; 71% (CI: 61%-81%), 85% (CI: 81%-89%) and 74% (CI: 67%-81%) respectively. The percentage of perforation requiring surgery was significantly greater in the Western countries (0.53%; CI: 0.10-1.16) compared to Eastern countries (0.01%; CI: 0%-0.05%). ESD procedure times were longer in Western countries (110 min vs 77 min).

CONCLUSION

Eastern countries show better ESD outcomes compared to Western countries. Availability of local ESD expertise and regional outcomes should be considered for decision making to treat gastrointestinal lesions with ESD.

Clinicopathological features of laterally spreading colorectal tumors and their association with advanced histology and invasiveness: An experience from Honam province of South Korea: A Honam Association for the Study of Intestinal Diseases (HASID)

Background and aims

Laterally spreading colorectal tumors (LSTs) are divided into four subtypes, including homogenous (HG), nodular mixed (NM), flat elevated (FE), and pseudo-depressed (PD), based on their different endoscopic morphologies. The aim of this study was to investigate the clinicopathological significance of LST subtypes and their association with advanced histology.

Methods

We investigated the medical records of consecutive patients with LST who initially underwent endoscopic resection at five university hospitals in Honam province of South Korea between January 2012 and December 2013. A total of 566LST lesions removed via endoscopic procedures were collected retrospectively for data analysis.

Results

The PD, FE, and NM subtypes were more common in the distal colon and the HG subtype in the proximal colon. The PD subtype had the biggest tumor size, followed by the NM subtype. The frequency of adenomatous pit pattern was significantly higher in the HG, NM, and FE subtypes than in the PD subtype. In contrast, the frequency of cancerous pit pattern was significantly higher in the PD subtype than in the other three subtypes. The rate of advanced histology (high-grade dysplasia or carcinoma) among the LSTs was 36.0%. The risk of advanced histology increased in the distal colon compared with the proximal colon. The PD subtype had the highest incidence of villous component, advanced histology,submucosal invasion, and postprocedure perforation among the four subtypes. The distal colon as tumor site, larger tumor size, PD subtype, and villous component were associated with a statistically significant increased risk of advanced histology.

Conclusion

Our results indicate that the location, size, endoscopic subtype, and histologic component of the LSTs are associated with an increased risk of advanced histology. Therefore, these clinicopathological parameters may be useful in selecting therapeutic strategies in the clinical setting.

Endoscopic mucosal resection and endoscopic submucosal dissection for colorectal lesions: A systematic review

AIM

To assess the efficacy and safety of endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) for the treatment of colorectal lesions.

METHODS

A literature search was conducted from January 2000 to May 2015. The main outcomes were: recurrence after "en bloc" and "piecemeal" resection; procedure related adverse events; the EMR endoscopic success rate and the completely eradicated resection rate (R0) after ESD.

RESULTS

A total of 66 studies were included in the analysis. The total number of lesions was 17950 (EMR: 11.873; ESD: 6077). Recurrence rate was higher in the EMR than ESD group (765/7303l vs. 50/3910 OR 8.19, 95% CI 6.2-10.9 p<0.0001). EMR-en bloc resection was achieved in 6793/10803 lesions (62.8%) while ESD-en bloc resection was obtained in 5500/6077 lesions (90.5%) (OR 0.18, p<0.0001, 95% CI 0.16-0.2). Perforation occurred more frequently in ESD than in EMR group (p<0.0001, OR 0.19, 95% CI 0.15-0.24).

CONCLUSIONS

Endoscopic resection of large colorectal lesions is safe and effective. Compared with EMR, ESD results in higher "en bloc" resection rate and lower local recurrence rate, however ESD has high procedure-related complication rates.

Efficacy and safety of endoscopic resection of large colorectal polyps: a systematic review and meta-analysis

OBJECTIVE

To assess the efficacy and safety of endoscopic resection of large colorectal polyps.

DESIGN

Relevant publications were identified in MEDLINE/EMBASE/Cochrane Central Register for the period 1966-2014. Studies in which ≥20 mm colorectal neoplastic lesions were treated with endoscopic resection were included. Rates of postendoscopic resection surgery due to non-curative resection or adverse events, as well as the rates of complete endoscopic removal, invasive cancer, adverse events, recurrence and mortality, were extracted. Study quality was ascertained according to Newcastle-Ottawa Scale. Forest plot was produced based on random effect models. I2 statistic was used to describe the variation across studies due to heterogeneity. Meta-regression analysis was also performed.

RESULTS

50 studies including 6442 patients and 6779 large polyps were included in the analyses. Overall, 503 out of 6442 patients (pooled rate: 8%, 95% CI 7% to 10%, I2=78.6%) underwent surgery due to non-curative endoscopic resection, and 31/6442 (pooled rate: 1%, 95% CI 0.7% to 1.4%, I2=0%) to adverse events. Invasive cancer at histology, non-curative endoscopic resection, synchronous lesions and recurrence accounted for 58%, 28%, 2.2% and 5.9% of all the surgeries, respectively. Endoscopic perforation occurred in 96/6595 (1.5%, 95% CI 1.2% to 1.7%) polyps, while bleeding in 423/6474 (6.5%, 95% CI 5.9% to 7.1%). Overall, 5334 patients entered in surveillance, 502/5836 (8.6%, 95% CI 7.9% to 9.3%) being lost at follow-up. Endoscopic recurrence was detected in 735/5334 patients (13.8%, 95% CI 12.9% to 14.7%), being an invasive cancer in 14/5334 (0.3%, 95% CI 0.1% to 0.4%). Endoscopic treatment was successful in 664/735 cases (90.3%, 95% CI 88.2% to 92.5%). Mortality related with management of large polyps was reported in 5/6278 cases (0.08%, 95% CI 0.01% to 0.15%).

CONCLUSIONS

Endoscopic resection of large polyps appeared to be an extremely effective and safe intervention. However, an adequate endoscopic surveillance is necessary for its long-term efficacy.

Safe and Efficient Colonic Endoscopic Submucosal Dissection Using an Injectable Hydrogel

Endoscopic submucosal dissection (ESD) has not yet been widely adopted in the treatment of early colonic cancers due to the greater technical difficulty involved, longer procedure time, and the increased risk of perforation. Adequate mucosal elevation by submucosal injection is crucial for en bloc resection and prevention of perforation during colonic ESD. This study is aimed to evaluate the efficacy of an injectable thermoreversible hydrogel as the colonic submucosal agent for the first time. Triblock copolymer poly(lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) was synthesized, and its concentrated aqueous solution was injected into the colonic submucosa of living minipig and spontaneously transformed into an in situ hydrogel with adequate mucosal elevation at body temperature. Such a mucosal lifting lasted for a longer time than that created by the control group, glycerol fructose. Colonic ESD was then performed with the administration of hydrogels at various polymer concentrations or glycerol fructose. All colonic lesions were successfully resected en bloc after one single injection of the hydrogel, and repeated injections were not needed. No evidence of major hemorrhage, perforation and tissue damage were observed. Considering the injection pressure, duration of mucosal elevation and efficacy of "autodissection", the hydrogel containing 15 wt % polymer was the optimized system for colonic ESD. Consequently, the thermoreversible hydrogel is an ideal submucosal fluid that provides a durable mucosal lifting and makes colonic ESD accessible to a large extent. In particular, the efficacy of "autodissection" after one single injection of the hydrogel simplifies significantly the procedures while minimizing the complications.

Large Colorectal Lesions: Evaluation and Management

In the last years, a distinctive interest has been raised on large polypoid and non-polypoid colorectal tumors, and specially on flat neoplastic lesions ≥20 mm tending to grow laterally, the so called laterally spreading tumors (LST). Real or virtual chromoendoscopy, endoscopic ultrasound or magnetic resonance should be considered for the estimation of submucosal invasion of these neoplasms. Lesions suitable for endoscopic resection are those confined to the mucosa or selected cases with submucosal invasion ≤1000 μm. Polypectomy or endoscopic mucosal resection remain a first-line therapy for large colorectal neoplasms, whereas endoscopic submucosal dissection in high-volume centers or surgery should be considered for large LSTs for which en bloc resection is mandatory.

Non-polypoid colorectal neoplasms: Classification, therapy and follow-up

In the last years, an increasing interest has been raised on non-polypoid colorectal tumors (NPT) and in particular on large flat neoplastic lesions beyond 10 mm tending to grow laterally, called laterally spreading tumors (LST). LSTs and large sessile polyps have a greater frequency of high-grade dysplasia and local invasiveness as compared to pedunculated lesions of the same size and usually represent a technical challenge for the endoscopist in terms of either diagnosis and resection. According to the Paris classification, NPTs are distinguished in slightly elevated (0-IIa, less than 2.5 mm), flat (0-IIb) or slightly depressed (0-IIc). NPTs are usually flat or slightly elevated and tend to spread laterally while in case of depressed lesions, cell proliferation growth progresses in depth in the colonic wall, thus leading to an increased risk of submucosal invasion (SMI) even for smaller neoplasms. NPTs may be frequently missed by inexperienced endoscopists, thus a careful training and precise assessment of all suspected mucosal areas should be performed. Chromoendoscopy or, if possible, narrow-band imaging technique should be considered for the estimation of SMI risk of NPTs, and the characterization of pit pattern and vascular pattern may be useful to predict the risk of SMI and, therefore, to guide the therapeutic decision. Lesions suitable to endoscopic resection are those confined to the mucosa (or superficial layer of submucosa in selected cases) whereas deeper invasion makes endoscopic therapy infeasible. Endoscopic mucosal resection (EMR, piecemeal for LSTs > 20 mm, en bloc for smaller neoplasms) remains the first-line therapy for NPTs, whereas endoscopic submucosal dissection in high-volume centers or surgery should be considered for large LSTs for which en bloc resection is mandatory and cannot be achieved by means of EMR. After piecemeal EMR, follow-up colonoscopy should be performed at 3 mo to assess resection completeness. In case of en bloc resection, surveillance colonoscopy should be scheduled at 3 years for adenomatous lesions ≥ 1 cm, or in presence of villous features or high-grade dysplasia patients (regardless of the size), while less intensive surveillance (colonoscopy at 5-10 years) is needed in case of single (or two) NPT < 1 cm presenting tubular features or low-grade dysplasia at histology.

Inter-observer agreement in the endoscopic classification of colorectal laterally spreading tumors: a multicenter study between experts and trainees

BACKGROUND AND AIM

The risk of cancer varies with the subtype of colorectal "laterally spreading tumors" (LSTs). However, visual interpretations vary among endoscopists. The aim of this study was to evaluate inter-observer agreement and accuracy in the endoscopic classification of LST subtypes among experts and trainees.

METHODS

In total, 40 LST images were collected and reviewed independently by 14 gastroenterology experts and 10 trainees. All investigators recorded their findings as one of the following four categories: homogeneous, nodular mixed, flat-elevated, and pseudo-depressed. Agreement was assessed in terms of the kappa (κ) statistic and AC1 estimate. Accuracy is reported as percentage agreement with the gold standard, based on the gross morphology of the resected specimens.

RESULTS

Of the possible 91 pair-wise κ estimates among experts, 41 (45.1%) were >0.75, indicating excellent agreement, while only 2 (4.44%) of the 45 pair-wise κ estimates among trainees were >0.75. Agreements for individual LST subtypes in the trainee group were significantly lower than those in the expert group. The κ and AC1 estimates showed similar values in individual subtypes of LSTs. The overall accuracy of LST was also significantly higher for the experts than the trainees (85.9 vs. 72.5%, P < 0.001). Notably, the flat-elevated subtype showed the lowest agreement and accuracy and was frequently misclassified as the pseudo-depressed subtype by both groups.

CONCLUSIONS

Inter-observer agreement and accuracy for LST subtype classification differ significantly between experts and trainees. Implementation of an adequate training system for beginners is necessary to better identify colorectal LSTs.

Advanced endoscopic resection in the colon: recent innovations, current limitations and future directions

The major health burden of colorectal cancer is reduced by colonoscopic polypectomy. The majority of polyps encountered are diminutive in size and easily removed; however, endoscopic removal of lesions >20 mm in size is also effective and safe. Techniques have progressed, advancing the boundaries of endoscopic therapy to include resection of circumferential lesions and selected submucosal invasive cancers. While there are cost and safety advantages over surgical management, specific limitations of endoscopic resection remain, chiefly bleeding, perforation and recurrence. Recent studies highlight the utility of risk stratification and demonstrate the effectiveness of endoscopic treatment of complications; however, strategies for prevention remain elusive. Prediction of submucosal invasive cancers through systematic assessment of lesion morphology and surface pattern is now established. Harnessing submucosal invasive cancer prediction and risk stratification allows a shift toward lesion-specific therapy, the next paradigm in the management of advanced colonic lesions.

Clinicopathological characteristics of laterally spreading colorectal tumor

BACKGROUND AND AIMS

Laterally spreading tumor (LST) is a colorectal pre-cancerous lesion. Previous studies have demonstrated distinct LST clinicopathological characteristics in different populations. This study evaluated clinicopathological characteristics of LST in a Chinese population.

METHODS

A total of 259 Chinese LST patients with 289 lesions were recruited for endoscopic and clinicopathological analyses.

RESULTS

Among these 289 lesions, 185 were granular type (LST-G), whereas 104 were non-granular type (LST-NG). LST-G lesions were further classified into homogeneous G-type and nodular mixed G-type, while LST-NG lesions were further classified into flat elevated NG-type and pseudo-depressed NG-type. Clinically, these four LST subtypes showed distinct clinicopathological characteristics, e.g., lesion size, location, or histopathological features (high-grade intraepithelial neoplasia and submucosal carcinoma). The nodular mixed G-type showed larger tumor size and higher incidence of high-grade intraepithelial neoplasia compared to the other three subtypes, while pseudo-depressed NG-type lesions showed the highest incidence of submucosal carcinoma. Noticeably, no diffidence was detected between the lesions of homogeneous G-type and flat elevated NG-type with regard to the histopathological features. Histology of the malignancy potential was associated with nodular mixed G-type [OR = 2.41, 95% CI (1.09-5.29); P = 0.029], flat elevated NG-type [OR = 3.49, 95% CI (1.41-8.22); P = 0.007], Diameter ≥30 mm [OR = 2.56, 95% CI (1.20-5.20); P = 0.009], Villous adenoma [OR = 2.76, 95% CI (1.01-7.58); P = 0.048] and serrated adenoma [OR = 6.99, 95% CI (1.81-26.98); P = 0.005].

CONCLUSION

Chinese LSTs can be divided into four different subtypes, which show distinct clinicopathological characteristics. Morphology, size and pathological characteristics are all independent predictors of advanced histology.