Flat and depressed types of early colorectal cancers: from East to West

Approaches and considerations in the endoscopic treatment of T1 colorectal cancer

The detection of early colorectal cancer (CRC) is increasing through the implementation of screening programs. This increased detection enhances the likelihood of minimally invasive surgery and significantly lowers the risk of recurrence, thereby improving patient survival and reducing mortality rates. T1 CRC, the earliest stage, is treated endoscopically in cases with a low risk of lymph node metastasis (LNM). The advantages of endoscopic treatment compared with surgery include minimal invasiveness and limited tissue disruption, which reduce morbidity and mortality, preserve bowel function to avoid colectomy, accelerate recovery, and improve cost-effectiveness. However, T1 CRC has a risk of LNM. Thus, selection of the appropriate treatment between endoscopic treatment and surgery, while avoiding overtreatment, is challenging considering the potential for complete resection, LNM, and recurrence risk.

Molecular and clinicopathological differences between depressed and protruded T2 colorectal cancer

Background

Colorectal cancer (CRC) can be classified into four consensus molecular subtypes (CMS) according to genomic aberrations and gene expression profiles. CMS is expected to be useful in predicting prognosis and selecting chemotherapy regimens. However, there are still no reports on the relationship between the morphology and CMS.

Methods

This retrospective study included 55 subjects with T2 CRC undergoing surgical resection, of whom 30 had the depressed type and 25 the protruded type. In the classification of the CMS, we first defined cases with deficient mismatch repair as CMS1. And then, CMS2/3 and CMS4 were classified using an online classifier developed by Trinh et al. The staining intensity of CDX2, HTR2B, FRMD6, ZEB1, and KER and the percentage contents of CDX2, FRMD6, and KER are input into the classifier to obtain automatic output classifying the specimen as CMS2/3 or CMS4.

Results

According to the results yielded by the online classifier, of the 30 depressed-type cases, 15 (50%) were classified as CMS2/3 and 15 (50%) as CMS4. Of the 25 protruded-type cases, 3 (12%) were classified as CMS1 and 22 (88%) as CMS2/3. All of the T2 CRCs classified as CMS4 were depressed CRCs. More malignant pathological findings such as lymphatic invasion were associated with the depressed rather than protruded T2 CRC cases.

Conclusions

Depressed-type T2 CRC had a significant association with CMS4, showing more malignant pathological findings such as lymphatic invasion than the protruded-type, which could explain the reported association between CMS4 CRC and poor prognosis.

Efficacy of international web-based educational intervention in the detection of high-risk flat and depressed colorectal lesions higher (CATCH project) with a video: Randomized trial

OBJECTIVES

Three subcategories of high-risk flat and depressed lesions (FDLs), laterally spreading tumors non-granular type (LST-NG), depressed lesions, and large sessile serrated lesions (SSLs), are highly attributable to post-colonoscopy colorectal cancer (CRC). Efficient and organized educational programs on detecting high-risk FDLs are lacking. We aimed to explore whether a web-based educational intervention with training on FIND clues (fold deformation, intensive stool/mucus attachment, no vessel visibility, and demarcated reddish area) may improve the ability to detect high-risk FDLs.

METHODS

This was an international web-based randomized control trial that enrolled non-expert endoscopists in 13 Asian countries. The participants were randomized into either education or non-education group. All participants took the pre-test and post-test to read 60 endoscopic images (40 high-risk FDLs, five polypoid, 15 no lesions) and answered whether there was a lesion. Only the education group received a self-education program (video and training questions and answers) between the tests. The primary outcome was a detection rate of high-risk FDLs.

RESULTS

In total, 284 participants were randomized. After excluding non-responders, the final data analyses were based on 139 participants in the education group and 130 in the non-education group. The detection rate of high-risk FDLs in the education group significantly improved by 14.7% (66.6-81.3%) compared with -0.8% (70.8-70.0%) in the non-education group. Similarly, the detection rate of LST-NG, depressed lesions, and large SSLs significantly increased only in the education group by 12.7%, 12.0%, and 21.6%, respectively.

CONCLUSION

Short self-education focusing on detecting high-risk FDLs was effective for Asian non-expert endoscopists. (UMIN000042348).

Predictors for malignant potential and deep submucosal invasion in colorectal laterally spreading tumors

BACKGROUND

Colorectal laterally spreading tumors (LSTs) with malignant potential require en bloc resection by endoscopic submucosal dissection (ESD), but lesions with deep submucosal invasion (SMI) are endoscopically unresectable.

AIM

To investigate the factors associated with high-grade dysplasia (HGD)/carcinoma and deep SMI in colorectal LSTs.

METHODS

The endoscopic and histological results of consecutive patients who underwent ESD for colorectal LSTs in our hospital from June 2013 to March 2019 were retrospectively analyzed. The characteristics of LST subtypes were compared. Risk factors for HGD/carcinoma and deep SMI (invasion depth ≥ 1000 μm) were determined using multivariate logistic regression.

RESULTS

A total of 323 patients with 341 colorectal LSTs were enrolled. Among the four subtypes, non-granular pseudodepressed (NG-PD) LSTs (85.5%) had the highest rate of HGD/carcinoma, followed by the granular nodular mixed (G-NM) (77.0%), granular homogenous (29.5%), and non-granular flat elevated (24.2%) subtypes. Deep SMI occurred commonly in NG-PD LSTs (12.9%). In the adjusted multivariate analysis, NG-PD [odds ratio (OR) = 16.8, P < 0.001) and G-NM (OR = 7.8, P < 0.001) subtypes, size ≥ 2 cm (OR = 2.2, P = 0.005), and positive non-lifting sign (OR = 3.3, P = 0.024) were independently associated with HGD/carcinoma. The NG-PD subtype (OR = 13.3, P < 0.001) and rectosigmoid location (OR = 8.7, P = 0.007) were independent risk factors for deep SMI.

CONCLUSION

Because of their increased risk for malignancy, it is highly recommended that NG-PD and G-NM LSTs are removed en bloc through ESD. Given their substantial risk for deep SMI, surgery needs to be considered for NG-PD LSTs located in the rectosigmoid, especially those with positive non-lifting signs.

Endoscopic submucosal dissection for colorectal laterally spreading tumors: Clinical outcomes and predictors of technical difficulty

OBJECTIVE

We aimed to investigate the clinical outcomes of endoscopic submucosal dissection (ESD) for the treatment of colorectal laterally spreading tumors (LSTs) and the factors related to technical difficulty.

METHODS

Consecutive patients who underwent ESD for colorectal LSTs between June 2013 and January 2019 were retrospectively included. Factors associated with difficult ESD procedures (defined as conversion to piecemeal resection or discontinuation of endoscopic procedure), and dissection with a slow speed (<8 mm² /min), were determined using the logistic regression analysis.

RESULTS

A total of 325 patients with 342 colorectal LSTs (median size 20.0 mm) were enrolled. The proportions of granular (LST-G) and non-granular LST (LST-NG) were 62.9% and 37.1%, respectively. The overall en bloc and complete resection rates were 89.8% and 81.9%, respectively. The endoscopic procedure was discontinued in four lesions (1.2%), and 31 (9.1%) converted to piecemeal resection because of technical difficulty. Using multivariate analysis, positive non-lifting sign (odds ratio [OR] 19.9, P < 0.001), tumor size ≥20 mm (OR 10.0, P < 0.001), and less experienced endoscopists (OR 3.7, P = 0.005) were independent factors for technically difficult procedure. Positive non-lifting sign (OR 3.7, P = 0.004), lesion size <20 mm (OR 3.7, P < 0.001), LST-NG type (OR 1.8, P = 0.034), and less colorectal ESD experience (OR 1.9, P = 0.016) were independent factors of slow-speed dissection.

CONCLUSIONS

ESD was feasible and safe for treating colorectal LSTs. Positive non-lifting sign and tumor ≥20 mm indicated difficult ESD procedures. Technical failure was more likely to occur in lesions resected by less-experienced endoscopists. Dissection speed might be improved with more experienced operators.

Comparison of precutting endoscopic mucosal resection and endoscopic submucosal dissection for large (20-30 mm) flat colorectal lesions

BACKGROUND AND AIM

The complete and safe removal of large (≥ 20 mm) colorectal lesions is an area of concern. Endoscopic submucosal dissection (ESD) effectively removes these lesions compared with endoscopic mucosal resection (EMR). However, ESD requires advanced techniques, longer procedure time, and high cost. Precutting EMR (EMR-P) is a modified EMR method that overcomes the limitations of EMR. This study aimed to compare the efficacy and safety of EMR-P and ESD in large (20-30 mm) flat colorectal lesions.

METHODS

This was a retrospective analysis of cases in which 20- to 30-mm flat colorectal lesions were resected at Seoul St. Mary's Hospital from January 2014 to December 2019. Propensity score matching was performed to control for possible confounders.

RESULTS

Two hundred and ninety-nine patients were included in this study. After matching, 90 patients were assigned to each group. There were no significant difference in complete resection rates (92.2% vs 92.2%, P = 1.000), en bloc resection rates (95.6% vs 97.8%, P = 0.682), and mean size of lesions (22.9 ± 3.1 mm vs 23.0 ± 3.1 mm, P = 0.867) between EMR-P and ESD. Procedure time was significantly shorter with EMR-P (11.0 ± 6.5 min vs 37.0 ± 19.3 min, P < 0.001). The adverse events rate was not significantly different between both groups. No local recurrence occurred in both groups.

CONCLUSIONS

Precutting EMR was not significantly different to ESD in terms of complete resection rate and en bloc resection rate for 20- to 30-mm flat colorectal lesions without fibrosis. Furthermore, EMR-P has shorter procedure time than ESD. EMR-P could be considered one of standard treatments for large flat colorectal lesions.

Application of Artificial Intelligence in the Detection and Characterization of Colorectal Neoplasm

Endoscpists always have tried to pursue a perfect colonoscopy, and application of artificial intelligence (AI) using deep-learning algorithms is one of the promising supportive options for detection and characterization of colorectal polyps during colonoscopy. Many retrospective studies conducted with real-time application of AI using convolutional neural networks have shown improved colorectal polyp detection. Moreover, a recent randomized clinical trial reported additional polyp detection with shorter analysis time. Studies conducted regarding polyp characterization provided additional promising results. Application of AI with narrow band imaging in real-time prediction of the pathology of diminutive polyps resulted in high diagnostic accuracy. In addition, application of AI with endocytoscopy or confocal laser endomicroscopy was investigated for real-time cellular diagnosis, and the diagnostic accuracy of some studies was comparable to that of pathologists. With AI technology, we can expect a higher polyp detection rate with reduced time and cost by avoiding unnecessary procedures, resulting in enhanced colonoscopy efficiency. However, for AI application in actual daily clinical practice, more prospective studies with minimized selection bias, consensus on standardized utilization, and regulatory approval are needed. (Gut Liver 2021;15:-353)

Two histologic compartments in nonpolypoid conventional colon adenomas

Two intertwined compartments coexisting in nonpolypoid conventional (i.e. tubular or villous) adenomas are highlighted in this review: one built of dysplastic tissue on top and the other portraying crypts with irregular, corrupted shapes, albeit lined with normal epithelium, below. The latter compartment has remained unattended in the literature. Recently, however, the histologic characteristics of the nondysplastic compartment in nonpolypoid conventional adenomas were closely examined, and some of its biological attributes were unveiled. Studies with the proliferation marker ki67 showed that the crypts with irregular, corrupted shapes in the nondysplastic compartment displayed haphazardly distributed proliferating cell-domains. Given that the proliferating cells are generated by stem cells, the relocation of proliferating cell-domains in those crypts seems to be the result of a reorganization of the stem cells within the crypts. The abnormal distribution of proliferating cells, the finding of p53-upregulated cells, and of crypts in asymmetric fission suggest that the crypts in that compartment are histo-biologically altered, probably somatically mutated. This new information might contribute to unravel the riddle of crypto-histogenesis of nonpolypoid conventional adenomas of the colon. More research along these lines is necessary, before the biology of the crypts in the nondysplastic compartment can be fully translated into molecular terms.

Treatment policy for colonic laterally spreading tumors based on each clinicopathologic feature of 4 subtypes: actual status of pseudo-depressed type

BACKGROUND AND AIMS

Laterally spreading tumors (LSTs) are originally classified into 4 subtypes. Pseudo-depressed nongranular types (LSTs-NG-PD) are gaining attention because of their high malignancy potential. Previous studies discussed the classification of nongranular (LST-NG) and granular types (LST-G); however, the actual condition or indication for endoscopic treatment of LSTs-NG-PD remains unclear. We aimed to compare the submucosal invasion pattern of LSTs-NG-PD with the other 3 subtypes.

METHODS

A total of 22,987 colonic neoplasms including 2822 LSTs were resected endoscopically or surgically at Showa University Northern Yokohama Hospital. In these LSTs, 322 (11.4%) were submucosal invasive carcinomas. We retrospectively evaluated the clinicopathologic features of LSTs divided into 4 subtypes. In 267 LSTs resected en bloc, their submucosal invasion site was further evaluated.

RESULTS

The frequency of LSTs in all colonic neoplasms was significantly higher in women (14.9%) than in men (11.0%). Rates of submucosal invasive carcinoma were .8% in the granular homogenous type (LSTs-G-H), 15.2% in the granular nodular mixed type (LSTs-G-M), 8.0% in the nongranular flat elevated type (LSTs-NG-F), and 42.5% in LSTs-NG-PD. Tumor size was associated with submucosal invasion rate in LSTs-NG-F and LSTs-NG-PD (P < .001). The multifocal invasion rate of LSTs-NG-PD (46.9%) was significantly higher than that of LSTs-G-M (7.9%) or LSTs-NG-F (11.8%). In LSTs-NG-PD, the invasion was significantly deeper (≥1000 μm) if observed in 1 site.

CONCLUSIONS

For LSTs-G-M and LSTs-NG-F that may have invaded the submucosa, en bloc resection could be considered. Considering that LSTs-NG-PD had a higher submucosal invasion rate, more multifocal invasive nature, and deeper invasion tendency, regardless if invasion was only observed in 1 site, than LSTs-NG-F, we should endoscopically distinguish LSTs-NG-PD from LSTs-NG-F and strictly adopt en bloc resection by endoscopic submucosal dissection or surgery for LSTs-NG-PD. (Clinical trial registration number: UMIN 000020261.).

Efficacy and safety of endoscopic submucosal tunnel dissection for rectal laterally spreading tumors

BACKGROUND

Evidence that comprehensively compares the efficacy and safety of endoscopic submucosal tunnel dissection (ESTD) with endoscopic submucosal dissection (ESD) for rectal laterally spreading tumors (LSTs) is limited.

METHODS

Between January 2009 and June 2018, 143 rectal LSTs in 143 patients who had undergone either ESD (n = 84) or ESTD (n = 59) were included in the study. One-to-one propensity score matching (PSM) was performed, and 50 pairs were selected. The data on patient demographics, treatment information, pathology reports, adverse events and follow-up were collected.

RESULTS

Before PSM, the median specimen area was significantly larger in the ESTD group than in the ESD group (12.56 cm² vs. 6.32 cm², respectively; p < 0.001). The median dissection speed was significantly higher in the ESTD group than in the ESD group (24.53 mm²/min vs. 15.16 mm²/min, respectively; p < 0.001). After PSM, the median dissection speed was significantly higher in the ESTD group than in the ESD group (23.80 mm²/min vs. 17.12 mm²/min, respectively; p < 0.001). In multiple linear regression analysis, significant factors related to a higher dissection speed were the treatment method of ESTD (p < 0.001) and larger specimen area (p < 0.001).

CONCLUSIONS

ESTD appears to be a safe and effective method to treat rectal LSTs. Compared with ESD, ESTD appears to achieve a higher dissection speed for rectal LSTs.

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.

Comparison of the histopathological characteristics of large colorectal laterally spreading tumors according to growth pattern

OBJECTIVES

Colorectal laterally spreading tumors (LSTs) are widely recognized owing to their structural characteristics. This study aims to clarify the histopathological characteristics of large colorectal LSTs according to growth pattern.

METHODS

We studied 297 colorectal LSTs measuring ≥20 mm in diameter. The LSTs were classified into four types: granular homogenous type (LST-G-H), granular nodular mixed type (LST-G-M), non-granular flat elevated type (LST-NG-F), and non-granular pseudo-depressed type (LST-NG-PD). Retrospectively collected data were examined to compare the histopathological characteristics of LSTs according to the growth pattern.

RESULTS

LST-G-M lesions (142 lesions) were most common, followed by LST-NG-F (74 lesions), LST-G-H (61 lesions), and LST-NG-PD (20 lesions). The mean tumor diameter of LST-G lesions (38.5 ± 17.2 mm) was significantly greater than that of LST-NG lesions (26.3 ± 7.0 mm, P < 0.001). In particular, 45% of LST-G-M lesions were ≥40 mm in diameter. Adenomas accounted for 54% of LST-G-H lesions compared with only 10% of LST-NG-PD lesions. Pathological T1 carcinomas accounted for 55% of LST-NG-PD lesions and were not found among LST-G-H lesions.

CONCLUSIONS

The biological malignancy of colorectal LSTs differs considerably depending on the growth pattern even among large lesions and therefore should be considered when selecting treatment regimens.

Predictors of invasive cancer of large laterally spreading colorectal tumors: A multicenter study in Japan

Background and Aim

Although colorectal laterally spreading tumors (LSTs) can be classified into four subtypes, the histopathological characteristics are known to differ among these subtypes. We therefore performed a logistic regression analysis to determine whether the risk of pathological T1 cancer of large colorectal LSTs can be predicted based on factors such as endoscopic findings in a large group of patients enrolled in a multicenter study in Japan.

Methods

In the main study, we assessed 1236 colorectal adenomas or early cancers that were classified as LSTs measuring 20 mm or more in diameter and treated endoscopically. Logistic regression analysis was performed to determine whether factors such as the subtype of LST could be used to predict the risk of pathological T1 cancer. A validation study of 356 large colorectal LSTs was conducted to confirm the validity of the results obtained in the main study.

Results

The locations and tumor diameter of the LSTs in the main study were found to differ significantly according to the LST subclassification (P < 0.001). The frequency of pathological T1 cancers was the highest at 36% of LST nongranular pseudodepressed type, followed by 14% of LST nongranular flat‐elevated type, 11% of LST granular nodular mixed type, and 3% of LST granular homogenous type lesions. The risk of pathological T1 cancer was significantly associated with LST subclassification and tumor diameter. The area under the curve (AUC) was high (0.743). In the validation study, the AUC was 0.573.

Conclusions

In patients with large colorectal LSTs resected endoscopically, the risk of pathological T1 cancer can be predicted on the basis of the LST subclassification and tumor diameter.

Artificial intelligence and colonoscopy: Current status and future perspectives

BACKGROUND AND AIM

Application of artificial intelligence in medicine is now attracting substantial attention. In the field of gastrointestinal endoscopy, computer-aided diagnosis (CAD) for colonoscopy is the most investigated area, although it is still in the preclinical phase. Because colonoscopy is carried out by humans, it is inherently an imperfect procedure. CAD assistance is expected to improve its quality regarding automated polyp detection and characterization (i.e. predicting the polyp's pathology). It could help prevent endoscopists from missing polyps as well as provide a precise optical diagnosis for those detected. Ultimately, these functions that CAD provides could produce a higher adenoma detection rate and reduce the cost of polypectomy for hyperplastic polyps.

METHODS AND RESULTS

Currently, research on automated polyp detection has been limited to experimental assessments using an algorithm based on ex vivo videos or static images. Performance for clinical use was reported to have >90% sensitivity with acceptable specificity. In contrast, research on automated polyp characterization seems to surpass that for polyp detection. Prospective studies of in vivo use of artificial intelligence technologies have been reported by several groups, some of which showed a >90% negative predictive value for differentiating diminutive (≤5 mm) rectosigmoid adenomas, which exceeded the threshold for optical biopsy.

CONCLUSION

We introduce the potential of using CAD for colonoscopy and describe the most recent conditions for regulatory approval for artificial intelligence-assisted medical devices.

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.

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.

Morphology as a risk factor for the malignant potential of T2 colorectal cancer

Currently, depressed type T1 colorectal cancer is often detected and its malignant potential is being revealed. However, few reports have focused on the morphology of T2 colorectal cancer types. The aim of the present retrospective study was to clarify the characteristics of colorectal T2 cancer types derived from depressed type T1 cancer. The present study included 195 patients with colorectal T2 cancer surgically resected at a referral hospital between April 2001 and April 2009. A total of 48 lesions (25%) with lymph node metastasis and 4 (2%) with distant metastasis were found. The lesions were classified by their form during endoscopy into four categories: Group A, depressed type (the periphery consists of normal mucosa); group B, laterally spreading type; group C, protruded type; group D, ulcerative type (the periphery consists of neoplastic mucosa). Tumor size, lymphatic and venous involvement, lymph node metastasis, and distant metastasis were compared between the four categories. The distribution of patients were as follows: Group A, 73 (37%), group B, 26 (13%), group C, 24 (12%) and group D, 72 (37%). The average tumor size for each category was 23, 51, 30 and 36 mm for groups A, B, C and D, respectively. The number of positive findings for lymphatic involvement, venous involvement, lymph node metastasis and distant metastasis for each category were: Group A, 50 (69%), 54 (74%), 19 (26%) and 1 (1%); group B, 14 (54%), 12 (46%), 8 (31%) and 0 (0%); group C, 14 (58%), 8 (33%), 6 (25%) and 0 (0%); group D 35 (49%), 41 (57%), 16 (22%) and 3 (4%). Group A demonstrated a significantly smaller tumor size (P<0.01), and higher rates of lymphatic and venous involvement (P=0.0333 and P=0.0019, respectively). No significant differences were observed between categories with regards to nodal and distant metastases. Of the T2 cancer types, ~40% were the depressed type. Compared with the other forms, depressed type lesions exhibited a smaller tumor size, and higher rates of lymphatic and venous involvement, which suggested these lesions were of a more malignant nature.

iTRAQ-Based Proteomics Screen identifies LIPOCALIN-2 (LCN-2) as a potential biomarker for colonic lateral-spreading tumors

The improvement and implementation of a colonoscopy technique has led to increased detection of laterally spreading tumors (LSTs), which are presumed to constitute an aggressive type of colonic neoplasm. Early diagnosis and treatment of LSTs is clinically challenging. To overcome this problem, we employed iTRAQ to identify LST-specific protein biomarkers potentially involved in LST progression. In this study, we identified 2,001 differentially expressed proteins in LSTs using iTRAQ-based proteomics technology. Lipocalin-2 (LCN-2) was the most up-regulated protein. LSTs expression levels of LCN-2 and matrix metallopeptidase-9 (MMP-9) showed positive correlation with worse pathological grading, and up-regulation of these proteins in LSTs was also reflected in serum. Furthermore, LCN-2 protein overexpression was positively correlated with MMP-9 protein up-regulation in the tumor tissue and serum of LST patients (former r_s = 0.631, P = 0.000; latter r_s = 0.815, P = 0.000). Our results suggest that LCN-2 constitutes a potential biomarker for LST disease progression and might be a novel therapeutic target in LSTs.

Practical problems of measuring depth of submucosal invasion in T1 colorectal carcinomas

PURPOSE

Submucosal invasion depth (SID) in colorectal carcinoma (CRC) is an important factor in estimating risk of lymph node metastasis, but can be difficult to measure, leading to inadequate or over-extensive treatment. Here, we aimed to clarify the practical aspects of measuring SID in T1 CRC.

METHODS

We investigated 568 T1 CRCs that were resected surgically at our hospital from April 2001 to December 2013, and relationships between SID and clinicopathological factors, including the means of measurement, lesion morphology, and lymph node metastasis.

RESULTS

Of these 568 lesions, the SID was ≥1000 μm in 508 lesions. SIDs for lesions measured from the surface layer were all ≥1000 μm. Although lesions with SIDs ≥1000 μm were associated with significantly higher levels of unfavorable histologic types and lymphovascular infiltration than shallower lesions, a depth of ≥1000 μm was not a significant risk factor for lymph node metastasis (LNM) (6.7 vs. 9.8 %; P = 0.64), and no lesions for which the sole pathological factor was SID ≥1000 μm had lymph node metastasis. Protruded lesions showed deeper SIDs than other types.

CONCLUSIONS

Although we found several problems of measuring SID in this study, we also found, surprisingly, that SID is not a risk factor for lymph node metastasis, and its measurement is not needed to estimate the risk of lymph node metastasis.

Screening colonoscopy: what is the most reliable modality for the detection and characterization of colorectal lesions?

Colonoscopy is considered the best modality for the detection and treatment of colorectal polyps. However, some polyps still may not be detected. Although conventional white-light endoscopy is the gold standard for the detection of colorectal polyps, up to a fifth of lesions may be missed on screening colonoscopy, especially non-polypoid colorectal neoplasms. Recently, many studies have reported on various endoscopic modalities that improve the detection and characterization of colorectal lesions. Newly developed modalities might be helpful to recognize colorectal lesions; however, careful observation is required to identify flat/depressed lesions as well as hidden polyps during screening and surveillance colonoscopy.

Recent chemotherapy reduces the maximum-standardized uptake value of 18F-fluoro-deoxyglucose positron emission tomography in colorectal cancer

BACKGROUND/AIMS

The aim of this study was to evaluate the influence of recent chemotherapy on the patterns of the maximum-standardized uptake value (M-SUV) and sensitivity of (18)F-fluoro-deoxyglucose positron emission tomography/computed tomography ((18)F-FDG-PET/CT) in colorectal cancer.

METHODS

We retrospectively analyzed the FDG-PET/CT of 509 patients who underwent surgery for colorectal cancer. Subgroup analysis was performed according to chemotherapy status; 401 patients were not treated with chemotherapy and 108 patients were treated with chemotherapy within 6 months prior to surgery. Pathologic analysis of the surgical specimen was used as the gold standard.

RESULTS

The M-SUV was significantly lower in patients treated with chemotherapy than in those not treated with chemotherapy in pathologically confirmed same stages of disease. The difference in the sensitivity of the M-SUV according to chemotherapy status was greatest using a cutoff M-SUV value of 6.4 (p<0.001). The longest diameter of the primary tumor was the most important factor that correlated with M-SUV of the primary tumor irrespective of the chemotherapy effect (p<0.001). The M-SUV of the primary tumor was not an independent predictor of lymph node metastasis in colorectal cancer.

CONCLUSIONS

The results indicate that the M-SUV of FDG-PET/CT should be interpreted in the context of concurrent chemotherapy.

Clinicopathological differences of laterally spreading tumors arising in the colon and rectum

PURPOSE

Laterally spreading tumors (LST) have been recognized worldwide. The aim of our retrospective study was to evaluate the clinicopathological differences of LST arising in the colon and rectum.

METHODS

We investigated the clinical records of consecutive patients with LST that were endoscopically or surgically resected at our hospital between February 2006 and March 2011. LST were classified into three types: granular-homogenous (LST-GH), granular-nodular mixed (LST-GM), and nongranular (LST-NG) types. We also defined the hardly elevated flat lesion with a dilated pit pattern that occurs at the margins of LST as the "skirt." The clinicopathological characteristics of the LST arising in the colon and rectum, including the presence of the skirt, were compared.

RESULTS

A total of 496 colorectal LST in 435 patients were examined. LST-GM was predominant in the rectum, whereas LST-NG was predominant in the colon (p < 0.001). The mean tumor size was larger in the rectum (39.3 ± 17.9 mm) than the colon (25.8 ± 13.6 mm) (p < 0.001). Low-grade dysplasia frequency was lower in the rectum than the colon (4 vs. 37%, p < 0.001). The skirt was identified in 15 lesions (3.0%), with a higher incidence in the rectum than the colon (17 vs. 0.5%, p < 0.001). The skirt was found only in LST-GM.

CONCLUSIONS

A greater proportion of LST-GM, greater mean size, and lower incidence of low-grade dysplasia were found in rectal LST. The skirt was a novel and unique finding, primarily observed in rectal LST-GM cases.

Conventional endoscopic features are not sufficient to differentiate small, early colorectal cancer

AIM: To evaluate the depth of invasion of small, early colorectal cancers (ECCs) using conventional endoscopic features.

METHODS: From January 2005 to September 2011, colonoscopy cohort showed that a total of 72 patients with small colorectal cancers with the size less than 20 mm underwent colonoscopy at the Yonsei University College of Medicine, Seoul, South Korea. Among them, 8 patients were excluded due to incomplete medical records. Finally, a total of 64 ECCs with submucosa (SM) invasion and size less than 20 mm were included. One hundred fifty-two adenomas with size less than 20 mm were included as controls. Nine endoscopic features, including seven morphological findings (i.e., loss of lobulation, excavation, demarcated and depressed areas, stalk swelling, fullness, fold convergence, and bleeding ulcers), pit patterns, and non-lifting signs, were evaluated retrospectively. All endoscopic features were evaluated by two experienced endoscopists who have each performed over 1000 colonoscopies annually for more than five years without knowledge of the histology.

RESULTS: Among the morphological findings, the size of deep submucosal cancers was bigger than that of superficial lesions (16.9 mm vs 12.3 mm, P < 0.001). Also, demarcated depressed areas, stalk swelling, and fullness were more common in deep SM cancers than in superficial tumors (demarcated depressed areas: 52.0% vs 15.7%, P < 0.001; stalk swelling: 100% vs 4.2%, P < 0.001; fullness: 25.0% vs 0%, P = 0.001). Among deep SM cancers, 96% of polyps showed invasive pit patterns, whereas 19.4% of superficial tumors showed invasive pit patterns (P < 0.001). A positive non-lifting sign was more common in deep SM cancers (85.0% vs 28.6%, P < 0.001). Diagnostic accuracy of invasive morphology, invasive pit patterns, and non-lifting signs for deep SM cancers were 71%, 82%, and 75%, respectively.

CONCLUSION: Conventional endoscopic findings were insufficient to discriminate small, deep SM cancers from superficial SM cancers by white light, standard colonoscopy.

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.

Laterally spreading tumors of the colorectum: clinicopathologic features and malignant potential by macroscopic morphology

BACKGROUND/AIMS

Laterally spreading tumors (LSTs) are being increasingly reported nowadays. The aims of this study were to analyze the clinicopathologic characteristics and to identify the risk factors of malignancy in patients with LSTs by morphological subclassification.

PATIENTS AND METHODS

The authors retrospectively reviewed 326 LSTs (287 patients). Patient characteristics, endoscopic findings, and histologic findings were analyzed. Endoscopic findings were subdivided into homogeneous, mixed nodular, flat elevated, and pseudo-depressed subtypes. The clinicopathological features of these subtypes were compared.

RESULTS

Of the 287 patients treated, 173 (50.3 %) were male and overall mean patient age was 65 ± 10 years (ranged 35 to 83 year). Of the 326 LSTs diagnosed, 116 (35.6 %) were homogeneous and 102 (31.3 %) were flat elevated subtype. The location was significantly different among morphological subtype. Tumors of the mixed nodular subtype were significantly larger than the tumors of the other three subtypes (p = 0.00). Of the 326 lesions, 279 underwent endoscopic mucosal resection (granular type 88.1 % (177/201)/nongranular type 81.6 % (102/125)). Two hundred forty-nine lesions (76.4 %) were resected en bloc, and 45 lesions (13.8 %) were resected using the piecemeal technique. Piecemeal resection was significantly more common for the pseudo-depressed subtype (27.0 %, p = 0.00). The overall malignancy rate on a lesion basis was 8.6 %. The malignancy rate increased with lesion size and was higher for the pseudo-depressed (24.3 %) and the mixed nodular subtype (14.1 %). Submucosal invasion was noted for 16 % of pseudo-depressed lesions, and this was significantly higher than the invasion rates of the other subtypes (p = 0.06). By multivariate analysis, morphologic subtype, especially the pseudo-depressed or mixed nodular subtype and size larger than 20 mm were risk factor of malignancy.

CONCLUSIONS

The clinicopathological features of laterally spreading tumors differ with respect to macroscopic morphology, and the risk of malignant transformation is significantly higher for the mixed nodular or pseudo-depressed subtypes and lesion larger than 20 mm. Careful consideration is required when choosing a treatment modality, and lesions of the mixed nodular and pseudo-depressed subtypes should be completely removed.

Depressed-Type Colonic Lesions and "De Novo" Cancer in Familial Adenomatous Polyposis: A Colonoscopist's Viewpoint

Familial adenomatous polyposis (FAP) is the most common inherited polyposis syndrome. Almost all patients with FAP will develop colorectal cancer if their FAP is not identified and treated at an early stage. Although there are many reports about polypoid lesions and colorectal cancers in FAP patients, little information is available concerning depressed lesions in FAP patients. Several reports suggested that depressed-type lesions are characteristic of FAP and important in the light of their rapid growth and high malignancy. Here, we describe the occurrence of depressed-type lesions in FAP patients treated at our institution. Between April 2001 and March 2010, eight of 18 FAP patients had colorectal cancers. Depressed-type colorectal cancer was found in three patients. It should be kept in mind that depressed-type lesions occur even in FAP.

Clinical outcomes and factors related to resectability and curability of EMR for early colorectal cancer

BACKGROUND

EMR has emerged as an alternative therapeutic option for selected cases of early colorectal cancer (ECC). However, the factors associated with resectability and curability of EMR for ECC remain unknown.

OBJECTIVE

To investigate clinical outcomes and factors related to resectability and curability in ECC cases treated with EMR.

DESIGN

Retrospective study.

SETTING

Tertiary-care academic medical center.

PATIENTS

This study involved all patients in whom EMR was performed for ECC at Severance Hospital between March 1997 and August 2007. A total of 236 cases of ECC occurring in 231 patients (66.2% men) were enrolled.

INTERVENTION

EMR. Curative surgical resection and lymph node dissection were used in cases that were incompletely cured by EMR.

MAIN OUTCOME MEASUREMENTS

Resectability, curability, and recurrence.

RESULTS

Complete cure was achieved for 162 lesions (68.6%). Of the remaining 74 cases (31.4%), 69 (29.2%) were incompletely cured, and the other 5 (2.1%) had an undetermined resection status and ultimately required supplementary surgical resection for curative treatment. Location on the right side of the colon, piecemeal resection, and submucosal carcinoma were independently associated with incomplete resection, whereas depressed tumor type was independently related to incomplete cure. Among the ECC cases completely cured by EMR and followed for more than a year (n = 118), local recurrence was observed in one case (0.8%) during the median follow-up period of 39.4 months (range 12.4-123.1 months).

LIMITATIONS

Single-center, retrospective study.

CONCLUSION

Our data show that EMR is feasible and could be an effective option for treatment of ECC if the technique is applied with the appropriate indications.

Microsatellite alterations at selected tetranucleotide repeats are associated with morphologies of colorectal neoplasias

BACKGROUND & AIMS

Elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) occurs during microsatellite instability (MSI) that is not associated with major defects in DNA mismatch repair (MMR) but rather the reduced (heterogenous) expression of the MMR protein hMSH3; it occurs in sporadic colorectal tumors. We examined the timing of development of EMAST during progression of colorectal neoplasias and looked for correlations between EMAST and clinical and pathology features of tumors.

METHODS

We evaluated tumor samples from a cohort of patients that had 24 adenomas and 84 colorectal cancers. EMAST were analyzed after DNA microdissection of matched normal and tumor samples using the polymorphic tetranucleotide microsatellite markers MYCL1, D9S242, D20S85, D8S321, and D20S82; data were compared with clinical and pathology findings. Traditional MSI analysis was performed and hMSH3 expression was measured.

RESULTS

Moderately differentiated adenocarcinomas and poorly differentiated adenocarcinomas had higher frequencies of EMAST (56.9% and 40.0%, respectively) than well-differentiated adenocarcinomas (12.5%) or adenomas (33.3%) (P = .040). In endoscopic analysis, ulcerated tumors had a higher frequency of EMAST (52.3%) than flat (44.0%) or protruded tumors (20.0%) (P = .049). In quantification, all tumors with >3 tetranucleotide defects lost MSH3 (>75% of cells); nuclear heterogeneity of hMSH3 occurred more frequently in EMAST-positive (40.0%) than in EMAST-negative tumors (13.2%) (P = .010).

CONCLUSIONS

EMAST is acquired during progression of adenoma and well-differentiated carcinomas to moderately and poorly differentiated carcinomas; it correlates with nuclear heterogeneity for hMSH3. Loss of hMSH3 corresponds with multiple tetranucleotide frameshifts. The association between EMAST and ulcerated tumors might result from increased inflammation.

Indications for endoscopic resection of colorectal polyps and surveillance guidelines

We report three keynote lecture presentations from the Endoscopic Forum Japan 2009 at Otaru, Hokkaido, on 1-2 August 2009. We will discuss herein: (i) colorectal cancer screening focusing on a comparison between the National Polyp Study and the Japan Polyp Study; (ii) how to deal with small polyps <5 mm in diameter; (iii) the natural history of colorectal tumor development; (iv) the importance of follow up for local recurrence after endoscopic resection for colorectal polyps; and (v) screening for colorectal cancer using two new modalities, narrow-band imaging and autofluorescence imaging. A questionnaire was completed by everyone involved in the conference and the most important results were reported and then discussed by the participants.