Clinicopathological differences of laterally spreading tumors of the colorectum according to gross appearance

A simplified algorithm to evaluate the risk of submucosal invasive cancer in large (≥20 mm) nonpedunculated colonic polyps

BACKGROUND

Recognition of submucosal invasive cancer (SMIC) in large (≥20 mm) nonpedunculated colonic polyps (LNPCPs) informs selection of the optimal resection strategy. LNPCP location, morphology, and size influence the risk of SMIC; however, currently no meaningful application of this information has simplified the process to make it accessible and broadly applicable. We developed a decision-making algorithm to simplify the identification of LNPCP subtypes with increased risk of potential SMIC.

METHODS

Patients referred for LNPCP resection from September 2008 to November 2022 were enrolled. LNPCPs with SMIC were identified from endoscopic resection specimens, lesion biopsies, or surgical outcomes. Decision tree analysis of lesion characteristics identified in multivariable analysis was used to create a hierarchical classification of SMIC prevalence.

RESULTS

2451 LNPCPs were analyzed: 1289 (52.6%) were flat, 1043 (42.6%) nodular, and 118 (4.8%) depressed. SMIC was confirmed in 273 of the LNPCPs (11.1%). It was associated with depressed and nodular vs. flat morphology (odds ratios [ORs] 35.7 [95%CI 22.6-56.5] and 3.5 [95%CI 2.6-4.9], respectively; P<0.001); rectosigmoid vs. proximal location (OR 3.2 [95%CI 2.5-4.1]; P<0.001); nongranular vs. granular appearance (OR 2.4 [95%CI 1.9-3.1]; P<0.001); and size (OR 1.12 per 10-mm increase [95%CI 1.05-1.19]; P<0.001). Decision tree analysis targeting SMIC identified eight terminal nodes: SMIC prevalence was 62% in depressed LNPCPs, 19% in nodular rectosigmoid LNPCPs, and 20% in nodular proximal colon nongranular LNPCPs.

CONCLUSIONS

This decision-making algorithm simplifies identification of LNPCPs with an increased risk of potential SMIC. When combined with surface optical evaluation, it facilitates accurate lesion characterization and resection choices.

Prevalence of Endoscopically Curable Low-Risk Cancer Among Large (≥20 mm) Nonpedunculated Polyps in the Right Colon

BACKGROUND AND AIMS

Endoscopic submucosal dissection is increasingly promoted for the treatment of all large nonpedunculated colorectal polyps (LNPCPs) to cure potential low-risk cancers (superficial submucosal invasion without additional high-risk histopathologic features). The effect of a universal en bloc strategy on oncologic outcomes for the treatment of LNPCPs in the right colon is unknown. We evaluated this in a large Western population.

METHODS

A prospective cohort of patients referred for endoscopic resection (ER) of LNPCPs was analyzed. Patients found to have cancer after ER and those referred directly to surgery were included. The primary outcome was to determine the proportion of right colon LNPCPs with low-risk cancer.

RESULTS

Over 180 months until June 2023, 3294 sporadic right colon LNPCPs in 2956 patients were referred for ER at 7 sites (median size 30 [interquartile range 15] mm). A total of 63 (2.1%) patients were referred directly to surgery, and cancer was proven in 56 (88.9%). A total of 2851 (96.4%) of 2956 LNPCPs underwent ER (median size 35 [interquartile range 20] mm), of which 75 (2.6%) were cancers. The overall prevalence of cancer in the right colon was 4.4% (n = 131 of 2956). Detailed histopathologic analysis was possible in 115 (88%) of 131 cancers (71 after ER, 44 direct to surgery). After excluding missing histopathologic data, 23 (0.78%) of 2940 sporadic right colon LNPCPs were low-risk cancers.

CONCLUSIONS

The proportion of right colon LNPCPs referred for ER containing low-risk cancer amenable to endoscopic cure was <1%, in a large, multicenter Western cohort. A universal endoscopic submucosal dissection strategy for the management of right colon LNPCPs is unlikely to yield improved patient outcomes given the minimal impact on oncologic outcomes.

CLINICALTRIALS

gov, Numbers: NCT01368289, NCT02000141.

The feasibility of endoscopic resection for colorectal laterally spreading tumors

The present study aimed to investigate the feasibility and safety of endoscopic resection for colorectal laterally spreading tumors (LSTs) in different size groups. This retrospective study included 2699 patients with LSTs who underwent endoscopic treatment at the Second Xiangya Hospital of Central South University from May 2012 to February 2022. The patient baseline and procedure outcomes were compared between the < 5 cm group, 5-10 cm group, and ≥ 10 cm group. Meanwhile, lesions larger than 5 cm in diameter were longitudinally compared for endoscopic safety using ESD with surgical operation outcomes. There were 2105 patients in the < 5 cm group, 547 patients in the 5-10 cm group, and 47 patients in the ≥ 10 cm group. En bloc resection and R0 resection rates, the incidence of adverse events, length of stay (LOS), and medical costs significantly differed between the groups (P < 0.01). Comorbidity of diabetes or hypertension, history of antithrombotic drug use, lesion size, location, gross type, endoscopic procedures selection, and circumferential extent of the mucosal defect were independent risk factors for delayed bleeding (P < 0.05). En bloc resection, R0 resection, and lesion canceration were associated with local recurrence. For lesions larger than 5 cm in diameter, ESD had similar R0 resection and local recurrence rates compared with a surgical operation but a lower en bloc rate, LOS, and medical costs. Expert endoscopists can significantly increase en bloc and R0 resection rates and reduce the incidence of adverse events. Endoscopic resection results distinguish in different size groups of colorectal LSTs, yet its safety and feasibility are not inferior to a surgical operation.

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 treatment of early colorectal cancer

Early colorectal neoplasia is a localized precancerous lesion of the large intestine associated with negligible risk of lymphatic or systemic dissemination. Early neoplasia consists of adenoma with low- and high-grade dysplasia, intramucosal carcinoma and superficially invasive cancer without other high-risk features. In the majority of cases, early neoplastic lesions are detected by colonoscopy and treated by means of endoscopy resection replacing surgical treatment. Risk of invasive cancer should be stratified during diagnostic colonoscopy using morphological classifications and then, appropriate resection technique (endoscopic polypectomy, endoscopic mucosal resection, endoscopic submucosal dissection or full-thickness resection) is used. Success of endoscopic resection is assessed by histological examination of the resected specimen and in some cases, additional surgical resection with lymphadenectomy should be performed. Colonoscopic surveillance is needed due to the risk of local recurrence and metachronous lesions.

Risk of Covert Submucosal Cancer in Patients With Granular Mixed Laterally Spreading Tumors

BACKGROUND AND AIMS

Granular mixed laterally spreading tumors (GM-LSTs) have an intermediate level of risk for submucosal invasive cancer (SMICs) without clear signs of invasion (covert); the optimal resection method is uncertain. We aimed to determine the risk of covert SMIC in GM-LSTs based on clinical and endoscopic factors.

METHODS

We collected data from 693 patients (50.6% male; median age, 69 years) with colorectal GM-LSTs, without signs of invasion, who underwent endoscopic resection (74.2%) or endoscopic submucosal dissection (25.2%) at 7 centers in Italy from 2016 through 2019. We performed multivariate and univariate analyses to identify demographic and endoscopic factors associated with risk of SMIC. We developed a multivariate model to calculate the number needed to treat (NNT) to detect 1 SMIC.

RESULTS

Based on pathology analysis, 66 patients (9.5%) had covert SMIC. In multivariate analyses, increased risk of covert SMIC were independently associated with increasing lesion size (odds ratio per mm increase, 1.02, 95% CI, 1.01-1.03; P = .003) and rectal location (odds ratio, 3.08; 95% CI, 1.62-5.83; P = .004). A logistic regression model based on lesion size (with a cutoff of 40 mm) and rectal location identified patients with covert SMIC with 47.0% sensitivity, 82.6% specificity, and an area under the curve of 0.69. The NNT to identify 1 patient with a nonrectal SMIC smaller than 4 cm was 20; the NNT to identify 1 patient with a rectal SMIC of 4 cm or more was 5.

CONCLUSIONS

In an analysis of data from 693 patients, we found the risk of covert SMIC in patients with GM-LSTs to be approximately 10%. GM-LSTs of 4 cm or more and a rectal location are high risk and should be treated by en-bloc resection. ClinicalTrials.gov, Number: NCT03836131.

Interobserver agreement of the Paris and simplified classifications of superficial colonic lesions: a Western study

Background and study aims  The Paris classification of superficial colonic lesions has been widely adopted, but a simplified description that subgroups the shape into pedunculated, sessile/flat and depressed lesions has been proposed recently. The aim of this study was to evaluate the accuracy and inter-rater agreement among 13 Western endoscopists for the two classification systems. Methods  Seventy video clips of superficial colonic lesions were classified according to the two classifications, and their size estimated. The interobserver agreement for each classification was assessed using both Cohen k and AC1 statistics. Accuracy was taken as the concordance between the standard morphology definition and that made by participants. Sensitivity analyses investigated agreement between trainees (T) and staff members (SM), simple or mixed lesions, distinct lesion phenotypes, and for laterally spreading tumors (LSTs). Results  Overall, the interobserver agreement for the Paris classification was substantial (κ = 0.61; AC1 = 0.66), with 79.3 % accuracy. Between SM and T, the values were superimposable. For size estimation, the agreement was 0.48 by the κ-value, and 0.50 by AC1. For single or mixed lesions, κ-values were 0.60 and 0.43, respectively; corresponding AC1 values were 0.68 and 0.57. Evaluating the several different polyp subtypes separately, agreement differed significantly when analyzed by the k-statistics (0.08-0.12) or the AC1 statistics (0.59-0.71). Analyses of LSTs provided a κ-value of 0.50 and an AC1 score of 0.62, with 77.6 % accuracy. The simplified classification outperformed the Paris classification: κ = 0.68, AC1 = 0.82, accuracy = 91.6 %. Conclusions  Agreement is often measured with Cohen's κ, but we documented higher levels of agreement when analyzed with the AC1 statistic. The level of agreement was substantial for the Paris classification, and almost perfect for the simplified system.

Pathological Analysis and Endoscopic Characteristics of Colorectal Laterally Spreading Tumors

Objective

This study aims to analyze the endoscopic and pathological characteristics of colorectal laterally spreading tumors (LSTs) to assist malignant risk stratification to inform selection of the appropriate treatment strategy.

Methods

Patients with colorectal LST were selected as retrospective study objects. Characteristics, including endoscopic findings and the most common site of LSTs of different diameters and histological types, were analyzed. The risk factors for malignancy in colorectal LST were explored by multivariate logistic regression analysis.

Results

LSTs with diameters of ≥20 mm were found mainly in the rectum and mainly with granular-mixed (G-M) morphology (36% and 44.6%, respectively; p < 0.05), while LSTs with diameters of <20 mm were found mainly in the ascending colon and mainly with granular-homogenous (G-H) morphology (40.9% and 46.2%, respectively; p < 0.05). Adenoma was the main histological type in patients with tumors of all diameters. However, the cancerization rate of LSTs was 31% in patients with tumor diameter ≥20 mm, while there was no invasive cancer in patients with tumor diameter < 20 mm. In the low-grade dysphasia (adenoma) group, most of the lesions were located in the ascending colon and most had the morphology LST-G-H (35.8% and 39.2%, respectively; p < 0.05). In the cancerization group, most of the lesions were located in the rectum, with the morphology LST-G-M (51.6% and 67.2%, respectively; p < 0.05), and the diameter was larger than that of the adenoma group (33.84 ± 17.99 mm vs 21.68 ± 8.99 mm).

Conclusion

The rectum was the most common site for an LST with a diameter ≥20 mm and cancerization, of which the morphology was mainly LST-G-M (endoscopic submucosal dissection is the preferred treatment for this type of LST). LST malignancy was found to be correlated with lesion diameter, location, and morphological appearance.

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.).

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.

IS SUPERFICIAL COLORECTAL LESIONS WITH LOW AND HIGH GRADES INTRAEPITHELIAL NEOPLASMS MORE PREVALENT IN OLDER ABOVE 65 YEARS?

BACKGROUND

Colorectal cancer has a higher incidence in the rectum and sigmoid. However, with the expansion of the diagnosis of superficial lesions interest in the diagnosis and in the role they play in colorectal carcinogenesis has increased.

AIM

To verify the behavior of superficial lesions of the colon and rectum, comparing the pathological and endoscopic findings, below and above 65 years.

METHODS

Cross-sectional study with prospective evaluation of standard protocol, where 200 patients with colorectal superficial lesions were evaluated; they were submitted to colonoscopy and mucosectomy of these lesions. They were divided in two age groups, below and above 65 years.

RESULTS

One hundred-and-eight were women (54%) and 92 men (46%). Most colon lesions were localized in the right colon (95%) and the remaining (5%) in the rectum. In endoscopy, 77.20% were granular lesions in patients under 65 years and 77.90% above. Colon histology showed low grade intraepithelial neoplasia, being 69.79% in patients under and 73.70% in above 65 years. In rectum, above 65 years the incidence of high-grade intraepithelial neoplasia was higher (66.70%).

CONCLUSION

The superficial colorectal lesions have been more endoscopically diagnosed today, and the highest incidence is the granular type, both in the colon and rectum, regardless of age. Regardless the age, histologically colon lesions were more as low grade intraepithelial neoplasia. In rectum, there was distinction for both age groups, being more frequent high grade intraepithelial neoplasia in patients over 65 years.

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.

A Novel Model Predicts Postoperative Pathology of Colorectal High-Grade Intraepithelial Neoplasia

BACKGROUND

To analyze the consistency of endoscopic biopsy of colorectal high-grade intraepithelial neoplasia (HGIN) and pathological diagnosis and to explore the value of preoperative examination in differentiating HGIN from invasive carcinoma.

METHODS

Clinicopathological data of 79 patients with colorectal HGIN undergoing preoperative endoscopic biopsy from January 2012 to December 2017 were retrospectively analyzed.

RESULTS

Pathologically, 57 cases (72.8%) were diagnosed as invasive carcinoma and 22 (27.8%) as HGIN. Tumor size ≥3 cm, ulcer on the surface of the lesion, HGIN without adenoma, platelet to lymphocyte ratio, neutrophil to lymphocyte ratio, lymph node enlargement, and spiculation of the peri-intestinal fat on computed tomography were associated with postoperative invasive carcinoma. Multivariate analysis showed that a longest diameter ≥3 cm, preoperative diagnosis of HGIN without adenoma, and spiculation of the peri-intestinal fat were independent factors for a postoperative diagnosis of invasive carcinoma. Depending on the weight of these three independent factors in binary logistic regression analysis, a comprehensive scoring model was established. When the score was ≥1.5, the sensitivity and specificity for the diagnosis of invasive carcinoma were 86.0% and 81.8%, respectively. Utilizing the prediction index, the area under the receiver operating characteristic curve was 0.869.

CONCLUSIONS

A diagnosis of colorectal HGIN by colonoscopy is poorly consistent with the postoperative pathological diagnosis. The scoring model established in this study for identifying colorectal infiltrating carcinoma is simple and feasible. When the comprehensive score is ≥ 1.5, an aggressive approach of surgical treatment is recommended.

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.

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.

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.

Early Outcomes of Endoscopic Submucosal Dissection for Colorectal Neoplasms According to Clinical Indications

BACKGROUND

Although endoscopic submucosal dissection has been shown to be safe and effective for colorectal tumors, its clinical outcomes vary.

OBJECTIVE

The aim of this study is to assess the outcomes of endoscopic submucosal dissection according to clinical indications.

DESIGN

This is a prospective, multicenter, single-arm study.

SETTING

The study was conducted at special hospitals for colorectal diseases and cancers.

PATIENTS

The study population included consecutive patients aged 20 to 80 years who underwent colorectal endoscopic submucosal dissection for 1) early colorectal cancer, 2) laterally spreading tumors ≥2 cm in diameter, and 3) submucosal tumors.

INTERVENTIONS

Procedures were performed by experienced colonoscopists.

MAIN OUTCOME MEASURES

The primary end points were en bloc and curative resection rates. En bloc resection was defined as endoscopic one-piece resection without tumor fragmentation. Curative resection was defined as en bloc resection and no pathologic requirement for additional surgery. Secondary end points included procedure time, complications, and hospital stay.

RESULTS

Of 321 patients, 317 (98.8%) underwent en bloc resection and 231 (72.0%) underwent curative resection. The mean procedure time was 46.2 minutes. Mean hospital stay after the procedure was 3.1 days. Perforation occurred in 2 patients (0.6%), and bleeding occurred in 10 (3.1%) patients. All patients with complications were treated by endoscopic clipping or nonoperative management. Fifteen patients (4.7%) underwent additional radical surgery owing to the risks of lymph node metastasis. Although tumor size was smaller and procedure time shorter in the submucosal tumor group than in the laterally spreading tumor or early colorectal cancer group, there were no differences in clinical outcomes including en bloc and curative resection rates. Submucosal fibrosis was the only factor affecting endoscopic submucosal dissection procedure-related complications.

LIMITATIONS

Early outcomes in a limited population and the potential for selection bias were limitations of this study.

CONCLUSIONS

Outcomes of colorectal endoscopic submucosal dissection were acceptable in selected patients, with no difference in outcomes according to clinical indications. Because submucosal fibrosis can increase complications, it should be minimized before endoscopic submucosal dissection.

Clinical significance and validity of the subclassification for colorectal laterally spreading tumor granular type

BACKGROUND AND AIM

Colorectal laterally spreading tumor granular type (LST-G) is generally divided into two subtypes based on morphology. Here, we retrospectively investigated the clinical significance of a concrete, objective LST-G subclassification.

METHODS

This study examined 636 consecutive cases that were resected endoscopically or surgically. LST-G was subclassified as follows: Type 1, a lesion with homogenous uniform granules with uniform (<5 mm) nodules; Type 2, a lesion with granules and small nodules (≥5 mm, <10 mm); or Type 3, a lesion accompanied by large nodules (≥10 mm). For the validation study, 194 images were compiled from 97 cases investigated using conventional colonoscopy and chromoendoscopy with indigo carmine dye spraying. Images were distributed in a randomized order to students without prior endoscopy experience, less-experienced endoscopists (LEE group), and highly experienced endoscopists (HEE group). Diagnostic accuracy and interobserver agreement were then evaluated.

RESULTS

There was no submucosal invasion in Type 1 lesions. The incidence of deep submucosal invasive carcinoma was higher for Type 3 lesions than for Type 2 lesions. Interobserver agreement was good in each group. Diagnostic accuracy was higher in the HEE group than in the student and LEE groups. Chromoendoscopy had a higher accuracy rate than conventional colonoscopy in the LEE and HEE groups (LEE, 0.74 vs 0.69, P < 0.05; HEE, 0.84 vs 0.78, P < 0.05).

CONCLUSIONS

This subclassification of LST-G according to the diameters of granules and nodules was both useful for choosing therapeutic strategies in the clinical setting and universally applicable.

A long-term follow-up study on the prognosis of endoscopic submucosal dissection for colorectal laterally spreading tumors

BACKGROUND AND AIMS

Colorectal laterally spreading tumors (LSTs) are divided into homogeneous (LST-G-H), nodular mixed (LST-G-M), flat elevated (LST-NG-F), and pseudodepressed (LST-NG-PD) subtypes. We hypothesized that based on the rates of advanced histology, the recurrence rates of the LST-NG-PD and LST-G-M groups may be higher than those of the other subgroups.

METHODS

Endoscopic submucosal dissection (ESD) was performed in 156 patients with a total of 177 LSTs. The clinicopathological features and long-term prognosis of ESD according to specific subtype were investigated.

RESULTS

LSTs were most commonly found in the rectum, and the highest percentage of rectal lesions was observed in the LST-G-M group (71.1% vs overall 55.4%, P = .032). The LST-G-M lesions were larger (60 ± 22 mm vs 40 ± 33 mm, P = .034) than the LST-G-H lesions. The LST-G-M group also demonstrated more high-grade intraepithelial neoplasias (32.2% vs 10.8%, P = .003) and submucosal carcinomas (13.6% vs 1.5%, P = .010) compared with the LST-G-H group. The LST-NG-PD group exhibited the highest incidence of submucosally invasive cancer (16.7%). The overall perforation rate was 2.3%. The perforation rate in the LST-NG group was higher than that in the LST-G group (5.7% vs 0.8%, P = .047). All recurrences (7.7%) were found by colonoscopy without any detection of cancers, and no difference was found among the subtypes.

CONCLUSIONS

No significant differences were observed among subgroups with 44.4 ± 16.3 months of follow-up. Considering that all recurrences were discovered by colonoscopy and most could be cured by repeated ESD, the LSTs of all subgroups require more intensive follow-up compared with smaller adenomatous lesions.

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.

Serrated and non-serrated precursor lesions of colorectal cancer

Although often viewed as a single disease, colorectal cancer more accurately represents a family of diseases with different precursor lesions. Conventional (tubular, tubulovillous and villous) adenomas are the most common neoplastic lesions occurring in the large intestine. They have adenomatous polyposis coli (APC) mutations and arise from dysplastic aberrant crypt foci, initially as polyclonal lesions. In sporadic tumours, neoplastic progression follows the traditional pathway (chromosomal instability pathway), resulting in CpG island methylator phenotype (CIMP)-negative, microsatellite-stable (MSS), BRAF and KRAS wild-type cancers. Germline mutations in the APC gene lead to familial adenomatous polyposis. Conventional adenomas are also the precursors of Lynch syndrome-associated microsatellite-instable (MSI-high) cancers. Sessile serrated adenoma/polyp (SSA/P) is the principal precursor lesion of the serrated pathway, in which BRAF mutation can lead to colorectal cancer with MSI-high CIMP-high or MSS CIMP-high phenotype. SSA/Ps have been associated with synchronous and metachronous invasive adenocarcinomas as well as so-called interval carcinomas. Serrated polyposis is rare but most likely underdiagnosed. Affected individuals bear an increased but unspecified risk for the development of colorectal cancer; close endoscopic surveillance is warranted. Traditional serrated adenomas (TSAs) are much less common than the other serrated lesions. Cancers originating from TSAs may show KRAS mutation with a CIMP-high MSS phenotype.

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.

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.

Does magnifying narrow-band imaging or magnifying chromoendoscopy help experienced endoscopists assess invasion depth of large sessile and flat polyps?

BACKGROUND

Distinguishing deep submucosa (SM) from superficial SM cancer in large sessile and flat colorectal polyps (>2 cm) is crucial in making the most appropriate therapeutic decision. We evaluated the additional role of magnifying narrow-band imaging (NBI) and magnifying chromoendoscopy (MCE) in assessing the depth of invasion in large sessile and flat polyps in comparison to morphological evaluation performed by experienced endoscopists.

METHODS

From May 2011 to December 2011, a total of 85 large sessile and flat polyps were analyzed. Endoscopic features of the polyps were independently evaluated by experienced endoscopists. Subsequently, the polyps were observed using magnifying NBI and MCE.

RESULTS

A total of 58 intramucosal lesions and 27 SM cancers (five superficial and 22 deep) were identified. The diagnostic accuracy of the experienced endoscopists, NBI, and MCE were 92.9, 90.6, and 89.4 %, respectively, for deep SM cancer. In combination with NBI or MCE, the diagnostic accuracy of the experienced endoscopists did not change significantly for deep SM cancer, with an accuracy of 95.3 % for both NBI and MCE.

CONCLUSIONS

Conventional colonoscopy can differentiate superficial from deep SM cancers with an accuracy of as high as 92.9 % in large sessile and flat polyps. Further diagnostic strategies are required in order to precisely assess the depth of invasion, especially in large colorectal polyps.

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.

Morphological change of a laterally spreading rectal tumor over a short period

BACKGROUND

Laterally spreading tumors (LSTs) are generally defined as superficial lesions ≥10 mm in diameter that typically extend laterally rather than vertically along the colonic wall. LSTs are usually categorized into 2 subtypes: granular type and nongranular type. Large nodules or depressed areas in granular-type LSTs (LST-Gs) are endoscopic findings of a cancerous component and sometimes represent submucosal invasion. However, the lateral growth and development of LST-Gs remains unclear.

CASE PRESENTATION

This case report describes a case of 79-year-old woman who underwent total colonoscopy due to a positive fecal occult blood test and was detected a LST-G, about 30 mm in diameter in the lower rectum. The lesion consisted of not only aggregated small and large nodules typically seen in LST-Gs but also the hardly elevated flat parts. In the flat part, there were dilated round pits and no evident capillary vessels. Three months later, the flat part increased in height, the dilated round pits were partly replaced by type IIIL pits, and capillary vessels were evident. The lesion was removed by endoscopic submucosal dissection, and diagnosed pathologically as tubular adenoma. We performed the sequence analyses on KRAS, BRAF, NRAS and PIK3CA genes in flat part and nodular part separately, and a mutation of KRAS gene at codon 146 was observed at only nodular part, suggesting probable that nodular part be a precancerous lesion.

CONCLUSION

This is a unique and suggestive case, providing information on progression of LST-Gs at the very early stage to carcinogenesis.

Endoscopy and polyps-diagnostic and therapeutic advances in management

Despite multiple efforts aimed at early detection through screening, colon cancer remains the third leading cause of cancer-related deaths in the United States, with an estimated 51000 deaths during 2013 alone. The goal remains to identify and remove benign neoplastic polyps prior to becoming invasive cancers. Polypoid lesions of the colon vary widely from hyperplastic, hamartomatous and inflammatory to neoplastic adenomatous growths. Although these lesions are all benign, they are common, with up to one-quarter of patients over 60 years old will develop pre-malignant adenomatous polyps. Colonoscopy is the most effective screening tool to detect polyps and colon cancer, although several studies have demonstrated missed polyp rates from 6%-29%, largely due to variations in polyp size. This number can be as high as 40%, even with advanced (> 1 cm) adenomas. Other factors including sub-optimal bowel preparation, experience of the endoscopist, and patient anatomical variations all affect the detection rate. Additional challenges in decision-making exist when dealing with more advanced, and typically larger, polyps that have traditionally required formal resection. In this brief review, we will explore the recent advances in polyp detection and therapeutic options.

Tracking the molecular features of nonpolypoid colorectal neoplasms: a systematic review and meta-analysis

OBJECTIVES

Nonpolypoid colorectal neoplasms (NP-CRNs) are proposed as a major contributor to the occurrence of interval cancers, but their underlying biology remains controversial. We conducted a systematic review and meta-analysis to clarify the major biological events in NP-CRNs.

METHODS

We systematically searched for studies examining molecular characteristics of NP-CRNs. We performed random effect meta-analyses. We measured the heterogeneity among studies using I(2) and possible publication bias using funnel plots.

RESULTS

Fifty-three studies on KRAS, APC, or BRAF mutations, microsatellite instability (MSI), CpG island methylator phenotype (CIMP), or DNA promoter hypermethylation were included. We observed less KRAS mutations (summary odds ratio (OR) 0.30, confidence interval (CI)=0.19-0.46, I(2)=77.4%, CI=70.1-82.9) and APC mutations (summary OR 0.42, CI=0.24-0.72, I(2)=22.6%, CI=0.0-66.7) in NP-CRNs vs. protruded CRNs, whereas BRAF mutations were more frequent (summary OR 2.20, CI=1.01-4.81, I(2)=0%, CI=0-70.8), albeit all with large heterogeneity. Less KRAS mutations were especially found in NP-CRNs subtypes: depressed CRNs (summary OR 0.12, CI=0.05-0.29, I(2)=0%, CI=0-67.6), non-granular lateral spreading tumors (LSTs-NG) (summary OR 0.61, CI=0.37-1.0, I(2)=0%, CI=0-74.6), and early nonpolypoid carcinomas (summary OR 0.11, CI=0.06-0.19, I(2)=0%, CI=0-58.3). MSI frequency was similar in NP-CRNs and protruded CRNs (summary OR 0.99, CI=0.21-4.71, I(2)=70.3%, CI=38.4-85.7). Data for promoter hypermethylation and CIMP were inconsistent, precluding meaningful conclusions.

CONCLUSIONS

This meta-analysis provides indications that NP-CRNs are molecularly different from protruded CRNs. In particular, some subtypes of NP-CRNs, the depressed and LST-NG, are featured by less KRAS mutations than polypoid CRNs. Prospective, multicenter studies are needed to clarify the molecular pathways underlying nonpolypoid colorectal carcinogenesis and potential implications for surveillance intervals.

Local residual neoplasia after endoscopic treatment of laterally spreading tumors during 15 months of follow-up

BACKGROUND

Among superficial neoplastic lesions of the colon and rectum, a laterally spreading tumor (LST) is a flat elevated type at least 10 mm in size. It can be treated by conventional endoscopic resection (CER). Nevertheless, local residual neoplasia (LRN) may occur during follow-up. The aim of this prospective study was to evaluate the occurrence of LRN and the risk factors for its presence.

METHODS

Consecutive patients referred for CER of an LST were included. Follow-up colonoscopies were performed after 3 and 15 months. LRN was defined histologically as the presence of neoplastic tissue in the post-CER site.

RESULTS

Of a total of 127 patients with 127 lesions, follow-up could not be completed in 48 (37.8%). Of the remaining 79 (62.2%) patients (64.6% men, mean age 66.1±9.7 years), 63 (79.7%) were negative and 16 (20.3%) were positive for the presence of LRN after 15 months. Of 62 (78.5%) patients without LRN after 3 months, 55 (88.7%) remained negative after 15 months. Of 17 (21.5%) patients with LRN after 3 months, eight (47.1%) were negative after 15 months. In a multivariate analysis, LST size of at least 20 mm was found to be a significant risk factor after 3 months (odds ratio, 5.837; 95% confidence interval 1.199-28.425; P=0.029). After 15 months, the only significant risk factor was the presence of LRN observed after 3 months (odds ratio, 6.0; 95% confidence interval, 1.793-20.073; P=0.004).

CONCLUSION

This prospective study shows that the occurrence of LRN is frequent and its treatment is less effective than reported previously. These are important limitations of CER and should be taken into consideration for the management of patients with LSTs.

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

PURPOSE

This study aims to investigate the clinicopathological features of specific subtypes of laterally spreading tumor (LST) and assessed the outcome of endoscopic submucosal dissection (ESD) based upon subdifferentiation status.

METHODS

A total of 137 LSTs were present in 135 patients; 96 were granular and 41 exhibited a nongranular pattern. Granular LSTs, subdivided into homogeneous and nodular mixed, and nongranular LSTs, subdivided into flat-elevated and pseudodepressed, were retrospectively evaluated with respect to clinicopathological features and results of ESD (en bloc R0 curative resection, procedure time, complication, and recurrence rate) according to specific subtype.

RESULTS

The distribution of high-grade intraepithelial neoplasia and submucosal carcinomas was more prominent among granular nodular mixed tumors than among granular homogeneous tumors (P = 0.007), whereas there was no significant difference between nongranular pseudodepressed tumors and flat-elevated tumors. The frequency of en bloc R0 curative resection did not differ significantly among specific subtypes. For nodular mixed and pseudodepressed lesions, the median tumor size was significantly larger (P < 0.001 for each) and mean procedure time was also longer (P < 0.05 for each) than for the other two subtypes. All complications, which included three perforations, five episodes of postoperative bleeding, and one recurrence, occurred in granular nodular mixed and nongranular pseudodepressed tumors.

CONCLUSION

The risk of cancer varies with the subtypes of LSTs. ESD is an effective treatment for LSTs, however ESD is more technically demanding and carries more complications in pseudodepressed and granular mixed subtypes.

[Non-serrated precursor lesions of colorectal tumours]

Non-serrated precursor lesions of colorectal tumours include conventional adenomas (tubular, tubulovillous and villous), inflammatory bowel disease-associated dysplasia (intraepithelial neoplasia), and hamartoma-associated dysplasia. This short review summarizes the current literature on the adenoma-carcinoma sequence, focusing on colonic stem cells and functional crypt organization, patterns of stem cell division, niche succession and clonal conversion in the formation of a monocryptal adenoma. The process of clonal interaction between neighboring crypts as well as the development of large monoclonal adenomas from small polyclonal precursor lesions is discussed in detail. Finally, the molecular pathogenesis as well as the clinical significance of inflammatory bowel disease- and hamartoma-associated carcinogenesis is addressed.