Today, endoscopy plays a crucial role not only in the detection of precancerous and malignant colorectal lesions, but also in the treatment of even widespread adenomas and T1 early cancers. In addition to classic polypectomy and endoscopic mucosal resection (EMR) using a snare, in recent years, endoscopic submucosal dissection (ESD) has become increasingly important. Marking, submucosal injection, circumferential incision of the mucosa around the lesion, tunneling, and submucosal dissection using a short diathermic knife facilitate the 'en bloc' resection of lesions larger than 3 cm, difficult to resect in one piece using a snare. Lesions with high-grade dysplasia or mucosal carcinoma are other good candidates aside from widespread adenomata with a high risk of recurrence after piecemeal resection. ESD allows R0 resection rates of more than 90% in specialized centers. Lesions of 20 cm have been removed 'en bloc' by expert endoscopists. ESD provides an optimal histopathologic yield and has a risk of recurrence as low as 3%. Endoscopic full-thickness resection using a special device (eFTRD) is another addition to the resection armamentarium. It is especially suitable for circumscribed lesions up to 2 cm in the middle and upper rectum. Endoscopic intermuscular dissection (EID) is a recent modification of ESD primarily in the rectum, including the inner, circular muscular layer into the resection specimen. In this way, it allows a histopathologic analysis of the entire submucosa beyond the mucosal and upper submucosal layer such as in ESD. This is especially important for T1 cancers invading the submucosa without any other risk factors of invasion.

Similar to T1 colon cancer (CC), risk stratification may guide T2 CC treatment and reduce unnecessary major surgery. In this study, prediction models were developed that could identify T2 CC patients with a lower risk of lymph node metastasis (LNM) for whom (intensive) follow-up after local treatment could be considered.

A nationwide cohort study was performed involving pT2 CC patients who underwent surgery between 2012 and 2020, using data from the Dutch ColoRectal Audit, which were linked to the Nationwide Pathology Databank. Four machine learning models were evaluated to predict LNM.

LNMs were found in 1877/9803 patients (19.1%). Independent risk factors included (younger) age (odds ratio [OR] 0.98, 95% confidence interval [CI] 0.979-0.990), left-sided CC (OR 1.5, 95% CI 1.4-1.7), poor differentiation (OR 1.7, 95% CI 1.4-2.2), and lymphovascular invasion (LVI; OR 4.1, 95% CI 3.6-4.7). A deficient mismatch repair (MMR) status significantly lowered the risk of LNM (OR 0.3, 95% CI 0.2-0.5). The general linear model demonstrated the highest prediction accuracy, achieving area under the receiver operating characteristic curves of 0.67 and 0.68, with good calibration. In the absence of risk factors, elderly patients (≥74 years of age) had a predicted risk of LNM of 10.7%, yet up to 30% experienced postoperative complications, with mortality rates reaching up to 3.5%. Patients with a deficient MMR status had a predicted risk of LNM of 6.1% if LVI was absent and the tumor was well-differentiated.

The risk of LNM should be weighed against surgical risks. The findings of this study will enable clinicians to make more deliberate considerations about these competing risks before making a shared decision.

Local excision is gaining acceptance as standard treatment for T1 colon cancer (CC); however, not all patients are eligible for endoscopic resection. Colonoscopy-assisted laparoscopic wedge resection (CAL-WR) is a relatively new technique that could fill the gap between endoscopic resection and major surgery. The aim of this study was to analyze the oncological safety of CAL-WR for CC.

A retrospective cohort study was performed, including patients that underwent CAL-WR for CC. Exclusion criteria were double tumors, <1 year follow-up, previous other colorectal malignancy, inflammatory bowel disease or synchronous metastases. The primary outcome was disease recurrence and the secondary outcome was overall survival.

Fifty-three patients were included; 35 patients were diagnosed with T1 CC. CAL-WR was radical (R0) for all T1 CC in 94.3% and 94.7% for tumors with deep submucosal invasion (sm2-3 Kikuchi). The mean follow-up was 3.3 years (Q1: 2.0; Q3: 4.3) for disease recurrence and 4.2 years (Q1: 2.8; Q3: 5.2) for overall survival. None of the patients with T1 CC had disease recurrence or died due to their malignancy. There were 14 patients with a T2 and 4 patients with a T3 CC, 17/18 patients underwent completion surgery. Three patients with T2 and one with T3 CC developed a locoregional recurrence (peritoneal). One patient with T3 CC developed lung metastases. Two patients with T3 and one with T2 CC died due to their malignancy.

This study suggests that CAL-WR is oncologically safe as treatment for T1 CC. The safety of incidental CAL-WR for >T1 CC, followed by completion surgery, remains unclear. Prospective studies are needed to evaluate these results.

Local full-thickness resection techniques for rectal cancer are limited by lesion size, location, or poor margin delineation. We aimed to evaluate the feasibility of endoscopic knife-assisted full-thickness resection (kFTR) guided by the pocket-detection method (PDM) for deeply invasive rectal cancer. Consecutive posterior-lateral rectal lesions suspected of deep submucosal invasion treated at a tertiary care center from February to October 2024 were retrospectively included. kFTR guided by PDM involved creating a submucosal pocket to detect and isolate the suspected invasive component (muscle-retracting sign), followed by muscularis propria incision and full-thickness resection. Technical success, accuracy of detecting deep submucosal invasion, and en-bloc resection rates were 100%. The median procedure time was 141.5 [IQR 123.7-179.5] minutes and the median hospitalization was 1 [IQR 1-7] day. No adverse events occurred. Histopathology showed R1-vertical margin in patient 1 (pT2 adenocarcinoma) and R0 resection in patients 2, 3, and 4 (pT1bsm3) after refinement of the procedure to include a ≥3 mm muscularis propria margin around the suspected invasive component. There was no recurrence at the first endoscopic follow-up of patients 1, 2, and 4. Patient 3 was sent to surgical low anterior resection due to multiple high-risk histological features. The previous kFTR did not impair surgery (no residual rectal carcinoma and 1/17 positive lymph nodes). Endoscopic kFTR guided by the PDM may be a feasible organ-preserving treatment for the detection and resection of deeply invasive posterior rectal cancer. Future studies are needed to ascertain whether rectal kFTR could represent a viable alternative to conventional surgical local excision techniques.

We investigated the clinical practice patterns of Korean endoscopists for the endoscopic resection of colorectal polyps.

From September to November 2021, an online survey was conducted regarding the preferred resection methods for colorectal polyps, and responses were compared with the international guidelines.

Among 246 respondents, those with <4 years, 4-9 years, and ≥10 years of experience in colonoscopy practices accounted for 25.6%, 34.1%, and 40.2% of endoscopists, respectively. The most preferred resection methods for non-pedunculated lesions were cold forceps polypectomy for ≤3 mm lesions (81.7%), cold snare polypectomy for 4-5 mm (61.0%) and 6-9 mm (43.5%) lesions, hot endoscopic mucosal resection (EMR) for 10-19 mm lesions (72.0%), precut EMR for 20-25 mm lesions (22.0%), and endoscopic submucosal dissection (ESD) for ≥26 mm lesions (29.3%). Hot EMR was favored for pedunculated lesions with a head size <20 mm and stalk size <10 mm (75.6%) and for those with a head size ≥20 mm or stalk size ≥10 mm (58.5%). For suspected superficial and deep submucosal lesions measuring 10-19 mm and ≥20 mm, ESD (26.0% and 38.6%) and surgery (36.6% and 46.3%) were preferred, respectively. The adherence rate to the guidelines ranged from 11.2% to 96.9%, depending on the size, shape, and histology of the lesions.

Adherence to the guidelines for endoscopic resection techniques varied depending on the characteristics of colorectal polyps. Thus, an individualized approach is required to increase adherence to the guidelines.

Combined endoscopic and laparoscopic surgery (CELS) has been used to resect colon polyps since the 1990s. These colon-sparing techniques, however, have not yet been widely adopted. With the evolution of technology in both diagnosing and treating colon cancer, colorectal surgeons should strive for a diverse and complete armamentarium through which they can best serve their patients. In this article, we hope to provide clarity on CELS by discussing three topics: (1) the history and fruition of CELS; (2) the techniques involved in CELS; and (3) the utility of CELS within different clinical scenarios. Our goal is to educate readers and stimulate consideration of CELS in select patients who might benefit greatly from these techniques.

Advanced endoscopy has been shown to be useful in the diagnosis and treatment of both benign and low-grade malignant colorectal lesions. In fact, advanced endoscopic procedures are being adopted as standard approaches to these lesions in many places around the world; however, their implementation in the United States has not been as widespread. We ascribe the difficulty in implementation to two reasons: (1) lack of advanced endoscopic training and (2) failure in reimbursement models as they relate to endoscopy. In this article, we hope to describe these barriers and inspire colorectal surgeons to try and overcome them. As surgical specialists with a mastery of endoscopic techniques, colorectal surgeons would be able to maximize benefit for their patients and minimize health care costs in the long run.

The concept of submucosal space, or rather the "third space", located between the intact mucosal flap and the muscularis propria layer of the gastrointestinal tract, represents a tunnel that the endoscopist could use to perform interventions in the muscularis propria layer or breech it to enter the mediastinum or the peritoneal cavity without full thickness perforation. The tunnel technique can be used both for the removal of mucosal tumours, called endoscopic submucosal tunnel dissection (ESTD), for the removal of subepithelial tumours (SELs), called submucosal tunnelling endoscopic resection (STER), and for the removal of extra-luminal lesions (for example in the mediastinum or in the rectum), called submucosal tunnelling endoscopic resection for extraluminal tumours (STER-ET). Aim of this updated narrative review, is to summarize the evidences that analyses indications, and outcomes of tunnelling techniques for the treatment of above mentioned lesions.

The current literature describes a variety of techniques detailed under the name of combined endoscopic-laparoscopic surgery (CELS) procedures. This systematic review of literature assessed the outcomes of colonoscopic-assisted laparoscopic-wedge resection (CAL-WR) in particular to evaluate its feasibility to remove colonic lesions that do not qualify for endoscopic resection.

Electronic databases (PubMed, Embase, and Cochrane) were searched for studies evaluating CAL-WR for the treatment of colonic lesions. Studies with missing full text, language other than English, systematic reviews, and studies with fewer than ten patients were excluded. The quality of the studies was assessed using the Newcastle-Ottawa Scale.

Out of 68 results, duplicate studies (n = 27) as well as studies that did not meet the inclusion criteria (n = 32) were removed. Nine studies were included, encompassing 326 patients who underwent a CAL-WR of the colon. The technical success rate varied from 93 to 100%, with an R0 resection rate of 91-100%. Morbidity ranged from 6% to 20%. The quality of the included studies was rated as low to moderate and contained heterogeneous terminology, methodology, and outcome measures.

There is insufficient high-quality data and substantial variation in outcome measures to draw firm conclusions regarding the value of CAL-WR. Although CAL-WR is a promising local resection technique for endoscopically unremovable neoplasms of the colon, further investigation of this technique in well-designed prospective, multicenter studies with predefined outcome measures is required.Trial registration: A protocol for this systematic review was registered in PROSPERO with the number CRD42023407966.

T1 colorectal cancer (CRC), defined by tumor invasion confined to the submucosa, has historically been managed by surgery. Improved understanding of recurrence and lymph node metastases risk, coupled with advances in endoscopic resection techniques, have led to an increasing capacity for organ-sparing local excision. Minimally invasive management of T1 CRC begins with optical evaluation of the lesion to diagnose invasive disease and quantify depth of invasion, which informs therapeutic decision making. Modality selection between various available endoscopic resection techniques depends upon lesion characteristics, technique risk-benefit profiles, and location-specific implications. Following endoscopic resection, established histopathology features determine the risk of recurrence and subsequent management including surveillance or adjuvant surgical excision. The management of non-operative candidates deviates from conventional recommendations with emerging treatment strategies in select populations.

The Zhongshan colorectal endoscopic submucosal dissection (CR-ESD) score model was proposed to grade the technical difficulty of CR-ESD. The objective of this study was to prospectively validate and update the score model.

A multicenter prospective cohort analysis of CR-ESD was conducted. Individual data on patients, lesions, and outcomes of CR-ESD were used to validate the original model and further refine the difficulty of the prediction model. Data were randomly divided into discovery and internal validation cohorts. A multivariate Cox regression analysis was conducted on the discovery cohort to develop an updated risk-scoring system, which was then validated.

Five hundred forty-eight patients with 565 colorectal lesions treated by ESD from 4 hospitals were included. In the prospective validation cohort, the area under the receiver-operating characteristic (ROC) curve for the original model was .707. Six risk factors were identified and assigned point values: tumor size (2 points for 30-50 mm, 3 points for ≥50 mm), at least two-thirds circumference of the lesion (3 points), tumor location in the cecum (2 points) or flexure (2 points), laterally spreading tumor-nongranular lesions (1 point), preceding biopsy sampling (1 point), and NBI International Colorectal Endoscopic type 3 (3 points). The updated model had an area under the ROC curve of .738 in the discovery cohort and of .782 in the validation cohort. Cases were categorized into easy (score = 0-1), intermediate (score = 2-3), difficult (score = 4-6), and very difficult (score ≥7) groups. Satisfactory discrimination and calibration were observed.

The original model achieved an acceptable level of prediction in the prospective cohort. The updated model exhibited superior performance and can be used in place of the previous version. (Clinical trial registration number: ChiCTR2100047087.).

In the current era of screening colonoscopy and increasing incidence of early rectal cancer, interventional endoscopy moves toward resections in deeper planes than the submucosal layer. Several reports support the use of endoscopic intermuscular dissection (EID) instead of endoscopic submucosal dissection (ESD) for the removal of deeply invasive rectal submucosal cancers. The resection plane into the intermuscular space, the space between the longitudinal (external) and circular (internal) muscle layer, allows radical removal of rectal invasive submucosal cancers. Furthermore, the technique offers the potential for dissection of scarred and severe fibrotic lesions in the rectum by cutting deeper and performing a partial myectomy avoiding the narrow submucosal space. We present 23 cases of EIDs both for deeply invasive rectal cancers and benign rectal lesions. This is the first report in the literature of EID resections for malignant and benign disease, including cases of severely fibrotic rectal lesions.

Implementation of population-based colorectal cancer screening programs has led to increases in the incidence of pT1 colorectal cancer. These incipient invasive cancers have a very good prognosis and can be treated locally, but more than half of these cases are treated with surgery due to the presence of histological high-risk criteria. These high-risk criteria are suboptimal, with no consensus among clinical guidelines, heterogeneity in definitions and assessment, and poor concordance in evaluation, and recent evidence suggests that some of these criteria considered high risk might not necessarily affect individual prognosis. Current criteria classify most patients as high risk with an indication for additional surgery, but only 2-10.5% have lymph node metastasis, and the residual tumor is present in less than 20%, leading to overtreatment. Patients with pT1 colorectal cancer have excellent disease-free survival, and recent evidence indicates that the type of treatment, whether endoscopic or surgical, does not significantly impact prognosis. As a result, the protective role of surgery is questionable. Moreover, surgery is a more aggressive treatment option, with the potential for higher morbidity and mortality rates. This article presents a comprehensive review of recent evidence on the clinical management of pT1 colorectal cancer. The review analyzes the limitations of histological evaluation, the prognostic implications of histological risk status and the treatment performed, the adverse effects associated with both endoscopic and surgical treatments, and new advances in endoscopic treatment.

The sole presence of deep submucosal invasion is shown to be associated with a limited risk of lymph node metastasis. This justifies a local excision of suspected deep submucosal invasive colon carcinomas (T1 CCs) as a first step treatment strategy. Recently Colonoscopy-Assisted Laparoscopic Wedge Resection (CAL-WR) has been shown to be able to resect pT1 CRCs with a high R0 resection rate, but the long term outcomes are lacking. The aim of this study is to evaluate the safety, effectiveness and long-term oncological outcomes of CAL-WR as primary treatment for patients with suspected superficial and also deeply-invasive T1 CCs.

In this prospective multicenter clinical trial, patients with a macroscopic and/or histologically suspected T1 CCs will receive CAL-WR as primary treatment in order to prevent unnecessary major surgery for low-risk T1 CCs. To make a CAL-WR technically feasible, the tumor may not include > 50% of the circumference and has to be localized at least 25 cm proximal from the anus. Also, there should be sufficient distance to the ileocecal valve to place a linear stapler. Before inclusion, all eligible patients will be assessed by an expert panel to confirm suspicion of T1 CC, estimate invasion depth and subsequent advise which local resection techniques are possible for removal of the lesion. The primary outcome of this study is the proportion of patients with pT1 CC that is curatively treated with CAL-WR only and in whom thus organ-preservation could be achieved. Secondary outcomes are 1) CAL-WR's technical success and R0 resection rate for T1 CC, 2) procedure-related morbidity and mortality, 3) 5-year overall and disease free survival, 4) 3-year metastasis free survival, 5) procedure-related costs and 6) impact on quality of life. A sample size of 143 patients was calculated.

CAL-WR is a full-thickness local resection technique that could also be effective in removing pT1 colon cancer. With the lack of current endoscopic local resection techniques for > 15 mm pT1 CCs with deep submucosal invasion, CAL-WR could fill the gap between endoscopy and major oncologic surgery. The present study is the first to provide insight in the long-term oncological outcomes of CAL-WR.

CCMO register (ToetsingOnline), NL81497.075.22, protocol version 2.3 (October 2022).

Local en bloc resection of pT1 colon cancer has been gaining acceptance during the last few years. In the absence of histological risk factors, the risk of lymph-node metastases (LNM) is negligible and does not outweigh the morbidity and mortality of an oncologic resection. Colonoscopy-assisted laparoscopic wedge resection (CAL-WR) has proved to be an effective and safe technique for removing complex benign polyps. The role of CAL-WR for the primary resection of suspected T1 colon cancer has to be established.

This retrospective study aimed to determine the radicality and safety of CAL-WR as a local en bloc resection technique for a suspected T1 colon cancer. Therefore, the study identified patients in whom high-grade dysplasia or a T1 colon carcinoma was suspected based on histology and/or macroscopic assessment, requiring an en bloc resection.

The study analyzed 57 patients who underwent CAL-WR for a suspected macroscopic polyp or polyps with biopsy-proven high-grade dysplasia or T1 colon carcinoma. For 27 of these 57 patients, a pT1 colon carcinoma was diagnosed at pathologic examination after CAL-WR. Histological risk factors for LNM were present in three cases, and 70% showed deep submucosal invasion (Sm2/Sm3). For patients with pT1 colon carcinoma, an overall R0-resection rate of 88.9% was achieved. A minor complication was noted in one patient (1.8%).

The CAL-WR procedure is an effective and safe technique for suspected high-grade dysplasia or T1-colon carcinoma. It may fill the gap for tumors that are macroscopic suspected for deep submucosal invasion, providing more patients an organ-preserving treatment option.

Limited data exists on the impact of advanced endoscopic resections on early oncological outcomes of malignant colorectal lesions, especially in the presence of perforation.

Retrospective chart review of patients who underwent advanced endoscopic resections and had adenocarcinoma was performed. The primary endpoint was cancer recurrence.

63 patients were included. Mean age was 64.6 years with 58.7% of the patients being male. Mean BMI was 30.2 kg/m² 12 patients underwent advanced endoscopic resections followed by surveillance, 5 patients had conversion to surgery due to intra-procedural perforation, and 5 patients due to incomplete resection. 41 patients underwent salvage surgery following a median of 5.4 weeks of initial endoscopic resection. Neither local nor distant recurrence was observed within a median follow-up of 21.2 months.

Advanced endoscopic procedures do not have negative impact on the early oncological outcomes of patients with malignant colorectal lesions, even in the presence of perforation.

En bloc local excision of suspected T1 colorectal cancer (CRC) provides optimal tumor risk assessment with curative intent. Endoscopic full-thickness resection (eFTR) with an over-the-scope device has emerged as a local excision technique for T1 CRCs, but data on the upper size limit for achieving a histological complete (R0) resection are lacking. We aimed to determine the influence of polyp size on the R0 rate.

eFTR procedures for suspected T1 CRCs performed between 2015 and 2021 were selected from the endoscopy databases of three tertiary centers. The main outcome was R0 resection, defined as tumor- and dysplasia-free margins (≥ 0.1 mm) for both the deep and lateral resection margins. Regression analysis was performed to identify risk factors for R1/Rx resection, mainly focusing on endoscopically estimated polyp size.

136 patients underwent eFTR for suspected T1 CRC (median size 15 mm [IQR 13-18 mm]; 83.1 % cancer). The rates of technical success and R0 resection were 87.5 % (119/136; 95 %CI 80.9 %-92.1 %) and 79.7 % (106/136; 95 %CI 72.1 %-85.7 %), respectively. Increasing polyp size was significantly associated with R1/Rx resection (risk ratio 2.35 per 5-mm increase, 95 %CI 1.80-3.07; P < 0.001). The R0 rate was 89.9 % (80/89) for polyps ≤ 15 mm, 71.4 % (25/35) for 16-20 mm, and 11.1 % (1/9) for those > 20 mm.

eFTR is associated with a 90 % R0 rate for T1 CRCs of ≤ 15 mm. Performing eFTR for polyps 16-20 mm should depend on access, their mobility, and the availability of alternative resection techniques. eFTR for > 20-mm polyps results in a high R1 rate and should not be recommended.

The risk of lymph node metastasis associated with deep submucosal invasion should be balanced against the mortality and morbidity of total mesorectal excision (TME). Dissection through the submucosa hinders radical deep resection, and full-thickness resection may influence the outcome of completion TME. Endoscopic intermuscular dissection (EID) in between the circular and longitudinal part of the muscularis propria could potentially provide an R0 resection while leaving the rectal wall intact.

In this prospective cohort study, the data of patients treated with EID for suspected deep submucosal invasive rectal cancer between 2018 and 2020 were analyzed. Study outcomes were the percentages of technical success, R0 resection, curative resection, and adverse events.

67 patients (median age 67 years; 73 % men) were included. The median lesion size was 25 mm (interquartile range 20-33 mm). The rates of overall technical success, R0 resection, and curative resection were 96 % (95 %CI 89 %-99 %), 81 % (95 %CI 70 %-89 %), and 45 % (95 %CI 33 %-57 %). Only minor adverse events occurred in eight patients (12 %).

EID for deep invasive T1 rectal cancer appears to be feasible and safe, and the high R0 resection rate creates the potential of rectal preserving therapy in 45 % of patients.

Diagnostics to differentiate deep submucosal invasive (invasion depth ≥1000 μm [T1b]) colorectal cancer (CRC) from muscularis propria invasive (T2) CRC are limited. We aimed to establish and validate a scoring system that differentiates T1b from T2.

A multicenter retrospective cross-validation study was performed. Four hundred sixty-one consecutive pathologically confirmed T1b or T2 CRCs were divided into the development (T1b, 222; T2, 189) and internal validation (T1b, 31; T2, 19) cohorts. Eight potential endoscopic findings were evaluated using the development cohort: loss of lobulation, deep depression, demarcated depressed area, protuberance within the depression, expanding appearance, fold convergency, erosion or white plaque, and Borrmann type 2 or 3 tumor. A scoring system that differentiates T1b from T2 was developed, and diagnostic performance was tested using the internal validation cohort by 8 endoscopists. External validation was conducted using 50 CRC images by 4 endoscopists from other institutions, including outside of Japan.

Multivariate analysis identified the following 5 independent predictive endoscopic findings of T2 CRC: deep depression (odds ratio [OR], 2.08; 95% confidence interval [CI], 1.07-4.04), demarcated depressed area (OR, 4.40; 95% CI, 1.39-13.9), 4-fold convergency or more (OR, 3.41; 95% CI, 1.90-6.11), erosion or white plaque (OR, 8.28; 95% CI, 2.77-24.7), and Borrmann type 2 or 3 tumor (OR, 8.76; 95% CI, 3.58-21.5). The area under the receiver-operating characteristic curve (AUROC) was .90 (95% CI, .87-.93) in the development cohort, .80 (95% CI, .76-.85) in the internal validation, and .76 (95% CI, .69-.83) in the external validation.

We established and validated a new scoring system to differentiate T1b from T2 CRC using 5 simple endoscopic findings.

Deep submucosal invasion (DSI) is considered a key risk factor for lymph node metastasis (LNM) and important criterion to recommend surgery in T1 colorectal cancer. However, metastatic risk for DSI is shown to be low in the absence of other histologic risk factors. This meta-analysis determines the independent risk of DSI for LNM.

Suitable studies were included to establish LNM risk for DSI in univariable analysis. To assess DSI as independent risk factor, studies were eligible if risk factors (eg, DSI, poor differentiation, lymphovascular invasion, and high-grade tumor budding) were simultaneously included in multivariable analysis or LNM rate of DSI was described in absence of poor differentiation, lymphovascular invasion, and high-grade tumor budding. Odds ratios (OR) and 95% CIs were calculated.

Sixty-seven studies (21,238 patients) were included. Overall LNM rate was 11.2% and significantly higher for DSI-positive cancers (OR, 2.58; 95% CI, 2.10-3.18). Eight studies (3621 patients) were included in multivariable meta-analysis and did not weigh DSI as a significant predictor for LNM (OR, 1.73; 95% CI, 0.96-3.12). As opposed to a significant association between LNM and poor differentiation (OR, 2.14; 95% CI, 1.39-3.28), high-grade tumor budding (OR, 2.83; 95% CI, 2.06-3.88), and lymphovascular invasion (OR, 3.16; 95% CI, 1.88-5.33). Eight studies (1146 patients) analyzed DSI as solitary risk factor; absolute risk of LNM was 2.6% and pooled incidence rate was 2.83 (95% CI, 1.66-4.78).

DSI is not a strong independent predictor for LNM and should be reconsidered as a sole indicator for oncologic surgery. The expanding armamentarium for local excision as first-line treatment prompts serious consideration in amenable cases to tailor T1 colorectal cancer management.

To elucidate whether a high level of microsatellite instability (MSI-high) in colon cancer influences the CT assessment of regional lymph node (rLN) morphology and diagnostic performance on predicting pathological node-negative (pN0) patients.

We retrospectively reviewed 507 patients with cecal/proximal ascending colon cancer (age, 63.0 ± 11.6 years; MSI-stable, n = 398; MSI-high, n = 109) who underwent right hemicolectomy between July 1, 2009, and December 31, 2018. Preoperative CT images were assessed for number of rLNs, long/short diameter of the largest rLN, and CT LN grade (CTN0, low probability of metastasis; CTN1, borderline; CTN2, high probability). Sensitivity, specificity, positive predictive value and negative predictive value for predicting pN0 was calculated. Multivariable logistic regression analysis was performed. Statistical significance was defined as P < 0.05.

A study population of 507 patients (mean age ± standard deviation, 63.0 ± 11.6; 264 women) were evaluated. In patients with rLN metastasis, the rLN long axis (pN1: P = 0.013, pN2: P = 0.039) and short axis (pN1: P = 0.001, pN2: P = 0.009) were both longer in MSI-high tumors compared with MSI-stable tumors. High specificity for predicting pN0 was only achieved in MSI-high tumors [sensitivity_MSI-stable = 58.3% (n = 137/235), specificity_MSI-stable = 71.2% (n = 116/163); sensitivity_MSI-high = 38.4% (n = 33/86), specificity_MSI-high = 91.3% (n = 21/23)]. Multivariable logistic regression indicated MSI-high (P < 0.001, odds ratio = 3.701), smaller LN long axis (P = 0.023, odds ratio = 0.905), and lower CT LN grade (CTN0: P = 0.009, odds ratio = 2.987; CTN1: P = 0.014, odds ratio = 2.195) as significant parameters in predicting pN0.

MSI-high colon cancer is associated with larger rLNs and high specificity for predicting pN0 on CT assessment.

Complete endoscopic resection and accurate histological evaluation for T1 colorectal cancer (CRC) are critical in determining subsequent treatment. Endoscopic full-thickness resection (eFTR) is a new treatment option for T1 CRC < 2 cm. We aimed to report clinical outcomes and short-term results.

Consecutive eFTR procedures for T1 CRC, prospectively recorded in our national registry between November 2015 and April 2020, were retrospectively analyzed. Primary outcomes were technical success and R0 resection. Secondary outcomes were histological risk assessment, curative resection, adverse events, and short-term outcomes.

We included 330 procedures: 132 primary resections and 198 secondary scar resections after incomplete T1 CRC resection. Overall technical success, R0 resection, and curative resection rates were 87.0 % (95 % confidence interval [CI] 82.7 %-90.3 %), 85.6 % (95 %CI 81.2 %-89.2 %), and 60.3 % (95 %CI 54.7 %-65.7 %). Curative resection rate was 23.7 % (95 %CI 15.9 %-33.6 %) for primary resection of T1 CRC and 60.8 % (95 %CI 50.4 %-70.4 %) after excluding deep submucosal invasion as a risk factor. Risk stratification was possible in 99.3 %. The severe adverse event rate was 2.2 %. Additional oncological surgery was performed in 49/320 (15.3 %), with residual cancer in 11/49 (22.4 %). Endoscopic follow-up was available in 200/242 (82.6 %), with a median of 4 months and residual cancer in 1 (0.5 %) following an incomplete resection.

eFTR is relatively safe and effective for resection of small T1 CRC, both as primary and secondary treatment. eFTR can expand endoscopic treatment options for T1 CRC and could help to reduce surgical overtreatment. Future studies should focus on long-term outcomes.

Growing numbers of patients with T1 CRC are being treated with local endoscopic resection only and as a result, the need for optimization of surveillance strategies for these patients also increases. We aimed to estimate the cumulative incidence and time pattern of CRC recurrences for endoscopically treated patients with T1 CRC.

Using a systematic literature search in PubMed, EMBASE, Web of Science and Cochrane Library (from inception till 15 May 2020), we identified and extracted data from studies describing the cumulative incidence of local or distant CRC recurrence for patients with T1 CRC treated with local endoscopic resection only. Pooled estimates were calculated using mixed-effect logistic regression models.

Seventy-one studies with 5167 unique, endoscopically treated patients with T1 CRC were included. The pooled cumulative incidence of any CRC recurrence was 3.3% (209 events; 95% CI, 2.6%-4.3%; I² = 54.9%), with local and distant recurrences being found at comparable rates (pooled incidences 1.9% and 1.6%, respectively). CRC-related mortality was observed in 42 out of 2519 patients (35 studies; pooled incidence 1.7%, 95% CI, 1.2%-2.2%; I² = 0%), and the CRC-related mortality rate among patients with recurrence was 40.8% (42/103 patients). The vast majority of recurrences (95.6%) occurred within 72 months of follow-up. Pooled incidences of any CRC recurrence were 7.0% for high-risk T1 CRCs (28 studies; 95% CI, 4.9%-9.9%; I² = 48.1%) and 0.7% (36 studies; 95% CI, 0.4%-1.2%; I² = 0%) for low-risk T1 CRCs.

Our meta-analysis provides quantitative outcome measures which are relevant to guidelines on surveillance after local endoscopic resection of T1 CRC.

Diagnostic support using artificial intelligence may contribute to the equalization of endoscopic diagnosis of colorectal lesions. We developed computer-aided diagnosis (CADx) support system for diagnosing colorectal lesions using the NBI International Colorectal Endoscopic (NICE) classification and the Japan NBI Expert Team (JNET) classification.

Using Residual Network as the classifier and NBI images as training images, we developed a CADx based on the NICE classification (CADx-N) and a CADx based on the JNET classification (CADx-J). For validation, 480 non-magnifying and magnifying NBI images were used for the CADx-N and 320 magnifying NBI images were used for the CADx-J. The diagnostic performance of the CADx-N was evaluated using the magnification rate.

The accuracy of the CADx-N for Types 1, 2, and 3 was 97.5%, 91.2%, and 93.8%, respectively. The diagnostic performance for each magnification level was good (no statistically significant difference). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the CADx-J were 100%, 96.3%, 82.8%, 100%, and 96.9% for Type 1; 80.3%, 93.7%, 94.1%, 79.2%, and 86.3% for Type 2A; 80.4%, 84.7%, 46.8%, 96.3%, and 84.1% for Type 2B; and 62.5%, 99.6%, 96.8%, 93.8%, and 94.1% for Type 3, respectively.

The multi-class CADx systems had good diagnostic performance with both the NICE and JNET classifications and may aid in educating non-expert endoscopists and assist in diagnosing colorectal lesions.

The indication for endoscopic resection for submucosally invasive colorectal cancer (T1-CRC) depends on the preoperative diagnosis of invasion depth. The aim of this investigation was to evaluate the association between barium enema examination (BE) profile views and depth of submucosal (SM) invasion in CRCs.

We reviewed the radiographic and endoscopic findings of 145 T1-CRCs diagnosed from 2008 to 2019. We measured the widths of horizontal and vertical rigidity under a BE profile view corresponding to CRC and compared the values with SM invasion depth. Horizontal rigidity was defined as the horizontal length and vertical rigidity as the vertical width of the barium defect corresponding to each target lesion. The most appropriate cut-off values for predicting SM invasion ≥1.8 mm were calculated by receiver operating characteristic curve analysis.

Values of horizontal rigidity (r = 0.626, P < 0.05) and vertical rigidity (r = 0.482, P < 0.05) correlated significantly with SM invasion depth. The most appropriate cut-off values for the prediction of SM invasion depth ≥ 1.8 mm were 4.5 mm for horizontal rigidity, with an accuracy of 80.7%; and 0.7 mm for vertical rigidity, with an accuracy of 77.9%. The prevalence of lympho-vascular invasion was significantly different when those cut-off values were applied (43.2% vs. 17.5% for horizontal rigidity, P < 0.005).

In T1-CRC, values of horizontal and vertical rigidities under a BE profile view were correlated with SM invasion depth. While the accuracy of the rigidities for the prediction of SM invasion depth ≥ 1.8 mm was not high, horizontal rigidity may be predictive of lympho-vascular invasion, thus aiding in therapeutic decision-making.

With the widely spreading population-based screening programs for colorectal cancer and recent improvements in endoscopic diagnosis, the number of endoscopic resections in subjects with T1 colorectal cancer has been increasing. Some reports suggest that endoscopic resection prior to surgical resection of T1 colorectal cancer has no adverse effect on prognosis and contributes to this tendency. The decision on the need for surgical resection as an additional treatment after endoscopic resection of T1 colorectal cancer should be made according to the metastasis risk to lymph nodes based on histopathological findings. Because lymph node metastasis occurs in approximately 10% of patients with T1 colorectal cancer according to current international guidelines, the remaining 90% of patients may be at an increased risk of surgical resection and associated postoperative mortality, with no clinical benefit derived from unnecessary surgical resection. Although a more accurate prediction system for lymph node metastasis is needed to solve this problem, risk stratification for lymph node metastasis remains controversial. In this review, we focus on the current status of risk stratification of T1 colorectal cancer metastasis to lymph nodes and outline future perspectives.

This study aimed to evaluate the clinical feasibility and oncologic safety of primary endoscopic submucosal dissection for cT1bN0M0 gastric cancer by identifying patients who had undergone curative resection after endoscopic submucosal dissection and patients who had undergone primary surgery but could be treated with endoscopic submucosal dissection.

A single-center retrospective cohort study was conducted on patients with cT1bN0M0 gastric cancer (size: ≤ 30 mm) and differentiated histology from January 2007 to May 2017. Submucosal invasion was evaluated using conventional endoscopy and endoscopic ultrasonography. Patients were divided into the primary endoscopic submucosal dissection and primary surgery groups according to initial treatment.

Curative resection rate was 65.0% (91/140) in the primary endoscopic submucosal dissection group. Of patients in the primary surgery group, 49.1% (82/167) were considered eligible for endoscopic submucosal dissection. No differences in en bloc resection rate were observed between pT1a and pT1b gastric cancers after endoscopic submucosal dissection (97.8 vs. 97.9%). However, the negative horizontal margin rate was higher in pT1a gastric cancer than pT1b gastric cancer (98.9 vs. 91.3%). There was no difference in overall survival among the curative treatment groups (log rank P = 0.310).

In this study, 173 (56.4%) out of 307 patients with cT1bN0M0 gastric cancer could avoid unnecessary surgery if primary endoscopic submucosal dissection was used. Based on these findings, it is necessary to add an appropriate indication for endoscopic submucosal dissection in patients with cT1b gastric cancer. Further management could be determined based on pathologic findings after primary endoscopic submucosal dissection.

Additional surgical resection (ASR) after endoscopic resection (ER) in patients with colorectal cancer (CRC) allows a complete staging and may decrease the recurrence rate, but no meta-analysis is available. This study aimed to compare the effectiveness of ER vs. ER + ASR as a treatment for patients with T1 (stage 1) CRC.

We performed a systematic search from databases (PubMed, Embase, and Cochrane library) for cohort studies published up to November 2019. The outcomes were overall survival (OS), local recurrence, recurrence, disease-specific survival, recurrence-free survival, and metastasis.

Seven studies were included. There were 1205 patients in the ASR group and 993 patients in the ER group. Compared with ER, ASR was associated with better OS (OR = 0.31, 95% CI: 0.18-0.53, P < 0.001) and a borderline significant difference in lower local recurrence rates (OR = 0.29, 95% CI: 0.08-1.01, P = 0.052), but no differences were observed in recurrences, disease-specific survival, recurrence-free survival, and distant metastasis. A sensitivity analysis was performed; excluding each study sequentially from the pooled analysis did not affect the overall conclusion of the study.

Compared with ER, ASR after ER could improve the overall survival for patients with T1 CRC.

Background and study aims  Patients who have undergone colorectal surgery for resection of cancer and benign lesions are at risk for recurrent, residual, or metachronous lesions at the anastomosis site. Surgical resection of such lesions is difficult because of adhesions, and a stoma may be required as there are risks for leakage after resection. The feasibility and safety of endoscopic submucosal dissection (ESD) for these lesions remain unknown. Therefore, this case series aimed to examine the feasibility and safety of ESD by evaluating the clinical outcomes. Patients and methods  We retrospectively investigated five patients who underwent ESD by a single expert for superficial neoplastic lesions at the anastomosis site after previous colorectal surgery. Results  R0 resections were achieved for all lesions. Mean procedure time was 160.6 minutes. Mean dimensions of the resected specimen and tumor were 52.4 mm and 31.8mm, respectively. None of the patients had complications or recurrence after surveillance colonoscopy 1-year post-resection. Conclusions  In an expert's hands, ESD at the anastomosis site might be feasible minimally invasive treatment for superficial neoplastic lesions.

The recurrence of T1 colorectal cancers is relatively rare, and the prognostic factors still remain obscure. This study aimed to clarify the risk factors for recurrence in patients with T1 colorectal cancers treated by endoscopic resection (ER) alone or surgical resection (SR) with lymph node dissection, respectively.

We reviewed 930 patients with resected T1 colorectal cancers (mean follow-up, 52.3 months). Patients were divided into two groups: those who underwent ER alone (298 cases), and those who underwent initial or additional SR with lymph node dissection (632 cases). Group differences in recurrence-free survival were evaluated using the Kaplan-Meier method and log-rank test. Associations between recurrence and clinicopathological features were evaluated in Cox regression analyses; hazard ratios (HRs) were calculated for the total population and each group.

Recurrence occurred in four cases (1.34%) in the ER group and six cases (0.95%) in the SR group (p = 0.32). Endoscopic resection, rectal location, and poor or mucinous (Por/Muc) differentiation were prognostic factors for recurrence in the total population. Por/Muc differentiation was prognostic factor in both groups. Female sex, depressed-type morphology, and lymphatic invasion were also prognostic factors in the ER group, but not in the SR group.

Endoscopic resection, rectal location, and Por/Muc differentiation are prognostic factors in the total population. For patients who undergo ER alone, female sex, depressed-type morphology, and lymphatic invasion are also risk factors for recurrence. For such patients, regional en-bloc surgery with lymph node dissection could reduce the risk of recurrence.