The incidence and mortality of colorectal cancer (CRC) in China are increasing in recent years. The clarified pathogenesis and detectable precancerous lesions of CRC make it possible to prevent, screen, and diagnose CRC at an early stage. With the development of endoscopic and surgical techniques, the choice of treatment for early CRC is also worth further discussion, and accordingly, a standard follow-up program after treatment needs to be established.

This clinical practice guideline (CPG) was developed following the recommended process of the World Health Organization, adopting Grading of Recommendations Assessment, Development and Evaluation (GRADE) in assessing evidence quality, and using the Evidence to Decision framework to formulate clinical recommendations, thereby minimizing bias and increasing transparency of the CPG development process. We used the Reporting Items for practice Guidelines in HealThcare (RIGHT) statement and Appraisal of Guidelines for Research and Evaluation II (AGREE II) as reporting and conduct guides to ensure the guideline's completeness and transparency.

This CPG comprises 46 recommendations concerning prevention, screening, diagnosis, treatment, and surveillance of CRC. In these recommendations, we have indicated protective and risk factors for CRC and made recommendations for chemoprevention. We proposed a suitable screening program for CRC based on the Chinese context. We also provided normative statements for the diagnosis, treatment, and surveillance of CRC based on existing clinical evidence and guidelines.

The 46 recommendations in this CPG are formed with consideration for stakeholders' values and preferences, feasibility, and acceptability. Recommendations are generalizable to resource-limited settings with similar CRC epidemiology pattern as China.

The introduction of widespread colonoscopy screening programs has helped in decreasing the incidence of Colorectal Cancer (CRC). However, 'back-to-back' colonoscopies revealed relevant percentage of missed adenomas. Quality indicators were created to further homogenize detection performances and decrease the incidence of post-colonoscopy CRC. Among them, the Adenoma Detection Rate (ADR), defined as the percentage obtained by dividing the number of endoscopic procedures in which at least one adenoma was resected, by the total number of procedures, was found to be inversely associated with the risks of interval colorectal cancer, advanced-stage interval cancer, and fatal interval cancer.

In this paper, we performed a comprehensive review of the literature focusing on promising new devices and technologies, which are meant to positively affect the endoscopist performance in detecting adenomas, therefore increasing ADR.

Considering the current knowledge, although several devices and technologies have been proposed with this intent, the recent implementation of AI ranked over all of the other strategies and it is likely to become the new standard within few years. However, the combination of different device/technologies need to be investigated in the future aiming at even further increasing of endoscopist detection performances.

Water exchange colonoscopy is the least painful method for unsedated colonoscopies. Simplified left colon water exchange (LWE) reduces the cecal intubation time but it is difficult to avoid the use of an additional pump. Minimal water exchange (MWE) is an improved novel method that eliminates the need for pumps, but it is not clear whether MWE has the same efficiency as LWE.

This was a prospective, randomized, controlled, noninferiority trial conducted in a tertiary hospital. Enrolled patients were randomized 1:1 to the LWE group or MWE group. The primary outcome was recalled insertion pain measured by a 4-point verbal rating scale. Secondary outcomes included adenoma detection rate (ADR), cecal intubation time, volume of water used, and patient willingness to repeat unsedated colonoscopy.

226 patients were included (LWE n = 113, MWE n = 113). The MWE method showed noninferior moderate/severe pain rates compared with the LWE method (10.6 % vs. 9.7 %), with a difference of 0.9 percentage points (99 % confidence interval [CI] -9.5 to 11.3; threshold, 15 %). ADR, cecal intubation time, and willingness to repeat unsedated colonoscopy were not significantly different between the two groups, but the mean volume of water used was significantly less with MWE than with LWE (163.7 mL vs. 407.2 mL; 99 %CI -298.28 to -188.69).

Compared with LWE, MWE demonstrated a noninferior outcome for insertion pain, and comparable cecal intubation time and ADR, but reduced the volume of water used and eliminated the need for a water pump.

Dye-based chromoendoscopy (DBC) could be effective in increasing the adenoma detection rate (ADR) in patients undergoing colonoscopy, but the technique is time-consuming and its uptake is limited. We aimed to assess the effect of DBC on ADR based on available randomized controlled trials (RCTs).

Four databases were searched up to April 2022 for RCTs comparing DBC with conventional colonoscopy (CC) in terms of ADR, advanced ADR, and sessile serrated adenoma detection rate as well as the mean adenomas per patient and non-neoplastic lesions. Relative risk (RR) for dichotomous outcomes and mean difference (MD) for continuous outcomes were calculated using random-effect models. The I² test was used for quantifying heterogeneity. Risk of bias was evaluated with the Cochrane tool.

Overall, 10 RCTs (5334 patients) were included. Indication for colonoscopy was screening or surveillance (3 studies) and mixed (7 studies). Pooled ADR was higher in the DBC group versus the CC group (95% CI, 48.1% [41.4%-54.8%] vs 39.3% [33.5%-46.4%]; RR, 1.20 [1.11-1.29]), with low heterogeneity (I² = 29%). This effect was consistent for advanced ADR (RR, 1.21 [1.03-1.42]; I² = .0%), sessile serrated adenomas (6.1% vs 3.5%; RR, 1.68 [1.15-2.47]; I² = 9.8%), and mean adenomas per patient (MD, .24 [.17-.31]) overall and in the right-sided colon (MD, .28 [.14-.43]). A subgroup analysis considering only trials using high-definition white-light endoscopy reduced the heterogeneity while still showing a significant increase in adenoma detection with DBC: 51.6% (95% confidence interval [CI], 47.1%-56.1%) and 59.1% (95% CI, 54.7-63.3%), RR = 1.14 (95% CI, 1.06-1.23), P = .0004, I² = .0%, P = .50.

Meta-analysis of RCTs showed that DBC increases key quality parameters in colonoscopy, supporting its use in everyday clinical practice.

Endoscopic submucosal dissection (ESD) allows an "en bloc" resection with safety margins (R0 resection) regardless of the size of the lesion. However, while R0 brings a real benefit for the patient, it is not considered sufficient by many experts to justify the technical difficulties and the longer procedure time compared to piecemeal mucosectomy. The aims of this review are to provide several technical and strategical tips to help you save time and become comfortable during ESD procedures. ESD is divided into several intertwined phases: injection, incision, access to the submucosae, and submucosal dissection itself. During injection there are some mistakes that should not be made: a superficial injection, or on the contrary, a too deep injection. A good needle and good injection technique are mandatory. Some techniques, such as repeated injection or prolonged lifting solution, can help maintain the lift. After this step, mucosal incision can be made, taking care to have a good margin to allow an R0 resection. Starting the mucosal incision from a small point allows calibration of the depth of the incision and then obtaining a nice incision. Trimming is also very important to widen submucosal access. Then comes the submucosal dissection itself. Strategies such as the tunnel strategy or the pocket creation method can help to facilitate dissection, but more importantly, traction systems have become unavoidable, especially in the stomach and colon. Most common complications are bleeding and perforation, and they usually can be managed endoscopically.

The utility of water-aided techniques (WT): water exchange (WE) and water immersion (WI) have been studied extensively in the literature for improving colonoscopy outcome metrics such as adenoma detection rate. Serrated polyps owing to their location and appearance have a high miss rate. The authors performed a systematic review and meta-analysis of studies comparing WT with the standard gas-assisted (GA) method to determine if there was any impact on serrated polyp detection rate (SPDR) and sessile serrated polyp detection rate.

The following databases were queried for this systematic review: Medline, EMBASE, Cochrane Library, CINAHL, and Web of Sciences. The authors only included randomized controlled trials (RCTs). The primary outcome was SPDR and secondary outcomes were sessile serrated polyp detection rate and cecal intubation rate. Risk ratios (RRs) were calculated for each outcome. A P-value <0.05 was considered to be statistically significant.

A total of 4 RCTs (5 arms) with 5306 patients (2571 in the GA group and 2735 in the WT group) were included. The SPDR was significantly increased for the WT group compared with GA (6.1% vs. 3.8%; RR, 1.63; 95% confidence interval, 1.24-2.13; P<0.001; I2=22.7%). A subgroup analysis for WE technique also demonstrated improved SPDR compared with the GA method (4.9% vs. 3.2%; RR, 1.57; 95% confidence interval, 1.15-2.14; P=0.004; I2=6.1%).

WT, particularly, the WE method results in improved SPDR. This technique should be encouraged in a clinical setting to detect these polyps to prevent interval colorectal cancer.

Colonoscopy is currently considered the optimal method to detect colorectal neoplasia; however, some adenomas remain undetected. While indigo carmine staining with a dye-spray catheter has demonstrated promising results for reducing the miss rate, we investigated the oral indigo carmine method. The aim of this study was to determine whether oral indigo carmine intake before standard colonoscopy increases the adenoma (and adenocarcinoma) detection rate (ADR) or the mean number of adenomas per patient (MAP).

The oral indigo carmine method was performed from April 2018 to July 2020 in two hospitals. Data were collected in a prospective manner and compared to the conventional group whose data were collected retrospectively and consecutively from January 2016 to March 2018. All data were anonymized.

Among the 704 patients included, colonoscopies were completely performed in 693 patients (347 in the indigo group). The ADR did not significantly differ between the groups: 42.3% vs. 40.3% (indigo vs. conventional group; odds ratio: 1.13; 95% confidence interval: 0.9-1.33, p = .33). The MAP was significantly greater in the indigo group (1.15) than that in the conventional group (0.82; p = .009). The cecal intubation rate and time to cecal intubation did not differ between the indigo and conventional group (98.6% vs. 98.3%, p = .83, and 6.2 min vs. 5.9 min, p = .39, respectively).

The routine use of oral indigo carmine does not lead to a higher ADR despite the higher MAP.

Colonoscopy screening for the detection and removal of colonic adenomas is central to efforts to reduce the morbidity and mortality of colorectal cancer. However, up to a third of adenomas may be missed at colonoscopy, and the majority of post-colonoscopy colorectal cancers are thought to arise from these. Adenomas have three-dimensional surface topographic features that differentiate them from adjacent normal mucosa. However, these topographic features are not enhanced by white light colonoscopy, and the endoscopist must infer these from two-dimensional cues. This may contribute to the number of missed lesions. A variety of optical imaging technologies have been developed commercially to enhance surface topography. However, existing techniques enhance surface topography indirectly, and in two dimensions, and the evidence does not wholly support their use in routine clinical practice. In this narrative review, co-authored by gastroenterologists and engineers, we summarise the evidence for the impact of established optical imaging technologies on adenoma detection rate, and review the development of photometric stereo (PS) for colonoscopy. PS is a machine vision technique able to capture a dense array of surface normals to render three-dimensional reconstructions of surface topography. This imaging technique has several potential clinical applications in colonoscopy, including adenoma detection, polyp classification, and facilitating polypectomy, an inherently three-dimensional task. However, the development of PS for colonoscopy is at an early stage. We consider the progress that has been made with PS to date and identify the obstacles that need to be overcome prior to clinical application.

Adenoma detection rate (ADR) is a quality metric for colorectal cancer screening. We performed a systematic review and network meta-analysis to assess the overall and comparative efficacies of different endoscopic techniques in adenoma detection.

We performed a systematic review of published articles and abstracts, through March 15, 2018, to identify randomized controlled trials of adults undergoing colonoscopy that compared the efficacy of different devices in detection of adenomas. Our final analysis included 74 2-arm trials that comprised 44948 patients. These studies compared efficacies of add-on devices (cap, endocuff, endo-rings, G-EYE), enhanced imaging techniques (chromoendoscopy, narrow-band imaging, flexible spectral imaging color enhancement, blue laser imaging), new scopes (full-spectrum endoscopy, extra-wide-angle-view colonoscopy, dual focus), and low-cost optimizing existing resources (water-aided colonoscopy, second observer, dynamic position change), alone or in combination with high-definition colonoscopy or each other. Primary outcome was increase in ADR. We performed pairwise and network meta-analyses, and appraised quality of evidence using GRADE.

Low-cost optimizing existing resources (odds ratio [OR], 1.29; 95% CI,1.17-1.43), enhanced imaging techniques (OR,1.21; 95% CI, 1.09-1.35), and add-on devices (OR,1.18; 95% CI, 1.07-1.29) were associated with a moderate increase in ADR compared with high-definition colonoscopy; there was low to moderate confidence in estimates. Use of newer scopes was not associated with significant increases in ADR compared with high-definition colonoscopy (OR, 0.98; 95% CI, 0.79-1.21). In our comparative efficacy analysis, no specific technology for increasing ADR was superior to others. We did not find significant differences between technologies in detection of advanced ADR, polyp detection rate, or mean number of adenomas/patient.

In a network meta-analysis of published trials, we found that low-cost optimization of existing resources to be as effective as enhanced endoscopic imaging, or add-on devices, in increasing ADR during high-definition colonoscopy.