Endoscopic resection for local residual or recurrent cancer after definitive chemoradiotherapy or radiotherapy for esophageal squamous cell carcinoma.

Chemoradiotherapy (CRT) and radiotherapy (RT) are treatment options for esophageal squamous cell carcinoma (ESCC), but local residual/recurrent cancer after CRT/RT is a major problem. Endoscopic resection (ER) is an effective treatment option for local residual/recurrent cancer. To ensure the efficacy of ER, complete removal of endoscopically visible lesions with cancer-free vertical margins is desired. This study aimed to identify the endoscopic parameters associated with the complete endoscopic removal of local residual/recurrent cancer. In this single-center, retrospective study, we used a prospectively maintained database to identify esophageal lesions that were diagnosed as local residual/recurrent cancer after CRT/RT and treated by ER between January 2012 and December 2019. We evaluated the associations of endoscopic R0 resection with findings on conventional endoscopy and endoscopic ultrasonography (EUS). In total, 98 lesions (83 cases) were identified from our database. The rate of endoscopic R0 resection was higher for flat lesions (100% versus 77%, P = 0.00014). EUS was performed for 24 non-flat lesions, and endoscopic R0 resection was achieved for 94% of lesions with an uninterrupted fifth layer. Flat lesions on conventional endoscopy and lesions with an uninterrupted fifth layer on EUS are good candidates for ER.

Usefulness of the ultrathin endoscope with a newly developed knife for complex esophageal endoscopic submucosal dissection.

Video 1Usefulness of an ultrathin endoscope with a newly developed knife for complex esophageal endoscopic submucosal dissection.

A single-center prospective study evaluating the usefulness of artificial intelligence for the diagnosis of esophageal squamous cell carcinoma in a real-time setting.

BACKGROUND: Several pre-clinical studies have reported the usefulness of artificial intelligence (AI) systems in the diagnosis of esophageal squamous cell carcinoma (ESCC). We conducted this study to evaluate the usefulness of an AI system for real-time diagnosis of ESCC in a clinical setting. METHODS: This study followed a single-center prospective single-arm non-inferiority design. Patients at high risk for ESCC were recruited and real-time diagnosis by the AI system was compared with that of endoscopists for lesions suspected to be ESCC. The primary outcomes were the diagnostic accuracy of the AI system and endoscopists. The secondary outcomes were sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and adverse events. RESULTS: A total of 237 lesions were evaluated. The accuracy, sensitivity, and specificity of the AI system were 80.6%, 68.2%, and 83.4%, respectively. The accuracy, sensitivity, and specificity of endoscopists were 85.7%, 61.4%, and 91.2%, respectively. The difference between the accuracy of the AI system and that of the endoscopists was - 5.1%, and the lower limit of the 90% confidence interval was less than the non-inferiority margin. CONCLUSIONS: The non-inferiority of the AI system in comparison with endoscopists in the real-time diagnosis of ESCC in a clinical setting was not proven. TRIAL REGISTRATION: Japan Registry of Clinical Trials (jRCTs052200015, 18/05/2020).

Predictors of stricture after non-circumferential endoscopic submucosal dissection of the esophagus and single-dose triamcinolone injection immediately after the procedure.

BACKGROUND AND AIMS: Local triamcinolone (TA) injection is widely used to prevent stricture formation after endoscopic submucosal dissection (ESD). However, stricture develops in up to 45% of patients despite this prophylactic measure. We therefore conducted a single-center prospective study to identify predictors of stricture after esophageal ESD and local TA injection. METHODS: Patients who underwent esophageal ESD and local TA injection and who were comprehensively assessed for lesion- and ESD-related factors were included in the study. Multivariate analyses were conducted to identify the predictors of stricture. RESULTS: A total of 203 patients were included in the analysis. Multivariate analysis identified residual mucosal width ≤5 mm (odds ratio [OR], 29.0; P < .0001) or 6 to 10 mm (OR, 3.7; P = .04), history of chemoradiotherapy (OR, 5.1; P = .045), and tumor in the cervical or upper thoracic esophagus (OR, 3.8; P = .018) as independent predictors of stricture. Based on the ORs of the predictors, patients were stratified into 2 groups according to stricture risk: patients in the high-risk group (residual mucosal width ≤5 mm or 6-10 mm with another predictor) had a stricture rate of 52.5% (31 of 59 cases), and patients in the low-risk group (residual mucosal width ≥11 mm or 6-10 mm without other predictors) had a stricture rate of 6.3% (9 of 144 cases). CONCLUSIONS: We identified predictors of stricture after ESD and local TA injection. Local TA injection prevented stricture formation after ESD in low-risk patients but was not sufficient to prevent stricture in high-risk patients. Additional interventions should thus be considered in high-risk patients. (University Hospital Medical Network Clinical Trials Registry number: UMIN 000028894.).

Impact of endoscopic surveillance on mortality of metachronous esophageal and head and neck cancer after esophageal endoscopic resection.

BACKGROUND AND AIM: As more superficial esophageal cancer (EC) patients are being treated with endoscopic resection (ER), it is important to understand the outcomes, including survival data, of patients who develop metachronous EC and head and neck cancer (HNC). We aimed to evaluate the long-term surveillance and survival outcomes of metachronous EC and HNC after esophageal ER. METHODS: This study included 627 patients who underwent ER of superficial esophageal squamous cell carcinoma from 2008 to 2016 and were generally followed by annual or biannual esophagogastroduodenoscopy up to 2019 at Osaka International Cancer Institute. Data on metachronous cancer development and causes of death were collected from an integrated database of hospital-based cancer registry and Vital Statistics of Japan. RESULTS: During a median (range) follow-up period of 67.4 (3.8-142.7) months, 230 patients (36.7%) developed 500 metachronous ECs and 126 patients (20.1%) developed 239 metachronous HNCs, post-ER of index EC. The 3-year, 5-year, and 7-year cumulative incidences were 25.8%, 36.0%, and 43.6% for metachronous EC and 10.9%, 16.0%, and 26.9% for metachronous HNC, respectively. No patients died of metachronous EC, and only seven patients (1.1%) died of metachronous HNC. The 3-year, 5-year, and 7-year disease-specific survival rates were 99.8%, 99.6%, and 98.6%, respectively. CONCLUSIONS: The incidences of metachronous EC and HNC increase with time over 5 years after esophageal ER; therefore, surveillance endoscopy should be continued over 5 years. Endoscopic surveillance is useful for survivors after esophageal ER given the high incidence and extremely low mortality of metachronous EC and HNC.

Clinical features of superficial esophagus squamous cell carcinoma according to alcohol-degrading enzyme ADH1B and ALDH2 genotypes.

BACKGROUND: Inactivated alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are related to esophageal carcinogenesis. We aimed to clarify the clinical features associated with the alcohol-degrading enzyme genotypes, ADH1B and ALDH2. We also investigated the risk factors for metachronous esophageal squamous cell carcinoma (ESCC) and head and neck SCC (HNSCC). METHODS: We conducted a single-center, retrospective study including patients with ESCC treated by endoscopic resection. Patients were recruited between October 2020 and September 2021. Buccal mucosal swabs were obtained from them to analyze the genetic polymorphisms affecting ADH (ADH1B) and ALDH (ALDH2) activity. Patients were categorized into three groups: both inactivated = double-inactivated group; inactivated ADH1B or ALDH2 = single-inactivated group; and both activated = activated group. RESULTS: Among the 297 enrolled patients, patients in the double-inactivated group were significantly younger (P < 0.001) and 60% of them were ≤ 50 years old. This group also had more ESCCs located in the upper esophagus (P < 0.001) and more simultaneous multiple ESCCs (P = 0.044). More than half of the patients had multiple Lugol-voiding lesions (LVLs) (P < 0.001) and heavy alcohol consumers (P = 0.012). Metachronous ESCC and HNSCC were more common in the double-inactivated group (P < 0.001, P = 0.001). Multivariate analysis identified located in the upper esophagus, multiple LVLs and history of HNSCC as risk factors for metachronous ESCC. CONCLUSIONS: Activation patterns of alcohol-metabolizing enzymes were related to age at ESCC onset, lesion location, and metachronous ESCC and HNSCC. Different approaches to the prophylaxis and treatment of esophageal cancer should be considered, depending on the enzyme activity pattern.

Indication of emergency colonoscopy after colorectal endoscopic submucosal dissection: A proposal of hematochezia scale.

BACKGROUND AND AIM: Hematochezia is a major adverse event associated with colorectal endoscopic submucosal dissection (ESD). This study aimed to distinguish between hematochezia that required endoscopic hemostasis and hematochezia that required no hemostasis. METHODS: This retrospective study included consecutive patients who underwent ESD for colorectal tumors at the Osaka International Cancer Institute between September 2017 and August 2020. The exclusion criteria were as follows: patients with coexisting advanced colorectal cancers or inflammatory bowel diseases, patients who received incomplete ESD or emergency surgery, or patients who underwent ESD for multiple lesions. We evaluated whether the patients had hematochezia and underwent emergency colonoscopy and hemostasis during hospitalization. The degree of hematochezia in the saved photographs was assessed using the hematochezia scale and classified as mild, moderate, or severe. Blood pressure, heart rate, time from ESD to first hematochezia, and total number of hematochezia episodes were also evaluated. RESULTS: Among the 437 patients who underwent ESD, 44 were excluded, and 393 patients were evaluated. Hematochezia was observed in 100 patients (25%). Emergency colonoscopy was performed in 12 patients (3%), and hemostasis was required in six patients (2%). For patients with hematochezia, only mild hematochezia and hematochezia that developed ≤ 48 h after ESD were significantly associated with no intervention for hemostasis. The positive predictive value for no intervention for hemostasis was 100% (93-100%) for mild hematochezia and 98% (93-100%) for hematochezia ≤ 48 h. CONCLUSIONS: Mild hematochezia and hematochezia ≤ 48 h were negative predictors of hemostasis, in which emergency colonoscopy may be avoided.

Utility of an artificial intelligence system for classification of esophageal lesions when simulating its clinical use.

Previous reports have shown favorable performance of artificial intelligence (AI) systems for diagnosing esophageal squamous cell carcinoma (ESCC) compared with endoscopists. However, these findings don't reflect performance in clinical situations, as endoscopists classify lesions based on both magnified and non-magnified videos, while AI systems often use only a few magnified narrow band imaging (NBI) still images. We evaluated the performance of the AI system in simulated clinical situations. We used 25,048 images from 1433 superficial ESCC and 4746 images from 410 noncancerous esophagi to construct our AI system. For the validation dataset, we took NBI videos of suspected superficial ESCCs. The AI system diagnosis used one magnified still image taken from each video, while 19 endoscopists used whole videos. We used 147 videos and still images including 83 superficial ESCC and 64 non-ESCC lesions. The accuracy, sensitivity and specificity for the classification of ESCC were, respectively, 80.9% [95% CI 73.6-87.0], 85.5% [76.1-92.3], and 75.0% [62.6-85.0] for the AI system and 69.2% [66.4-72.1], 67.5% [61.4-73.6], and 71.5% [61.9-81.0] for the endoscopists. The AI system correctly classified all ESCCs invading the muscularis mucosa or submucosa and 96.8% of lesions ≥ 20 mm, whereas even the experts diagnosed some of them as non-ESCCs. Our AI system showed higher accuracy for classifying ESCC and non-ESCC than endoscopists. It may provide valuable diagnostic support to endoscopists.

Safety and efficacy of cold versus hot snare polypectomy including colorectal polyps ≥1 cm in size.

Cold snare polypectomy (CSP; polypectomy without electrocautery) has spread rapidly worldwide during the past decade in what has been called "Cold Revolution". We performed a PubMed literature search for studies investigating CSP outcomes for colorectal polyps. Five randomized controlled trials (RCTs) assessed the complete resection rates (CRRs). The CRRs were similar regardless of the presence or absence of electrocautery, and the efficacy of submucosal injection for better CRRs is still controversial. Eight RCTs assessed the adverse events. The incidence of intraprocedural bleeding with cold procedures was comparable to or higher than that of hot procedures. The incidences of delayed bleeding were comparable to or lower with cold procedures, especially in patients taking anticoagulants. Fifteen studies have been reported on CSP for large (≥1 cm) colorectal polyps (10 retrospective studies, four prospective single-arm studies, and one prospective RCT). These studies reported that the safe cold procedures (a low intra- and post-procedural bleeding rate without perforation) could be implemented for lesions ≥1 cm. However, considering the incision depth of CSP and the local recurrence rate based on the current evidence, only large sessile serrated lesions (SSLs) can be candidates for cold procedures, and large adenomas should not be candidates for this procedure. Based on the current evidence, CSP seems to be the appropriate standard procedure for sub-centimeter colorectal low-grade adenomas due to its safety and simplicity. Thus, large SSLs can be candidates for cold procedures; however, careful inspection and further prospective studies are warranted to confirm the procedure's clinical relevance.

Positive predictive value of the clinical diagnosis of T1a-epithelial/lamina propria esophageal cancer depends on lesion size.

OBJECTIVES: Endoscopic resection (ER) is a minimally invasive treatment for esophageal squamous cell carcinoma (ESCC). However, stricture may develop after ER for widespread lesions. Application of ER is justified if these cancers are pathological T1a-epithelial/lamina propria (pEP/LPM) cancers that can be cured by ER. We conducted a study to clarify the association between pathological invasion depth and lesion size or circumference in clinical (c) EP/LPM cancers. METHODS: From our database, we identified patients diagnosed with cEP/LPM ESCC via endoscopic examination who underwent endoscopic or surgical tumor resection. The accuracy of the cEP/LPM ESCC diagnosis was determined by histologically diagnosing cancer invasion depth as a reference standard. RESULTS: Between January 2015 and December 2019, 1271 cancer patients were diagnosed with cEP/LPM ESCC, of which 1195 (94.0%) were correctly diagnosed with pEP/LPM cancer. The positive predictive value (PPV) classified according to lesion sizes of ≤25, 26-49, and ≥50 mm was 95.8% (981/1024 lesions), 89.7% (191/213 lesions), and 67.6% (23/34 lesions), respectively. PPV according to the circumferential extent of <3/4, ≥3/4, and <1, and whole was 94.6% (1164/1230 lesions), 75.0% (24/32 lesions), and 77.8% (7/9 lesions), respectively. In multivariate analysis, the PPV of cEP/LPM ESCC was significantly associated with lesion size (P < 0.001) and male sex. CONCLUSIONS: Between January 2015 and December 2019, 1271 cancer patients were diagnosed with cEP/LPM ESCC, of which 1195 (94.0%) were correctly diagnosed with pEP/LPM cancer. The PPV of cEP/LPM ESCC was related to lesion size. Treatment should be determined considering the high risk of cancer invasion into the muscularis mucosa or deeper in cEP/LPM cancers with a lesion size of ≥50 mm.

Delineating the extent of esophageal squamous cell carcinoma.

BACKGROUND: Lugol chromoendoscopy has been conventionally used for the detection and delineation of esophageal squamous cell carcinoma (SCC). However, the boundaries of some lesions are unclear even with Lugol chromoendoscopy, and there is a risk of residual lesions or over-excision. This study aimed to evaluate the utility of narrow-band imaging (NBI) for the delineation of esophageal SCC in endoscopic resection. METHODS: Among 367 esophageal SCCs endoscopically resected between January and December 2019 at our institute, this retrospective study included consecutive lesions, which were first marked with NBI, followed by Lugol chromoendoscopy. The proportion of residual cancer, which was defined as histologically proven cancer confirmed adjacent to the scar within 1 year after endoscopic resection, was evaluated. To evaluate whether the marks added by Lugol chromoendoscopy after NBI marking were more reliable, we evaluated the presence of cancer in the iodine-unstained area outside the NBI-determined marks, i.e., the cancerous area missed by NBI. The presence of cancer in the iodine-stained areas inside the NBI-determined marks, i.e., the cancerous area missed by Lugol, was also evaluated. These were compared to assess the risk of residual cancer in endoscopic resection with NBI and Lugol chromoendoscopy. RESULTS: Among 304 lesions, 2 (0.7%) residual cancers were detected. The cancerous area missed by NBI and the cancerous area missed by Lugol were identified in 18 (6%) and 43 (14%) lesions, respectively (P = 0.001). CONCLUSIONS: NBI might be acceptable for delineating the extent of esophageal SCCs that are difficult to delineate with Lugol chromoendoscopy.

Curative value of underwater endoscopic mucosal resection for submucosally invasive colorectal cancer.

BACKGROUND AND AIM: Occasionally, colorectal tumors without characteristics of deep submucosal invasion are found to be invasive upon pathological evaluation after endoscopic resection (ER). Because the resection depth for underwater endoscopic mucosal resection (UEMR) has not been clarified, we evaluated the feasibility of UEMR for pathologically invasive colorectal cancer (pT1-CRC). METHODS: We retrospectively investigated data on the backgrounds and outcomes of patients with pT1-CRC who underwent UEMR between January 2014 and June 2019 at our institute. As a reference standard, the backgrounds and outcomes of pT1-CRCs that had undergone conventional EMR (CEMR) were also investigated. RESULTS: Thirty-one patients (median age, 68 years [range, 32-88 years]; 22 men [71%]) were treated with UEMR. Median lesion size was 17 mm (range, 6-50 mm). The endoscopic complete resection rate was 100%. The overall en bloc resection rate was 77%, and the VM0, HM0, and R0 resection rates were 81%, 58%, and 55%, respectively. In cases of pT1a (invasion <1000 µm)-CRC (n = 14), the en bloc, VM0, and R0 resection rates were 92%, 100%, and 71%, respectively. Seventeen patients (five with risk factors for lymph node metastasis and 12 without) were followed up, and no local recurrence and distant metastasis were observed during the follow-up period (median follow-up period, 18 months [range, 6-62 months]) after UEMR. The outcomes of UEMR seemed to be comparable with those of CEMR (n = 32). CONCLUSIONS: The VM0 rate of UEMR for pT1-CRC, especially for pT1a-CRC, without characteristics of deep submucosal invasion seems feasible.

Esophageal metal stent for malignant obstruction after prior radiotherapy.

The association between severe adverse events (SAEs) and prior radiotherapy or stent type remains controversial. Patients with esophageal or esophagogastric junctional cancer who underwent stent placement (2005-2019) were enrolled in this retrospective study conducted at a tertiary cancer institute in Japan. The exclusion criteria were follow-up period of < 1 month and insufficient data on stent type or cancer characteristics. We used Mann-Whitney's U test for quantitative data and Fisher's exact test for categorical data. Multivariate analysis was performed using a logistic regression model. 107 stents were placed. Low radial-force stents (L group) were used in 51 procedures and high radial-force stents (H group) in 56 procedures. SAEs developed after nine procedures, the median interval from stent placement being 6 days (range, 1-141 days). SAEs occurred more frequently in the H (14%: 8/56) than in the L group (2%: 1/51) (P = 0.03). In patients who had undergone prior radiotherapy, SAEs were more frequent in the H (36%: 4/11) than in the L group (0%: 0/13) (P = 0.03). Re-obstruction and migration occurred after 16 and three procedures, respectively; these rates did not differ significantly between groups (P = 0.59, P = 1, respectively). Low radial-force stents may reduce the risk of SAEs after esophageal stenting.

Usefulness of an artificial intelligence system for the detection of esophageal squamous cell carcinoma evaluated with videos simulating overlooking situation.

OBJECTIVES: Artificial intelligence (AI) systems have shown favorable performance in the detection of esophageal squamous cell carcinoma (ESCC). However, previous studies were limited by the quality of their validation methods. In this study, we evaluated the performance of an AI system with videos simulating situations in which ESCC has been overlooked. METHODS: We used 17,336 images from 1376 superficial ESCCs and 1461 images from 196 noncancerous and normal esophagi to construct the AI system. To record validation videos, the endoscope was passed through the esophagus at a constant speed without focusing on the lesion to simulate situations in which ESCC has been missed. Validation videos were evaluated by the AI system and 21 endoscopists. RESULTS: We prepared 100 video datasets, including 50 superficial ESCCs, 22 noncancerous lesions, and 28 normal esophagi. The AI system had sensitivity of 85.7% (54 of 63 ESCCs) and specificity of 40%. Initial evaluation by endoscopists conducted with plain video (without AI support) had average sensitivity of 75.0% (47.3 of 63 ESCC) and specificity of 91.4%. Subsequent evaluation by endoscopists was conducted with AI assistance, which improved their sensitivity to 77.7% (P = 0.00696) without changing their specificity (91.6%, P = 0.756). CONCLUSIONS: Our AI system had high sensitivity for the detection of ESCC. As a support tool, the system has the potential to enhance detection of ESCC without reducing specificity. (UMIN000039645).

Validity of endoscopic resection for clinically diagnosed T1a-MM/T1b-SM1 N0 M0 esophageal squamous cell carcinoma.

BACKGROUND: Previous guidelines have not described clear recommendations for performing endoscopic resection (ER) of T1a-muscularis mucosa (MM)/T1b-submucosal (SM1) cancers that have invaded ≤ 200 µm because these are considered to have a non-negligible risk of metastasis based on previous analyses of pathologically diagnosed (p)MM/SM1 cancers. Considering that the indication for ER is determined based on a clinical diagnosis, the applicability of ER should be investigated in clinical (c)MM/SM1 but not pMM/SM1 cancers. This study aimed to evaluate validity of ER for cMM/SM1 cancers. METHODS: In total, 175 cMM/SM1 esophageal squamous cell carcinoma cases that were endoscopically or surgically resected between January 2008 and December 2018 were identified from a prospectively maintained database. We histologically evaluated resected specimens and divided them into low- (n = 92) and high-risk (n = 83) cancers for metastasis. RESULTS: Univariate analysis showed that longer tumor length and larger circumferential extent were significantly correlated with high-risk cancer (P < 0.001). Multivariate analysis showed that tumor circumference was an independent predictor of high-risk cancer (P = 0.036). The proportion of low-risk cancers among cases with ≤ 3/4, > 3/4 and < 1, and whole circumferential extent were 59, 17, and 14%, respectively, and the post-ER stricture rates of these groups were 12, 33, and 100%, respectively. CONCLUSION: ER is the first-line treatment for cMM/SM1 cancers with ≤ 3/4 circumferential extent considering that 59% of cMM/SM1 cancers were low-risk cancers for which ER is mostly curative. ER is not recommended for whole circumferential cMM/SM1 cancers given the low proportion of low-risk cancers and the high risk of stricture after ER.

Endoscopic findings in the soft palatal mucosa are associated with the risk of esophageal squamous cell carcinoma.

BACKGROUND AND AIM: We investigated endoscopic findings of the soft palatal mucosa to identify factors associated with esophageal squamous cell carcinoma (ESCC). METHODS: This study was conducted during endoscopic examinations of subjects at Osaka International Cancer Institute from January 2020 through May 2020. We took endoscopic images of the soft palate under non-magnifying and mild-magnifying observations. Subjects with ESCC or a history of ESCC were defined as the ESCC group. Two endoscopists who were blinded to subjects' clinical information interpreted 10 endoscopic findings: melanosis, brownish changes, whitish epithelium, vasodilation, circular alignment of dilated vessels, uneven surface, uneven epithelial color, uneven vessel visibility, palate ridge, and erosion. Subjects were interviewed about their alcohol use, smoking, and flushing reactions. RESULTS: Two hundred eighty-two subjects, including 151 in the ESCC group and 131 in the non-ESCC group, were included in the analysis. Univariate analyses and multivariate logistic regression demonstrated that melanosis, whitish epithelium, and vasodilation were significantly associated with ESCC. The positive likelihood ratios (PLRs) of melanosis, whitish epithelium, and vasodilation were 3.3, 4.2, and 2.8, respectively. Additionally, the PLRs for three of the endoscopic findings in subjects with drinking and smoking habits were higher than in those without these habits-PLRs ranging from 7.23 to 19.1. High PLRs for three endoscopic findings suggested a high possibility of ESCC. Interobserver agreement was substantial for whitish epithelium, moderate for melanosis, and fair for vasodilation. CONCLUSIONS: Three endoscopic findings in soft palate were considered to be useful as alarming signs that indicate ESCC risk.

Diagnosis of pharyngeal cancer on endoscopic video images by Mask region-based convolutional neural network.

OBJECTIVES: We aimed to develop an artificial intelligence (AI) system for the real-time diagnosis of pharyngeal cancers. METHODS: Endoscopic video images and still images of pharyngeal cancer treated in our facility were collected. A total of 4559 images of pathologically proven pharyngeal cancer (1243 using white light imaging and 3316 using narrow-band imaging/blue laser imaging) from 276 patients were used as a training dataset. The AI system used a convolutional neural network (CNN) model typical of the type used to analyze visual imagery. Supervised learning was used to train the CNN. The AI system was evaluated using an independent validation dataset of 25 video images of pharyngeal cancer and 36 video images of normal pharynx taken at our hospital. RESULTS: The AI system diagnosed 23/25 (92%) pharyngeal cancers as cancers and 17/36 (47%) non-cancers as non-cancers. The transaction speed of the AI system was 0.03 s per image, which meets the required speed for real-time diagnosis. The sensitivity, specificity, and accuracy for the detection of cancer were 92%, 47%, and 66% respectively. CONCLUSIONS: Our single-institution study showed that our AI system for diagnosing cancers of the pharyngeal region had promising performance with high sensitivity and acceptable specificity. Further training and improvement of the system are required with a larger dataset including multiple centers.

Real-time assessment of video images for esophageal squamous cell carcinoma invasion depth using artificial intelligence.

BACKGROUND: Although optimal treatment of superficial esophageal squamous cell carcinoma (SCC) requires accurate evaluation of cancer invasion depth, the current process is rather subjective and may vary by observer. We, therefore, aimed to develop an AI system to calculate cancer invasion depth. METHODS: We gathered and selected 23,977 images (6857 WLI and 17,120 NBI/BLI images) of pathologically proven superficial esophageal SCC from endoscopic videos and still images of superficial esophageal SCC taken in our facility, to use as a learning dataset. We annotated the images with information [such as magnified endoscopy (ME) or non-ME, pEP-LPM, pMM, pSM1, and pSM2-3 cancers] based on pathologic diagnosis of the resected specimens. We created a model using a convolutional neural network. Performance of the AI system was compared with that of invited experts who used the same validation video set, independent of the learning dataset. RESULTS: Accuracy, sensitivity, and specificity with non-magnified endoscopy (ME) were 87%, 50%, and 99% for the AI system and 85%, 45%, 97% for the experts. Accuracy, sensitivity, and specificity with ME were 89%, 71%, and 95% for the AI system and 84%, 42%, 97% for the experts. CONCLUSIONS: Most diagnostic parameters were higher when done by the AI system than by the experts. These results suggest that our AI system could potentially provide useful support during endoscopies.

Impact of submucosal saline solution injection for cold snare polypectomy of small colorectal polyps: a randomized controlled study.

BACKGROUND AND AIMS: Cold snare polypectomy (CSP) of small colorectal polyps is widely used. However, the technique is still troubled by insufficient resection depth, which may prevent precise pathologic evaluation. In this study, we investigated whether submucosal injection of saline solution helps to achieve deeper resection in CSP. METHODS: The study was a single-center, prospective, randomized trial. Patients with small (3- to 10-mm diameter) nonpedunculated adenomatous or sessile serrated colorectal polyps were randomly allocated to either conventional CSP (C-CSP) or CSP with submucosal injection (CSP-SI). Primary outcome was the rate of complete muscularis mucosae (MM) resection, defined by the proportion of MM under the tumor more than 80% of the tumor's horizontal dimension. Secondary outcomes were the rates of negative lateral and vertical margins, fragmentation of resected specimens, conversion to hot snare mucosal resection, intraprocedural bleeding, delayed bleeding, and perforation. RESULTS: Two hundred fourteen patients were randomly assigned to the CSP-SI (n = 107) or C-CSP (n = 107) group. The rate of complete MM resection was 43.9% in the CSP-SI group and 53.3% in the C-CSP group, a statistically insignificant difference. The rates of negative lateral margin and vertical margin (42.3% and 56.7%, respectively) in the CSP-SI group were significantly lower than those (58% and 76%) in the C-CSP group (P = .03 and P = .006, respectively). There was no polypectomy-related major bleeding or perforation. CONCLUSIONS: Saline solution injection into the submucosa did not improve the resection depth of CSP of small colorectal polyps, and the method resulted in lower rates of negative lateral and vertical margins of resected lesions. (Clinical trial registration number: UMIN000037980.).