Surgical step recognition in laparoscopic distal gastrectomy using artificial intelligence: a proof-of-concept study.

PURPOSE: Laparoscopic distal gastrectomy (LDG) is a difficult procedure for early career surgeons. Artificial intelligence (AI)-based surgical step recognition is crucial for establishing context-aware computer-aided surgery systems. In this study, we aimed to develop an automatic recognition model for LDG using AI and evaluate its performance. METHODS: Patients who underwent LDG at our institution in 2019 were included in this study. Surgical video data were classified into the following nine steps: (1) Port insertion; (2) Lymphadenectomy on the left side of the greater curvature; (3) Lymphadenectomy on the right side of the greater curvature; (4) Division of the duodenum; (5) Lymphadenectomy of the suprapancreatic area; (6) Lymphadenectomy on the lesser curvature; (7) Division of the stomach; (8) Reconstruction; and (9) From reconstruction to completion of surgery. Two gastric surgeons manually assigned all annotation labels. Convolutional neural network (CNN)-based image classification was further employed to identify surgical steps. RESULTS: The dataset comprised 40 LDG videos. Over 1,000,000 frames with annotated labels of the LDG steps were used to train the deep-learning model, with 30 and 10 surgical videos for training and validation, respectively. The classification accuracies of the developed models were precision, 0.88; recall, 0.87; F1 score, 0.88; and overall accuracy, 0.89. The inference speed of the proposed model was 32 ps. CONCLUSION: The developed CNN model automatically recognized the LDG surgical process with relatively high accuracy. Adding more data to this model could provide a fundamental technology that could be used in the development of future surgical instruments.

Comparison of the survival outcomes between retrocolic and antecolic Roux-en-Y reconstruction after gastrectomy for gastric cancer.

Background: There are two methods of Roux-en-Y (RY) reconstruction after gastrectomy: the antecolic route (ACR) and retrocolic route (RCR). There is no evidence to support that the ACR achieves comparable long-term survival. Methods: This was a multi-center historical cohort study. Patients diagnosed with clinical T3/4a and any N stage who underwent open gastrectomy and R0 resection for gastric adenocarcinoma between January 2006 and December 2012 were enrolled. The primary outcome was the hazard ratio of ACR for overall survival, with adjustment for confounding factors by propensity score matching, and a Cox proportional hazards model. Results: A total of 1758 eligible patients were identified from the database. After matching, 410 patients in the ACR and RCR groups were included in the final analysis. The adjusted hazard ratio (95% CI) for ACR was 1.148 (0.870-1.492). The five-year survival rates in the ACR and RCR groups were 74.3% (69.5-78.4) and 77.3% (72.3-81.2), respectively. The short-term surgical outcomes of the two groups did not differ to a statistically significant extent. Conclusion: The route used to lift the jejunum in RY reconstruction did not affect the incidence of long-term survival or postoperative complications. The ACR and RCR are both acceptable options for RY reconstruction during gastric cancer surgery.

Feasibility of laparoscopic/robot-assisted surgery for Borrmann type 4 gastric cancer: a comparison study with conventional open surgery.

BACKGROUND: Laparoscopic surgery for early gastric cancer is regarded as a standard of care because of robust evidences obtained by several phase-III trials. Furthermore, the efficacy of laparoscopic radical surgery for advanced gastric cancer has been also reported. Meanwhile, the feasibility of laparoscopic surgery for Bormann type 4 gastric cancer, special type with unfavorable prognosis, remains unclear since excluded from eligibility of these trials. METHODS: This study included 100 patients with type 4 gastric cancer who underwent laparoscopic/robot-assisted (minimally invasive surgery (MIS) group; n = 32) or open (Open group; n = 68) curative surgery between 2008 and 2021. After propensity score matching, 30 patients in each group were extracted for analysis. Clinical data, including surgical and midterm survival outcomes, were retrospectively compared between the two groups. RESULTS: Incidences of postoperative complication (≥ Clavien-Dindo grade III) were recorded in 23.3% in the MIS group and 13.3% in the Open group, but no statistical significance was demonstrated (P = 0.50). The 3-year overall survival rate in the MIS group was better than that in the Open group (80.2% vs. 53.5%, log-rank, P = 0.03). The trend of recurrence site was similar. Multivariate analysis showed that adjuvant chemotherapy was an independent favorable prognostic factor (hazard ratio, 0.33, 95% confidence interval 0.11-0.93) for overall survival. MIS was indicated as a favorable prognostic factor (hazard ratio, 0.39, 95% confidence interval 0.39-1.07), but without statistical difference. CONCLUSION: While multidisciplinary treatment is mainstay of treatment because of the poor prognosis of this disease, minimally invasive surgery may play an important role in treatment if appropriate patient selection is done. Further analyses with larger sample size are necessary to reach a final conclusion regarding oncological efficacy.

Automatic surgical phase recognition-based skill assessment in laparoscopic distal gastrectomy using multicenter videos.

BACKGROUND: Gastric surgery involves numerous surgical phases; however, its steps can be clearly defined. Deep learning-based surgical phase recognition can promote stylization of gastric surgery with applications in automatic surgical skill assessment. This study aimed to develop a deep learning-based surgical phase-recognition model using multicenter videos of laparoscopic distal gastrectomy, and examine the feasibility of automatic surgical skill assessment using the developed model. METHODS: Surgical videos from 20 hospitals were used. Laparoscopic distal gastrectomy was defined and annotated into nine phases and a deep learning-based image classification model was developed for phase recognition. We examined whether the developed model's output, including the number of frames in each phase and the adequacy of the surgical field development during the phase of supra-pancreatic lymphadenectomy, correlated with the manually assigned skill assessment score. RESULTS: The overall accuracy of phase recognition was 88.8%. Regarding surgical skill assessment based on the number of frames during the phases of lymphadenectomy of the left greater curvature and reconstruction, the number of frames in the high-score group were significantly less than those in the low-score group (829 vs. 1,152, P < 0.01; 1,208 vs. 1,586, P = 0.01, respectively). The output score of the adequacy of the surgical field development, which is the developed model's output, was significantly higher in the high-score group than that in the low-score group (0.975 vs. 0.970, P = 0.04). CONCLUSION: The developed model had high accuracy in phase-recognition tasks and has the potential for application in automatic surgical skill assessment systems.

Advantages of robotic gastrectomy for overweight patients with gastric cancer: a comparison study of robotic gastrectomy and conventional laparoscopic gastrectomy.

PURPOSE: A high body mass index (BMI) generally increases the risk of postoperative complications because of the intraperitoneal adipose tissue. Robotic gastrectomy (RG) decreases the surgical difficulty of conventional laparoscopic gastrectomy (LG) for these patients. We conducted the present study to identify the advantages of RG over LG for overweight patients. METHODS: We reviewed clinical data on patients who underwent either LG or RG at the National Cancer Center Hospital East between January, 2014 and May, 2022. RESULTS: The 1298 patients eligible patients were divided into a non-overweight cohort (n = 996) (LG, n = 818; RG, n = 178) and an overweight cohort (n = 302) (LG, n = 250; RG, n = 52) according to a BMI cut-off of 25 kg/m2. In the overweight cohort, the RG group had a lower incidence of grade ≥ III postoperative complications (0.0 vs. 8.8%, p = 0.01) and grade ≥ II postoperative complications (11.5 vs. 22.0%, p = 0.12) than the LG group. Multivariate analysis identified that RG was significantly associated with a lower incidence of grade ≥ II postoperative complications in the overweight cohort (odds ratio, 0.33; 95% confidence interval, 0.12-0.87; p = 0.02). CONCLUSIONS: RG may reduce the risk of postoperative complications, compared with conventional LG, in overweight patients.

Survival outcomes of laparoscopic versus open total gastrectomy with nodal dissection for gastric cancer in a high-volume Japanese center: A propensity score-matched analysis.

Aim: To compare the survival outcomes of laparoscopic total gastrectomy (LTG) with those of open total gastrectomy (OTG) in gastric cancer. Methods: Using an in-house database, this single-center study reviewed clinical data for patients who underwent surgery for gastric adenocarcinoma in 2008-2018. The patients were divided into an LTG group and an OTG group. Results: Data for 638 patients were screened. After exclusions, 580 patients (LTG, n = 212; OTG, n = 368) were enrolled. Noting that the OTG group included more advanced tumors, 1:1 propensity score matching was implemented to reduce any selection bias, leaving 326 patients (LTG, n = 163; OTG, n = 163; pStage I/II/III = 147/87/92) for further analysis. The operation time was longer and blood loss was less in the LTG group. The postoperative hospital stay was shorter in the LTG group than in the OTG group (9 d vs 10 d；P = .040). There was no significant difference in the incidence of grade III or worse postoperative complications (8.9% vs 11.0%). Five-year overall survival was better in the LTG group (84.9% vs 73.5%; P = .0010, log-rank test), but there was no significant difference in overall survival according to pStage (I, 93.0% vs 89.0%; II, 85.8% vs 77.5%; III, 64.1% vs 52.5%). There was a similar trend in relapse-free survival. Distribution of recurrence sites was comparable. Conclusion: LTG may provide survival outcomes similar to those of OTG when performed by an experienced surgical team. Further evidence is required for final conclusions, especially regarding its efficacy for stage II/III.

Impact of postoperative intra-abdominal infectious complications on survival outcomes in patients with gastric cancer who underwent laparoscopic surgery.

BACKGROUND: Postoperative intra-abdominal infection is known to adversely affect survival outcomes in patients with gastric cancer; however, previous reports have investigated this complication only in open surgery. This adverse effect is expected to be weakened by less invasive surgery, such as a laparoscopic approach, by way of maintaining immune function. METHODS: This study included 1223 patients with gastric cancer who underwent open (n = 439) or laparoscopic (n = 784) curative surgery between 2010 and 2015. For each approach, patients were divided into two groups based on presence or absence of postoperative intra-abdominal infection of Clavien-Dindo grade II or higher (C-group and NC-group, respectively). Survival outcomes were compared in propensity-matched cohorts to evaluate the impact of the complication. RESULTS: The incidences of Clavien-Dindo ≥ grade II postoperative intra-abdominal infectious complications were 9.7% (43/439) in open surgery and 9.8% (70/714) in laparoscopic surgery. After propensity score matching, 86 patients in open surgery and 138 in laparoscopic surgery were extracted for analysis. The 5-year overall survival rate in the open C-group (n = 43) was worse than that in the open NC-group (n = 43) but with no significant difference (70.9% vs. 82.8%, log-rank P = 0.18). The 5-year overall survival rates were equivalent between the laparoscopic C-group (n = 69) and the laparoscopic NC-group (n = 69) (90.5% vs. 90.4%, log-rank P = 0.99). CONCLUSION: In general, postoperative intra-abdominal infection adversely affects survival outcomes; however, its impact may be weakened by less invasive surgery. Further evaluation using larger datasets is necessary before reaching definitive conclusions.

The Significance of Staging Laparoscopy in Detection of Radiologically Occult Peritoneal Carcinomatosis in Gastric Cancer With Gastric Outlet Obstruction: Consideration of The Optimal Treatment Approach.

BACKGROUND/AIM: Gastric cancer with gastric outlet obstruction (GOO) is generally found at an advanced stage and with an unfavorable prognosis. This study was performed to examine the prevalence of radiologically occult peritoneal carcinomatosis in GOO and determine the optimal treatment strategy. PATIENTS AND METHODS: This single-center study was a retrospective review of the clinical data of 186 patients with locally advanced gastric cancer at the distal stomach who underwent surgery from 2008 to 2016. These patients were divided into two groups according to the presence or absence of GOO due to cancer progression: With GOO (n=71) and without GOO (n=115). RESULTS: The incidence of peritoneal carcinomatosis [with macroscopic peritoneal deposits (P1)/positive peritoneal cytology (CY1)] detected at laparotomy/laparoscopy was significantly higher in the group with GOO than in the group without (32.4% vs. 9.6%, p<0.01). The R0 resection rate was lower in the group with GOO (62.0% vs. 87.0%, p<0.01). The 5-year overall survival rate was also lower in the group with GOO (43.9% vs. 68.5%, p<0.01). However, in the subset of patients who underwent R0 surgery, the 5-year rates were similar for the two groups (67.4% vs. 73.1%, p=0.91). The multivariable analysis showed that a type 3 tumor appearance (odds ratio=3.66) and presence of GOO (odds ratio=2.87) were predictors of peritoneal carcinomatosis. CONCLUSION: The prevalence of radiologically occult peritoneal carcinomatosis in gastric cancer with GOO exceeded 30%. Staging laparoscopy (gastrojejunal bypass, if needed) should be performed to determine the optimal treatment plan.

The impact of hiatal hernia on survival outcomes in patients with gastroesophageal junction adenocarcinoma.

Aim: A hiatal hernia (HH) complicates the diagnosis and surgical treatment of gastroesophageal junction (GEJ) cancer. This study aimed to investigate the effect of HH on the survival outcomes of GEJ cancer patients. Methods: This single-center study reviewed clinical data of 78 patients with GEJ adenocarcinoma who underwent R0 resection from 2008 to 2017. The patients were divided into two groups according to whether they presented with or without HH: the HH (+) group (n = 46) and the HH (-) group (n = 32). Results: Patients in the HH (+) group were older than those in the HH (-) group (69.0 vs 67.5 years, P = .018). Regarding surgical outcomes, intra-abdominal infectious complications was more common in the HH (+) group than in the HH (-) group (23.9% vs 9.4%, respectively; P = .089), particularly abscess formation (17.4% vs 3.1%, respectively; P = .036). Neither overall survival (OS) nor relapse-free survival (RFS) differed between the two groups. However, survival rates were significantly worse in a subset of patients with T3-4 disease (OS: log-rank, P = .036) (RFS: log-rank, P = .040) in the HH (+) group. In a multivariate analysis for OS in this cohort, HH was an independent prognostic factor (hazard ratio 3.60; 95% confidence interval 1.06-11.9, P = .032). Conclusion: Hiatal hernia may adversely affect surgical and survival outcomes in patients with GEJ cancer. Thus, surgical strategy must be carefully considered in these patients.

Feasibility and quality of life assessment of laparoscopic proximal gastrectomy using double-tract reconstruction.

PURPOSE: As the frequency of cancer in the proximal stomach or around the esophagogastric junction (EGJ) increases worldwide, the use of laparoscopic proximal gastrectomy (LPG) has expanded. This study evaluated the safety of LPG with double-tract reconstruction (LPG-DT) and the resulting quality of life (QOL) of patients. METHODS: In this retrospective cohort study, we reviewed the data of patients who underwent LPG-DT via linear-stapled esophagojejunostomy for gastric or EGJ cancer between 2013 and 2019, and outcomes were compared with those of laparoscopic total gastrectomy with Roux-en-Y reconstruction (LTG-RY) peMME000372rformed over the same period. Surgical outcomes, changes of nutritional parameters, and chronological QOL as evaluated using the Postgastrectomy Syndrome Assessment Scale (PGSAS-37) questionnaire were compared in the propensity-matched cohorts. RESULTS: In total, 289 patients (99 LPG-DT and 190 LTG-RY) were eligible and the outcomes were evaluated in the propensity-matched cohorts (n = 75 each). Operative time and the incidence of complications (≥ grade III) were comparable. Reflux esophagitis was more frequent in the LPG-DT group (8.0% vs. 0%), whereas the incidence of anastomotic stricture did not differ. The percentage rates of body weight loss and hemoglobin reduction were lower in the LPG-DT group at any time point within postoperative 2 years but show no statistical differences. In PGSAS-37 (n = 26, n = 23), the diarrhea and quality of ingestion scores were slightly better in the LPG-DT group. CONCLUSIONS: The present study suggested that our LPG-DT is feasible and safe in appropriately selected patients, and it may provide slightly better outcomes in nutrition and QOL compared with LTG-RY.

Delta-shaped gastroduodenostomy after totally laparoscopic distal gastrectomy for gastric cancer: comparative study of original and modified methods.

BACKGROUND: Delta-shaped anastomosis (DA) has been widely accepted as a standard procedure for intracorporeal Billroth-I reconstruction after laparoscopic distal gastrectomy. We introduced DA in 2010 at our hospital and later developed a modified DA method in which a stapled corner of the duodenal stump was removed simultaneously with closure of an entry hole to reduce postoperative complications. METHODS: The clinical data of 507 patients undergoing laparoscopic distal gastrectomy with DA from October 2010 through December 2018 were retrospectively collected from our in-house database. On the basis of the reviewed data, patients were divided into two groups: the original DA group (org-DA, n = 392) and the modified DA group (mod-DA, n = 115). Surgical outcomes, postoperative nutritional parameters, and endoscopic findings 1 year after surgery were compared between the two groups. RESULTS: Baseline characteristics were similar between the two groups. Anastomotic stricture occurred in three patients (0.8%) in the org-DA group and one patient (0.9%) in the mod-DA group (P = 0.911). Anastomotic leakage was recorded in five patients (1.3%) in the org-DA group and none of the patients (0%) in the mod-DA group (P = 0.593). One year after surgery, the change in body weight in the org-DA group/mod-DA group was - 8.1%/- 7.0% (P = 0.285), and the change in hemoglobin level was - 5.0%/- 3.9% (P = 0.012). Endoscopic examination at the 1-year follow-up in the mod-DA group showed smaller amounts of food residue (P = 0.008) as well as less residual gastritis (P < 0.001) than in the org-DA group. CONCLUSIONS: The modified DA method can be performed safely with a complication rate comparable with the original DA method. Furthermore, better postoperative function is expected because of its more natural anatomy and physiology resulting from the modified method.

Can laparoscopic spleen-preserving splenic hilar lymph node dissection replace prophylactic splenectomy for proximal advanced gastric cancers that invade the greater curvature?

BACKGROUND AND OBJECTIVES: Proximal advanced gastric cancer that invades the greater curvature is often treated by prophylactic splenectomy because of a risk for metastasis to the splenic hilar lymph node (station No.10). We evaluated whether laparoscopic spleen-preserving splenic hilar dissection (SPSHD) could be a better approach. METHODS: We reviewed records of patients with proximal gastric cancer who underwent total gastrectomy with No.10 dissection between 2012 and 2018 using our in-house database set. We divided patients by whether they had received SPSHD or splenectomy, first to compare surgical outcomes, and subsequently to analyze survival outcomes among patients with tumors invading the greater curvature. RESULTS: Of 145 patients enrolled in this study, 82 had SPSHDs and 63 had splenectomies. All SPSHDs were laparoscopic; 80% of splenectomies were laparotomic. Morbidity ≥ grade III was seen in 8.5% of the SPSHD group and 11.1% of the splenectomy group. The median number of retrieved No. 10 nodes was three in each group. In multivariable analysis, SPSHD was not an independent prognostic factor among patients whose tumors invaded the greater curvature (n = 73). Among propensity-matched cohorts (n = 25 each), 5-year relapse-free survival rates were 77.6% in the SPSHD group and 49.9% in the splenectomy group. CONCLUSION: Laparoscopic SPSHD can potentially replace prophylactic splenectomy.

Feasibility of laparoscopic total gastrectomy with splenectomy for proximal advanced gastric cancer: A comparative study with open surgery.

INTRODUCTION: Total gastrectomy with splenectomy (TGS) is sometimes performed for treatment of locally advanced gastric cancer invading the greater curvature because metastasis to splenic hilar nodes is expected. Despite the widespread use of laparoscopic procedures, the feasibility of laparoscopic TGS (LTGS) has been scarcely reported because of its technical difficulties. METHODS: This retrospective single-institutional study included 93 consecutive patients with proximal advanced gastric cancer who underwent either LTGS or open TGS (OTGS) from 2010 to 2018. The patients who underwent LTGS (n = 12) were compared with a 1:2 ratio propensity score-matched cohort of patients who underwent OTGS (n = 20). Clinical outcomes were retrospectively reviewed and compared between the two groups. RESULTS: The patients' baseline characteristics were well balanced between the two groups. The operating time was longer (332.5 vs 222.5 minutes, P < .01) but the blood loss volume was smaller (34.5 vs 426 mL, P < .01) in the LTGS than OTGS group. The incidence of postoperative morbidity (≥ Clavien-Dindo grade III) was much lower (0.0% vs 36.8%, P = .02) and the median postoperative hospital stay was shorter (9 vs 11 days, P < .01) in the LTGS than OTGS group. The median number of harvested No. 10 or 11 days lymph nodes was equivalent between the two groups. CONCLUSIONS: Although TGS is not a common procedure, LTGS may be safely performed in selected patients when carried out by an experienced surgical team. The oncological safety remains unclear and needs to be further examined in future trials.