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.

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.

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.

Possible candidates for splenic hilar nodal dissection among patients with upper advanced gastric cancer without invasion of the greater curvature.

BACKGROUND: Spleen preserving D2 total gastrectomy without dissection of the splenic hilar nodes (#10) is a standard operation for upper advanced gastric cancer without invasion of the greater curvature (UGC-wGC). However, some patients with #10 metastasis have survived after splenectomy with dissection of #10. This study explored possible candidates for dissection of #10 among patients with UGC-wGC by examining the metastatic rate and the therapeutic index. METHODS: This study retrospectively reviewed data of patients treated in National Cancer Center Hospital (Japan) between 2000 and 2012. We applied the following inclusion criteria: (1) ≥ D2 total gastrectomy with splenectomy, (2) UGC-wGC, and (3) gastric adenocarcinoma histology. Univariate and multivariate analyses were performed to identify risk factors for #10 metastasis. RESULTS: A total of 366 patients were examined; #10 metastasis was observed in 4.4% (16/366). The multivariate analysis revealed that location (posterior vs. others, P = 0.025) and histology (undifferentiated vs. differentiated, P = 0.048) were significant factors for #10 metastasis among sex, age, tumor size, dominant circumferential location, macroscopic type, depth of invasion, and histology. The incidence of #10 metastasis was 14.9% (7/47) for tumors located on the posterior wall with undifferentiated type histology. The 5-year overall survival rate of these patients was 42.9%, and the therapeutic index was 6.38, which was the second highest value among the second-tier nodal stations. CONCLUSION: Even for upper advanced gastric cancer without invasion of the greater curvature, dissection of #10 could be justified for tumors located on the posterior wall with undifferentiated type histology.

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.

Late complication after gastrectomy for clinical stage I cancer: supplementary analysis of JCOG0912.

BACKGROUND: Late complications following gastric cancer surgery, including postgastrectomy syndromes, are complex problems requiring a solution. Reported risk factors for developing late complications include surgery-related factors, such as the surgical approach and the extent of resection and reconstruction. However, this has not been assessed in a prospective study with a large sample size. Therefore, this study aimed to evaluate associations between surgery-related factors and the development of late complications. Data from the JCOG0912 trial were used. It compared laparoscopy-assisted distal gastrectomy (LADG) to open distal gastrectomy (ODG) in clinical stage I gastric cancer patients. METHODS: This study included 881/921 patients enrolled in the JCOG0912 trial. The incidence of late complications was compared between the ODG and the LADG arms. In addition, associations between surgery-related factors and the development of late complications were assessed by multivariable analyses using the proportional odds model to identify relevant risk factors. RESULTS: There was no difference in the type or number of patients with late complications between the LADG and the ODG arms. The multivariable analysis for each late complication revealed that the Billroth-I reconstruction (vs. R-en-Y or Billroth-II) had a lower risk of cholecystitis [odds ratio (OR) 0.187, 95% confidence interval (CI) 0.039-0.905, P = 0.037] or ileus (OR 0.116, 95%CI 0.033-0.406, P < 0.001), and pylorus-preserving gastrectomy (vs. R-en-Y or Billroth-II) had a higher risk of reflux esophagitis (OR 3.348, 95% CI 1.371-8.176, P = 0.008). The surgical approach was not a risk factor for any late complications. CONCLUSION: Differences in surgical approaches did not constitute a risk for developing late complications after gastrectomy. Billroth-I reconstruction reduced the risk of ileus and cholecystitis, but pylorus-preserving gastrectomy carried a risk for reflux esophagitis.

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.

Effects of let-7a microRNA and C-C chemokine receptor type 7 expression on cellular function and prognosis in esophageal squamous cell carcinoma.

BACKGROUND: C-C chemokine receptor type 7 (CCR7) participates in chemotactic and metastatic responses in various cancers, including in esophageal squamous cell carcinoma (ESCC). The microRNA (miRNA) let-7a suppresses migration and invasion of various types of cancer cells by downregulating CCR7 expression. METHODS: The expression levels of CCR7 and let-7a were measured in the cell lines, tumor, and peritumoral tissues of ESCC patients. KYSE cell lines were transfected with synthetic let-7a miRNA and a let-7a miRNA inhibitor, and their CCR7 expression levels as well as invasive ability were evaluated. A highly invasive cell line was established via an invasion assay, and CCR7 expression level along with let-7a level was subsequently evaluated. Cancer cells overexpressing CCR7 were injected subcutaneously into mice, and the animals were monitored for tumor growth along with lymph node metastasis. RESULTS: A negative correlation between CCR7 and let-7a expression was observed in the ESCC cell lines as well as in tissue samples from patients. Synthetic let-7a decreased CCR7 expression level, while the let-7a inhibitor increased it. In vitro, the established highly invasive cancer cells with high and low levels of CCR7 and let-7a expression, respectively, exhibited a greater invasive ability than the wild-type cell line. The cells were associated with tumor growth and lymph node metastasis in mice. Patients in the high-CCR7/low-let-7a group had the worst prognosis, with a five-year recurrence free survival (5-RFS) rate of 37.5%, followed by the high-CCR7/high-let-7a (5-RFS: 60.0%) and low-CCR7 (5-RFS: 85.7%; p = 0.038) groups. CONCLUSIONS: The expression of CCR7 was downregulated by let-7a miRNA in esophageal cancer cells. The decrease in let-7a expression level led to the increased expression level of CCR7 in ESCC cells, consequently increasing their invasive ability and malignancy and resulting in a worse prognosis for ESCC patients. TRIAL REGISTRATION: Retrospectively registered.

The prognostic impact of macroscopic serosal change on resectable advanced gastric cancer.

BACKGROUND: Advanced gastric cancer sometimes causes macroscopic serosal change (MSC) due to direct invasion or inflammation. However, the prognostic significance of MSC remains unclear. METHODS: A total of 1410 patients who had been diagnosed with deeper-than-pathological-T2 gastric cancer and undergone R0 gastrectomy with lymph node dissection at the National Cancer Center Hospital during January 2000 and December 2012 were restrospectively reviewed. RESULTS: MSC was not found in 108 of the 506 patients with pathological T4a (21.3%), whereas it was detected in 250 of the 904 patients with pathological T2-T3 (27.7%). The sensitivity, specificity and accuracy for diagnosing pathological serosa exposed (SE) by MSC were 78.7, 72.3 and 74.6%, respectively. The MSC-positive cases had a worse 5-year overall survival (OS) than the MSC-negative cases in pT3 (72.9% vs. 84.3%, p = 0.001), pT4a (56.2% vs. 73.4%, p = 0.001), pStageIIB (76.0% vs. 88.4%, p = 0.005), pStageIIIA (63.4% vs. 75.6%, p = 0.019), pStageIIIB (53.6% vs. 69.2%, p = 0.029) and pStage IIIC (27.6% vs. 50.0%, p = 0.062). A multivariate analysis showed that MSC was a significant independent predictor for the OS (hazard ratio [HR]: 1.587, 95%CI 1.209-2.083, p = 0.001) along with the tumor depth (HR: 7.742, 95%CI: 2.935-20.421, p < 0.001), nodal status (HR:5.783, 95% CI 3.985-8.391, p < 0.001) and age (HR:2.382, 95%CI: 1.918-2.957, p < 0.001). Peritoneal recurrence rates were higher in the MSC-positive cases than in the MSC-negative cases at each pT stage. CONCLUSIONS: In this study, the MSC was one of the independent prognostic factors in patients with resectable locally advanced gastric cancer.

Intraoperative blood loss as an independent prognostic factor for curative resection after neoadjuvant chemotherapy for gastric cancer: a single-center retrospective cohort study.

PURPOSE: Surgery-induced factors such as postoperative infectious complications (PICs) and intraoperative blood loss (IBL) have a negative impact on the survival of patients undergoing surgery for gastric cancer. A recent study showed that neoadjuvant chemotherapy (NAC) could reduce the negative impact of PICs; hence, we conducted the present study to investigate if NAC can also reduce the negative prognostic impact of IBL. METHODS: We reviewed 115 gastric cancer patients treated with NAC and radical gastrectomy. The cut-off for IBL predicting the long-term survival was assessed by a receiver operating characteristic curve. The Cox proportional hazard model was used to evaluate the association between patient characteristics including IBL, overall survival, and disease-free survival. RESULTS: The cut-off for IBL was set at 990 ml. Twenty-six patients had excessive IBL exceeding 990 ml (22.6%) and PICs developed in 33 patients (28.7%). The body mass index, IBL, ypT, and ypN were significant independent prognostic predictors, but PICs were not. CONCLUSION: NAC did not decrease the risk induced by excessive IBL. The prophylactic effect of NAC on surgery-induced risk was inconsistent.

Is surgery alone sufficient for treating T1 gastric cancer with extensive lymph node metastases?

BACKGROUND: Whether or not surgery alone is sufficient for treating patients with pathological stage T1N2M0 (Stage IIA), T1N3a/bM0 (Stage IIB/IIIB), and T3N0M0 (Stage IIA) gastric cancer who were not indicated for adjuvant treatment according to the Japanese gastric cancer treatment guideline remains unclear. METHODS: We retrospectively reviewed the clinical records of 236 patients who had been diagnosed with pT1N2-3b/pT3N0 gastric cancer and undergone R0 gastrectomy with lymph node dissection between January 2000 and December 2012 at the National Cancer Center Hospital, Japan. RESULTS: The 5-year recurrence-free survival (RFS) rates (95% confidence interval [CI]) of the patients with pathological (p) T1N2-3b and T3N0 cancer were 73.9% (63.1-84.7) and 89.5% (84.0-95.0), respectively. The only significant prognostic factors for the survival identified by a multivariate Cox regression analysis in patients with pT1N2-3 cancer were the pN stage (N3a/N2: hazard ratio [HR] 2.940, 95% CI 1.314-5.577; N3b/N2: HR 8.688, 95% CI 3.096-24.382) and tumor diameter (<30/ ≥ 30 mm) (HR 2.919; 95% CI 1.351-6.304). We divided the patients with pT1N2-3 gastric cancer into 3 risk categories (high, moderate, low) using these 2 significant prognostic factors and found that the 5-year RFS rates were significantly different among the 3 risk groups (low risk, 93.0%; moderate risk, 66.7%; high risk, 25.0%; P < 0.001). CONCLUSIONS: pT3N0 and large pT1N2 with a diameter ≥ 30 mm had an excellent prognosis, while pT1N2-3 with at least N3a/b or a tumor diameter < 30 mm showed a relatively poor prognosis. These patients may be candidates for adjuvant chemotherapy.

Different risks of nodal metastasis by tumor location in remnant gastric cancer after curative gastrectomy for gastric cancer.

BACKGROUND: Curative surgery for remnant gastric cancer (RGC) after gastrectomy for gastric cancer (GC) can be challenging. We examined the risk factors for lymph node metastasis in RGC, especially for tumors located at the greater curvature (G) or non-greater curvature (NG), to determine the appropriate indications of curative surgery. METHODS: Data from the two high-volume centers of Japan between 1998 and 2018 were retrospectively reviewed. Among the 137 patients enrolled in this study, 34 were classified as the G group and 103 as the NG group. The incidence of lymph node metastasis and its risk factors was evaluated. RESULTS: Lymph node metastasis was observed in 21.2% (29/137), including 38.2% (13/34) in the G group and 15.5% (16/103) in the NG group (p = 0.008). A logistic regression analysis showed that tumor location of G or NG (p = 0.042), tumor size (p = 0.002) and depth of invasion (p = 0.009) were significant independent risk factors for nodal metastasis. Risk classification using these factors showed that clinical T1-T2 with a maximum size < 35 mm located at the non-greater curvature had the lowest nodal metastatic risk (4.3%). CONCLUSIONS: Tumor location at the G or NG was a significant risk factor for nodal metastasis in RGC. When selecting curative surgery for RGC, physicians should consider the nodal metastatic risk calculated by the tumor location, size and depth of invasion.

Predictive value of the surgical Apgar score on postoperative complications in advanced gastric cancer patients treated with neoadjuvant chemotherapy followed by radical gastrectomy: a single-center retrospective study.

BACKGROUND: The surgical Apgar score (SAS) or modified SAS (mSAS) has been reported as a simple and easy risk assessment system for predicting postoperative complications in primary surgery for gastric cancer. However, few studies have described the SAS's utility in gastric surgery after neoadjuvant chemotherapy (NAC). METHODS: One hundred and fifteen patients who received NAC and radical gastrectomy from 2008 and 2015 were included in this study. The SAS was determined by the estimated blood loss (EBL), lowest intraoperative mean arterial pressure, and lowest heart rate. The mSAS was determined by the EBL reassessed using the interquartile values. The predictive values of the SAS/mSAS for postoperative complications were assessed with univariate and multiple logistic regression analyses. RESULTS: Among the 115 patients, 41 (35.7%) developed postoperative complications. According to analyses with receiver operating characteristic curves of the SAS and mSAS for predicting postoperative complications, the cut-off value of the mSAS was set at 8. The rates of anastomotic leakage, pancreatic fistula, and arrhythmia in patients with high mSAS (> 8) values were higher than in those with low (0-3) and moderate [1-4] mSAS values. A multiple logistic regression analysis showed that the operation time, body mass index, and diabetes mellitus were independent risk factors for postoperative complications. The mSAS was not a significant predictor. CONCLUSION: The predictive value of SAS or mSAS for morbidity may be limited in patients who undergo gastric cancer surgery after NAC. Future prospective studies with a large sample size will be needed to confirm the present results.

The Therapeutic Survival Benefit of Splenic Hilar Nodal Dissection for Advanced Proximal Gastric Cancer Invading the Greater Curvature.

BACKGROUND: The Japan Clinical Oncology Group phase 3 study confirmed the survival non-inferiority of spleen-preserving surgery against splenectomy for advanced proximal gastric cancer not invading the greater curvature. However, the efficacy of #10 lymph node (LN) dissection for tumors that involve the greater curvature remains unclear. METHODS: Data from patients who underwent D2-total gastrectomy with splenectomy between January 2000 and December 2012 were retrospectively reviewed. The study included 593 patients. The patients were split into two groups, with 212 patients in the tumor invasion of the greater curvature (Gre) group and 381 patients in the non-Gre group. Survival curves and the state of LN metastasis and the index of estimated benefit from LN dissection of each station were evaluated. RESULTS: The incidence of #10 LN metastasis was 8.1% (48/593): 15.1% in the Gre group and 4.2% in the non-Gre group. The 5-year overall survival rates for the patients with and without #10 metastasis were respectively 46.9 and 50.2% (P = 0.829) in the Gre group and 49.6 and 62.3% (P = 0.074) in the non-Gre group. The indices for #10 LN dissection were 7.1 in the Gre group and 2.3 in the non-Gre group. In the Gre group, the node station with the highest index was #3, followed by #4d, #1, #4sb, #4sa, #7, #2, #10 (index > 7). CONCLUSION: The splenic hilar nodes should be prioritized as a component of D2 lymphadenectomy for advanced gastric cancer invading the greater curvature based on its high metastatic rate and index.

Correction to: Oncological safety of proximal gastrectomy for T2/T3 proximal gastric cancer.

The correct name of the corresponding author should be "Takaki Yoshikawa", and not "Takaki Yoshiaki" as given in the original publication of the article.

Does neoadjuvant chemotherapy cancel out the negative survival impact induced by surgical complications after gastrectomy?

BACKGROUND: Postoperative infectious complications (ICs) are associated with a poor prognosis following gastric cancer surgery. Neoadjuvant chemotherapy (NAC) targeting scirrhous-type or bulky nodal disease reportedly exerts a prophylactic effect on the negative impact of ICs. However, a recent study clearly showed that NAC for scirrhous-type disease had no survival benefit. We investigated this prophylactic effect and significant interactions among subgroups of histological response, macroscopic type, and bulky nodal disease. METHODS: We examined 115 patients who received NAC followed by radical gastrectomy between January 2008 and December 2015. The overall survival (OS) and disease-free survival (DFS) were compared between those with and without ICs. Our cohort included 62 with type 4/giant type 3, 44 with bulky nodal disease/para-aortic nodal disease, and 25 with other diseases. RESULTS: A histological response was observed in 80 patients (69.5%). Thirty three (28.7%) developed ICs. There was no significant difference in the OS [hazard ratio (HR) 0.96; 95% confidence interval (CI) 0.47-1.99, p = 0.920] or DFS (HR 0.74; 95% CI 0.40-1.38, p = 0.342) by the presence of ICs. The HR was 1.00 in patients who had no response to NAC (grade 0/1a) and 0.95 in those who responded to NAC (grade 1b/2/3). No subgroups showed significant interactions for the OS. CONCLUSIONS: NAC may cancel out the negative impact of morbidity on the survival in advanced gastric cancer patients. The prophylactic effects by NAC do not depend on the tumor type or histological response.

Oncological safety of proximal gastrectomy for T2/T3 proximal gastric cancer.

BACKGROUND: It remains unclear whether total gastrectomy is necessary for patients with proximal T2/T3 gastric cancer. To explore the oncological safety of proximal gastrectomy for proximal T2/T3 gastric cancer, in this study, we evaluated the metastatic rates in and the therapeutic effect of dissection of key distal lymph node stations that are usually excluded in proximal gastrectomy. METHODS: In this study, we examined 202 patients seen between January 2000 and December 2012, who underwent total gastrectomy with lymph node dissection (D1/D1+/D2; 2/17/183) and was pathologically diagnosed as T2/T3 gastric cancer exclusively located in the upper third of the stomach. The theoretical therapeutic necessity of dissecting lymph nodes at each lymph node station was evaluated based on the therapeutic index calculated by multiplying the frequency of metastasis at each station and the 5-year survival rate of patients with metastasis to that station. RESULTS: The 5-year overall survival rate (95% confidence interval) was 72.9% (65.5-80.3). The metastatic rates at #4d and #12a were very low (0.99% and 0.006%, respectively), and those at #5 and #6 were zero, and therapeutic indices for #4d, #5, #6 and #12a were zero. On the other hand, the most frequent metastatic station was #3, followed by #1, #2 and #7 (overall metastatic rate > 12%), which was consistent with the order of the therapeutic indices. CONCLUSIONS: Considering the nodal stations that need to be dissected, proximal gastrectomy would be the choice and oncologically safe for patients with T2/T3 proximal gastric cancer.

Key nodal stations for predicting splenic hilar nodal metastasis in upper advanced gastric cancer without invasion of the greater curvature.

Background: Standard surgery for upper advanced gastric cancer without invasion of the greater curvature (UGC-GC) is spleen-preserving D2 total gastrectomy without dissection of the splenic-hilar nodes (#10). However, some patients with nodal metastasis to #10 survive more than 5 years due to nodal dissection of #10. If nodal metastasis to #10 is predictable based on the positivity of other nodes dissected by the current standard surgery without #10 nodal dissection, physicians may be able to consider #10 dissection. Methods: This study retrospectively reviewed data from the National Cancer Center Hospital in Japan between 2000 and 2012. We selected cases that met the following criteria: (1) D2 or more total gastrectomy with splenectomy, (2) UGC-GC, and (3) histological type is gastric adenocarcinoma. We performed univariate and multivariate analyses concerning lymph node stations associated with #10 metastasis. Results: A total of 366 patients were examined. A multivariate analysis revealed that #10 metastasis was associated with positivity of the nodes along the short gastric arteries (#4sa) and distal nodes along the splenic artery (#11d) (#4sa: p = 0.003, #11d: p = 0.016). When either key node was positive, the metastatic rate of #10 was 24.4%, and the therapeutic value index was 13.3. Conclusions: #4sa and #11d were key lymph nodes predicting #10 nodal metastasis in UGC-GC. When these key nodes are positive on computed tomography before surgery or according to a rapid pathological examination during surgery, dissection of #10 should be considered even if upper advanced tumors are not invading the greater curvature.

Risk factors for abdominal surgical infectious complications after distal gastrectomy for gastric cancer: A post-hoc analysis of a randomized controlled trial (JCOG0912).

BACKGROUND: Abdominal surgical infectious complications (ASIC) after gastrectomy for gastric cancer impair patients' survival and quality of life. JCOG0912 was conducted to compare laparoscopy-assisted distal gastrectomy with open distal gastrectomy for clinical stage IA or IB gastric cancer. The present study aimed to identify risk factors for ASIC using prospectively collected data. METHODS: We performed a post-hoc analysis of the risk factors for ASIC using the dataset from JCOG0912. All complications were evaluated according to the Clavien-Dindo classification (CD). ASIC was defined as CD grade I or higher anastomotic leakage, pancreatic fistula, abdominal abscess, and wound infection. Analyses were performed using the logistic regression model for univariable and multivariable analyses. RESULTS: A total of 910 patients were included (median age, 63 years; male sex, 61 %). Among them, ASIC occurred in 5.8 % of patients. In the univariable analysis, male sex (odds ratio [OR] 2.855, P = 0.003), diabetes (OR 2.565, P = 0.029), and Roux-en-Y (R-Y) reconstruction (vs. Billroth Ⅰ, OR 2.707, P = 0.002) were significant risk factors for ASIC. In the multivariable analysis, male sex (OR 2.364, P = 0.028) and R-Y reconstruction (vs. Billroth Ⅰ, OR 2.310, P = 0.015) were independent risk factors for ASIC. CONCLUSIONS: Male sex and R-Y reconstruction were risk factors for ASIC after distal gastrectomy. Therefore, when performing surgery on male patients or when R-Y reconstruction is selected after gastrectomy for gastric cancer, surgeons should pay special attention to prevent ASIC.