Objective:To compare and evaluate recurrence patterns after robotic-assisted gastrectomy (RAG) versus laparoscopic-assisted gastrectomy (LAG).Methods:This was a retrospective cohort study of 2915 consecutive patients with gastric adenocarcinoma confirmed by postoperative histology as T1-4aN0-3M0, who had undergone minimally invasive radical gastrectomy at four large gastric cancer treatment centers (Fujian Medical University Union Hospital: 1426 patients; the First Affiliated Hospital, Nanchang University: 1108; Tianjin Medical University Cancer Institute and Hospital: 196; and First Affiliated Hospital of Xi'an Jiaotong University: 185 cases) between 1 January 2015 and 30 June 2019. 930 patients had undergone RAG (RAG group) and 1985 had undergone LAG (LAG group). We assessed the following characteristics: age, sex, body mass index, American Society of Anesthesiologists score, comorbidities, tumor size, extent of surgery, extent of lymph node dissection, pT, pN, year of surgery, and adjuvant chemotherapy, after propensity score matching (1:1). There were no significant differences in baseline clinical characteristics between the two groups formed by propensity score matching (837 in each group) (all P>0.05). The 3-year recurrence-free survival (RFS), recurrence pattern, and conditional RFS were compared. Results:We detected no significant differences in the overall recurrence rate at 3 years (128/837 [15.3%] vs. 141/837 [16.8%], P=0.387) or time to recurrence (15.7±8.1 months vs. 16.4±8.4 months, P=0.449) between the RAG and LAG groups. Peritoneal recurrence was the most common type of recurrence in both groups (55 [6.6%] vs. 69 [8.2%], P=0.524). The difference in 3-year RFS between the RAG and LAG groups was not statistically significant (83.2% vs. 82.5%, P=0.781). We found that age > 60 years, total gastrectomy, and worse pT stage and pN stage were independent risk factors for recurrence in the study patients (all P<0.05), whereas the surgical procedure (RAG or LAG) was not an independent risk factor for RFS ( P=0.242). The 3-year conditional RFS at various time points was comparable between the two groups (1 year postoperatively: 84.6% vs. 84.7%, P=0.793; 3 years postoperatively: 91.5% vs. 94.9%, P=0.647). Conclusions:In this multicenter study of patients with locally resectable gastric cancer, we demonstrated that RAG performed by surgeons at large gastric cancer centers is not inferior to LAG in 3-year recurrence rate or recurrence patterns.

Objective:To compare and evaluate recurrence patterns after robotic-assisted gastrectomy (RAG) versus laparoscopic-assisted gastrectomy (LAG).Methods:This was a retrospective cohort study of 2915 consecutive patients with gastric adenocarcinoma confirmed by postoperative histology as T1-4aN0-3M0, who had undergone minimally invasive radical gastrectomy at four large gastric cancer treatment centers (Fujian Medical University Union Hospital: 1426 patients; the First Affiliated Hospital, Nanchang University: 1108; Tianjin Medical University Cancer Institute and Hospital: 196; and First Affiliated Hospital of Xi'an Jiaotong University: 185 cases) between 1 January 2015 and 30 June 2019. 930 patients had undergone RAG (RAG group) and 1985 had undergone LAG (LAG group). We assessed the following characteristics: age, sex, body mass index, American Society of Anesthesiologists score, comorbidities, tumor size, extent of surgery, extent of lymph node dissection, pT, pN, year of surgery, and adjuvant chemotherapy, after propensity score matching (1:1). There were no significant differences in baseline clinical characteristics between the two groups formed by propensity score matching (837 in each group) (all P>0.05). The 3-year recurrence-free survival (RFS), recurrence pattern, and conditional RFS were compared. Results:We detected no significant differences in the overall recurrence rate at 3 years (128/837 [15.3%] vs. 141/837 [16.8%], P=0.387) or time to recurrence (15.7±8.1 months vs. 16.4±8.4 months, P=0.449) between the RAG and LAG groups. Peritoneal recurrence was the most common type of recurrence in both groups (55 [6.6%] vs. 69 [8.2%], P=0.524). The difference in 3-year RFS between the RAG and LAG groups was not statistically significant (83.2% vs. 82.5%, P=0.781). We found that age > 60 years, total gastrectomy, and worse pT stage and pN stage were independent risk factors for recurrence in the study patients (all P<0.05), whereas the surgical procedure (RAG or LAG) was not an independent risk factor for RFS ( P=0.242). The 3-year conditional RFS at various time points was comparable between the two groups (1 year postoperatively: 84.6% vs. 84.7%, P=0.793; 3 years postoperatively: 91.5% vs. 94.9%, P=0.647). Conclusions:In this multicenter study of patients with locally resectable gastric cancer, we demonstrated that RAG performed by surgeons at large gastric cancer centers is not inferior to LAG in 3-year recurrence rate or recurrence patterns.

Chemotherapy resistance plays a pivotal role in the prognosis and therapeutic failure of patients with colorectal cancer(CRC).Cisplatin(DDP)-resistant cells exhibit an inherent ability to evade the toxic chemotherapeutic drug effects which are characterized by the activation of slow-cycle programs and DNA repair.Among the elements that lead to DDP resistance,O6-methylguanine(O6-MG)-DNA-meth-yltransferase(MGMT),a DNA-repair enzyme,performs a quintessential role.In this study,we clarify the significant involvement of MGMT in conferring DDP resistance in CRC,elucidating the underlying mechanism of the regulatory actions of MGMT.A notable upregulation of MGMT in DDP-resistant cancer cells was found in our study,and MGMT repression amplifies the sensitivity of these cells to DDP treatment in vitro and in vivo.Conversely,in cancer cells,MGMT overexpression abolishes their sensi-tivity to DDP treatment.Mechanistically,the interaction between MGMT and cyclin dependent kinase 1(CDK1)inducing slow-cycling cells is attainted via the promotion of ubiquitination degradation of CDK1.Meanwhile,to achieve nonhomologous end joining,MGMT interacts with XRCC6 to resist chemotherapy drugs.Our transcriptome data from samples of 88 patients with CRC suggest that MGMT expression is co-related with the Wnt signaling pathway activation,and several Wnt inhibitors can repress drug-resistant cells.In summary,our results point out that MGMT is a potential therapeutic target and predictive marker of chemoresistance in CRC.

Objective:To investigate the predictive value of Charlson comorbidity index (CCI) in the operative prognosis of colorectal cancer (CRC).Methods:The retrospective cohort study was conducted. The clinicopathological data of 1 337 CRC patients who underwent surgery in the First Affiliated Hospital of Xi'an Jiaotong University from January 2013 to February 2019 were collected. There were 774 males and 563 females, aged 62(range, 22?80)years. All patients were evaluated by CCI. Observation indicators: (1) clinicopathological characteristics of CRC patients undergoing operation; (2) follow-up and survival; (3) prognostic factors analysis of CRC patients undergoing operation; (4) establishment and evaluation of a nomogram prediction model based on CCI. Follow-up was conducted using the telephone interview or outpatient examination to detect the survival of patients up to March 2020. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was analyzed using the t test. Measurement data with skewed distribution were described as M(range) or M( Q1, Q3), and comparison between groups was analyzed using the Mann-Whitney U test. Count data were described as absolute numbers or percentages, and comparison between groups was analyzed using the chi-square test. Non-para-meter rank sum test was used for comparison of ordinal data. The Kaplan‐Meier method was used to calculate survival rates and draw survival curves, and Log-Rank test was used for survival analysis. Univariate and multivariate analyses were performed using the COX proportional hazard regression model. The independent risk factors were included into R4.0.4 software to construct a nomogram prediction model. The receiver operating characteristic (ROC) curve was drawn, and the area under curve (AUC) was used to evaluate discrimination of the nomogram prediction model. The C-index and calibration chart were used to evaluate consistency of the nomogram prediction model. Results:(1) Clinicopathological characteristics of CRC patients undergoing operation. Of the 1 337 patients, there were 1 041 cases with CCI ≤3 and 296 cases with CCI ≥4. Age, cases with non-smoking history, smoking cessation or smoking history, cases without or with R 0 resection, cases with low, moderate, well differentiated tumor, cases in stage Ⅰ?Ⅱ or Ⅲ?Ⅳ of clinical TNM staging, preoperative carcinoembryonic antigen (CEA) were 61(53,68)years, 717, 43, 281, 12, 1 029, 123, 859, 59, 666, 375, 3.22(1.84,7.75)μg/L for the 1 041 patients with CCI ≤3, versus 70(61,75)years, 217, 19, 60, 43, 253, 48, 237, 11, 102, 194, 5.55(2.43,17.64)μg/L for the 296 patients with CCI ≥4, showing significant differences in the above indicators between them ( Z=?10.50, χ2=7.34, 104.51, Z=?2.31, χ2=82.14, Z=?5.78, P<0.05). (2) Follow-up and survival. All the 1 337 patients were followed up for 31(range, 1?84)months. Of the 1 337 patients, 1 024 cases survived and 313 cases died. The 1-, 3-, 5-year survival rates were 94.8%, 85.5%, 80.1% for the 1 041 patients with CCI ≤3, versus 73.6%, 46.9%, 34.0% for the 296 patients with CCI ≥4, showing significant differences between them ( χ2=181.93, P<0.05). (3) Prognostic factors analysis of CRC patients undergoing operation. Results of univariate analysis showed that age, smoking history (having a history of smoking), tumor location (decending colon-sigmoid colon, recto-sigmoid junction-rectum), R 0 resection, tumor differentiation degree (moderate differentiation, well differentiation), clinical TNM staging, postoperative radio-therapy and chemotherapy, preoperational CEA and CCI were related factors for operative prognosis of CRC patients ( odds ratios=1.76, 0.71, 0.72, 0.61, 0.08, 0.39, 0.13, 3.02, 0.60, 2.41, 4.96, 95% confidence intervals as 1.39?2.23, 0.53?0.93, 0.52?0.99, 0.47?0.78, 0.06?0.11, 0.30?0.50, 0.05?0.31, 2.39?3.81, 0.48?0.76, 1.92?3.01, 3.97?6.20, P<0.05). Results of multivariate analysis showed that age >60 years, clinical TNM staging as stage Ⅲ?Ⅳ, preoperational CEA >5 μg/L and CCI ≥4 were independent risk factors for operative prognosis of CRC patients ( odds ratios=1.29, 1.88, 1.77, 2.84, 95% confidence intervals as 1.00?1.65, 1.45?2.44, 1.40?2.23, 2.20?3.67, P<0.05);tumor located in descending colon to sigmoid colon and recto-sigmoid junction to rectum, R 0 resection,tumor differen-tiation degree as moderate and well differentiation, postoperative radiotherapy and chemotherapy were independent protect factors for operative prognosis of CRC patients ( odds ratios=0.71, 0.72, 0.27, 0.50, 0.25, 0.56, 95% confidence intervals as 0.51?0.98, 0.56?0.93, 0.19?0.37, 0.38?0.65, 0.10?0.62, 0.44?0.70, P<0.05) (4) Establishment and evaluation of a nomogram prediction model based on CCI. Based on age, tumor location, R 0 resection, tumor differentiation degree, clinical TNM staging, postoperative radiotherapy and chemotherapy, preoperational CEA and CCI of multivariate analysis results, a nomogram prediction model for operative prognosis of CRC patients was established. The nomogram score was 1.0 for age >60 years, 18.0 for tumor located in proximal colon, 9.0 for tumor located in distal colon, 53.0 for non-R 0 resection, 62.0 for low differentiated tumor, 31.0 for morderate differentiated tumor, 32.0 for stage Ⅲ?Ⅳ of clinical TNM staging, 26.0 for no postoperative radiotherapy and chemotherapy, 4.6 for each increase of 100 μg/L in preoperative CEA and 12.6 for each increase of 1 score in CCI respectively. The total of different scores for risk factors was used to evaluate total 1, 3, 5-year survival rates. The ROC curve was drawn to evaluate the predictive ability for prognosis of nomogram model, with the AUC as 0.75 (95% confidence interval as 0.71?0.79, P<0.05). The C-index was 0.80 (95% confidence interval as 0.77?0.72). The calibration chart showed a good consistency between the probability of survival predicted by nomogram and the actual probability of survival. Conclusions:Age >60 years, stage Ⅲ?Ⅳ of clinical TNM staging, preoperational CEA >5 μg/L and CCI ≥4 are independent risk factors for operative prognosis of CRC patients. Tumor located in descending colon to sigmoid colon and recto-sigmoid junction to rectum, R 0 resection, tumor differentiation degree as moderate and well differentiation, postoperative radiotherapy and chemotherapy are independent protective factors for operative prognosis of CRC patients. The nomogram prediction model contributes to prediction of the survival of CRC patients.

【Objective】 To explore the correlation of preoperative fibrinogen-to-albumin ratio （FAR） with the clinicopathological characteristics and prognosis of patients with rectal cancer so as to clarify the role of coagulation function and nutritional status in the occurrence and progression of tumors. 【Methods】 We retrospectively analyzed the clinicopathological data of 647 patients with rectal cancer who underwent radical resection in The First Affiliated Hospital of Xi’an Jiaotong University from January 1， 2013 to December 31， 2016. According to the optimal cut-off point value of FAR determined by receiver operating characteristic curve， 647 rectal cancer patients were divided into high FAR level group and low FAR level group. The correlation between different preoperative FAR levels and clinicopathological characteristics of rectal cancer patients was analyzed. Multivariate Cox regression analysis was used to analyze the independent risk factors for the prognosis of rectal cancer patients. R software was used to construct the nomogram， and C index and calibration chart were used to evaluate the prediction efficiency of the nomogram. 【Results】 Preoperative FAR levels had a good predictive value for the prognosis of rectal cancer patients. The area under ROC curve was 0.771， the optimal cut-off point was 0.092， and the Youden index was 0.446. There were statistically significant differences in age， T stage， N stage， TNM stage， preoperative CEA levels and preoperative CA19-9 levels between rectal cancer patients with different preoperative FAR levels （P<0.05）. The overrall survival and disease-free survival of rectal cancer patients with different preoperative FAR levels had statistically significant differences （P<0.05）. In the multivariate analysis， preoperative FAR levels （≥0.092， HR=3.298， 95% CI： 2.365―4.600， P<0.001）， age （≥60 years， HR=2.110， 95% CI： 1.479―3.012， P<0.001）， TNM stage （Ⅲ grade， HR=6.743， 95% CI： 2.771―16.771， P<0.001）， grade of differentiation （poor， HR=1.639， 95% CI： 1.104―2.432，P=0.014）， preoperative CA19-9 levels （≥37 U/mL， HR=2.205， 95% CI： 1.529―3.180， P<0.001） and not perform postoperative chemoradiotherapy（HR=1.792， 95% CI： 1.294―2.480，P<0.001） were independent risk factors of overall survival for patients with rectal cancer. OS and DFS nomograms of rectal cancer were established by the Rlanguage software， and the C-index was （0.781， 95% CI： 0.749―0.815； 0.754， 95% CI： 0.693―0.760）， respectively. The calibration curve of the nomogram showed high consistence between predictions and actual results for 1-year， 3-year， 5-year OS and DFS. 【Conclusion】 The preoperative high FAR level was an independent risk factor for the prognosis of patients with rectal cancer. It can be supplemented with pathological factors such as TNM stage as prognostic indicators for patients with rectal cancer， which may be helpful for clinicians to follow up or make beneficial treatment for rectal cancer patients.

Objective:To evaluate the feasibility, safety and efficacy of robotic-assisted lateral lymph node dissection for mid-low advanced rectal cancer.Methods:A retrospective cohort study was performed. Inclusion criteria: (1) age between 18 and 80 years old; (2) rectal adenocarcinoma diagnosed by pathology; (3) without distant metastasis by preoperative CT or MRI; (4) patients underwent robotic-assisted total mesorectal resection (TME). Exclusion criteria: (1) conversion to open surgery; (2) multiple primary tumors; (3) patients underwent combined multiple organ resection. According to the above criteria, 137 patients undergoing robotic-assisted mid-low rectal cancer resection in the First Affiliated Hospital of Xi′an Jiaotong University from December 2016 to April 2019 were enrolled. Ninety-seven cases underwent robotic-assisted total mesorectal excision (TME group) and 40 underwent robotic-assisted total mesorectal resection with lateral lymph node dissection (LLND) (TME+LLND group, pelvic LLND was performed with neurovascular guidance to retain pelvic autonomic nerves in the order of the left side the first and then the right side). The propensity score matching of 1:1 was performed with R software, based on age, sex, BMI, ASA classification, distance from tumor to the anal verge, preoperative chemoradiotherapy history, preoperative abdominal surgery history, the size of tumors and TNM stage. The operative indicators, postoperative recovery, pathology and postoperative complications within 30 days were compared between the two groups.Results:A total of 72 cases were successfully matched (36 in each group), and there were no statistically significant differences in baseline data between the two groups (all P>0.05). The operation time of TME+LLND group was significantly longer than that of TME group [275.0 (180-405) minutes vs. 220.0 (140-320) minutes, Z=-3.680, P<0.001], while there were no statistically significant differences in blood loss during operation, time to postoperative first flatus, postoperative hospital stay, total hospital cost, tumor differentiation, and distal resection length of margin (all P>0.05). Circumferential resection margin was all negative in both groups. The number of harvested lymph modes in the TME+LLND groups was higher than that in the TME group [26 (18-37) vs. 14 (9-36), Z=-6.407, P<0.001]. In addition, there were no statistically significant differences in postoperative morbidity and Clavien-Dindo classification of complication within 30 days between the two groups (both P>0.05). Conclusions:Although robotic lateral lymph node dissection requires longer operation time, it is a feasible, safe and effective procedure.

Objective:To evaluate the feasibility, safety and efficacy of robotic-assisted lateral lymph node dissection for mid-low advanced rectal cancer.Methods:A retrospective cohort study was performed. Inclusion criteria: (1) age between 18 and 80 years old; (2) rectal adenocarcinoma diagnosed by pathology; (3) without distant metastasis by preoperative CT or MRI; (4) patients underwent robotic-assisted total mesorectal resection (TME). Exclusion criteria: (1) conversion to open surgery; (2) multiple primary tumors; (3) patients underwent combined multiple organ resection. According to the above criteria, 137 patients undergoing robotic-assisted mid-low rectal cancer resection in the First Affiliated Hospital of Xi′an Jiaotong University from December 2016 to April 2019 were enrolled. Ninety-seven cases underwent robotic-assisted total mesorectal excision (TME group) and 40 underwent robotic-assisted total mesorectal resection with lateral lymph node dissection (LLND) (TME+LLND group, pelvic LLND was performed with neurovascular guidance to retain pelvic autonomic nerves in the order of the left side the first and then the right side). The propensity score matching of 1:1 was performed with R software, based on age, sex, BMI, ASA classification, distance from tumor to the anal verge, preoperative chemoradiotherapy history, preoperative abdominal surgery history, the size of tumors and TNM stage. The operative indicators, postoperative recovery, pathology and postoperative complications within 30 days were compared between the two groups.Results:A total of 72 cases were successfully matched (36 in each group), and there were no statistically significant differences in baseline data between the two groups (all P>0.05). The operation time of TME+LLND group was significantly longer than that of TME group [275.0 (180-405) minutes vs. 220.0 (140-320) minutes, Z=-3.680, P<0.001], while there were no statistically significant differences in blood loss during operation, time to postoperative first flatus, postoperative hospital stay, total hospital cost, tumor differentiation, and distal resection length of margin (all P>0.05). Circumferential resection margin was all negative in both groups. The number of harvested lymph modes in the TME+LLND groups was higher than that in the TME group [26 (18-37) vs. 14 (9-36), Z=-6.407, P<0.001]. In addition, there were no statistically significant differences in postoperative morbidity and Clavien-Dindo classification of complication within 30 days between the two groups (both P>0.05). Conclusions:Although robotic lateral lymph node dissection requires longer operation time, it is a feasible, safe and effective procedure.

Objective To investigate the learning curve of Da Vinci robot-assisted laparoscopic radical gastrectomy for gastric cancer.Methods The retrospective cohort study was conducted.The clinicopathological data of 42 patients who underwent Da Vinci robot-assisted radical gastrectomy for gastric cancer in the First Affiliated Hospital of Xi'an Jiaotong University from October 2017 to August 2018 were collected.There were 30 males and 12 females,aged from 36 to 84 years,with an average age of 59 years.The learning curve was evaluated using the cumulative sum (CUSUM) analysis and the best fitting curve method.According to the minimum number of surgeries required to cross the learning curve,the patients were divided into learning stage group and mastery stage group.Then general data and surgical efficacy of the two groups were compared.Observation indicators:(1) surgical situations;(2) results of CUSUM analysis;(3) comparison of general data between the two groups;(4) comparison of surgical efficacy between the two groups;(5) follow-up.Patients were followed up by outpatient examination or telephone interview to detect the postoperative complications,tumor recurrence and metastasis up to February 2019.Measurement data with normal distribution were presented as Mean±SD,and comparison between groups was done using the independent sample t test.Count data were represented as absolute number,and comparison between groups was analyzed using the chi-square test or Fisher exact propability.Comparison of ordinal data between groups was analyzed using the Mann-Whitney U test.Results (1) Surgical situations:all the 42 patients underwent Da Vinci robot-assisted radical gastrectomy for gastric cancer successfully,without conversion to open surgery or perioperative death.Fourteen out of 42 patients underwent Da Vinci robot-assisted total radical gastrectomy and 28 underwent Da Vinci robot-assisted distal radical gastrectomy.The operation time and docking time were (213±31)minutes and (26± 11)minutes.The operation time and docking time had a tendency to decreasing as the surgical cases increasing.(2) Results of CUSUM analysis.The CUSUM learning curve were best modeled as a polynomial with equation:CUSUM (operation time)=0.016 9X3-1.913 3X2+ 50.985X-16.595,CUSUM (docking time) =0.012 8X3-1.070 7X2 + 22.189X-23.097 respectively (X means the surgical case).The P value of fitting test of models was ＜ 0.05,with goodness-of-fit (R2) as 0.960 and 0.985.The CUSUM learning curve of operation time reached its peak when the number of surgical cases accumulated to the 19th case.Nineteen cases were the minimum number of surgeries required to cross the learning curve.Similarly,The CUSUM learning curve of docking time reached its peak when the number of surgical cases accumulated to the 14th case,and 14 cases were the minimum number of surgeries required to skillfully master robot installation across the learning curve.(3) Comparison of general data between the two groups:patients were divided into learning stage group and mastery stage group with 19 cases as the cut-off point.Males,females,age,body mass index (BMI),cases in grade 1,2,3 of American society of anesthesiologists (ASA),cases with previous abdominal surgery history,cases with basic diseases,cases in T1,T2,T3,T4 stages of preoperative ultrasonic gastroscopic tumor T staging,maximum tumor diameter,cases in Ⅰ,Ⅱ,Ⅲ stages of postoperative clinical staging,cases with total gastrectomy and distal gastrectomy (surgical method) were 14,5,(60± 13)years,(23.7±2.9)kg/m2,1,16,2,3,8,5,3,3,8,(4.1±3.5)cm,6,7,6,10,9 in the learning stage group,and 16,7,(58±10)years,(23.7±1.3)kg/m2,1,17,5,2,14,3,6,9,5,(4.7±2.7)cm,8,9,6,18,5 in the mastery stage group,respectively.There was no significant difference in the sex,age,BMI,ASA score,basic diseases,preoperative ultrasonic gastroscopic tumor T staging,maximum tumor diameter,postoperative clinical staging,and surgical method between the two groups (x2 =0.086,t =0.475,-0.007,Z =-0.884,x2 =1.469,Z =-0.301,t =-0.651,Z =-0.079,-0.236,x2 =3.076,P ＞ 0.05).There was no significant difference in the previous abdominal surgery history between the two groups (P ＞ 0.05).(4) Comparison of surgical efficacy between the two groups:operation time,volume of intraoperative blood loss,number of lymph nodes harvested,time to first liquid food intake,cases with postoperative complications and duration of postoperative hospital stay were (230±25) minutes,(176± 103) mL,21±7,(5.1 ± 2.0) days,2,(9.3± 2.5)days in the learning stage group,and (191±18) minutes,(95±41)mL,21±6,(4.7±1.7)days,3,(8.4± 2.1)days in the mastery stage group,respectively.There were statistically significant differences in the operation time and volume of intraoperative blood loss between the two groups (t =5.951,-3.359,P＜0.05).There was no statistically significant difference in number of lymph nodes harvested,time to first liquid food intake,and duration of postoperative hospital stay between the two groups (t =-0.120,0.538,1.303,P＞0.05).There was no significant difference in the cases with postoperative complications between the two groups (P＞0.05).(5) Follow-up:all the 42 patients were followed up for 6-16 months,with a median time of 11 months.No serious long-term complications,tumor recurrence and metastasis or death occurred during the follow-up.Conclusions The CUSUM learning curve of Da Vinci robot-assisted radical gastrectomy for gastric cancer can be divided into the learning stage and the mastery stage.It is suggested that the surgeons need to finish 19 cases or more to master Da Vinci robot-assisted radical gastrectomy for gastric cancer.

Objective: To evaluate combined robotic and endoscopic surgery in the third space for gastric submucosal tumors(SMTs). Methods: Combined surgery in 4 patients were compared with 19 patients who underwent laparoscopic wedge resection between Aug 2017 and Feb 2018. Results: R₀ resection was achieved in all combined surgery patients. The operation time was longer (112±29 )min vs. (93±11 ) min (t=2.338, P<0.05), but less blood loss, (11±6)ml vs.(59±6)ml (t=15.102, P<0.01). In combined surgery group, there was a larger tumor over resected tissue percentage, 65.4%±28.2% vs.22.8%±19.6% ( t=3.680, P<0.05). Combined surgery group patients were with earlier first breaking wind (3±1.4) d vs.(4.1±0.9) d (t=2.026, P>0.05), and shorter hospital stay (6.5±1.3) d vs.( 8.5±0.6) d (t=4.902, P<0.01), but a little higher hospitalization costs(57 651±10 097)rmb vs.(42 620±5 086)rmb (t=4.508, P<0.01). There were no major postoperative complications occurred in neither groups, nor tumor recurrences after 3-month follow-up. Conclusion Combined robotic and endoscopic surgery in the third space for submucosal gastric tumors is a novel operation with short operation time, less blood loss and good result.

Objective To study the skills and effects of endoscopic retrograde appendicitis therapy (ERAT) in treating patients with uncomplicated acute appendicitis .Methods We enrolled 21 patients with suspected acute appendicitis who then underwent emergent ERAT between October 2014 and January 2015 .The data of treatment were collected and the operative skills and effects of ERAT were analyzed . Results ERAT was completed successfully in all the patients ,resulting in a success rate of 100% .Mean operation time of ERAT was (49 .7 ± 18 .2) min and mean hospital stay was (3 .3 ± 1 .6)d .Cannulation of the appendix lumen was the most critical step of ERAT ,and cannulation time [(5 .7 ± 4 .9)min , P< 0 .05] was shortened significantly by the use of LoopTip guidewire . Fourteen patients with intraluminal appendicoliths (7 of massive appendicoliths , 4 of sand‐like appendicoliths and 3 of sand‐like appendicoliths with luminal stenosis ) underwent endoscopic lithotomy successfully with balloon or basket ,with the success rate of 100% .One patient who presented perforation after appendicolith removal by basket was cured with conservative treatment .Appendix stent was inserted ,then pulled out after 1 week in 9 patients ,while no complaint or complication of the stent was observed .Operation time of ERAT shortened with the increase of case number .Conclusion ERAT is an effective and safe therapy for treating patients with uncomplicated acute appendicitis .The high success rate and safety of ERAT will be achieved by selecting suitable instruments for cannulation and appendicolith removal ,deciding suitable indications for stenting ,and accumulating of operative cases .