To explore the pathogenesis of anterior resection syndrome by magnetic resonance imaging rectal defecography

BACKGROUND Over 90%of rectal cancer patients develop low anterior resection syndrome(LARS)after sphincter-preserving resection.The current globally recognized evaluation method has many drawbacks and its subjectivity is too strong,which hinders the research and treatment of LARS.AIM To evaluate the anorectal function after colorectal cancer surgery by quantifying the index of magnetic resonance imaging(MRI)defecography,and pathogenesis of LARS.METHODS We evaluated 34 patients using the standard LARS score,and a new LARS evaluation index was established using the dynamic images of MRI defecography to verify the LARS score.RESULTS In the LARS score model,there were 10(29.41%)mild and 24(70.58%)severe cases of LARS.The comparison of defecation rate between the two groups was 29.36±14.17%versus 46.83±18.62%(P=0.004);and MRI-rectal compliance(MRI-RC)score was 3.63±1.96 versus 7.0±3.21(P=0.001).Severe and mild LARS had significant differences using the two evaluation methods.There was a significant negative correlation between LARS and MRI-RC score(P<0.001),and they had a negative correlation with defecation rate(P=0.028).CONCLUSION MRI defecography and standard LARS score can both be used as an evaluation index to study the pathogenesis of LARS.

Machine learning model for prediction of low anterior resection syndrome following laparoscopic anterior resection of rectal cancer:A multicenter study

BACKGROUND Low anterior resection syndrome(LARS)severely impairs patient postoperative quality of life,especially major LARS.However,there are few tools that can accurately predict major LARS in clinical practice.AIM To develop a machine learning model using preoperative and intraoperative factors for predicting major LARS following laparoscopic surgery of rectal cancer in Chinese populations.METHODS Clinical data and follow-up information of patients who received laparoscopic anterior resection for rectal cancer from two medical centers(one discovery cohort and one external validation cohort)were included in this retrospective study.For the discovery cohort,the machine learning prediction algorithms were developed and internally validated.In the external validation cohort,we evaluated the trained model using various performance metrics.Further,the clinical utility of the model was tested by decision curve analysis.RESULTS Overall,1651 patients were included in the present study.Anastomotic height,neoadjuvant therapy,diverting stoma,body mass index,clinical stage,specimen length,tumor size,and age were the risk factors associated with major LARS.They were used to construct the machine learning model to predict major LARS.The trained random forest(RF)model performed with an area under the curve of 0.852 and a sensitivity of 0.795(95%CI:0.681-0.877),a specificity of 0.758(95%CI:0.671-0.828),and Brier score of 0.166 in the external validation set.Compared to the previous preoperative LARS score model,the current model exhibited superior predictive performance in predicting major LARS in our cohort(accuracy of 0.772 for the RF model vs 0.355 for the preoperative LARS score model).CONCLUSION We developed and validated a robust tool for predicting major LARS.This model could potentially be used in the clinic to identify patients with a high risk of developing major LARS and then improve the quality of life.

Effect of low anterior resection syndrome on quality of life in colorectal cancer patients:A retrospective observational study

BACKGROUND Low anterior resection syndrome(LARS)is a common complication of anuspreserving surgery in patients with colorectal cancer,which significantly affects patients'quality of life.AIM To determine the relationship between the incidence of LARS and patient quality of life after colorectal cancer surgery and to establish a LARS prediction model to allow perioperative precision nursing.METHODS We reviewed the data from patients who underwent elective radical resection for colorectal cancer at our institution from April 2013 to June 2020 and completed the LARS score questionnaire and the European Organization for Research and Treatment of Cancer Core Quality of Life and Colorectal Cancer Module questionnaires.According to the LARS score results,the patients were divided into no LARS,mild LARS,and severe LARS groups.The incidence of LARS and the effects of this condition on patient quality of life were determined.Univariate and multivariate analyses were performed to identify independent risk factors for the occurrence of LARS.Based on these factors,we established a risk prediction model for LARS and evaluated its performance.RESULTS Among the 223 patients included,51 did not develop LARS and 171 had mild or severe LARS.The following quality of life indicators showed significant differences between patients without LARS and those with mild or severe LARS:Physical,role,emotional,and cognitive function,total health status,fatigue,pain,shortness of breath,insomnia,constipation,and diarrhea.Tumor size,partial/total mesorectal excision,colostomy,preoperative radiotherapy,and neoadjuvant chemotherapy were identified to be independent risk factors for LARS.A LARS prediction model was successfully established,which demonstrated an accuracy of 0.808 for predicting the occurrence of LARS.CONCLUSION The quality of life of patients with LARS after colorectal cancer surgery is significantly reduced.

Application of electroacupuncture in the prevention of low anterior resection syndrome after rectal cancer surgery

BACKGROUND Low anterior resection syndrome(LARS)is one of the common postoperative complications in patients with rectal cancer,which seriously affects their postoperative recovery and quality of life(QoL).Electroacupuncture therapy is one of the characteristic therapies of traditional Chinese medicine.There are few reports on the prevention and treatment of LARS by electroacupuncture therapy.AIM To explore the clinical effectiveness of electroacupuncture in managing rectal cancer patients with postoperative LARS.METHODS A total of 50 patients with LARS after rectal cancer surgery were retrospectively selected as the research subjects.According to the treatment methods,they were divided into an observation group(n=25)and a control group(n=25).During the four-week treatment period,the control group received standard defecation function training,while the observation group received electroacupuncture care and traditional defecation function training.The anal pressure index(which includes anal resting pressure,anal systolic pressure,and maximum tolerable volume),European Organization of Research and Treatment of Cancer(EORTC)QoL C30(QLQ-C30)score,LARS Scale(LARSS)score,Wexner anal incontinence scale score,Xu Zhongfa five-item 10-point scale score,and the occurrence of adverse reactions were compared between the two groups before and after treatment.RESULTS The experimental group showed considerably enhanced LARSS scores compared to those in the control group after four weeks of treatment.In the first week,second week,and fourth week,the LARSS score and Wexner anal incontinence scale score decreased,and the Xu Zhong method five-item 10-point scale score increased,with significant differences(P<0.05).The experimental group showed substantial improvements in anal resting pressure,anal systolic pressure,and maximum tolerance volume after undergoing 4 wk of therapy in the untreated group(P<0.05).The experimental group's QLQ-C30 score on the EORTC QoL questionnaire was higher than that of the control group during the 1st,2nd,and 4th wk(P<0.05).No significant variation between the groups in the frequency of adverse reactions(P>0.05)was observed.CONCLUSION Electroacupuncture positively impacted LARS following rectal cancer surgery,effectively improving clinical symptoms and anal pressure indicators and patients’standard of life.

Expressions of Connexin and Par-3 in the Distal Margin of Rectal Cancer after Ultra-low Anterior Resection

This study examined the expression of connexin and protease-activated receptor 3 （par-3） in the distal resection margin of rectal cancer and the correlation of the expression of the two proteins with tumor relapse. A total of 40 patients with rectal cancer underwent ultra-low anterior resection with curved cutter stapler. The pathological specimens were divided into 3 groups in terms of sampling sites： tumor group, 2.0-cm group （in which the tissues were harvested 2.0 cm distal to the tumor tissues）, 3.0-cm group （in which the tissues were taken 3.0 cm away from the tumor tissues）. All the samples were pathologically observed and then measured for the expression of connexin and par-3 by employing immunohistochemistry and Western blotting. The operations in this series went uneventfully. No anastomotic stoma bleeding, stenosis and death occurred postoperatively. Histopathologically, in the tumor group, epithelial cells lost normal pattern of arrangement and polarity, and were loosely connected and even detached. In the 3.0-cm group, the epithelia had normal appearance, obvious cell polarity and essentially intact cell junction. Immunohistochemistry and Western blotting indicated that the 3.0-cm group had the strongest expression of connexin and par-3, and the expression in the 2.0-cm group and the tumor group was relatively weak. There existed significant difference in the expression of the two proteins among the three groups （P〈0.05 for all）. It was concluded that the down-regulated connexin and par-3 in the distal margin of rectal cancer tissues may indicate the progression of the disease and high likelihood of recurrence and metastasis. Although no tumor cells were found in the sections of the 2.0cm group, the decreased expression of connexin and par-3 may suggest the development of anaplasia and the increased odds of tumor relapse. Therefore, we are led to speculate that tumor resection only including 2.0 cm of unaffected rectum could not completely avoid the distant metastasis and local relapse.

LOW ANTERIOR RESECTION TREATMENT FOR MIDDLE AND LOWER RECTAL CANCER

Objective:To evaluate the results of low anteriorresection treatment for middle and lower rectal cancer. Methods:Clinical and follow-up data of 196 patients with middle and lower rectal cancer who received low anteriorresection treatment from June 1991 to June 2001 wereretrospectively analyzed. Results: anterior resectiontechnique including double stapling technique、pull-through and Park抯 operations could get a standard radicalresection and had no significant differences in 1, 3, 5 and 10 years survival rates comparing with the abdominoperineal resection(Miles?. Conclusion:The experience suggests that the low anterior resection technique was safe and simplehad less bleeding and fewer complications and couldincrease the life-quality of the patients with rectal cancer.

Transanal minimally invasive surgery to rescue anastomosis following leak after low anterior resection: A case report

Restorative low anterior resection(LAR)for rectal cancer carries a significant risk of anastomotic leak:One of the most feared complications in colorectal surgery.Operative management may include takedown of the anastomosis and end colostomy which,in some cases,is permanent.Other contemporary operative measures include over the scope clips and Endosponge.Recently,there have been case reports and a Society of American Endoscopic and Gastrointestinal Surgeons video on the novel use of transanal minimally invasive surgery(TAMIS)in the management of anastomotic leak.We present a 59-year-old female who underwent LAR after declining radiotherapy for a bulky 9 cm rectal tumour 9-10 cm from the anal verge.Following clinical deterioration,computed tomography demonstrated an anastomotic leak communicating with a 5-cm pelvic collection containing gas.At laparoscopy,pus and faeculent material were washed from the pelvic cavity and drains were placed.Intra-operative endoscopy demonstrated a 7-8 mm dehiscence at the anastomosis.The defect(approximately 7 cm from the anal verge)was successfully closed using TAMIS and a running V-lock suture.The patient recovered well and was discharged home on post-operative day 20.In this case,a low colorectal anastomotic leak was successfully rescued with TAMIS.This novel technique may be useful in the armamentarium of colorectal surgeons experienced in TAMIS.

Assessment and management of low anterior resection syndrome after sphincter preserving surgery for rectal cancer

Many patients develop a variety of bowel dysfunction after sphincter preserving surgeries(SPS)for rectal cancer.The bowel dysfunction usually manifests in the form of low anterior resection syndrome(LARS),which has a negative impact on the patients'quality of life.This study reviewed the LARS after SPS,its mechanism,risk factors,diagnosis,prevention,and treatment based on previously published studies.Adequate history taking,physical examination of the patients,using validated questionnaires and other diagnostic tools are important for assessment of LARS severity.Treatment of LARS should be tailored to each patient.Multimodal therapy is usually needed for patients with major LARS with acceptable results.The treatment includes conservative management in the form of medical,pelvic floor rehabilitation and transanal irrigation and invasive procedures including neuromodulation.If this treatment failed,fecal diversion may be needed.In conclusion,Initial meticulous dissection with preservation of nerves and creation of a neorectal reservoir during anastomosis and proper Kegel exercise of the anal sphincter can minimize the occurrence of LARS.Pre-treatment counseling is an essential step for patients who have risk factors for developing LARS.

Magnetic resonance imaging-based deep learning model to predict multiple firings in double-stapled colorectal anastomosis

BACKGROUND Multiple linear stapler firings during double stapling technique(DST)after laparoscopic low anterior resection(LAR)are associated with an increased risk of anastomotic leakage(AL).However,it is difficult to predict preoperatively the need for multiple linear stapler cartridges during DST anastomosis.AIM To develop a deep learning model to predict multiple firings during DST anastomosis based on pelvic magnetic resonance imaging(MRI).METHODS We collected 9476 MR images from 328 mid-low rectal cancer patients undergoing LAR with DST anastomosis,which were randomly divided into a training set(n=260)and testing set(n=68).Binary logistic regression was adopted to create a clinical model using six factors.The sequence of fast spin-echo T2-weighted MRI of the entire pelvis was segmented and analyzed.Pure-image and clinical-image integrated deep learning models were constructed using the mask region-based convolutional neural network segmentation tool and three-dimensional convolutional networks.Sensitivity,specificity,accuracy,positive predictive value(PPV),and area under the receiver operating characteristic curve(AUC)was calculated for each model.RESULTS The prevalence of≥3 linear stapler cartridges was 17.7%(58/328).The prevalence of AL was statistically significantly higher in patients with≥3 cartridges compared to those with≤2 cartridges(25.0%vs 11.8%,P=0.018).Preoperative carcinoembryonic antigen level>5 ng/mL(OR=2.11,95%CI 1.08-4.12,P=0.028)and tumor size≥5 cm(OR=3.57,95%CI 1.61-7.89,P=0.002)were recognized as independent risk factors for use of≥3 linear stapler cartridges.Diagnostic performance was better with the integrated model(accuracy=94.1%,PPV=87.5%,and AUC=0.88)compared with the clinical model(accuracy=86.7%,PPV=38.9%,and AUC=0.72)and the image model(accuracy=91.2%,PPV=83.3%,and AUC=0.81).CONCLUSION MRI-based deep learning model can predict the use of≥3 linear stapler cartridges during DST anastomosis in laparoscopic LAR surgery.This model might help determine the best anastomosis strategy by avoiding DST when there is a high probability of the need for≥3 linear stapler cartridges.

Anastomotic leakage in rectal cancer surgery:Retrospective analysis of risk factors

BACKGROUND Anastomotic leakage(AL)after restorative surgery for rectal cancer(RC)is associated with significant morbidity and mortality.AIM To ascertain the risk factors by examining cases of AL in rectal surgery in this retrospective cohort study.METHODS To identify risk factors for AL,a review of 583 patients who underwent rectal resection with a double-stapling colorectal anastomosis between January 2007 and January 2022 was performed.Clinical,demographic and operative features,intraoperative outcomes and oncological characteristics were evaluated.RESULTS The incidence of AL was 10.4%,with a mean time interval of 6.2±2.1 d.Overall mortality was 0.8%.Mortality was higher in patients with AL(4.9%)than in patients without leak(0.4%,P=0.009).Poor bowel preparation,blood transfusion,median age,prognostic nutritional index<40 points,tumor diameter and intraoperative blood loss were identified as risk factors for AL.Location of anastomosis,number of stapler cartridges used to divide the rectum,diameter of circular stapler,level of vascular section,T and N status and stage of disease were also correlated to AL in our patients.The diverting ileostomy did not reduce the leak rate,while the use of the transanastomic tube significantly did.CONCLUSION Clinical,surgical and pathological factors are associated with an increased risk of AL.It adversely affects the morbidity and mortality of RC patients.

EVALUATION OF PHYSIOLOGIC FUNCTION OF COLONIC POUCHANASTOMOSES AFTER EXCISION FOR RECTAL CANCER

Objective: To study the physiology value of colonic pouch anastomosis after rectal cancer excision. Methods: Forty-six patients with total mesonectal excision for carcinoma were randomized to either a straight (Group A, n=23) or a colonic pouch anastomosis (Group B, n=23). The neorectal physiologic function of patients in both groups was evaluated, which included laboratory studies. Results: Sphincter pressures in both groups were similar. Preoperative compliance of the rectum was restored after surgery in the Group B, 0.296 (0.224–0.347) L/Kpa, but there was a significant decrease after surgery in the Group A, 0.194 (0.112–0.235) L/Kpa P<0.001. By a multiple regression analysis, neo-rectal complicance was associated with favorable clinical function, and hypermotility of the canal was associated with adverse clinical function. Conclusion: Colonic pouch-anastomosis restores neorectal compliance, which is important for good function after low anterior resection.

Anorectal dysfunction in patients with mid-low rectal cancer after surgery: A pilot study with three-dimensional high-resolution manometry

BACKGROUND The quality of life in patients who develop low anterior resection syndrome(LARS)after surgery for mid-low rectal cancer is seriously impaired.The underlying pathophysiological mechanism of LARS has not been fully investigated.AIM To assess anorectal function of mid-low rectal cancer patients developing LARS perioperatively.METHODS Patients diagnosed with mid-low rectal cancer were included.The LARS score was used to evaluate defecation symptoms 3 and 6 mo after anterior resection or a stoma reversal procedure.Anorectal functions were assessed by threedimensional high resolution anorectal manometry preoperatively and 3-6 mo after surgery.RESULTS The study population consisted of 24 patients.The total LARS score was decreased at 6 mo compared with 3 mo after surgery(P<0.05),but 58.3%(14/24)lasted as major LARS at 6 mo after surgery.The length of the high-pressure zone of the anal sphincter was significantly shorter,the mean resting pressure and maximal squeeze pressure of the anus were significantly lower than those before surgery in allpatients (P < 0.05), especially in the neoadjuvant therapy group after surgery (n = 18). The focalpressure defects of the anal canal were detected in 70.8% of patients, and those patients had higherLARS scores at 3 mo postoperatively than those without focal pressure defects (P < 0.05). Spasticperistaltic contractions from the new rectum to anus were detected in 45.8% of patients, whichwere associated with a higher LARS score at 3 mo postoperatively (P < 0.05).CONCLUSIONThe LARS score decreases over time after surgery in the majority of patients with mid-low rectalcancer. Anorectal dysfunctions, especially focal pressure defects of the anal canal and spasticperistaltic contractions from the new rectum to anus postoperatively, might be the majorpathophysiological mechanisms of LARS.

Colonic pouch confers better bowel function and similar postoperative outcomes compared to straight anastomosis for low rectal cancer

BACKGROUND With advancements in laparoscopic technology and the wide application of linear staplers,sphincter-saving procedures are increasingly performed for low rectal cancer.However,sphincter-saving procedures have led to the emergence of a unique clinical disorder termed anterior rectal resection syndrome.Colonic pouch anastomosis improves the quality of life of patients with rectal cancer>7 cm from the anal margin.But whether colonic pouch anastomosis can reduce the incidence of rectal resection syndrome in patients with low rectal cancer is unknown.AIM To compare postoperative and oncological outcomes and bowel function of straight and colonic pouch anal anastomoses after resection of low rectal cancer.METHODS We conducted a retrospective study of 72 patients with low rectal cancer who underwent sphincter-saving procedures with either straight or colonic pouch anastomoses.Functional evaluations were completed preoperatively and at 1,6,and 12 mo postoperatively.We also compared perioperative and oncological outcomes between two groups that had undergone low or ultralow anterior rectal resection.RESULTS There were no significant differences in mean operating time,blood loss,time to first passage of flatus and excrement,and duration of hospital stay between the colonic pouch and straight anastomosis groups.The incidence of anastomotic leakage following colonic pouch construction was lower(11.4%vs 16.2%)but not significantly different than that of straight anastomosis.Patients with colonic pouch construction had lower postoperative low anterior resection syndrome scores than the straight anastomosis group,suggesting better bowel function(preoperative:4.71 vs 3.89,P=0.43;1 mo after surgery:34.2 vs 34.7,P=0.59;6 mo after surgery:22.70 vs 29.0,P<0.05;12 mo after surgery:15.5 vs 19.5,P=0.01).The overall recurrence and metastasis rates were similar(4.3%and 11.4%,respectively).CONCLUSION Colonic pouch anastomosis is a safe and effective procedure for colorectal reconstruction after low and ultralow rectal resections.Moreover,colonic pouch construction may provide better functional outcomes compared to straight anastomosis.

Limited segmental rectal resection in the treatment of deeply infiltrating rectal endometriosis:10 years’experience from a tertiary referral unit

Background.The management of symptomatic rectal endometriosis is a challenging condition that may necessitate limited stripping or limited segmental anterior rectal resection(LSARR)depending upon the extent and severity of the disease.Objective.To report the efficacy of LSARR in terms of pain,quality of life and short-and long-term complications—in particular,those pertaining to bowel function.Methods.The case notes of all patients undergoing LSARR were reviewed.The analysed variables included surgical complications,overall symptomatic improvement rate,dysmenorrhoea,dyspareunia,and dyschezia.Chronic pain was measured using a visual analogue scale.Quality of life was measured using the EQ-5D questionnaire.Bowel symptoms were assessed using the Memorial Sloan Kettering Cancer Centre(MSKCC)questionnaire.Results.Seventy-four women who underwent LSARR by both open and laparoscopic approaches were included in this study.Sixty-nine(93.2%)women reported improvement in pain and the same percentage would recommend the similar procedure to a friend with the same problem.Approximately 42%of women who wished to conceive had at least one baby.The higher frequency of defecation was a problem in the early post-operative period but this settled in later stages without influencing the quality of life score.Post-operative complications were recorded in 14.9%of cases.Conclusions.LSARR for rectal endometriosis is associated with a high degree of symptomatic relief.Pain relief achieved following LSARR does not appear to degrade with time.As anticipated,some rectal symptoms persist in few patients after long-term follow-up but LSARR is nonetheless still associated with a very high degree of patient satisfaction.

Risk factors for nonclosure of defunctioning stoma and stoma-related complications among low rectal cancer patients after sphincter-preserving surgery

Background::Defunctioning stoma is widely used to reduce anastomotic complications in rectal cancer surgery.However,the complications of stoma and stoma reversal surgery should not be underestimated.Furthermore,in some patients,stoma reversal failed.Here,we investigated the complications of defunctioning stoma surgery and subsequent reversal surgery and identify risk factors associated with the failure of getting stoma reversed.Methods::In total,154 patients who simultaneously underwent low anterior resection and defunctioning stoma were reviewed.Patients were divided into two groups according to whether their stoma got reversed or not.The reasons that patients received defunctioning stoma and experienced stoma-related complications and the risk factors for failing to get stoma reversed were analysed.Results::The mean follow-up time was 47.54(range 4.0-164.0)months.During follow-up,19.5%of the patients suffered stoma-related long-term complications.Only 79(51.3%)patients had their stomas reversed.The morbidity of complications after reversal surgery was 45.6%,and these mainly consisted of incision-related complications.Multivariate analyses showed that pre-treatment comorbidity(HR=3.17,95%CI 1.27-7.96,P=0.014),postoperative TNM stage(HR=2.55,95%CI 1.05-6.18,P=0.038),neoadjuvant therapy(HR=2.75,95%CI 1.07-7.05,P=0.036),anastomosis-related complications(HR=4.52,95%CI 1.81-11.29,P=0.001),and disease recurrence(HR=24.83,95%CI 2.90-213.06,P=0.003)were significant independent risk factors for a defunctioning stoma to be permanent.Conclusions::Defunctioning stoma is an effective method to reduce symptomatic anastomotic leakage,but the stoma itself and its reversal procedure are associated with high morbidity of complications,and many defunctioning stomas eventually become permanent.Therefore,surgeons should carefully assess preoperatively and perform defunctioning stomas in very high risk patients.In addition,doctors should perform stoma reversal surgery more actively to prevent temporary stomas from becoming permanent.

新辅助放化疗加直肠癌切除术后外科切缘的放射性损伤:吻合口漏的预判线索

背景:对于直肠癌切除术后吻合口状态及其对吻合口漏的影响,目前鲜有研究报道。本研究旨在分析新辅助放化疗+直肠前切除术后外科切缘可能受到的放射性损伤,以及其与吻合口漏发生的关系。方法:回顾性纳入2014-2015年间连续收治的161例直肠前切除手术患者,包括行新辅助放化疗、单纯新辅助化疗或未行术前新辅助治疗者。采用一种专门的组织病理学评分和黏膜下层微血管密度,来对手术切缘标本进行评估。采用倾向评分匹配方法来平衡基线资料。分析吻合口漏与组织病理学特征的相关性。结果:54例新辅助放化疗患者中13例术后发生吻合口漏,48例新辅助化疗患者中5例术后发生吻合口漏,而59例未行新辅助治疗的患者中有7例出现术后吻合口漏。倾向评分匹配后,新辅助放化疗、新辅助化疗和未行新辅助治疗三组患者近切缘组织病理评分中位数(范围)分别为3(0-8)、0(0-3)和0(0-2)(P<0.001),远切缘组织病理评分分别为4(2-9)、0(0-4)和0(0-3)(P<0.001);近切缘微血管密度平均数(标准差)分别为21.7(7.9)、27.2(8.6)和27.3(9.4)(P=0.003),远切缘微血管密度分别为18.1(9.3)、25.2(12.9)和24.9(7.4)(P<0.001)。在新辅助放化疗患者中,吻合口漏的发生与组织病理学评分增高(P=0.003)及微血管密度减少(P=0.004)密切相关。结论:新辅助放化疗后,直肠癌切除术的外科切缘存在一定程度的放射性损伤。近切缘放射性损伤越严重,吻合口漏发生概率越高。