Mesorectal fat area as a useful predictor of the difficulty of robotic-assisted laparoscopic total mesorectal excision for rectal cancer

Predictors of difficulty in robotic splenic flexure mobilization during rectal cancer surgery

PURPOSE

In surgery for rectal cancer, splenic flexure mobilization is sometimes necessary to ensure a tension-free colorectal anastomosis with adequate blood supply. Splenic flexure mobilization is regarded as a challenging and risky maneuver, but there are no clear indicators of its difficulty in rectal cancer surgery. This study evaluated the impact of clinical and anatomical factors, including splenic flexure height measured qualitatively on the basis of vertebral level using computed tomography, on the difficulty of splenic flexure mobilization during rectal cancer surgery.

METHODS

The enrolled patients underwent robotic splenic flexure mobilization during rectal surgery for primary rectal cancer at Shizuoka Cancer Center in Japan between December 2011 and March 2022. All patients were scheduled to undergo splenic flexure mobilization preoperatively, and all procedures were carried out following a standardized approach. Linear regression analysis was conducted to determine the clinical and anatomical factors significantly influencing the operative time of the abdominal phase, which is defined as the duration from lymph node dissection around the inferior mesenteric artery to the mobilization of the sigmoid and descending colon, including the splenic flexure.

RESULTS

The median operative time for the abdominal phase was 88 min (range, 39-179 min). Univariate analysis revealed that the following variables were significantly correlated with a prolonged abdominal phase: higher body mass index, larger visceral fat area, and higher splenic flexure. In a multiple linear regression analysis, only higher splenic flexure remained significantly associated with a longer abdominal phase (p < 0.01).

CONCLUSIONS

Splenic flexure height measured on the basis of vertebral level using computed tomography may be useful for predicting the difficulty of robotic splenic flexure mobilization in surgery for rectal cancer.

Role of pelvimetry in predicting surgical outcomes and morbidity in rectal cancer surgery: A retrospective analysis

BACKGROUND

Rectal cancer has increased in incidence, and surgery remains the cornerstone of multimodal treatment. Pelvic anatomy, particularly a narrow pelvis, poses challenges in rectal cancer surgery, potentially affecting oncological outcomes and postoperative complications.

AIM

To investigate the relationship between radiologically assessed pelvic anatomy and surgical outcomes as well as the impact on local recurrence following rectal cancer surgery.

METHODS

We retrospectively analyzed 107 patients with rectal adenocarcinoma treated with elective rectal surgery between January 1, 2017, and September 1, 2022. Pelvimetric measurements were performed using computed tomography (CT)-based two-dimensional methods (n = 77) by assessing the pelvic inlet area in mm², and magnetic resonance imaging (MRI)-based three-dimensional techniques (n = 52) using the pelvic cavity index (PCI). Patient demographic, clinical, radiological, surgical, and pathological characteristics were collected and analyzed in relation to their pelvimetric data.

RESULTS

When patients were categorized based on CT measurements into narrow and normal/wide pelvis groups, a significant association was observed with male sex, and a lower BMI was more common in the narrow pelvis group (P = 0.002 for both). A significant association was found between a narrow pelvic structure, indicated by low PCI, and increased surgical morbidity (P = 0.049). Advanced age (P = 0.003) and male sex (P = 0.020) were significantly correlated with higher surgical morbidity. Logistic regression analysis identified four parameters that were significantly correlated with local recurrence: older age, early perioperative readmission, longer operation time, and a lower number of dissected lymph nodes (P < 0.05). However, there were no significant differences between the narrow and normal/wide pelvis groups in terms of the operation time, estimated blood loss, or overall local recurrence rate (P > 0.05).

CONCLUSION

MRI-based pelvimetry may be valuable in predicting surgical difficulty and morbidity in rectal cancer surgery, as indicated by the PCI. The observed correlation between low PCI and increased surgical morbidity suggests the potential importance of a preoperative MRI-based pelvimetric evaluation. In contrast, CT-based pelvimetry did not show significant differences in predicting surgical outcomes or cancer recurrence, indicating that the utility of pelvimetry alone may be limited in these respects.

Prescribing preoperative weight loss prior to major non-bariatric surgery for patients with elevated weight: a national provider survey (PREPARE provider survey)

Background

The surgical patient with obesity presents several challenges in intraoperative and postoperative care. We designed this cross-sectional survey to assess surgeon willingness to prescribe preoperative very low energy diets (VLEDs) and practice patterns in prescribing preoperative weight loss interventions for patients with obesity undergoing non-bariatric abdominal surgery.

Methods and findings

We conducted a cross-sectional survey of practicing surgeons in Canada who perform major non-bariatric abdominal surgery, reported in accordance with the Consensus-Based Checklist for Reporting of Survey Studies and utilizing non-probability convenience sampling. The primary outcome was willingness to prescribe preoperative VLED to obese patients undergoing major non-bariatric abdominal surgery for both benign and malignant indications. We created a multivariable proportional odds model to identify factors associated with willingness to prescribe VLEDs. A total of 78 participants completed and returned the survey (response rate 10.9%; mean age 43.54 ± 8.13 years; 48.72% female). Most surgeons (79.5%) felt that obesity significantly impacted the technical difficulty of their operations. We identified a disconnect between those surgeons who were willing prescribe VLEDs vs. those who actually prescribed them (78.2% vs. 30.8%, respectively). Approximately half of the surgeons reported being unfamiliar with VLEDs. Regression analysis identified practicing in academic institutions was associated with increased willingness to prescribe [odds ratio (OR) 3.71, 95% confidence intervals (CI) 1.01-13.7, p < 0.01].

Conclusion

Although the majority of surgeons feel that obesity adversely impacts perioperative care, only one-third routinely discuss preoperative VLEDs with their patients. Opportunities to increase awareness and evaluate the impact of VLEDs on patient outcomes remain high.

Predictive model of the surgical difficulty of robot-assisted total mesorectal excision for rectal cancer: a multicenter, retrospective study

Rectal cancer robotic surgery is becoming more and more common, but evidence for predicting surgical difficulty is scarce. Our goal was to look at the elements that influence the complexity of robot-assisted total mesorectal excision (R-TME) in the medical care of middle and low rectal cancer as well as to establish and validate a predictive model on the basis of these factors. Within this multicenter retrospective investigation, 166 consecutive patients receiving R-TME between January 2021 and December 2022 with middle and low rectal cancer were included and categorized according to the median operation time. A nomogram was created to forecast the procedure's complexity after variables that could affect its difficulty were found using logistic regression analysis. Using R software, a total of 166 patients were randomly split into two groups: a test group (48 patients) and a training group (118 patients) at a ratio of 7 to 3. The median operation time of all patients was 207.5 min; patients whose operation time was ≥ 207.5 min were allocated to the difficult surgery group (83 patients), and patients whose operation time was < 207.5 min were allocated to the nondifficult surgery group. Multivariate analysis revealed that body mass index (BMI), the gap between the tumor and the anal verge and the posterior rectal mesenteric thickness were independent predictors of surgical duration. A clinical predictive model was created and assessed employing the above independent predictors. The results of the receiver operating characteristic (ROC) analysis revealed the adequate discriminative ability of the predictive model. Our study revealed that it is feasible to predict surgical difficulty by obtaining clinical and magnetic resonance parameters for imaging (the gap between the anal verge and the tumour, and posterior mesorectal thickness), and these predictions could be useful in making clinical decisions.

[Germany's first robot-assisted kidney transplantation from a deceased donor: a good option in obese recipients-with the right team]

Robot-assisted kidney transplantations have been performed in Europe since 2015. In Germany, the technique is slowly spreading - most recently, 3 urological centers performed this type of procedure. We present the first case of a post-mortem, robot-assisted kidney transplantation in Germany in a 60-year-old patient. In addition to the surgical technique and the clinical course, the opportunities of this surgical technique and its challenges are discussed in particular. In summary, the experience at our center is consistent with the findings from the literature that robot-assisted post-mortem kidney transplantation is a safe method for supplementing the principles of open transplantation surgery with the advantages of minimally invasive methods.

Simple pelvimetry predicts the pelvic manipulation time in robot-assisted low and ultra-low anterior resection for rectal cancer

PURPOSE

This study explored the difficulty factors in robot-assisted low and ultra-low anterior resection, focusing on simple measurements of the pelvic anatomy.

METHODS

This was a retrospective analysis of the clinical data of 61 patients who underwent robot-assisted low and ultra-low anterior resection for rectal cancer between October 2018 and April 2023. The relationship between the operative time in the pelvic phase and clinicopathological data, especially pelvic anatomical parameters measured on X-ray and computed tomography (CT), was evaluated. The operative time in the pelvic phase was defined as the time between mobilization from the sacral promontory and rectal resection.

RESULTS

Robot-assisted low and ultra-low anterior resections were performed in 32 and 29 patients, respectively. The median operative time in the pelvic phase was 126 (range, 31-332) min. A multiple linear regression analysis showed that a short distance from the anal verge to the lower edge of the cancer, a narrow area comprising the iliopectineal line, short anteroposterior and transverse pelvic diameters, and a small angle of the pelvic mesorectum were associated with a prolonged operative time in the pelvic phase.

CONCLUSION

Simple pelvic anatomical measurements using abdominal radiography and CT may predict the pelvic manipulation time in robot-assisted surgery for rectal cancer.

Deep pelvis and low visceral fat mass as risk factors for neurogenic bladder after rectal cancer surgery

BACKGROUND

Postoperative neurogenic bladder (PONB) frequently occurs as a complication after rectal cancer surgery. This study aimed to analyze risk factors for developing PONB after rectal cancer surgery, particularly the association between pelvic anatomy and visceral fat mass.

METHODS

We included 138 patients who underwent rectal resection for lower rectal cancer in our department between 2017 and 2021. PONB was defined as the need for urethral catheter reinsertion or oral medication administration for urinary retention after catheter removal with severe NB that required treatment for ≥ 60 days. We obtained visceral fat area (VFA) at the umbilical level based on a CT scan and measured five pelvic dimensions.

RESULTS

Of the 138 patients, 19 developed PONB, with 16 being severe cases. PONB more frequently occurs in patients with a height of < 158 cm, age ≥ 70 years, surgery lasting ≥ 8 h, intraoperative bleeding volume ≥ 150 mL, lateral lymph node dissection, and narrower pelvis. It was more prevalent in cases with low VFA. Conversely, gender, body mass index (BMI), and medical history showed no significant correlations. Multivariate analysis revealed older age, prolonged surgery, and low VFA as independent risk factors for PONB. Independent risk factors for severe PONB included low VFA, older age, prolonged surgery, and deep pelvis.

CONCLUSION

Lower VFA, older age, and prolonged surgery are independent risk factors for developing PONB. Additionally, a deep pelvis is an independent risk factor for severe PONB. Delicate surgical techniques should consider the risk of nerve injury in cases with low VFA and deep pelvis.

The impact of obesity on postoperative outcomes following surgery for colorectal cancer: analysis of the National Inpatient Sample 2015-2019

BACKGROUND

The global burden of obesity has reached epidemic proportions, placing great strain on the North American healthcare system. We designed a retrospective cohort database study comparing postoperative morbidity and healthcare resource utilization between patients living with and without obesity undergoing surgery for colorectal cancer.

METHODS

Adult patients undergoing resection for colorectal cancer were identified from the 2015 to 2019 National Inpatient Sample database. Patients were stratified according to obesity status (i.e., body mass index of 30 kg/m2). Propensity score matching (PSM) with 1:1 nearest-neighbour matching was performed according to demographic, operative, and hospital characteristics. The primary outcome was postoperative morbidity. Secondary outcomes included system-specific postoperative complications, postoperative mortality, length of stay, total admission healthcare cost, and post-discharge disposition. McNemar's and Wilcoxon matched pairs signed rank tests were performed.

RESULTS

After PSM, 7565 non-obese and 7565 obese patients were included. Patients with obesity had a 10% increase in relative risk of overall in-hospital postoperative morbidity (23.1% versus 25.6%, P = 0.0015) and a $4564 increase in hospitalization cost ($70 248 USD versus $74 812 USD, P = 0.0004). Patients with obesity were more likely to require post-operative ICU admission (5.0% versus 8.0%, P < 0.0001) and less likely to be discharged home after their index operation (68.3% versus 64.2%, P = 0.0022).

CONCLUSION

Patients with obesity undergoing surgery for colorectal cancer may be at an increased risk of in-hospital postoperative morbidity. They may also be more likely to have increased hospitalization costs, post-operative ICU admissions, and to not be discharged directly home. Preoperative optimization via weight loss strategies should be further explored.

LASSO-based nomogram predicts the risk factors of low anterior resection syndrome for middle and low rectal cancer underwent robotic surgery

BACKGROUND

This study aims to analyze the influencing factors of postoperative Low Anterior Resection Syndrome (LARS) in patients with middle and low rectal cancer who underwent robotic surgery. It also seeks to predict the probability of LARS through a visual, quantitative, and graphical nomogram. This approach is expected to lower the risk of postoperative LARS in these patients and improve their quality of life through effective prevention and early intervention.

PATIENTS AND METHODS

This research involved patients with middle and low rectal cancer who underwent robotic surgery in the Department of Gastrointestinal Surgery at the First Affiliated Hospital of Nanchang University from January 2015 to October 2022. A series of intestinal dysfunction symptoms arising from postoperative rectal cancer were diagnosed and graded using LARS scoring criteria. After the initial screening of all variables related to LARS with Lasso regression, they were included in logistic regression for further univariate and multivariate analysis to identify independent risk factors for LARS. A prediction model was then constructed.

RESULTS

The study included 358 patients. The parameters identified by Lasso regression included obstruction, BMI, tumor localization, maximum tumor diameter, AJCC stage, stoma, neoadjuvant therapy (NAT), and postoperative adjuvant therapy (AT). Univariate and multivariate analyses indicated that a higher BMI, lower tumor localization, higher AJCC stage, neoadjuvant therapy, and postoperative adjuvant therapy were independent risk factors for total LARS. The AUC of the prediction nomogram was 0.834, with a sensitivity of 0.825 and specificity of 0.741. The calibration curve demonstrated excellent concordance with the nomogram, indicating the prediction curve fit the diagonal well.

CONCLUSION

Higher BMI, lower tumor localization, higher AJCC stage, neoadjuvant therapy, and adjuvant therapy were identified as independent risk factors for total LARS. A new predictive nomogram for postoperative LARS in patients with middle and low rectal cancer undergoing robotic surgery was developed, proving to be stable and reliable. This tool will assist clinicians in managing the postoperative treatment of these patients, facilitating better clinical decision-making and maximizing patient benefits.

Short-term outcomes of robotic tumor-specific mesorectal resection of rectal cancer: surgical techniques in mesorectal division using rolling division of the mesorectum

BACKGROUND

This study aims to report our surgical techniques for robot-assisted laparoscopic anterior resection, specifically focusing on mesorectal division using rolling division of the mesorectum, and to elucidate short-term outcomes at a single institution. Tumor-specific mesorectal excision (TSME) is commonly performed for resection of a tumor located in the upper rectum. However, especially in a narrow pelvis, it is difficult to perform appropriate mesorectal division at an adequate distance from the tumor in robot-assisted laparoscopic anterior resection.

METHODS

Retrospective case series of patients with rectal cancer who underwent robot-assisted TSME using rolling division of mesorectum. Patient characteristics, perioperative clinical results, surgical and pathological details were recorded.

RESULTS

A total of 198 patients underwent robot-assisted TSME for rectal cancer using rolling division of mesorectum between May 2019 and December 2023.The tumor was located in the upper rectum in 45 patients, middle rectum in 115 patients and lower rectum in 38 patients. The types of resections were 40 high anterior resection and 158 low anterior resections. The median operation time was 175 (range 109-310) min, and median mesorectal division time was 24 (range 15-45) min. Median blood loss was 3 (range 0-20) ml; no patients required blood transfusion. The overall complication rate of Clavien-Dindo classification grades I-IV was 7.1%. Anastomotic leakage was observed in two patients (1.0%) with grade III. There was no surgical mortality in this series.

CONCLUSION

This robotic technique for anterior resection is a feasible and reliable procedure for achieving sufficient and safe TSME in this cohort.

Short-term and long-term outcomes after robotic radical surgery for rectal gastrointestinal stromal tumor

BACKGROUND

The optimal approach for ensuring both complete resection and preservation of anal function in rectal gastrointestinal stromal tumor (GIST) remains unknown. The aim of this study was to clarify short-term and long-term outcomes after robotic radical surgery for rectal GIST.

METHODS

A total of 13 patients who underwent robotic radical surgery for rectal GIST between December 2011 and April 2022 were included. All robotic procedures were performed using a systematic approach. A supplemental video of robotic radical surgery for rectal GIST is attached. The short-term outcome was the incidence of postoperative complications during the first 30 days after surgery. Surgical outcomes were retrieved from a prospective database. Long-term outcomes, including overall survival and recurrence-free survival, were determined in all patients.

RESULTS

Median distance from the tumor to the anal verge was 4.0 cm. Surgical margins were negative in all patients. Two patients underwent neoadjuvant imatinib therapy. All patients underwent sphincter-preserving surgery. None underwent conversion to open or laparoscopic surgery. The incidence of postoperative Clavien-Dindo grade II and grade ≥ III complications was 7.7% and 0%, respectively. The median postoperative hospital stay was 7 days. Twelve patients (92.3%) underwent stoma closure within 5 months of the initial surgery. Median follow-up time was 76 months. The 5-year overall survival and recurrence-free survival rates were both 100%. None of the patients had recurrence.

CONCLUSION

Short-term and long-term outcomes after radical robotic surgery for rectal GIST were favorable. Robotic surgery might be a useful surgical approach for rectal GIST.

PREscribing preoperative weight loss prior to major non-bariatric abdominal surgery for patients with Elevated weight: Patient and Provider Survey Protocols (PREPARE surveys)

BACKGROUND

Preoperative very low energy diet (VLED) interventions are used routinely in patients undergoing bariatric surgery, a surgical subspecialty that deals almost exclusively with patients with obesity. Yet, their use and study has been limited in non-bariatric abdominal surgery. To investigate the use of VLEDs in non-bariatric surgery, we plan on conducting a randomized controlled trial (RCT). Prior to proceeding, however, we have designed two surveys as important pre-emptive studies aimed at elucidating patient and provider perspectives regarding these interventions.

METHODS

The patient survey is a cross-sectional, single-center survey aimed at assessing the safety, adherence, barriers to adherence, and willingness to participate in preoperative optimization protocols with VLEDs prior to undergoing elective non-bariatric intra-abdominal surgery (S1 File). The population of interest is all adult patients with obesity undergoing elective non-bariatric intra-abdominal surgery at St. Joseph's Healthcare Hamilton who were prescribed a course of preoperative VLED. The primary outcomes will be safety and adherence. The target sample size is 35 survey responses. The provider survey is a cross-sectional national survey of practicing surgeons in Canada who perform major non-bariatric abdominal surgery aimed assessing the willingness and ability to prescribe preoperative weight loss interventions amongst practicing Canadian surgeons who perform major non-bariatric abdominal surgery (S2 File). The population of interest is independent practicing surgeons in Canada who perform major non-bariatric abdominal surgery. The primary outcome will be willingness to prescribe preoperative VLED to patients with obesity undergoing major non-bariatric abdominal surgery for both benign and malignant indications. The target sample size is 61 survey responses. Descriptive statistics will be used to characterize the sample populations. To determine variables associated with primary outcomes in the surveys, regression analyses will be performed.

DISCUSSION

These survey data will ultimately inform the design of an RCT evaluating the efficacy of preoperative VLEDs for patients with obesity undergoing major abdominal surgery.

Study on sex differences and potential clinical value of three-dimensional computerized tomography pelvimetry in rectal cancer patients

BACKGROUND

Laparoscopic rectal cancer radical surgery is a complex procedure affected by various factors. However, the existing literature lacks standardized parameters for the pelvic region and soft tissues, which hampers the establishment of consistent conclusions.

AIM

To comprehensively assess 16 pelvic and 7 soft tissue parameters through computerized tomography (CT)-based three-dimensional (3D) reconstruction, providing a strong theoretical basis to address challenges in laparoscopic rectal cancer radical surgery.

METHODS

We analyzed data from 218 patients who underwent radical laparoscopic surgery for rectal cancer, and utilized CT data for 3D pelvic reconstruction. Specific anatomical points were carefully marked and measured using advanced 3D modeling software. To analyze the pelvic and soft tissue parameters, we employed statistical methods including paired sample t-tests, Wilcoxon rank-sum tests, and correlation analysis.

RESULTS

The investigation highlighted significant sex disparities in 14 pelvic bone parameters and 3 soft tissue parameters. Males demonstrated larger measurements in pelvic depth and overall curvature, smaller measurements in pelvic width, a larger mesorectal fat area, and a larger anterior-posterior abdominal diameter. By contrast, females exhibited wider pelvises, shallower depth, smaller overall curvature, and an increased amount of subcutaneous fat tissue. However, there were no significant sex differences observed in certain parameters such as sacral curvature height, superior pubococcygeal diameter, rectal area, visceral fat area, waist circumference, and transverse abdominal diameter.

CONCLUSION

The reconstruction of 3D CT data enabled accurate pelvic measurements, revealing significant sex differences in both pelvic and soft tissue parameters. This study design offer potential in predicting surgical difficulties and creating personalized surgical plans for male rectal cancer patients with a potentially "difficult pelvis", ultimately improving surgical outcomes. Further research and utilization of these parameters could lead to enhanced surgical methods and patient care in laparoscopic rectal cancer radical surgery.

Nomogram for predicting the surgical difficulty of laparoscopic total mesorectal excision and exploring the technical advantages of robotic surgery

Background

Total mesorectal excision (TME), represents a key technique in radical surgery for rectal cancer. This study aimed to construct a preoperative nomogram for predicting the surgical difficulty of laparoscopic total mesorectal excision (L-TME) and to investigate whether there were potential benefits of robotic TME (R-TME) for patients with technically challenging rectal cancer.

Methods

Consecutive mid-low rectal cancer patients receiving total mesorectal excision were included. A preoperative nomogram to predict the surgical difficulty of L-TME was established and validated. Patients with technically challenging rectal cancer were screened by calculating the prediction score of the nomogram. Then patients with technically challenging rectal cancer who underwent different types of surgery, R-TME or L-TME, were analyzed for comparison.

Results

A total of 533 consecutive patients with mid-low rectal cancer who underwent TME at a single tertiary medical center between January 2018 and January 2021 were retrospectively enrolled. Multivariable analysis demonstrated that mesorectal fat area, intertuberous distance, tumor size, and tumor height were independent risk factors for surgical difficulty. Subsequently, these variables were used to construct the nomogram model to predict the surgical difficulty of L-TME. The area under the receiver operating characteristic curve of the nomogram was 0.827 (95% CI 0.745 - 0.909) and 0.809 (95% CI 0.674- 0.944) in the training and validation cohort, respectively. For patients with technically challenging rectal cancer, R-TME was associated with a lower diverting ileostomy rate (p = 0.003), less estimated blood loss (p < 0.043), shorter procedure time (p = 0.009) and shorter postoperative hospital stay (p = 0.037).

Conclusion

In this study, we established a preoperative nomogram to predict the surgical difficulty of L-TME. Furthermore, this study also indicated that R-TME has potential technical advantages for patients with technically challenging rectal cancer.

A history of bariatric surgery before surgery for colorectal cancer may improve short-term postoperative outcomes: Analysis of the national inpatient sample 2015-2019

BACKGROUND

Bariatric surgery is the most effective and sustainable form of weight loss. Bariatric surgery before elective operations for colorectal pathology may improve postoperative outcomes. To compare patients with and without prior bariatric surgery undergoing surgery for colorectal cancer in terms of postoperative morbidity and health care use.

METHODS

Adult patients undergoing resection for colorectal cancer from 2015 to 2019 were identified from the National Inpatient Sample. Patients were stratified according to their history of bariatric surgery. Propensity score matching with 4:1 nearest-neighbor matching was performed according to demographic, operative, and hospital characteristics. The primary outcome was postoperative morbidity. Secondary outcomes included system-specific postoperative complications, postoperative mortality, postoperative length of stay, total admission health care cost, and post-discharge disposition. McNemar's test and Wilcoxon matched-pairs signed-rank test were performed.

RESULTS

After propensity score matching, 1,197 patients without prior bariatric surgery and 376 patients with prior bariatric surgery were included. Patients with prior bariatric surgery had an absolute reduction of 6.5% in overall in-hospital postoperative morbidity (19.1% vs 25.6%, P < .0001), a $5,256 decrease in hospitalization cost ($70,344 vs $75,600, P = .034), and were more likely to be discharged home after their index operation (72.9% vs 63.9%, P < .0001).

CONCLUSION

Bariatric surgery before surgery for colorectal cancer may be associated with decreased postoperative morbidity and health care use. Bariatric surgery and other forms of rapid and effective weight loss, such as very low-energy diets, should be evaluated further for the optimization of obese patients before nonbariatric abdominal surgery.

Development and validation of a nomogram for predicting operating time in laparoscopic anterior resection of rectal cancer

Aims

The goal of this study is to create and verify a nomogram estimate operating time in rectal cancer (RC) patients based on clinicopathological factors and MRI/CT measurements before surgery.

Materials and Methods

The nomogram was developed in a cohort of patients who underwent laparoscopic anterior resection (L-AR) for RC. The clinicopathological and pelvis parameters were collected. Risk factors for a long operating time were determined by univariate and multivariate logistic regression analyses, and a nomogram was established with independent risk factors. The performance of the nomogram was evaluated. An independent cohort of consecutive patients served as the validation dataset.

Results

The development group recruited 159 RC patients, while 54 patients were enrolled in the validation group. Independent risk factors identified in multivariate analysis were a distance from the anal verge <5 cm (P = 0.024), the transverse diameter of the pelvic inlet (P < 0.001), mesorectal fat area (P = 0.017), and visceral fat area (P < 0.001). Then, a nomogram was built based on these four independent risk factors. The C-indexes of the nomogram in the development and validation group were 0.886 and 0.855, respectively. And values of AUC were the same with C-indexes in both groups. Besides, the calibration plots showed satisfactory consistency between actual observation and nomogram-predicted probabilities of long operating time.

Conclusions

A nomogram for predicting the risk of long operating duration in L-AR of RC was developed. And the nomogram displayed a good prediction effect and can be utilized as a tool for evaluating operating time preoperatively.

Association between body fat composition and disease duration, clinical activity, and intravenous corticosteroid-induced response in inflammatory bowel disease

BACKGROUND

Body fat composition is believed to be associated with the progression, medical response, and prognosis of inflammatory bowel disease (IBD). Hence, we conducted this study to explore if fat metrics were associated with the disease activity of severe IBD and the response to intravenous corticosteroids (IVCS).

METHODS

We included 69 patients with ulcerative colitis (UC) and 72 patients with Crohn's disease (CD) who had previously received IVCS during hospitalization. We quantified individual fat distribution using abdominal computed tomography slices. The correlations between fat parameters and disease activity were available with Spearman correlation analysis. The prediction model was developed using independent risk factors derived from multivariable logistic regression analysis. Model discrimination was evaluated leveraging the receiver operating characteristic curve. 1000 bootstrap resamples internally validated the model's prediction performance.

RESULTS

Notable differences in age, nutritional status, serum cytomegalovirus replication, stool condition, and extraintestinal involvement between UC and CD patients were observed. UC subjects who responded to IVCS had higher subcutaneous adipose tissue index (SATI), visceral adipose tissue index (VATI), and mesorectal adipose tissue index (MATI) than non-responders. IVCS-responding CD individuals had lower VATI and mesenteric fat index (MFI) than non-responders. CD patients with a prolonged disease duration had a decreased SATI and an elevated MFI. VATI and MATI were reduced as UC clinically progressed, while more prominent clinical activity in CD correlated with increased VATI, MATI, and MFI. A high SATI indicated that patients with UC were more prone to be IVCS responders. For patients with CD, levels of VATI and MFI were negatively associated with effective IVCS treatment. The established models showed a discriminative accuracy of 0.834 [95% confidence interval (CI) 0.740-0.928] in the UC cohort and 0.871 (95% CI 0.793-0.949) in the CD cohort. Repeated samples supported the reliability of the developed models (AUCUC = 0.836, 95% CI 0.735-0.919; AUCCD = 0.876, 95% CI 0.785-0.946).

CONCLUSION

Human fat indexes represent novel imaging biomarkers for identifying IBD patients who respond to IVCS, thus building accelerated therapy regimens and avoiding the adverse effects of ineffective IVCS.

Region-specific deep learning models for accurate segmentation of rectal structures on post-chemoradiation T2w MRI: a multi-institutional, multi-reader study

Introduction

For locally advanced rectal cancers, in vivo radiological evaluation of tumor extent and regression after neoadjuvant therapy involves implicit visual identification of rectal structures on magnetic resonance imaging (MRI). Additionally, newer image-based, computational approaches (e.g., radiomics) require more detailed and precise annotations of regions such as the outer rectal wall, lumen, and perirectal fat. Manual annotations of these regions, however, are highly laborious and time-consuming as well as subject to inter-reader variability due to tissue boundaries being obscured by treatment-related changes (e.g., fibrosis, edema).

Methods

This study presents the application of U-Net deep learning models that have been uniquely developed with region-specific context to automatically segment each of the outer rectal wall, lumen, and perirectal fat regions on post-treatment, T2-weighted MRI scans.

Results

In multi-institutional evaluation, region-specific U-Nets (wall Dice = 0.920, lumen Dice = 0.895) were found to perform comparably to multiple readers (wall inter-reader Dice = 0.946, lumen inter-reader Dice = 0.873). Additionally, when compared to a multi-class U-Net, region-specific U-Nets yielded an average 20% improvement in Dice scores for segmenting each of the wall, lumen, and fat; even when tested on T2-weighted MRI scans that exhibited poorer image quality, or from a different plane, or were accrued from an external institution.

Discussion

Developing deep learning segmentation models with region-specific context may thus enable highly accurate, detailed annotations for multiple rectal structures on post-chemoradiation T2-weighted MRI scans, which is critical for improving evaluation of tumor extent in vivo and building accurate image-based analytic tools for rectal cancers.

The impact of mesorectal fat area on recurrence following total mesorectal excision for lower rectal cancer

BACKGROUND

The mesorectal fat area (MFA) at the tip of the ischial spines on magnetic resonance imaging has been used to characterize mesorectal morphology. Recent studies reported that a larger MFA correlated with difficulties in rectal cancer surgery. However, the relationship between MFA and rectal cancer prognosis remains unclear. This study evaluated the impact of MFA on recurrence following robotic total mesorectal excision (TME) for rectal cancer.

METHODS

Patients who underwent robotic TME for lower rectal cancer from December 2011 to December 2016 were enrolled. Cox regression analysis was performed to determine variables associated with relapse-free survival (RFS). Patients were divided into groups based on MFA, and RFS was compared.

RESULTS

Of 230 patients, 173 (75.3%) were male. The median age was 63 years, and median MFA was 19.7 cm2. In multivariate analysis, smaller MFA (hazard ratio [HR], 0.93; 95% confidence interval [CI], 0.88-0.97; p < 0.01), p/yp stage II (HR, 3.81; 95% CI, 1.40-10.35; p < 0.01), and p/yp stage III (HR, 5.35; 95% CI, 1.88-15.27; p < 0.01) were independently associated with worse RFS. Sex, body mass index, and visceral fat area were not correlated with RFS. In the median follow-up period of 60.8 months, patients with MFA < 19.7 cm2 had a significantly lower 5-year RFS rate (72.7%) than those with MFA ≥ 19.7 cm2 (85.0%).

CONCLUSIONS

Smaller MFA was associated with worse RFS in patients undergoing robotic TME for lower rectal cancer. MFA is considered to be a prognostic factor in rectal cancer.

Establishment of Surgical Difficulty Grading System and Application of MRI-Based Artificial Intelligence to Stratify Difficulty in Laparoscopic Rectal Surgery

(1) Background: The difficulty of pelvic operation is greatly affected by anatomical constraints. Defining this difficulty and assessing it based on conventional methods has some limitations. Artificial intelligence (AI) has enabled rapid advances in surgery, but its role in assessing the difficulty of laparoscopic rectal surgery is unclear. This study aimed to establish a difficulty grading system to assess the difficulty of laparoscopic rectal surgery, as well as utilize this system to evaluate the reliability of pelvis-induced difficulties described by MRI-based AI. (2) Methods: Patients who underwent laparoscopic rectal surgery from March 2019 to October 2022 were included, and were divided into a non-difficult group and difficult group. This study was divided into two stages. In the first stage, a difficulty grading system was developed and proposed to assess the surgical difficulty caused by the pelvis. In the second stage, AI was used to build a model, and the ability of the model to stratify the difficulty of surgery was evaluated at this stage, based on the results of the first stage; (3) Results: Among the 108 enrolled patients, 53 patients (49.1%) were in the difficult group. Compared to the non-difficult group, there were longer operation times, more blood loss, higher rates of anastomotic leaks, and poorer specimen quality in the difficult group. In the second stage, after training and testing, the average accuracy of the four-fold cross validation models on the test set was 0.830, and the accuracy of the merged AI model was 0.800, the precision was 0.786, the specificity was 0.750, the recall was 0.846, the F1-score was 0.815, the area under the receiver operating curve was 0.78 and the average precision was 0.69; (4) Conclusions: This study successfully proposed a feasible grading system for surgery difficulty and developed a predictive model with reasonable accuracy using AI, which can assist surgeons in determining surgical difficulty and in choosing the optimal surgical approach for rectal cancer patients with a structurally difficult pelvis.

Does the mesorectal fat area impact the histopathology metrics of the specimen in males undergoing TME for distal rectal cancer?

The aim of this study was to evaluate whether the mesorectal fat area (MFA) has an impact on the histopathology metrics of the specimen in male patients undergoing robotic total mesorectal excision (rTME) for cancer in the distal third of the rectum. Prospectively collected data of patients undergoing rTME for resectable rectal cancer by five surgeons during 3 years were extracted from the REgistry of Robotic SURgery for RECTal cancer (RESURRECT). MFA was measured at preoperative MRI. Distal rectal cancer was defined as within 6 cm from the anal verge. Specimen metrics included circumferential resection margin (CRM) measured by pathologists as involved if < 1 mm, distal resection margin (DRM) and TME quality. Of 890 patients who underwent rTME for rectal cancer, a subgroup analysis compared 116/581 (33.4%) with MFA > 20 cm2 to 231/581 (66.6%) with MFA ≤ 20 cm2. The mean CRM in patients with MFA > 20 cm2 was neither statistically nor clinically significantly different from patients with MFA ≤ 20 m2 (6.8 ± 5.6 mm vs. 6.0 ± 7.5 mm; p = 0.544). The quality of TME did not significantly differ: complete TME 84.3% vs. 80.3%; nearly complete TME 12.9% vs. 10.1%; incomplete TME 6.8% vs. 5.6%. The DRM was not significantly different: 1.9 ± 1.9 cm vs. 1.9 ± 2.5 cm; p = 0.847. In addition, the intraoperative complication rate was not significantly different: 4.3% (n = 5) vs. 2.2% (n = 5) (p = 0.314). This prospective multicenter study did not find any evidence to support that larger MFA would result in poorer histopathology metrics of the specimen when performing rTME in male patients with distal rectal cancer.

Does the mesorectal fat area impact the histopathology metrics of the specimen in males undergoing TME for distal rectal cancer?

The aim of this study was to evaluate whether the mesorectal fat area (MFA) has an impact on the histopathology metrics of the specimen in male patients undergoing robotic total mesorectal excision (rTME) for cancer in the distal third of the rectum. Prospectively collected data of patients undergoing rTME for resectable rectal cancer by five surgeons during 3 years were extracted from the REgistry of Robotic SURgery for RECTal cancer (RESURRECT). MFA was measured at preoperative MRI. Distal rectal cancer was defined as within 6 cm from the anal verge. Specimen metrics included circumferential resection margin (CRM) measured by pathologists as involved if < 1 mm, distal resection margin (DRM) and TME quality. Of 890 patients who underwent rTME for rectal cancer, a subgroup analysis compared 116/581 (33.4%) with MFA > 20 cm² to 231/581 (66.6%) with MFA ≤ 20 cm². The mean CRM in patients with MFA > 20 cm² was neither statistically nor clinically significantly different from patients with MFA ≤ 20 m² (6.8 ± 5.6 mm vs. 6.0 ± 7.5 mm; p = 0.544). The quality of TME did not significantly differ: complete TME 84.3% vs. 80.3%; nearly complete TME 12.9% vs. 10.1%; incomplete TME 6.8% vs. 5.6%. The DRM was not significantly different: 1.9 ± 1.9 cm vs. 1.9 ± 2.5 cm; p = 0.847. In addition, the intraoperative complication rate was not significantly different: 4.3% (n = 5) vs. 2.2% (n = 5) (p = 0.314). This prospective multicenter study did not find any evidence to support that larger MFA would result in poorer histopathology metrics of the specimen when performing rTME in male patients with distal rectal cancer.

Development of artificial blood loss and duration of excision score to evaluate surgical difficulty of total laparoscopic anterior resection in rectal cancer

PURPOSE

Total laparoscopic anterior resection (tLAR) has been gradually applied in the treatment of rectal cancer (RC). This study aims to develop a scoring system to predict the surgical difficulty of tLAR.

METHODS

RC patients treated with tLAR were collected. The blood loss and duration of excision (BLADE) scoring system was built to assess the surgical difficulty by using restricted cubic spline regression. Multivariate logistic regression was used to evaluate the effect of the BLADE score on postoperative complications. The random forest (RF) algorithm was used to establish a preoperative predictive model for the BLADE score.

RESULTS

A total of 1,994 RC patients were randomly selected for the training set and the test set, and 325 RC patients were identified as the external validation set. The BLADE score, which was built based on the thresholds of blood loss (60 ml) and duration of surgical excision (165 min), was the most important risk factor for postoperative complications. The areas under the curve of the predictive RF model were 0.786 in the training set, 0.640 in the test set, and 0.665 in the external validation set.

CONCLUSION

This preoperative predictive model for the BLADE score presents clinical feasibility and reliability in identifying the candidates to receive tLAR and in making surgical plans for RC patients.

Advances in pelvic imaging parameters predicting surgical difficulty in rectal cancer

Due to the fixed bony structure of the pelvis, the pelvic operation space is limited, complicating the surgical operation of rectal cancer, especially middle and low rectal cancer. The closer the tumor is to the anal verge, the smaller the operative field and operating space, the longer the operative time, and the greater the incidence of intraoperative side injuries and postoperative complications. To date, there is still no clear definition of a difficult pelvis that affects the surgical operation of rectal cancer. Few related research reports exist in the literature, and views on this aspect are not the same between countries. Therefore, it is particularly important to predict the difficulty of rectal cancer surgery in a certain way before surgery and to select the surgical method most suitable for each case during the treatment of rectal cancer.

Three-dimensional visualization of the total mesorectal excision plane for dissection in rectal cancer surgery and its ability to predict surgical difficulty

Total mesorectal excision (TME) for rectal cancer is often technically challenging. We aimed to develop a method for three-dimensional (3D) visualization of the TME dissection plane and to evaluate its ability to predict surgical difficulty. Sixty-six patients with lower rectal cancer who underwent robot-assisted surgery were retrospectively analyzed. A 3D TME dissection plane image for each case was reconstructed using Ziostation2. Subsequently, a novel index that reflects accessibility to the deep pelvis during TME, namely, the TME difficulty index, was defined and measured. Representative bony pelvimetry parameters and clinicopathological factors were also analyzed. The operative time for TME was used as an indicator of surgical difficulty. Univariate regression analysis revealed that sex, body mass index, mesorectal fat area, and TME difficulty index were associated with the operative time for TME, whereas bony pelvimetry parameters were not. Multivariate regression analysis found that TME difficulty index (β = - 0.398, P = 0.0025) and mesorectal fat area (β = 0.223, P = 0.045) had significant predictability for the operative time for TME. Compared with conventional bony pelvimetry parameters, the TME difficulty index and mesorectal fat area might be more useful in predicting the difficulty of rectal cancer surgery.

Associations of muscle and adipose tissue parameters with long-term outcomes in middle and low rectal cancer: a retrospective cohort study

OBJECTIVE

To investigate the role of preoperative body composition analysis for muscle and adipose tissue distribution on long-term oncological outcomes in patients with middle and low rectal cancer (RC) who received curative intent surgery.

METHODS

A total of 155 patients with middle and low rectal cancer who underwent curative intent surgery between January 2014 and December 2016 were included for the final analysis. Skeletal muscle area (SMA), skeletal muscle radiodensity (SMD), visceral fat area (VFA) and mesorectal fat area (MFA) were retrospectively measured using preoperative CT images. To standardize the area according to patient stature, SMA was divided by the square of the height (m²) and the skeletal muscle mass index (SMI, cm²/m²) was obtained. Each median values of the distribution in male and female served as cut-off point for SMI, SMD, VFA, and MFA, respectively. Univariate and multivariate analysis were performed to evaluate the association between body composition and long-term oncological outcomes. Overall survival (OS) measured in months from the day of primary surgery until death for any cause. Disease-free survival (DFS) was defined as the interval between surgery and tumor recurrence. The Kaplan-Meier method with log-rank testing was used to validate prognostic biomarkers. Intraclass correlation coefficient (ICC) was used to evaluate interobserver and intraobserver reproducibility for SMA, SMD, MFA,VFA.

RESULTS

During the follow-up period, 42 (27.1%) patients had tumor recurrence; 21 (13.5%) patients died. The sex-specific median value of SMI was 28.6 cm²/m² for females and 48.2 cm²/m² for males. The sex-specific median value of SMD was 34.7 HU for females and 37.4 HU for males. The sex-specific median value of VFA was 123.1 cm² for females and 123.2 cm² for males. The sex-specific median value of MFA was 13.8 cm² for females and 16.0 cm² for males. In the Cox regression multivariate analysis, SMI (P = 0.036), SMD (P = 0.022), and postoperative complications grades (P = 0.042) were significantly different between death group and non-death group; SMD (P = 0.011) and MFA (P = 0.022) were significantly different between recurrence group and non-recurrence group. VFA did not show any significant differences. By the Kaplan-Meier method with log-rank testing, DFS was significantly longer in patients with high-MFA (P = 0.028) and shorter in patients with low-SMD (P = 0.010), OS was significantly shorter in patients with low-SMI (P = 0.034) and low-SMD (P = 0.029).

CONCLUSIONS

Quantitative evaluation of skeletal muscle mass and adipose tissue distributions at initial diagnosis were important predictors for long-term oncologic outcomes in RC patients. SMD and SMI were independent factors for predicting OS in patients with middle and low rectal cancer who had radical surgery. SMD and MFA were independent factors for predicting DFS in patients with middle and low rectal cancer who had radical surgery.

Quantitative assessment of the microstructure of the mesorectum with different prognostic statuses by intravoxel incoherent motion diffusion-weighed magnetic resonance imaging

BACKGROUND

The mesorectum surrounding the rectum provides an ideal substrate for tumour spread. However, preoperative risk assessment is still an issue. This study aimed to investigate the microstructural features of mesorectum with different prognostic statuses by intravoxel incoherent motion diffusion-weighted imaging (IVIM DWI).

METHODS

Patients with pathologically proven rectal adenocarcinoma underwent routine high-resolution rectal magnetic resonance imaging (MRI) and IVIM DWI sequences were acquired. The MRI-detected circumferential resection margin (mrCRM) and extramural vascular invasion (mrEMVI) were evaluated. IVIM parameters of the mesorectum adjacent to (MAT) and distant from (MDT) the tumour were measured and compared between and within the prognostic factor groups.

RESULTS

The positive mrCRM (pMAT < 0.001; pMDT = 0.013) and mrEMVI (pMAT = 0.001; pMDT < 0.001) groups demonstrated higher D values in the MAT and MDT than the corresponding negative groups. Conversely, the positive mrCRM (p = 0.001) and mrEMVI (p < 0.001) groups both demonstrated lower f values in the MAT. Similarly, in the self-comparison between the MAT and MDT in the above subgroups, D showed a significant difference in all subgroups (p < 0.001 for all), and f showed a significant difference in the positive mrCRM (p = 0.001) and mrEMVI (p = 0.002) groups. Moreover, the MAT displayed a higher D* in the positive mrCRM (p = 0.014), negative mrCRM (p = 0.009) and negative mrEMVI groups (p < 0.001).

CONCLUSION

The microstructure of the mesorectum in patients with rectal cancer with poor prognostic status shows changes based on IVIM parameters. IVIM parameters might be promising imaging biomarkers for risk assessment of tumour spread in mesorectum preoperatively.

BMI and pelvimetry help to predict the duration of laparoscopic resection for low and middle rectal cancer

BACKGROUND

In rectal cancer surgery, recent studies have found associations between clinical factors, especially pelvic parameters, and surgical difficulty; however, their findings are inconsistent because the studies use different criteria. This study aimed to evaluate common clinical factors that influence the operative time for the laparoscopic anterior resection of low and middle rectal cancer.

METHODS

Patients who underwent laparoscopic radical resection of low and middle rectal cancer from January 2018 to December 2020 were retrospectively analyzed and classified according to the operative time. Preoperative clinical and magnetic resonance imaging (MRI)-related parameters were collected. Logistic regression analysis was used to identify factors for predicting the operative time.

RESULTS

In total, 214 patients with a mean age of 60.3 ± 8.9 years were divided into two groups: the long operative time group (n = 105) and the short operative time group (n = 109). Univariate analysis revealed that the male sex, a higher body mass index (BMI, ≥ 24.0 kg/m²), preoperative treatment, a smaller pelvic inlet (< 11.0 cm), a deeper pelvic depth (≥ 10.7 cm) and a shorter intertuberous distance (< 10.1 cm) were significantly correlated with a longer operative time (P < 0.05). However, only BMI (OR 1.893, 95% CI 1.064-3.367, P = 0.030) and pelvic inlet (OR 0.439, 95% CI 0.240-0.804, P = 0.008) were independent predictors of operative time. Moreover, the rate of anastomotic leakage was higher in the long operative time group (P < 0.05).

CONCLUSION

Laparoscopic rectal resection is expected to take longer to perform in patients with a higher BMI or smaller pelvic inlet.

Predictors of operative difficulty in robotic low anterior resection for rectal cancer

AIM

This study evaluates the relationship of tumour and anatomical features with operative difficulty in robotic low anterior resection performed by four experienced surgeons in a high-volume colorectal cancer practice.

METHODS

Data from 382 patients who underwent robotic low anterior resection by four expert surgeons between January 2016 and June 2019 were included in the analysis. Operating time was used as a measure of operative difficulty. Univariate and multivariate mixed models were used to identify associations between baseline characteristics and operating time, with surgeon as a random effect, thereby controlling for variability in surgeon speed and proficiency. In an exploratory analysis, operative difficulty was defined as conversion to laparotomy, a positive margin or an incomplete mesorectum.

RESULTS

Median operating time was 4.28 h (range 1.95-11.33 h) but varied by surgeon from 3.45 h (1.95-6.10 h) to 5.93 h (3.33-11.33 h) (P < 0.001). Predictors of longer operating time in multivariate analysis were male sex, higher body mass index, neoadjuvant radiotherapy, low tumour height, greater sacral height and larger mesorectal area at the S5 vertebral level. Conversion occurred in two cases (0.5%), and incomplete mesorectum and positive margins were found in nine (2.4%) and 19 (5.0%) patients, respectively. Neoadjuvant radiotherapy and larger pelvic outlet were the only characteristics associated with the exploratory measure of difficulty.

CONCLUSION

Predicting operative difficulty based on easy to identify, preoperative radiological and clinical variables is feasible in robotic anterior resection.

New Frontiers in Management of Early and Advanced Rectal Cancer

It is important to understand advances in treatment options for rectal cancer. We attempt to highlight advances in rectal cancer treatment in the form of a systematic review. Early-stage rectal cancer focuses on minimally invasive endoluminal surgery, with importance placed on patient selection as the driving factor for improved outcomes. To achieve a complete pathologic response, various neoadjuvant chemoradiation regimens have been employed. Short-course radiation therapy, total neoadjuvant chemotherapy, and others provide unique advantages with select patient populations best suited for each. With a clinical complete response, a "watch and wait" non-operative surveillance has been introduced with preliminary equivalency to radical resection. Various modalities for total mesorectal excision, such as robotic or transanal, have advantages and can be utilized in select patient populations. Tumors demonstrating solid organ or peritoneal spread, traditionally defined as unresectable lesions conveying a terminal diagnosis, have recently undergone advances in hepatic and pulmonary metastasectomy. Hepatic and pulmonary metastasectomy has demonstrated clear advantages in 5-year survival over standard chemotherapy. With the peritoneal spread of colorectal cancer, HIPEC with cytoreductive therapy has emerged as the preferred treatment. Understanding the various therapeutic interventions will pave the way for improved patient outcomes.

Can MRI pelvimetry predict the technical difficulty of laparoscopic rectal cancer surgery?

PURPOSE

Selection of an open or minimally invasive approach to total mesorectal excision (TME) is generally based on surgeon preference and an intuitive assessment of patient characteristics but there consensus on criteria to predict surgical difficulty. Pelvimetry has been used to predict the difficult surgical pelvis, typically using only bony landmarks. This study aimed to assess the relationship between pelvic soft tissue measurements on preoperative MRI and surgical difficulty.

METHODS

Preoperative MRIs for patients undergoing laparoscopic rectal resection in the Australasian Laparoscopic Cancer of the Rectum Trial (ALaCaRT) were retrospectively reviewed by two blinded surgeons and pelvimetric variables measured. Pelvimetric variables were analyzed for predictors of successful resection of the rectal cancer, defined by clear circumferential and distal resection margins and completeness of TME.

RESULTS

There was no association between successful surgery and any measurement of distance, area, or ratio. However, the was a strong association between the primary outcome and the estimated total pelvic volume on adjusted logistic regression analysis (OR = 0.99, P = 0.01). For each cubic centimeter increase in the pelvic volume, there was a 1% decrease in the odds of successful laparoscopic rectal cancer surgery. Intuitive prediction of unsuccessful surgery was correct in 43% of cases, and correlation between surgeons was poor (ICC = 0.18).

CONCLUSIONS

A surgeon's intuitive assessment of the difficult pelvis, based on visible MRI assessment, is not a reliable predictor of successful laparoscopic surgery. Further assessment of pelvic volume may provide an objective method of defining the difficult surgical pelvis.

Posterior mesorectal thickness as a predictor of increased operative time in rectal cancer surgery: a retrospective cohort study

BACKGROUND

In rectal cancer surgery, larger mesorectal fat area has been shown to correlate with increased intraoperative difficulty. Prior studies were mostly in Asian populations with average body mass indices (BMIs) less than 25 kg/m². This study aimed to define the relationship between radiological variables on pelvic magnetic resonance imaging (MRI) and intraoperative difficulty in a North American population.

METHODS

This is a single-center retrospective cohort study analyzing all patients who underwent low anterior resection (LAR) or transanal total mesorectal excision (TaTME) for stage I-III rectal adenocarcinoma from January 2015 until December 2019. Eleven pelvic magnetic resonance imaging measures were defined a priori according to previous literature and measured in each of the included patients. Operative time in minutes and intraoperative blood loss in milliliters were utilized as the primary indicators of intraoperative difficulty.

RESULTS

Eighty-three patients (39.8% female, mean age: 62.4 ± 11.6 years) met inclusion criteria. The mean BMI of included patients was 29.4 ± 6.2 kg/m². Mean operative times were 227.2 ± 65.1 min and 340.6 ± 78.7 min for LARs and TaTMEs, respectively. On multivariable analysis including patient, tumor, and MRI factors, increasing posterior mesorectal thickness was significantly associated with increased operative time (p = 0.04). Every 1 cm increase in posterior mesorectal thickness correlated with a 26 min and 6 s increase in operative time. None of the MRI measurements correlated strongly with BMI.

CONCLUSION

As the number of obese rectal cancer patients continues to expand, strategies aimed at optimizing their surgical management are paramount. While increasing BMI is an important preoperative risk factor, the present study identifies posterior mesorectal thickness on MRI as a reliable and easily measurable parameter to help predict operative difficulty. Ultimately, this may in turn serve as an indicator of which patients would benefit most from pre-operative resources aimed at optimizing operative conditions and postoperative recovery.

Pelvimetric and Nutritional Factors Predicting Surgical Difficulty in Laparoscopic Resection for Rectal Cancer Following Preoperative Chemoradiotherapy

AIM

Laparoscopic total mesorectal excision (LaTME) following preoperative chemoradiotherapy (PCRT) in locally advanced rectal cancer (LARC) is technically demanding. The present study is intended to evaluate predictive factors of surgical difficulty of LaTME following PCRT by using pelvimetric and nutritional factors.

METHOD

Consecutive LARC patients receiving LaTME after PCRT were included. Surgical difficulty was classified based upon intraoperative (operation time, blood loss, and conversion) and postoperative outcomes (postoperative hospital stay and morbidities). Pelvimetry was performed using preoperative T2-weighted MRI. Nutritional factors such as albumin-to-globulin ratio (AGR) and prognostic nutritional index (PNI) were calculated. Multivariable logistic analysis was used to identify predictors of high surgical difficulty. A predictive nomogram was developed and validated internally.

RESULTS

Among 294 patients included, 36 (12.4%) patients were graded as high surgical difficulty. Logistic regression analysis demonstrated that previous abdominal surgery (OR = 6.080, P = 0.001), tumor diameter (OR = 1.732, P = 0.003), intersphincteric resection (vs. low anterior resection, OR = 13.241, P < 0.001), interspinous distance (OR = 0.505, P = 0.009), and preoperative AGR (OR = 0.041, P = 0.024) were independently predictive of high surgical difficulty of LaTME after PCRT. Then, a predictive nomogram was built (C-index = 0.867).

CONCLUSION

Besides previous abdominal surgery, type of surgery (intersphincteric resection), tumor diameter, and interspinous distance, we found that preoperative AGR could be useful for the prediction of surgical difficulty of LaTME after PCRT. A predictive nomogram for surgical difficulty may aid in planning an appropriate approach for rectal cancer surgery after PCRT.

Morphometric assessment of the mesorectal fat in Chinese Han population: A clinical MRI study

The study aimed to analyze morphometric assessment of the mesorectal fat thickness and its correlation with body mass index in Chinese Han population. The anterior, posterior, right lateral, and left lateral mesorectal fat thickness were measured using MRI T2-weighted images. The mean distance from the rectal wall to the mesorectal fascia were 3.8, 8.4, 11.3, and 11.7 mm in anterior, posterior, right lateral, and left lateral portion, respectively. The mesorectal area, rectal area, mesorectal fat thickness area, and rectal height were 2395.3 ± 691.1 mm2, 709.6 ± 403.5 mm2, 1685.7 ± 525.3 mm2, and 9.1 ± 0.8 cm. BMI was found to be directly proportional to and statistically significant to the mesorectal fat area (p = 0.01). Since the mean mesorectal fat thickness was found to be <12 mm, T3d staged rectal cancer is less likely to be found in an average Chinese population that may affect the overall-survival and progression-free survival in rectal cancer patients. Anterior portion of the rectum was least thick compared to all other sides. Therefore, extra-caution should be taken in handling tumors on the anterior part of the rectum.

MRI pelvimetry-based evaluation of surgical difficulty in laparoscopic total mesorectal excision after neoadjuvant chemoradiation for male rectal cancer

Purpose

Laparoscopic total mesorectal excision (LaTME) is technically demanding in rectal cancer after neoadjuvant chemoradiotherapy (NCRT). This study aimed to predict the surgical difficulty of LaTME after NCRT based on pelvimetric parameters.

Methods

This study enrolled 147 patients who underwent LaTME after NCRT. The surgical difficulty was graded as high or low according to the operative time, estimated blood loss, conversion to open surgery, postoperative hospital stay, and postoperative complications. Pelvimetry parameters were collected based on preoperative MRI. A logistic regression analysis was performed to identify predictors of high surgical difficulty, and a nomogram was developed.

Results

Totally, 18 (12.2%) patients were graded as high surgical difficulty. High surgical difficulty was correlated with a shorter interspinous distance (P = 0.014), a small angle α and γ (P = 0.008, P = 0.008, respectively), and a larger mesorectal area and mesorectal fat area (P = 0.041, P = 0.046, respectively). Tumor distance from the anal verge (OR = 0.619, P = 0.024), tumor diameter (OR = 3.747, P = 0.004), interspinous distance (OR = 0.127, P = 0.007), and angle α (OR = 0.821, P = 0.039) were independent predictors of high surgical difficulty. A predictive nomogram was developed with a C-index of 0.867.

Conclusion

A shorter tumor distance from the anal verge, larger tumor diameter, shorter interspinous distance, and smaller angle α could help to predict high surgical difficulty of LaTME in male LARC patients after NCRT.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00595-020-02211-3.

3D pelvimetry and biometric measurements: a surgical perspective for colorectal resections

PURPOSE

Male sex, high BMI, narrow pelvis, and bulky mesorectum were acknowledged as clinical variables correlated with a difficult pelvic dissection in colorectal surgery. This paper aimed at comparing pelvic biometric measurements in female and male patients and at providing a perspective on how pelvimetry segmentation may help in visualizing mesorectal distribution.

METHODS

A 3D software was used for segmentation of DICOM data of consecutive patients aged 60 years, who underwent elective abdominal CT scan. The following measurements were estimated: pelvic inlet, outlet, and depth; pubic tubercle height; distances from the promontory to the coccyx and to S3/S4; distance from S3/S4 to coccyx's tip; ischial spines distance; pelvic tilt; offset angle; pelvic inlet angle; angle between the inlet/sacral promontory/coccyx; angle between the promontory/coccyx/pelvic outlet; S3 angle; and pelvic inlet to pelvic depth ratio. The measurements were compared in males and females using statistical analyses.

RESULTS

Two-hundred patients (M/F 1:1) were analyzed. Out of 21 pelvimetry measurements, 19 of them documented a significant mean difference between groups. Specifically, female patients had a significantly wider pelvic inlet and outlet but a shorter pelvic depth, and promontory/sacral/coccyx distances, resulting in an augmented inlet/depth ratio when comparing with males (p < 0.0001). The sole exceptions were the straight conjugate (p = 0.06) and S3 angle (p = 0.17). 3D segmentation provided a perspective of the mesorectum distribution according to the pelvic shape.

CONCLUSION

Significant differences in the structure of pelvis exist in males and females. Surgeons must be aware of the pelvic shape when approaching the rectum.

Surgical technique for mesorectal division during robot-assisted laparoscopic tumor-specific mesorectal excision (TSME) for rectal cancer using da Vinci Si surgical system: the simple switching technique (SST)

In a narrow pelvic cavity, performing sufficient tumor-specific mesorectal excision (TSME) is difficult. Even in robot-assisted laparoscopic surgery (RALS), mesorectal division is difficult in a narrow pelvic cavity. To overcome this difficulty, we invented a novel method of mesorectal division. In this new approach, we switched the fenestrated bipolar forceps and the double-fenestrated forceps with each other so that both instruments were placed on the same (right) side of the patient. After the mesorectal fat and vessels were coagulated using the fenestrated bipolar forceps, coagulated tissues were divided using the monopolar scissors in the same direction. We named this technique the "simple switching technique (SST)". We retrospectively collected data and evaluated the usefulness of SST in 24 consecutive patients who underwent RALS TSME between July 2018 and January 2020. Twelve patients underwent SST, and 12 patients underwent other conventional surgical methods (non-SST). The median operation time for mesorectal division was 809.5 s (range 395-1491 s) in the SST group and 985.5 s (range 493-2353 s) in the non-SST group. The coefficient of variation for non-SST was 0.545, which was > 1.5 times the coefficient of 0.360 for SST. Although no significant differences were found for operation time for mesorectal division, the operation time for mesorectal division by SST tended to be shorter than by non-SST (P = 0.157). No significant differences were found regarding short-term outcomes between the groups. SST is feasible and can be an optional method of mesorectal division in RALS TSME.

The role of MRI pelvimetry in predicting technical difficulty and outcomes of open and minimally invasive total mesorectal excision: a systematic review

BACKGROUND

The difficulty of performing total mesorectal excision (TME) for rectal cancer partly relies on the surgeon's subjective assessment of the individual patient's pelvic anatomy and tumour characteristics, which generally influences the choice of platform used (open, laparoscopic, robotic or trans-anal surgery). Recent studies have found associations between several anatomical pelvic measurements and surgical difficulty. The aim of this study was to systematically review existing data reporting the use of magnetic resonance imaging (MRI)-based pelvic measurements to predict technical difficulty and outcomes of TME, and determine whether pelvimetry could optimise patient-specific selection of a particular surgical approach.

METHODS

MEDLINE, Embase and Cochrane Library databases were systematically searched for studies reporting MRI-based pelvic measurements in patients undergoing surgery for rectal cancer, and the effect of these measurements on surgical difficulty.

RESULTS

Eleven studies reporting the association between MRI-pelvimetry measurements and rectal cancer surgical outcomes were included. Indicators for surgical difficulty used in the included studies were involved circumferential resection margin, longer operative time, incomplete TME, higher blood loss, anastomotic leak, conversion to open surgery and overall complications. Bony pelvic measurements which were associated with increased surgical difficulty in more than one study were a smaller interspinous distance, a smaller intertubercle distance, a smaller pelvic inlet and larger pubic tubercle height. Two studies identified larger mesorectal fat area as a predictor of surgical difficulty.

CONCLUSIONS

Bony pelvic measurements may predict surgical difficulty during TME, however, use of different indicators of difficulty limit comparison between studies. Early data suggest MRI soft tissue measurements may predict surgical difficulty and warrants further investigation.

Mesorectal fat area and mesorectal area affect the surgical difficulty of robotic-assisted mesorectal excision and intersphincteric resection respectively in different ways

AIM

Many studies have demonstrated predictors of the difficulty of laparoscopic anterior resection for rectal cancer. Few studies focus on the influence of pelvic dimensions on robotic-assisted mesorectal excision (ME) and intersphincteric resection (ISR). This study aimed to evaluate the influences of the mesorectal fat area (MFA) and mesorectal area on the difficulty of robotic sphincter-saving surgery.

METHODS

We included 156 patients with middle and low rectal cancer who underwent robotic sphincter-saving surgery. Clinical and anatomical factors, including the pelvic dimensions, were collected. Linear regression was performed for variables associated with surgical duration. We also performed subgroup analyses for robotic-assisted ME and ISR. Logistic regression was used to find variables associated with transanal dissection.

RESULTS

For patients with middle or low rectal cancer, the sacral length and tumour distance from the anal verge were independently associated with surgical duration. The pT stage, sacral length and the MFA were independent predictors for the surgical duration of robotic-assisted ME. By contrast, a small mesorectal area was independently related to a longer duration of robotic-assisted ISR. The pelvic outlet length was independently associated with the use of transanal dissection for ISR.

CONCLUSION

It is suggested that a large MFA could affect the difficulty of ME in robotic-assisted ME, while a small mesorectal area could increase the surgical difficulty of robotic-assisted ISR for low rectal cancer. Besides, the pelvic outlet length was associated with the use of transanal dissection. Further studies are needed to validate the results and draw more scientific conclusions.

Pelvic fat volume reduction with preoperative very low energy diet (VLED): implications for rectal cancer surgery in the obese

BACKGROUND

Obese patients have higher complication rates after pelvic surgery. Laparoscopic rectal surgery may not be possible in the obese individual due to mesorectal, total pelvic and general visceral fat volumes. Very low energy diets reduce visceral fat but the changes within the pelvis and mesorectum are unknown. The aim of the present study was to quantify the proportion of fat lost from total pelvic and mesorectal fat with a very low energy diet (VLED) and define simple, accessible measurements that correlate with expected volume reduction.

METHODS

A study was conducted on proportion change in mesorectal and intrapelvic fat volumes in patients on a VLED prior to bariatric surgery at the Alfred Hospital in Melbourne. The VLED was a standardized 4-week meal replacement. Proportion change in mesorectal and intrapelvic fat volumes were measured. Patients had standardized pre-diet and post-diet magnetic resonance imaging (MRI) of the pelvis. Body mass index, weight and girth measures were obtained. Adipose quantification analysis was performed using Q-Fat.

RESULTS

Nine patients were included in this study, who were preparing for bariatric (not colorectal) surgery (5 females, median age 42 years, range 27-59 years) pre-protocol body mass index was 55.8 (range 39.5-60.6 kg/m²); median weight was 163 kg. Median mesorectal fat reduction was 29.9% (range 11.6-66.6%). Linear regression showed a relationship between the amount of mesorectal fat reduction and two variables: patient height and the distance from S1 to the posterior aspect of the rectum on MRI. The relationship predicted response to the diet (R² 67%, p = 0.040).

CONCLUSIONS

Very low energy diets result in a clinically significant reduction in mesorectal fat with a lesser change in total pelvic fat, suggesting that very low energy diets may be useful for preparation for pelvic surgery in the obese. The distance from S1 to the posterior rectum correlates well with mesorectal reduction, making this a valuable clinical tool when volumetric analysis is not possible. This analysis is limited to the quantification of the effect of the diet and cannot comment on the safety of this approach before pelvic cancer surgery.

Prediction of transabdominal total mesorectal excision difficulty according to the angle of pelvic floor muscle

BACKGROUND

Total mesorectal excision (TME) is challenging to perform in a deep, narrow pelvis. While previous studies used pelvimetry to assess bony pelvic structures, there is no consensus on exact definition of deep, narrow pelvis. We hypothesized that the shape of pelvic floor muscle may impact the performance of transabdominal pelvic dissection. We aimed to evaluate which parameters of the shape of pelvic floor muscle impact the difficulty of TME and present a predictive reference value for TME difficulty.

METHODS

From January 2015 to December 2015, 85 consecutive patients who had undergone curative resection for middle to lower rectal cancer were retrospectively studied. Pelvimetry was performed using preoperative T2-weighted magnetic resonance imaging. Predictive factor analysis for surgical duration was studied using linear regression. Mann-Whitney U test, comparing surgical duration between two groups classified by predictive factor, was used for the analysis of reference value.

RESULTS

Multivariate analysis revealed that body mass index, protective stoma, number of surgeon, and incline angle of pelvic floor muscle (β) were independent predictors of surgical duration. Test statistics of Mann-Whitney U for the difference in surgical duration between groups above and below a β of 54° were maximized.

CONCLUSIONS

The incline angle of pelvic floor muscle is an independent predictor of surgical duration. In patients with steeper incline of PFM, transabdominal TME is expected to be difficult. This index is novel, but needs to be further validated.

Risk factors for anastomotic leak after esophagectomy for cancer: A NSQIP procedure-targeted analysis

BACKGROUND

Anastomotic leak is the most common major complication after esophagectomy. We investigated the 2016 American College of Surgeons National Surgical Quality Improvement Program esophagectomy targeted database to identify risk factors for anastomotic leak.

METHODS

Patients who underwent esophagectomy for cancer were included. Patients experiencing an anstomotic leak were identified, and univariate and multivariable logistic regression was performed to identify variables independently associated with anastomotic leak.

RESULTS

Of 915 patients included, 83% were male and the median age was 64 years. Patients with anastomotic leak more frequently had additional complications (87% vs 36%, P < .001). Rates of reoperation (64% vs 11%, P < .001) and mortality (8% vs 2%, P = .001) were higher in patients with anastomotic leak. After adjusting for patient and procedure characteristics, prolonged operative time (for each additional 30-minutes; adjusted odds ratios (AOR) 1.068, 95% CI, 1.022-1.115, P = .003), increased preoperative WBC count (for each 3000/µL increase; AOR 1.323, 95% CI, 1.048-1.670, P = .019), pre-existing diabetes (AOR 1.601, 95% CI, 1.012-2.534, P = .045), and perioperative transfusion (AOR 1.777, 95% CI, 1.064-2.965, P = .028) were independently associated with anastomotic leak.

CONCLUSION

Both patient and procedure-related factors are associated with anastomotic leak. Though frequently non-modifiable, these findings could facilitate risk stratification and early detection of anastomotic leak to reduce associated morbidity.