Safety and factors contributing to the difficulty of laparoscopic surgery for rectal cancer treated with preoperative chemoradiotherapy

Construction of a nomogram model to predict technical difficulty in performing laparoscopic sphincter-preserving radical resection for rectal cancer

BACKGROUND

Colorectal surgeons are well aware that performing surgery for rectal cancer becomes more challenging in obese patients with narrow and deep pelvic cavities. Therefore, it is essential for colorectal surgeons to have a comprehensive understanding of pelvic structure prior to surgery and anticipate potential surgical difficulties.

AIM

To evaluate predictive parameters for technical challenges encountered during laparoscopic radical sphincter-preserving surgery for rectal cancer.

METHODS

We retrospectively gathered data from 162 consecutive patients who underwent laparoscopic radical sphincter-preserving surgery for rectal cancer. Three-dimensional reconstruction of pelvic bone and soft tissue parameters was conducted using computed tomography (CT) scans. Operative difficulty was categorized as either high or low, and multivariate logistic regression analysis was employed to identify predictors of operative difficulty, ultimately creating a nomogram.

RESULTS

Out of 162 patients, 21 (13.0%) were classified in the high surgical difficulty group, while 141 (87.0%) were in the low surgical difficulty group. Multivariate logistic regression analysis showed that the surgical approach using laparoscopic intersphincteric dissection, intraoperative preventive ostomy, and the sacrococcygeal distance were independent risk factors for highly difficult laparoscopic radical sphincter-sparing surgery for rectal cancer (P < 0.05). Conversely, the anterior-posterior diameter of pelvic inlet/sacrococcygeal distance was identified as a protective factor (P < 0.05). A nomogram was subsequently constructed, demonstrating good predictive accuracy (C-index = 0.834).

CONCLUSION

The surgical approach, intraoperative preventive ostomy, the sacrococcygeal distance, and the anterior-posterior diameter of pelvic inlet/sacrococcygeal distance could help to predict the difficulty of laparoscopic radical sphincter-preserving surgery.

Comparative analysis of robotic and laparoscopic surgery for mid and low rectal cancer in patients with varied body mass indexes: evaluating of short-term outcomes

The main aim of this study was to evaluate and contrast the efficacy of robotic and laparoscopic surgical procedures in the treatment of low and mid rectal cancer in different BMI (body mass index) groups. The clinical records of patients who had laparoscopic or robotic proctectomy at a single center between December 2019 and August 2023 were analyzed. Then we utilized a classification framework to categorize individuals based on their BMI into three unique groups: non-obese, overweight, and obese. The short-term efficacy was evaluated. A consecutive sample of 1413 patients was included in this retrospective investigation. 1158 people out of the total sample chose laparoscopic surgery, whereas 255 people chose robotic surgery. In the group of obese people, robotic surgery showed a statistically significant decrease in blood loss compared to laparoscopic surgery (P = 0.026). People who were overweight or obese were in the hospital for a shorter amount of time after robotic surgery than after laparoscopic surgery (P = 0.033 and P = 0.031, respectively). People with different BMIs in the robotic surgery group took less time to have a flatus passage and oral intake those in the laparoscopic surgery group. Oncological outcomes and the frequency of complications were comparable between the two treatments with different BMIs. Surgical resection of patients undergoing low-anterior surgery may benefit from a robotic approach, particularly in overweight and obese patients.

Interpretable machine learning model to predict surgical difficulty in laparoscopic resection for rectal cancer

Background

Laparoscopic total mesorectal excision (LaTME) is standard surgical methods for rectal cancer, and LaTME operation is a challenging procedure. This study is intended to use machine learning to develop and validate prediction models for surgical difficulty of LaTME in patients with rectal cancer and compare these models' performance.

Methods

We retrospectively collected the preoperative clinical and MRI pelvimetry parameter of rectal cancer patients who underwent laparoscopic total mesorectal resection from 2017 to 2022. The difficulty of LaTME was defined according to the scoring criteria reported by Escal. Patients were randomly divided into training group (80%) and test group (20%). We selected independent influencing features using the least absolute shrinkage and selection operator (LASSO) and multivariate logistic regression method. Adopt synthetic minority oversampling technique (SMOTE) to alleviate the class imbalance problem. Six machine learning model were developed: light gradient boosting machine (LGBM); categorical boosting (CatBoost); extreme gradient boost (XGBoost), logistic regression (LR); random forests (RF); multilayer perceptron (MLP). The area under receiver operating characteristic curve (AUROC), accuracy, sensitivity, specificity and F1 score were used to evaluate the performance of the model. The Shapley Additive Explanations (SHAP) analysis provided interpretation for the best machine learning model. Further decision curve analysis (DCA) was used to evaluate the clinical manifestations of the model.

Results

A total of 626 patients were included. LASSO regression analysis shows that tumor height, prognostic nutrition index (PNI), pelvic inlet, pelvic outlet, sacrococcygeal distance, mesorectal fat area and angle 5 (the angle between the apex of the sacral angle and the lower edge of the pubic bone) are the predictor variables of the machine learning model. In addition, the correlation heatmap shows that there is no significant correlation between these seven variables. When predicting the difficulty of LaTME surgery, the XGBoost model performed best among the six machine learning models (AUROC=0.855). Based on the decision curve analysis (DCA) results, the XGBoost model is also superior, and feature importance analysis shows that tumor height is the most important variable among the seven factors.

Conclusions

This study developed an XGBoost model to predict the difficulty of LaTME surgery. This model can help clinicians quickly and accurately predict the difficulty of surgery and adopt individualized surgical methods.

Propensity matched analysis of robotic and laparoscopic operations for mid-low rectal cancer: short-term comparison of anal function and oncological outcomes

Laparoscopic surgery for rectal cancer, while in some respects equivalent or even preferable to open surgery, is challenged in specific conditions where the tumor is located in the middle and lower third of the rectum. Robotic surgery equipped with a superior arm of machinery and gained better visualization can compensate for the deficiency of the laparoscopic approach. This study adopted a propensity matched analysis to compare the functional and oncological short-term outcomes of laparoscopic and robotic surgery. All patients who underwent proctectomy have been collected prospectively between December 2019 and November 2022. After censoring for inclusion criteria, we performed a propensity matching analysis. A detailed collection of post-operative examination indicators was performed, while the K-M survival curves were plotted to analyze post-operative oncology outcomes. The LARS scale was designed to evaluate the anal function of patients in the form of questionnaires. Totally, 215 patients underwent robotic operations while 1011 patients selected laparoscopic operations. Patients matched 1∶1 by propensity score were divided into the robotic and laparoscopic groups, 210 cases were included in each group. All patients underwent a follow-up for a median period of 18.3 months. Robotic surgery was connected with an enhanced recovery including the earlier time to first flatus passage without ileostomy (P = 0.050), the earlier time to liquid diet without ileostomy (P = 0.040), lower incidence of urinary retention (P = 0.043), better anal function 1 month after LAR without ileostomy (P < 0.001), longer operative time (\P = 0.042), compared with laparoscopic operations. The oncological outcomes and occurrence of other complications were comparable between the two approaches. For mid-low rectal cancer, robotic surgery could be recognized as an effective technique with identical short-term outcomes of oncology and better anal function in comparison to laparoscopic surgery. However, multi-center studies with larger samples are expected to validate the long-term outcomes of robotic surgery.

Prognosis Comparisons of Laparoscopy versus Open Surgery for Rectal Cancer Patients after Preoperative Chemoradiotherapy: A Meta-Analysis

AIM

We aimed to compare the oncological outcomes of laparoscopy and open resection for patients with rectal cancer following neoadjuvant chemoradiotherapy (NCRT).

METHODS

We searched the publications that compared the efficacy of laparoscopic surgery and open thoracotomy in treatment outcomes of rectal cancer after NCRT. All trials analyzed the summary hazard ratios of the endpoints of interest, including survival and individual postoperative complications.

RESULTS

Totally, 10 trials met our inclusion criteria. The pooled analysis of 3-year disease-free survival (OR 1.39, 95% CI 0.93-2.06; p = 0.11) and 3-year overall survival (OR 1.01, 95% CI 0.70-1.45; p = 0.97) showed that laparoscopic surgery did not achieve beneficial effects compared with open thoracotomy. The pooled result of duration of surgery indicated that laparoscopic surgery was associated with a trend for longer surgery time (SMD 27.53, 95% CI 1.34-53.72; p = 0.04), shorter hospital stay (SMD -1.64, 95% CI -2.70 to -0.58; p = 0.002), more postoperative complications (OR 0.77, 95% CI 0.60-0.99; p = 0.04), and decreased blood loss (SMD -49.87, 95% CI -80.61 to -19.14; p = 0.001). However, the number of removed lymph nodes, positive circumferential resection margin, as well as complications after surgery showed significant differences between the 2 groups.

CONCLUSIONS

We focused on current evidence and reviewed the studies indicating that similar oncological outcomes were associated with laparoscopic surgery following NCRT for patients with locally advanced lower rectal cancer in comparison with open surgery.

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.

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.

Effects of preceding endoscopic treatment on laparoscopic surgery for early rectal cancer

AIM

Endoscopic treatment for rectal cancer, such as endoscopic mucosal resection and endoscopic submucosal dissection, causes inflammation, oedema and fibrosis in the surrounding tissue. However, little is known about the effect of these endoscopic therapies on salvage laparoscopic rectal surgery. The objective of this retrospective cohort study was to analyse the effect of preceding endoscopic treatment on the outcomes of laparoscopic surgery for rectal cancer.

METHOD

We analysed 53 patients who underwent laparoscopic surgery for rectal cancer with clinical Tis or T1 at our department between May 2011 and June 2019. Data from 30 patients who underwent laparoscopic surgery after preceding endoscopic treatment (Group E + S) were compared with those of 23 patients who underwent laparoscopic surgery alone (Group S).

RESULTS

There was no significant difference between the groups with respect to preoperative details. The mean operative time tended to be longer in Group E + S, and the volume of intra-operative blood loss was greater in Group E + S than in Group S (median 63 ml vs 10 ml, P = 0.049). There were no significant differences between the groups in other surgical parameters or oncological outcomes.

CONCLUSION

Laparoscopic surgery after endoscopic treatment for rectal cancer may be difficult due to an increased risk of intra-operative bleeding. Long-term prognosis after surgery was not affected by preceding endoscopic treatment in rectal cancer.

Results of laparoscopic resection in high-risk rectal cancer patients

PURPOSE

Obesity, neoadjuvant-radiotherapy, tumour proximity to the anal verge and previous abdominal surgery are factors that might increase the intra-operative difficulty of laparoscopic rectal cancer surgery. However, whether patients with these 'high-risk' characteristics are subject to worse short- or long-term outcomes is debated. The aim of this study is to examine the short- and long-term clinical and oncological outcomes of patients receiving laparoscopic rectal surgery with any of these high-risk characteristics and compare them with patients that do not possess any of these high-risk features.

METHODS

For the purpose of this study data from consecutive patients receiving laparoscopic rectal cancer resections between 2006 and 2016 from two centres were analysed. High-risk patients were defined as patients with either one of the following characteristics: BMI ≥ 30, neoadjuvant chemoradiotherapy, tumour < 8 cm from the anal verge and previous abdominal surgery.

RESULTS

A total of 313 patients were identified (227 high risk, 86 low risk). Short-term outcomes were similar between the two groups with the exception of blood loss and length of stay, which were higher in the high-risk group (10 vs 2.5 ml, p = 0.045; 7 vs 5 days, p = 0.001). There were no statistically significant differences in 5-year overall survival (79.7% vs 79.8%, p = 0.757), disease-free survival (76.8% vs 69.3%, p = 0.175), distant disease-free interval (84.8% vs 79.7%, p = 0.231) and local recurrence-free interval (100%, 97.4%, p = 0.162) between the two groups.

CONCLUSION

Similar short- and long-term outcomes can be achieved in high-risk and low-risk patients receiving laparoscopic rectal surgery. The presented data support the suitability of laparoscopic surgery for this group of patients.

Learning Curve of Robotic Rectal Surgery With Lateral Lymph Node Dissection: Cumulative Sum and Multiple Regression Analyses

OBJECTIVE

This study aimed to assess the learning curve of robotic rectal surgery, a procedure that has gained increasing focus in recent years because it is expected that the advanced devices used in this approach provide advantages resulting in a shorter learning curve than that of laparoscopic surgery. However, no studies have assessed the learning curve of robotic rectal surgery, especially when lateral lymph node dissection is required.

DESIGN

This was a nonrandomized, retrospective study from a single institution.

SETTING

All consecutive patients who underwent robotic rectal or sigmoid colon surgery by a single surgeon between February 2012 and July 2016 in the University of Tokyo Hospital were enrolled. The learning curve for console time was assessed using a cumulative sum analysis and multiple linear regression analysis.

PARTICIPANTS

A total of 131 consecutive patients underwent robotic rectal or sigmoid colon surgery performed by a single experienced surgeon. Of these, 41 patients received lateral lymph node dissection.

RESULTS

A cumulative sum plot for console time demonstrated that the learning period could be divided into 3 phases: Phase I, Cases 1 to 19; Phase II, Cases 20 to 78; and Phase III, Cases 79 to 131. Multiple linear regression analysis indicated that console time decreased significantly from one phase to another (Phase I-II, Δconsole time 83.0 minutes; Phase II-III, Δconsole time 40.1 minutes). Other factors affecting console time included body mass index, operative procedure, and lateral lymph node dissection, but not neoadjuvant therapy (such as chemoradiotherapy) or depth of invasion. Lateral lymph node dissection required an additional 138.4 minutes.

CONCLUSIONS

Our findings suggest that the first phase of the learning curve consists of the first 19 cases, which seems sufficient to master the manipulation of robotic arms and to understand spatial relationships unique to the robotic procedure.

Comparison Between Laparoscopic and Open Resection Following Neoadjuvant Chemoradiotherapy for Mid-Low Rectal Cancer Patients: A Meta-Analysis

INTRODUCTION

The optimal approach of resection for mid-low rectal cancer after neoadjuvant chemoradiotherapy (nCRT) is still controversial. The aim of this meta-analysis was to clarify the safety and feasibility of laparoscopic surgery compared with open resection.

MATERIALS AND METHODS

We performed a literature search for studies on PubMed, Embase and Cochrane Library up to March 1, 2018. Review Manager software was applied for data analysis. We used weighted mean difference (WMD) for continuous parameters and odds ratio (OR) for dichotomous variables. Confidence interval (CI) was set at 95% and a P value <.05 was considered statistically significant.

RESULTS

A total of seven studies met the inclusion criteria for the meta-analysis: 466 patients in laparoscopic group and 491 in open group. The pooled result revealed that laparoscopic resection had a favorable blood loss (WMD = -116.88 mL; 95% CI: -189.78 to -43.99; P = .002), analogous lymph nodes harvest (WMD = -0.30; 95% CI: -1.29 to 0.70; P = .56), less postoperative complications (OR = 0.63; 95% CI: 0.46-0.88; P = .006), shorter time to pass first flatus (WMD = -0.76 day; 95% CI: -1.00 to -0.51; P < .00001), and stay in hospital (WMD = -2.71 days; 95% CI: -4.54 to -0.88; P = .004), despite similar operating time (WMD = 11.17 minutes; 95% CI: -14.37 to 36.70; P = .39).

CONCLUSIONS

Laparoscopic resection might be a technically safe and feasible approach for mid-low rectal cancer patients after nCRT compared with open resection.

The short-term outcomes of robotic sphincter-preserving surgery for rectal cancer: comparison with open and laparoscopic surgery using a propensity score analysis

PURPOSE

The aim of this study is to clarify the short-term outcomes of robotic sphincter-preserving surgery for rectal cancer in a retrospective study.

METHODS

The short-term outcomes of robotic sphincter-preserving surgery (n = 130) were retrospectively compared to open (n = 234) and laparoscopic surgery (n = 318) by a propensity score analysis.

RESULTS

Robotic surgery was performed more frequently for patients with lower rectal cancer (55%) than open (30%, p < 0.0001) or laparoscopic surgery (36%, p < 0.0001). None of the robotic surgery cases were converted to open surgery. After propensity score matching, robotic surgery was found to be associated with a longer operation time (342 vs. 230 min, p < 0.0001) and less blood loss (7 vs. 420 mL, p < 0.0001) than open surgery. The overall complication rate of robotic surgery was lower than that of open surgery (13 vs. 28%, p = 0.032). Robotic surgery was associated with a lower incidence of surgical site infections (SSIs) than laparoscopic surgery (0 vs. 7%, p = 0.028). There were no cases of anastomotic leakage after robotic surgery. The circumferential resection margin was involved in 0.8% of the patients who underwent robotic surgery; the incidence did not differ among the treatment groups.

CONCLUSIONS

Although robotic surgery for rectal cancer was associated with a longer operation time, it was associated with a very low incidence of SSIs. The degree of safety was comparable to both open and laparoscopic surgery.

Correlations between the sizes of lateral pelvic lymph nodes and metastases in rectal cancer patients treated with preoperative chemoradiotherapy

BACKGROUND

Lateral pelvic lymph node (LLN) dissection is suggested to improve the prognosis of rectal cancer patients; however, accurate diagnosis of LLN metastasis is challenging, especially after preoperative chemoradiotherapy (CRT). The aim of this study was to clarify the diagnostic value of LLN size in rectal cancer patients treated with CRT in terms of metastasis.

METHODS

A total of 204 LLNs dissected from 29 rectal cancer patients treated with CRT were examined. The correlation between the resected LLN size (long and short axes) and patients' metastasis status was examined.

RESULTS

The long axes of metastatic LLNs were significantly longer than those of non-metastatic LLNs (11.0 ± 5.3 versus 4.4 ± 2.8 mm, respectively; P < 0.0001) as were the short axes (8.1 ± 4.5 versus 2.3 ± 1.2 mm, respectively; P < 0.0001). Receiver operating characteristic analyses of the long and short axes indicated optimal cut-off values of 7 and 4 mm for the prediction of pathological LLN metastasis; the area under the curve values were 0.89 and 0.96, respectively. The accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the long axis for the prediction of pathological metastasis were 82.4, 88.2, 82.2, 48.4 and 97.2%, respectively; those of the short axis were 91.7, 94.1, 87.1, 59.3 and 98.7%, respectively.

CONCLUSIONS

The sizes of LLNs significantly correlated with patients' pathological statuses, and their accuracies for the prediction of pathological metastases were high. However, in contrast to the very high NPVs, the PPVs were low (approximately 50%).

Robotic vs laparoscopic rectal surgery in high-risk patients

AIM

Laparoscopic rectal surgery is associated with a steep learning curve and high conversion rate despite progress in equipment design and consistent practice. The robotic system has shown an advantage over the laparoscopic approach due to stable three-dimensional views, improved dexterity and better ergonomics. These factors make the robotic approach more favourable for rectal surgery. The aim of this study was to compare the perioperative outcomes of laparoscopic and robotic rectal cancer surgery in high-risk patients.

METHOD

A prospectively collected dataset for high-risk patients who underwent rectal cancer surgery between May 2013 and November 2015 was analysed. Patients with any of the following characteristics were defined as high risk: a body mass index ≥30, male gender, preoperative chemoradiotherapy, tumour <8 cm from the anal verge and previous abdominal surgery.

RESULTS

In total, 184 high-risk patients were identified: 99 in the robotic group and 85 in the laparoscopic group. Robotic surgery was associated with a significantly higher sphincter preservation rate (86% vs 74%, P = 0.045), shorter operative time (240 vs 270 min, P = 0.013) and hospital stay (7 vs 9 days, P = 0.001), less blood loss (10 vs 100 ml, P < 0.001) and a smaller conversion rate to open surgery (0% vs 5%, P = 0.043) compared with the laparoscopic technique. Reoperation, anastomotic leak rate, 30-day mortality and oncological outcomes were comparable between the two techniques.

CONCLUSION

Robotic surgery in high-risk patients is associated with higher sphincter preservation, reduced blood loss, smaller conversion rates, and shorter operating time and hospital stay. However, further studies are required to evaluate this notion.

Impact of Body Mass Index on Surgical and Oncological Outcomes in Laparoscopic Total Mesorectal Excision for Locally Advanced Rectal Cancer after Neoadjuvant 5-Fluorouracil-Based Chemoradiotherapy

Aims

To evaluate the impact of body mass index (BMI) on the surgical outcome of laparoscopic total mesorectal excision (laTME) for locally advanced rectal cancer (LARC, clinically staged as UICC stage II/III) after neoadjuvant chemoradiotherapy (nCRT).

Methods

312 LARC patients undergoing laTME after nCRT were divided into nonobese (BMI < 25.0 kg/m², n = 249) and obese (BMI ≥ 25.0 kg/m², n = 63) groups. Preoperative radiotherapy was delivered in 45–50.4 Gy/25f, 5 days/week, and concurrent chemotherapy using FOLFOX or CapeOX. Technical feasibility, postoperative and oncological outcome were compared between groups.

Results

Obese patients had significantly longer operative time (P = 0.004). There was no significant difference regarding estimated blood loss, conversion, postoperative recovery, and morbidities. Multivariate analysis demonstrated that higher ASA score and abdominoperineal resection were risk factors for postoperative complications and diverting stoma was a protective factor. The length of resection margin, circumferential resection margin involvement, and number of lymph node retrieved were comparable. With a median follow-up time of 55 months (ranging 20–102 months), oncological outcome was comparable in terms of overall survival, local recurrence, and distant metastasis.

Conclusions

Obesity does not affect surgical or oncological outcome of laTME after nCRT. LaTME may be feasible and safe to obese LARC patients after nCRT in a specialized center.

Monitoring neoadjuvant therapy responses in rectal cancer using multimodal nonlinear optical microscopy

Most patients with rectal cancer have a better prognosis after receiving neoadjuvant therapy because of its remarkable curative effect. However, no device delivers real-time histopathologic information on treatment response to help clinicians tailor individual therapeutic strategies. We assessed the potential of multimodal nonlinear optical microscopy to monitor therapeutic responses, including tumoral and stromal responses. We found that two-photon excited fluorescence imaging can, without labeling, identify colloid response, inflammatory cell infiltration, vascular proliferation, and tumor regression. It can also directly detect rare residual tumor cells, which may be helpful for distinguishing tumor shrinkage from tumor fragmentation. In addition, second harmonic generation imaging shows the ability to monitor three types of fibrotic responses: mature, intermediate, and immature. We also determined nonlinear spectra, collagen density, and collagen orientation indexes to quantitatively analyze the histopathologic changes induced by neoadjuvant therapy in rectal cancer. Our work demonstrates that nonlinear optical microscopy has the potential to become a label-free, real-time, in vivo medical imaging technique and provides the groundwork for further exploration into the application of nonlinear optical microscopy in a clinical setting.

Short-term surgical outcomes and patient quality of life between robotic and laparoscopic extralevator abdominoperineal excision for adenocarcinoma of the rectum

Introduction Some studies advocate a laparoscopic extralevator abdominoperineal excision (l-ELAPE) approach for low rectal cancer. The da Vinci™ robot (r-ELAPE) technique has potential to overcome some limitations of l-ELAPE, such as reduction of the learning curve and more precise tissue handling. It is unknown whether this approach results in improved surgical or quality of life outcomes compared with l-ELAPE. This study aimed to address this issue. Methods Consecutive patients having undergone either robotic or laparoscopic ELAPE for adenocarcinoma were studied. All operations were performed by two surgeons experienced in laparoscopic and recently introduced robotic surgery. Surgical outcomes were determined by postoperative histology and short-term complications. Quality of life was prospectively assessed using the European Organisation for Research and Treatment of Cancer QLC-CR30 and QLC-CR29 questionnaires. Results A total of 22 patients (11 r-ELAPE) with a median follow-up of 13 months (8 months robotic; 22 months laparoscopic) were studied. The groups were similarly matched for age, gender, American Society of Anesthesiologists status, preoperative chemoradiotherapy and tumour height. All had R0 resection. There was no significant difference in short-term surgical outcomes between groups. There was no significant difference in mean global health scores between the two groups (74 ± 14 r-ELAPE vs. 73 ± 10 l-ELAPE). The r-ELAPE group had a lower mean impotence score compared with the I-ELAPE group (55.5 ± 40 vs. 72.2 ± 44), although this was not statistically significant. Conclusions The newly introduced r-ELAPE was non-inferior to l-ELAPE in either patient quality of life or surgical outcomes. Robotic surgery could be particularly beneficial in the technically challenging area of low rectal cancer surgery with a shorter learning curve than laparoscopy.

Factors Influencing Difficulty of Laparoscopic Abdominoperineal Resection for Ultra-Low Rectal Cancer

PURPOSE

Our current study was conducted to identify patients' anatomic, pathologic, and clinical factors to predict difficulty of performing laparoscopic abdominoperineal resection for ultra-low rectal cancer.

MATERIALS AND METHODS

Records of 117 consecutive patients with rectal cancer 2 to 5 cm from the anal verge were retrospectively reviewed. Using univariate and multivariate linear or logistic regression models, standardized operative time and blood loss, as well as postoperative morbidity were utilized as endpoints to screen patients' multiple variables to predict operative difficulty.

RESULTS

Multivariate linear regression analysis showed body mass index (BMI) (estimate=0.07, P=0.0056), interspinous distance (estimate=-0.02, P=0.0011), tumor distance from anal verge (estimate=-0.17, P=0.0355), prior abdominal surgery (estimate=0.51, P=0.0180), preoperative chemoradiotherapy (estimate=0.67, P=0.0146), and concurrent diseases (hypertension and/or diabetes mellitus) (estimate=0.49, P=0.0122) are predictors for standardized operative time. Age (estimate=0.02, P=0.0208) and concurrent diseases (estimate=0.43, P=0.0476) were factors related to standardized blood loss. BMI (estimate=0.15, P=0.0472) was the only predictor for postoperative morbidity based on logistic regression analysis.

CONCLUSIONS

Age, BMI, interspinous distance, tumor distance from anal verge, prior abdominal surgery, preoperative chemoradiotherapy, and concurrent diseases influence the difficulty of performing laparoscopic abdominoperineal resection for ultra-low rectal cancer. Standardized operative time allows researchers to amass samples by pooling data from all published studies, thus building reliable models to predict operative difficulty for clinical use.

Oncological Outcomes of Lateral Pelvic Lymph Node Metastasis in Rectal Cancer Treated With Preoperative Chemoradiotherapy

BACKGROUND

Oncological outcomes of lateral pelvic lymph node metastasis in rectal cancer treated with preoperative chemoradiotherapy remain to be elucidated.

OBJECTIVE

The purpose of this study was to clarify the therapeutic effect of chemoradiotherapy on lateral pelvic lymph node metastasis, the risk factors of lateral pelvic lymph node metastasis, and oncological outcomes of lateral pelvic lymph node dissection after chemoradiotherapy.

DESIGN

This was a nonrandomized, retrospective study.

SETTINGS

The study was conducted at a tertiary referral university hospital.

PATIENTS

Patients with rectal cancer treated with chemoradiotherapy and radical surgery from 2003 to 2015 (N = 222) were included.

INTERVENTIONS

Radiation (total, 50.4 Gy in 28 fractions) with concomitant fluorouracil-based chemotherapy was administered. Lateral pelvic lymph nodes with a diameter of ≥8 mm before chemoradiotherapy were selectively dissected.

MAIN OUTCOME MEASURES

Frequency and risk factors of lateral pelvic lymph node metastasis were examined.

RESULTS

Lateral pelvic lymph node dissection was performed in 31 patients (14.0%), and 16 (51.6%) of these patients were pathologically diagnosed as positive for metastasis. Among the patients treated with total mesorectal excision alone (n = 191), 2 (0.9%) had recurrence in the lateral pelvic lymph node area, which was pathologically confirmed after salvage R0 resection. T category downstaging (73.3% vs 12.5%; p < 0.01) and high histological regression of the primary lesion (73.3% vs 18.8%; p < 0.01) were more frequent in patients with pathologically negative lateral pelvic lymph nodes than in those with positive lateral pelvic lymph nodes. Young age, short distance from the anal verge, and enlarged lateral pelvic lymph node before chemoradiotherapy were associated with lateral pelvic lymph node metastasis.

LIMITATIONS

The study was limited by its retrospective nature and small study population.

CONCLUSIONS

The incidence of lateral pelvic lymph node metastasis after chemoradiotherapy was estimated to be 8.1% (18/222). Young age, short distance from the anal verge, and enlarged lateral pelvic lymph node before chemoradiotherapy were risk factors of lateral pelvic lymph node metastasis after chemoradiotherapy.

Effect of Neoadjuvant Chemoradiotherapy on Locally Advanced Rectal Mucinous Adenocarcinoma: A Propensity Score-Matched Study

Aims. To compare the surgical and oncological outcomes of rectal mucinous adenocarcinomas treated with neoadjuvant chemoradiotherapy versus surgery alone. Methods. A total of 167 locally advanced rectal mucinous adenocarcinoma patients treated with neoadjuvant chemoradiotherapy and surgery alone between 2008 and 2014 were matched using propensity score; the surgical and oncological outcomes were compared. Results. Ninety-six patients were matched. Postoperative morbidity was similar between groups. Sphincter preservation rate was higher in patients receiving neoadjuvant chemoradiotherapy (79.2% versus 60.4%, P = 0.045), especially for tumors ≥ 3 cm but ≤5 cm from the anal verge (75.0% versus 44.0%, P = 0.036). With a median follow-up of 54.8 months, the 5-year overall survival rate (neoadjuvant chemoradiotherapy versus surgery alone: 79.6% versus 67.1%; P = 0.599) and disease-free survival rate (75.6% versus 64.2%; P = 0.888) were similar. The 5-year local recurrence rate was lower in patients receiving neoadjuvant chemoradiotherapy (7.7% versus 26.0%, P = 0.036), while no difference was observed in distant metastasis. A poor response to chemoradiation was associated with higher local recurrence (P = 0.037). Conclusions. Compared with surgery alone, neoadjuvant chemoradiotherapy was found to increase the sphincter preservation rate and reduce local recurrence, thus being beneficial for locally advanced rectal mucinous adenocarcinoma patients.

Factors Predicting Difficulty of Laparoscopic Low Anterior Resection for Rectal Cancer with Total Mesorectal Excision and Double Stapling Technique

BACKGROUND

Laparoscopic sphincter-preserving low anterior resection for rectal cancer is a surgery demanding great skill. Immense efforts have been devoted to identifying factors that can predict operative difficulty, but the results are inconsistent.

OBJECTIVE

Our study was conducted to screen patients' factors to build models for predicting the operative difficulty using well controlled data.

METHOD

We retrospectively reviewed records of 199 consecutive patients who had rectal cancers 5-8 cm from the anal verge. All underwent laparoscopic sphincter-preserving low anterior resections with total mesorectal excision (TME) and double stapling technique (DST). Data of 155 patients from one surgeon were utilized to build models to predict standardized endpoints (operative time, blood loss) and postoperative morbidity. Data of 44 patients from other surgeons were used to test the predictability of the built models.

RESULTS

Our results showed prior abdominal surgery, preoperative chemoradiotherapy, tumor distance to anal verge, interspinous distance, and BMI were predictors for the standardized operative times. Gender and tumor maximum diameter were related to the standardized blood loss. Temporary diversion and tumor diameter were predictors for postoperative morbidity. The model constructed for the operative time demonstrated excellent predictability for patients from different surgeons.

CONCLUSIONS

With a well-controlled patient population, we have built a predictable model to estimate operative difficulty. The standardized operative time will make it possible to significantly increase sample size and build more reliable models to predict operative difficulty for clinical use.