The minimum distal resection margin in rectal cancer surgery and its impact on local recurrence - A retrospective cohort analysis

[Postoperative Imaging Findings of Colorectal Surgery: A Pictorial Essay]

Postoperative colorectal imaging studies play an important role in the detection of surgical complications and disease recurrence. In this pictorial essay, we briefly describe methods of surgery, imaging findings of their early and late complications, and postsurgical recurrence of cancer and inflammatory bowel disease.

Unraveling variations and enhancing prediction of successful sphincter-preserving resection for low rectal cancer: a post hoc analysis of the multicentre LASRE randomized clinical trial

BACKGROUND

Accurate prediction of successful sphincter-preserving resection (SSPR) for low rectal cancer enables peer institutions to scrutinize their own performance and potentially avoid unnecessary permanent colostomy. The aim of this study is to evaluate the variation in SSPR and present the first artificial intelligence (AI) models to predict SSPR in low rectal cancer patients.

STUDY DESIGN

This was a retrospective post hoc analysis of a multicenter, non-inferiority randomized clinical trial (LASRE, NCT01899547) conducted in 22 tertiary hospitals across China. A total of 604 patients who underwent neoadjuvant chemoradiotherapy (CRT) followed by radical resection of low rectal cancer were included as the study cohort, which was then split into a training set (67%) and a testing set (33%). The primary end point of this post hoc analysis was SSPR, which was defined as meeting all the following criteria: (1) sphincter-preserving resection; (2) complete or nearly complete TME, (3) a clear CRM (distance between margin and tumour of 1 mm or more), and (4) a clear DRM (distance between margin and tumour of 1 mm or more). Seven AI algorithms, namely, support vector machine (SVM), logistic regression (LR), extreme gradient boosting (XGB), light gradient boosting (LGB), decision tree classifier (DTC), random forest (RF) classifier, and multilayer perceptron (MLP), were employed to construct predictive models for SSPR. Evaluation of accuracy in the independent testing set included measures of discrimination, calibration, and clinical applicability.

RESULTS

The SSPR rate for the entire cohort was 71.9% (434/604 patients). Significant variation in the rate of SSPR, ranging from 37.7 to 94.4%, was observed among the hospitals. The optimal set of selected features included tumour distance from the anal verge before and after CRT, the occurrence of clinical T downstaging, post-CRT weight and clinical N stage measured by magnetic resonance imaging. The seven different AI algorithms were developed and applied to the independent testing set. The LR, LGB, MLP and XGB models showed excellent discrimination with area under the receiver operating characteristic (AUROC) values of 0.825, 0.819, 0.819 and 0.805, respectively. The DTC, RF and SVM models had acceptable discrimination with AUROC values of 0.797, 0.766 and 0.744, respectively. LR and LGB showed the best discrimination, and all seven AI models had superior overall net benefits within the range of 0.3-0.8 threshold probabilities. Finally, we developed an online calculator based on the LGB model to facilitate clinical use.

CONCLUSIONS

The rate of SSPR exhibits substantial variation, and the application of AI models has demonstrated the ability to predict SSPR for low rectal cancers with commendable accuracy.

Quality assessment of surgery for colorectal cancer: Where do we stand?

Quality assurance in surgery has been one of the most important topics of debate among colorectal surgeons in the past decade. It has produced new surgical standards that led in part to the impressive oncological outcomes we see in many units today. Total mesorectal excision, complete mesocolic excision (CME), and the Japanese D3 lymphadenectomy are now benchmark techniques embraced by many surgeons and widely recommended by surgical societies. However, there are still ongoing discrepancies in outcomes largely based on surgeon performance. This is one of the main reasons why many countries have shifted colorectal cancer surgery only to high volume centers. Defining markers of surgical quality is thus a perquisite to ensure that standards and oncological outcomes are met at an institutional level. With the evolution of CME surgery, various quality markers have been described, mostly based on measurements on the surgical specimen and lymph node yield, while others have proposed radiological markers (i.e. arterial stumps) measured on postoperative scans as part of the routine cancer follow-up. There is no ideal marker; however, taken together and assembled into a new score or set of criteria may become a future point of reference for reporting outcomes of colorectal cancer surgery in research studies and defining subspecialization requirements both at an individual and hospital level.

Tumor regression and safe distance of distal margin after neoadjuvant therapy for rectal cancer

Neoadjuvant therapy has been widely employed in the treatment of rectal cancer, demonstrating its utility in reducing tumor volume, downstaging tumors, and improving patient prognosis. It has become the standard preoperative treatment modality for locally advanced rectal cancer. However, the efficacy of neoadjuvant therapy varies significantly among patients, with notable differences in tumor regression outcomes. In some cases, patients exhibit substantial tumor regression, even achieving pathological complete response. The assessment of tumor regression outcomes holds crucial significance for determining surgical approaches and establishing safe margins. Nonetheless, current research on tumor regression patterns remains limited, and there is considerable controversy surrounding the determination of a safe margin after neoadjuvant therapy. In light of these factors, this study aims to summarize the primary patterns of tumor regression observed following neoadjuvant therapy for rectal cancer, categorizing them into three types: tumor shrinkage, tumor fragmentation, and mucinous lake formation. Furthermore, a comparison will be made between gross and microscopic tumor regression, highlighting the asynchronous nature of regression in the two contexts. Additionally, this study will analyze the safety of non-surgical treatment in patients who achieve complete clinical response, elucidating the necessity of surgical intervention. Lastly, the study will investigate the optimal range for safe surgical resection margins and explore the concept of a safe margin distance post-neoadjuvant therapy.

Close distal margin is associated with locoregional rectal cancer recurrence: A multicenter study

BACKGROUND AND OBJECTIVES

The importance of the radial margin for rectal cancer resection is well understood. However, surgeons have deemphasized the distal margin, accepting very close distal margins to perform sphincter-preserving surgery. We hypothesized that distal margins < 1 cm would be an independent risk factor for locoregional recurrence. The objective was to determine whether close distal margins are associated with increased locoregional recurrence risk.

METHODS

This was a multi-institutional retrospective cohort study conducted at six academic medical centers including patients who received low anterior resection surgery for primary rectal cancer between 2007 and 2018.

RESULTS

Of 556 low anterior resection patients, the rate of close distal margin was 12.8% (n = 71), and the locoregional recurrence rate was 5.0% (n = 28). The locoregional recurrence rate for close distal margin cases was 9.9% (n = 7) compared to 4.3% (n = 21) for distal margins ≥1.0 cm. In multivariable analysis, the only factor significantly associated with locoregional recurrence was close distal margin (adjusted odds ratio: 2.80, confidence interval: 1.08-7.25, p = 0.035).

CONCLUSIONS

Rectal cancer patients with close distal margins (<1 cm) following low anterior resection had a significantly higher risk for locoregional recurrence. Therefore, the decision to perform low anterior resection with margins < 1 cm should be taken with caution.

Distal Tumor Spread in Rectal Cancer-How Low Should We Go?

BACKGROUND

Distal tumor spread (DTS) is an adverse prognostic factor in rectal cancer correlating with advanced stage disease. We aimed to assess prevalence and location of distal tumor spread and impact of neoadjuvant chemoradiotherapy (NACRT) in patients who underwent proctectomy for rectal cancer.

METHODS

The pathology database at our institution was queried for all patients who underwent proctectomy with curative intent for rectal cancer from 1/2008 to 12/2016. Specimen slides were re-evaluated by a single expert rectal cancer pathologist to verify diagnosis and measure the distance to the distal resection margin. Main outcome measures were 3-year overall and disease-free survival.

RESULTS

275 consecutive patients were identified. 109/111 patients with clinical stage 3 disease received preoperative neoadjuvant chemoradiotherapy. DTS was found in 13 (4.7%) specimens, 6 with intra-mural and 7 with extra-mural distal tumor spread. DTS was found only in patients with clinical stage 3 disease. Length of DTS from the distal end of the tumor ranged from 0 to 30 mm; in only 4 specimens DTS was >10 mm. A positive distal resection margin was found in 5/275 (1.8%) specimens.

CONCLUSION

A macroscopically tumor-free margin may suffice in patients with pre-treatment stage 1 or 2 disease. Furthermore, a 1 cm margin is adequate in most patients with stage 3 disease.

Risk factors affecting benign anastomotic stricture in anterior and low anterior resections for colorectal cancer: a single-center retrospective cohort study

PURPOSE

Although not as life-threatening as anastomotic leakage, anastomotic stricture reduces the quality of life. The risk factors for such an important life complication have not been revealed. This article examines the risk factors affecting anastomotic strictures due to colorectal cancers.

METHODS

Patients who underwent anterior and low anterior resection for colorectal cancer under elective conditions between 2015 and 2021 were included in the study. The patients were divided into two groups, those who developed anastomotic stricture and those who did not. The parameters determined between the two groups were compared, and multivariate analysis of statistically significant parameters was performed.

RESULTS

A total of 375 patients were included in the study. The anastomotic stricture was detected in 36 (9.6%) patients. In the multivariate analysis, non-mobilization of the splenic flexure and a proximal clean surgical margin of < 10 cm and a distal surgical margin of < 2 cm were identified as risk factors affecting anastomotic stricture. The risk factor with the highest odds ratio in the development of anastomotic stricture is the non-mobilization of the splenic flexure (p = 0.001, OR 11.375).

CONCLUSION

It is recommended that the mobilization of the splenic flexure to reduce the development of strictures. In addition, a clean surgical margin of 10 cm proximally and 2 cm distally and high ligation of the inferior mesenteric artery may reduce the development of stricture.

Impact of Microscopically Positive (≤1 mm) Distal Margins on Disease Recurrence in Rectal Cancer Treated by Neoadjuvant Chemoradiotherapy

BACKGROUND

The adequate distal resection margin is still controversial in rectal cancer treated by neoadjuvant chemoradiotherapy (nCRT). The aim of this study was to assess the impact of a distal margin of ≤1 mm on locoregional recurrence-free survival (LRRFS).

METHODS

Among 255 patients treated with nCRT and surgery at the National Cancer Institute of Milan, 83 (32.5%) had a distal margin of ≤1 mm and 172 (67.5%) had a distal margin of >1 mm. Survival analyses were performed to assess the impact of distal margin on 5-year LRRFS, as well as Cox survival analysis. The role of distal margin on survival was analyzed according to different tumor regression grades (TRGs).

RESULTS

The overall 5-year LRRFS rate was 77.6% with a distal margin of ≤1 mm vs. 88.3% with a distal margin of >1 mm (Log-rank p = 0.09). Only stage ypT4 was an independent predictor of worse LRRFS (HR 15.14, p = 0.026). The 5-year LRRFS was significantly lower in TRG3-5 patients with a distal margin of ≤1 mm compared to those with a distal margin of >1 mm (68.5% vs. 84.2%, p = 0.027), while no difference was observed in case of TRG1-2 (p = 0.77).

CONCLUSIONS

Low-responder rectal cancers after nCRT still require a distal margin of >1 mm to reduce the high likelihood of local relapse.

The Impact of Narrow and Infiltrated Distal Margin After Proctectomy for Rectal Cancer on Patients' Outcomes: a Systematic Review and Meta-analysis

Rectal cancer is a common tumor within a difficult anatomic constraint. Total mesorectal excision with longitudinal and circumferential free margins is considered imperative for good prognosis. In this article, the authors systematically reviewed all published literature with specific Mesh terms until the end of year 2019. Thereafter, retrieved articles were assessed using the Newcastle-Ottawa Scale and meta-analysis was conducted comparing local recurrence among 1-cm, 5-mm, and narrow (< 1-mm)/infiltrated margins. Thirty-nine articles were included in the study. Macroscopic distal margin < 1 cm carried a higher incidence of recurrence for those who did not receive neoadjuvant radiation, without affecting neither estimated overall nor disease-free survival. Less than 5-mm margin after radiation therapy is accepted oncologically. Infiltrated margins and narrow margins (< 1 mm) microscopically are associated with higher incidence of local recurrence and shorter overall and disease-free survival. Surgeons should aim at 1-cm safety margin in radiotherapy-naïve patients and microscopic free margin > 1 mm for those who received neoadjuvant therapy. The cost/benefit of reoperation for patients with infiltrated margins is still inadequately studied.

Advantages of ligating the rectum with gauze pad band in laparoscopic anterior resection of rectal cancer: a propensity score matched analysis

Purpose

It is difficult to maintain sufficient tension throughout laparoscopic anterior resection with total mesorectal excision, which causes a decline in surgical quality. We used a soft, inexpensive gauze pad band pulling the rectal tube to analyze the effect of surgery.

Methods

A gauze pad band was positioned at the proximal of the tumor, followed by fastening the rectal tube and ligating the rectum. 233 patients undergoing laparoscopic anterior resection for mid to low rectal cancer were enrolled between January 2018 and December 2020. After propensity score matching, 63 cases were selected in gauze pad band group and 126 cases were selected in traditional group. The two groups were compared in preoperative, intraoperative, and pathological characteristics.

Results

Compared to traditional group, the median operation duration (203 min vs. 233 min, p < 0.001) and the median intraoperative bleeding (48 ml vs. 67 ml, p < 0.001) were lesser in gauze pad band group. A higher percentage of one cartridge transection of rectum (36/63 vs. 51/126, p = 0.030), shorter length of cartridges used (6.88 ± 1.27 cm vs. 7.28 ± 1.25 cm, p = 0.040), and longer distal resection margin (2.74 ± 0.76 cm vs. 2.16 + 0.68 cm, p < 0.001) were found in the gauze pad band group. The completeness of total mesorectal excision (61/63 vs. 109/126, p = 0.022), harvested lymph nodes (19 vs. 17, p < 0.001) and positive lymph nodes (1 vs. 0, p = 0.046) were higher in gauze pad band group.

Conclusion

Ligation of the rectum with a gauze pad band allows for a reduction in operative time and intraoperative bleeding while increasing the rate of one cartridge transection. It also protected the quality of total mesorectal excision and membrane anatomy.

Trial registration: Not applicable.

Association of levels of metabolites with the safe margin of rectal cancer surgery: a metabolomics study

Background

Rectal cancer is one of the most lethal of gastrointestinal malignancies. Metabonomics has gradually developed as a convenient, inexpensive and non-destructive technique for the study of cancers.

Methods

A total of 150 tissue samples from 25 rectal cancer patients were analyzed by liquid chromatography–mass spectrometry (LC–MS), and 6 tissue samples were collected from each patient (group 1: tumor; group 2: 0.5 cm from tumor; group 3:1 cm from tumor; group 4:2 cm from tumor; group 5:3 cm from tumor and group 6:5 cm from tumor). The differential metabolites of tumor tissues and 5 cm from the tumor (normal tissues) were first selected. The differential metabolites between tumor tissues and normal tissues were regrouped by hierarchical clustering analysis, and further selected by discriminant analysis according to the regrouping of clustering results. The potential safe margin of clinical T(cT)1,cT2 stage rectal cancer and cT3,cT4 stage rectal cancer at the metabolomic level was further identified by observing the changes in the level of differential metabolites within the samples from group 1 to group 6.

Results

We found 22 specific metabolites to distinguish tumor tissue and normal tissue. The most significant changes in metabolite levels were observed at 0.5 cm (cT1, cT2) and 2.0 cm (cT3, cT4) from the tumor, while the changes in the tissues afterwards showed a stable trend.

Conclusions

There are differential metabolites between tumor tissues and normal tissues in rectal cancer. Based on our limited sample size, the safe distal incision margin for rectal cancer surgery in metabolites may be 0.5 cm in patients with cT1 and cT2 stage rectal cancer and 2.0 cm in patients with cT3 and cT4 stage rectal cancer.

Is a Distal Resection Margin of ≤ 1 cm Safe in Patients with Intermediate- to Low-Lying Rectal Cancer? A Systematic Review and Meta-Analysis

BACKGROUND

It is generally accepted that the distal resection margin of intermediate- to low-lying rectal cancer should be greater than 2 cm and at least 1 cm in special cases. This study intends to investigate whether a distal resection margin ≤ 1 cm affects tumor outcomes for patients with intermediate- to low-lying rectal cancer.

METHODS

A systematic review of the literature was conducted. Sixteen studies included data for distal resection margins ≤ 1 cm (1684 cases) and > 1 cm (5877 cases), and 5 studies included survival data. Meta-analysis was used to compare the local recurrence rate and long-term survival of patients with distal resection margins > or ≤ 1 cm.

RESULTS

The local recurrence rate in the ≤ 1-cm margin group (9.5%) was 2.3% higher than that in the > 1-cm margin group (7.2%) according to a fixed-effects model (RR [95% CI] 1.42 [1.18, 1.70], P < 0.001). The overall survival results of the five 1-cm margin studies showed an HR (95% CI) of 0.96 (0.75, 1.24) (P = 0.78). Subgroup analysis showed that the local recurrence rate in the subgroup with perioperative treatment was 1.2% lower in the ≤ 1-cm margin group (8.3%) than in the > 1-cm margin group (9.5%) (RR [95% CI] 0.97 [0.63, 1.49], P = 0.90). In the surgery alone subgroup, the local recurrence rate was 4.7% higher in the ≤ 1-cm margin group (12.4%) than in the > 1-cm group (7.7%) (RR [95% CI] 1.76 [1.09, 2.83], P = 0.02).

CONCLUSIONS

For patients with intermediate- to low-lying rectal cancer undergoing surgery alone, a distal resection margin ≤ 1 cm may be not safe.

Evaluation of Nursing Effects of Pelvic Floor Muscle Rehabilitation Exercise on Gastrointestinal Tract Rectal Cancer Patients Receiving Anus-preserving Operation by Intelligent Algorithm-based Magnetic Resonance Imaging

Based on magnetic resonance imaging (MRI) technology under artificial intelligence algorithm, the postoperative nursing effects of pelvic floor muscle rehabilitation exercise on gastrointestinal tract rectal cancer (RC) patients were investigated. A total of 88 patients receiving RC anus-preserving surgery in hospital were selected. The included patients were divided randomly into the experimental group (44 cases) and the control group (44 cases). Patients in the control group engaged in Kegel motion, while patients in the experimental group underwent self-designed comprehensive pelvic floor training. Anorectum function rating scale and quality of life questionnaire for colorectal cancer (EORTC QLQ-CR29) were utilized to compare and analyze anus functions and living quality of patients in the two groups. Besides, all patients in two groups received MRI examinations, and images were processed by a convolutional neural network (CNN) algorithm. The results showed that in MRI images, there were significant signal differences between lesion tissues and normal tissues. After being processed by an artificial intelligence algorithm, the definition of MRI images was remarkably enhanced with clearer lesion edges. The quality of images was also significantly improved. Besides, the comparison of anus functions of patients in two groups showed that the differences demonstrated statistical meaning after the intervention (P < 0.05). In conclusion, artificial intelligence algorithm-based MRI and comprehensive pelvic floor muscle exercise showed significant application prospects and values in the recovery of patients' intestinal functions after RC anus-preserving surgery.

Intraoperative adverse events as a risk factor for local recurrence of rectal cancer after resection surgery

AIM

Failure to achieve a radical resection as well as intraoperative rectal perforation are important risk factors for local recurrence after rectal cancer surgery, but the importance of other intraoperative adverse events for the prognosis is unknown. The aim of this study was to assess the occurrence of intraoperative adverse events during rectal cancer surgery, and to determine whether these were associated with an increased risk of local recurrence.

METHODS

A retrospective population-based cohort study was undertaken, including all patients in Region Västra Götaland, Sweden, who had undergone primary resection surgery for rectal cancer diagnosed between 2010 and 2014, registered in the Swedish Colorectal Cancer Registry. Data were retrieved from the registry and through review of the medical records.

RESULTS

In total, 1208 patients were included in the study of whom 78 (6%) developed local recurrence during the follow-up period of at least 5 years. Intraoperative adverse events were common and occurred in 62/78 (79%) of patients with local recurrence compared to 604/1130 (53%) of patients without local recurrence. In multivariate analysis intraoperative adverse events were found to be an independent risk factor for local recurrence of rectal cancer, as were nonradical resection, a high pathological T stage, the presence of lymph node metastases, type of surgery and refraining from rectal washout during anterior resection and Hartmann's procedure.

CONCLUSIONS

Intraoperative adverse events were found to be an independent risk factor for local recurrence of rectal cancer and could possibly be used together with other known risk factors to select patients for intensified postoperative surveillance.

Oncological results in rectal cancer patients with a subcentimetre distal margin after laparoscopic-assisted sphincter-preserving surgery

Background

Distal resection margin (DRM) is closely associated with sphincter‐preserving surgery and oncological safety for patients with mid‐low rectal cancers. However, the optimal DRM has not been determined.

Methods

Data of 378 rectal cancer patients who underwent laparoscopic‐assisted sphincter‐preserving surgery from 2009 to 2015 were retrospectively analysed. Patients were divided into two groups based on DRM: ≤1 cm (n = 74) and >1 cm (n = 304). To minimize the differences between the two groups, propensity‐score matching on baseline features was performed.

Results

Before propensity‐score matching, no significant differences in 5‐year disease‐free survival (DFS) (92.8% versus 81.3%, P = 0.128) and 5‐year overall survival (OS) (83.7% versus 82.2%, P = 0.892) were observed in patients with DRMs of ≤1 cm (n = 74) and >1 cm (n = 304), respectively. After propensity‐score matching (1:1), there were also no significant differences in DFS (88.1% versus 78.2%, P = 0.162) and OS (84.5% versus 84.9%, P = 0.420) between the DRM of ≤1 cm group (n = 65) and >1 cm group (n = 65), respectively. A total of 44 patients received preoperative chemoradiotherapy (CRT). In this cohort, the 5‐year local recurrence (LR) rates (P = 0.118) and the 5‐year DFS rates (P = 0.298) were not significantly different between the two groups. A total of 334 patients received surgery without neoadjuvant CRT. There were also no significant differences in the 5‐year LR rates (P = 0.150) and 5‐year DFS rates (P = 0.172) between the two groups.

Conclusions

When aiming to achieve at least a 1–2 cm distal clinical resection margin, a histological resection margin of <1 cm on the DRM gave equivalent clinical outcomes to a DRM of >1 cm.

Brazilian society of surgical oncology: Guidelines for the surgical treatment of mid-low rectal cancer

BACKGROUND

Colorectal cancer (CRC) is the third leading cause of cancer in North America, Western Europe, and Brazil, and represents an important public health problem. It is estimated that approximately 30% of all the CRC cases correspond to tumors located in the rectum, requiring complex multidisciplinary treatment. In an effort to provide surgeons who treat rectal cancer with the most current information based on the best evidence in the literature, the Brazilian Society of Surgical Oncology (SBCO) has produced the present guidelines for rectal cancer treatment that is focused on the main topics related to daily clinical practice.

OBJECTIVES

The SBCO developed the present guidelines to provide recommendations on the main topics related to the treatment of mid-low rectal cancer based on current scientific evidence.

METHODS

Between May and June 2021, 11 experts in CRC surgery met to develop the guidelines for the treatment of mid-low rectal cancer. A total of 22 relevant topics were disseminated among the participants. The methodological quality of a final list with 221 sources was evaluated, all the evidence was examined and revised, and the treatment guideline was formulated by the 11-expert committee. To reach a final consensus, all the topics were reviewed via a videoconference meeting that was attended by all 11 of the experts.

RESULTS

The prepared guidelines contained 22 topics considered to be highly relevant in the treatment of mid-low rectal cancer, covering subjects related to the tests required for staging, surgical technique-related aspects, recommended measures to reduce surgical complications, neoadjuvant strategies, and nonoperative treatments. In addition, a checklist was proposed to summarize the important information and offer an updated tool to assist surgeons who treat rectal cancer provide the best care to their patients.

CONCLUSION

These guidelines summarize concisely the recommendations based on the most current scientific evidence on the most relevant aspects of the treatment of mid-low rectal cancer and are a practical guide that can help surgeons who treat rectal cancer make the best therapeutic decision.

Treatment outcomes of patients with involved resection margin after rectal cancer surgery: A nationwide population-based cohort study in South Korea

BACKGROUND

The involvement of resection margins after rectal cancer surgery by malignant tumors is a negative prognostic factor. Therefore, it is important to analyze treatment outcomes and establish adjuvant therapy.

METHODS

The Health Insurance Review and Assessment Service collects data from medical institutions in South Korea. We reviewed the database of this prospectively collected cohort for patients who underwent curative resection for rectal cancer.

RESULTS

Of the 5,620 patients, 113 (2.0%) were diagnosed with resection margin involvement after surgery. The resection margins of patients with mid-rectal cancer, pathologic stage III, mucinous/signet ring cell carcinoma, and undergoing emergency surgery were more frequently involved. Neoadjuvant chemoradiotherapy was a significant preventive factor for resection margin involvement (odds ratio = 0.53; 95% confidence interval [CI], 0.32-0.87; p = 0.012). The OS of patients with adjuvant treatment was better than that of patients without adjuvant treatment (5-year overall survival [OS]: 62.8% vs. 46.3%, p = 0.02). The administration of chemoradiotherapy was also significantly associated with better OS (hazard ratio = 0.36; 95% CI, 0.17-0.77; p = 0.009).

CONCLUSION

Efforts to acquire wider resection margins are necessary for patients with mid-rectal cancer, pathologic stage III, mucinous/signet ring cell carcinoma, and emergency surgery. Neoadjuvant chemoradiotherapy was a significant preventive factor for involved resection margin. Patients with resection margin involvement showed better OS after adjuvant treatment than those without adjuvant treatment. The adjuvant chemoradiotherapy was helpful to prevent the worse prognosis of these patients.

Initial experience of Chinese surgical robot "Micro Hand S″ assisted versus open and laparoscopic total mesorectal excision for rectal cancer: Short-term outcomes in a single center

BACKGROUND

A Chinese surgical robot, Micro Hand S, was introduced for clinical use as a novel robotic platform. This study aimed to comprehensively compare the early experience of the Micro Hand S robot-assisted total mesorectal excision (TME) with conventional approaches.

METHODS

Between May 2017 and April 2018, 99 consecutive patients who underwent open, laparoscopic and Micro Hand S robot-assisted TME (O-/L-/RTME) for rectal cancer were included. Clinical and pathological outcomes were retrospectively analyzed. Surgical success as the primary endpoint was defined as the absence of (i) conversion, (ii) incomplete TME, (iii) involved circumferential and distal resection margins (CRM/DRM), (iv) severe complications.

RESULTS

The rate of surgical success was similar (89.7 vs. 86.4 vs. 84.6%, p = 0.851) in the three groups and the respective incidences were as follows: conversion (not applicable, 4.5 vs. 2.3%, p = 1.000), incomplete TME (6.9 vs. 6.8 vs. 3.8%, p = 0.980), involved CRM/DRM (0 vs. 2.3 vs. 3.8%, p = 0.592), severe complications (3.4 vs. 4.5 vs. 7.7%, p = 0.844). Compared with open and laparoscopic surgery, the robotic surgery was associated with longer operative time, less blood loss, earlier first flatus time and liquid intake time, and shorter length of hospital stay (p < 0.05).

CONCLUSIONS

The Micro Hand S assisted TME is safe and feasible, showing comparable outcomes than conventional approaches, with superiority in blood loss, recovery of bowel function, length of hospital stay, but with increased operative time.

The risk factors of local recurrence and distant metastasis on pT1/T2N0 mid-low rectal cancer after total mesorectal excision

Background

Radical resection is associated with good prognosis among patients with cT1/T2Nx rectal cancer. However, still some of the patients experienced cancer recurrence following radical resection. This study tried to identify the postoperative risk factors of local recurrence and distant metastasis separately.

Methods

This retrospective, single-center study comprised of 279 consecutive patients from Linkou branch of Chang Gung Memorial Hospital in 2005–2016 with rectal adenocarcinoma, pT1/T2N0M0 at distance from anal verge ≤ 8cm, who received curative radical resection.

Results

The study included 279 patients with pT1/pT2N0 mid-low rectal cancer with median follow-up of 73.5 months. Nineteen (6.8%) patients had disease recurrence in total. Nine (3.2%) of them had local recurrence, and fourteen (5.0%) of them had distant metastasis. Distal resection margin < 0.9 (cm) (hazard ratio = 4.9, p = 0.050) was the risk factor of local recurrence. Preoperative carcinoembryonic antigen (CEA) ≥ 5 ng/mL (hazard ratio = 9.3, p = 0.0003), lymph node yield (LNY) < 14 (hazard ratio = 5.0, p = 0.006), and distal resection margin < 1.4cm (hazard ratio = 4.0, p = 0.035) were the risk factors of distant metastasis.

Conclusion

For patients with pT1/pT2N0 mid-low rectal cancer, current multidisciplinary treatment brings acceptable survival outcome. Insufficient distal resection margin attracted the awareness of risk factors for local recurrence and distant metastasis as a foundation for future research.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02223-4.

Optimising functional outcomes in rectal cancer surgery

Background

By improved surgical technique such as total mesorectal excision (TME), multimodal treatment and advances in imaging survival and an increased rate of sphincter preservation have been achieved in rectal cancer surgery. Minimal-invasive approaches such as laparoscopic, robotic and transanal-TME (ta-TME) enhance recovery after surgery. Nevertheless, disorders of bowel, anorectal and urogenital function are still common and need attention.

Purpose

This review aims at exploring the causes of dysfunction after anterior resection (AR) and the accordingly preventive strategies. Furthermore, the indication for low AR in the light of functional outcome is discussed. The last therapeutic strategies to deal with bowel, anorectal, and urogenital disorders are depicted.

Conclusion

Functional disorders after rectal cancer surgery are frequent and underestimated. More evidence is needed to define an indication for non-operative management or local excision as alternatives to AR. The decision for restorative resection should be made in consideration of the relevant risk factors for dysfunction. In the case of restoration, a side-to-end anastomosis should be the preferred anastomotic technique. Further high-evidence clinical studies are required to clarify the benefit of intraoperative neuromonitoring. While the function of ta-TME seems not to be superior to laparoscopy, case-control studies suggest the benefits of robotic TME mainly in terms of preservation of the urogenital function. Low AR syndrome is treated by stool regulation, pelvic floor therapy, and transanal irrigation. There is good evidence for sacral nerve modulation for incontinence after low AR.