Circumferential resection margin as a prognostic factor after rectal cancer surgery: A large population-based retrospective study

Imaging and Metabolic Diagnostic Methods in the Stage Assessment of Rectal Cancer

Rectal cancer (RC) is a prevalent malignancy with significant morbidity and mortality rates. The accurate staging of RC is crucial for optimal treatment planning and patient outcomes. This review aims to summarize the current literature on imaging and metabolic diagnostic methods used in the stage assessment of RC. Various imaging modalities play a pivotal role in the initial evaluation and staging of RC. These include magnetic resonance imaging (MRI), computed tomography (CT), and endorectal ultrasound (ERUS). MRI has emerged as the gold standard for local staging due to its superior soft tissue resolution and ability to assess tumor invasion depth, lymph node involvement, and the presence of extramural vascular invasion. CT imaging provides valuable information about distant metastases and helps determine the feasibility of surgical resection. ERUS aids in assessing tumor depth, perirectal lymph nodes, and sphincter involvement. Understanding the strengths and limitations of each diagnostic modality is essential for accurate staging and treatment decisions in RC. Furthermore, the integration of multiple imaging and metabolic methods, such as PET/CT or PET/MRI, can enhance diagnostic accuracy and provide valuable prognostic information. Thus, a literature review was conducted to investigate and assess the effectiveness and accuracy of diagnostic methods, both imaging and metabolic, in the stage assessment of RC.

Clinical outcomes of neoadjuvant chemoradiotherapy followed by total mesorectal excision in locally advanced rectal cancer with mesorectal fascia involvement

PURPOSE

For the treatment of locally advanced rectal cancer (LARC), research on primary lesions with mesorectal fascia (MRF) involvement is lacking. This study analyzed the clinical outcomes and efficacy of dose-escalated neoadjuvant concurrent chemoradiotherapy (NCRT) to patients with LARC involving MRF.

MATERIALS AND METHODS

We retrospectively reviewed 301 patients who were diagnosed with LARC involving MRF and underwent NCRT followed by total mesorectal excision (TME). Patients who received radiotherapy (RT) doses of ≤50.4 Gy were defined as the non-boost group, while ≥54.0 Gy as the boost group. Pathological tumor response and survival outcomes, including intrapelvic recurrence-free survival (IPRFS), distant metastases-free survival (DMFS) and overall survival (OS), were analyzed.

RESULTS

A total of 269 patients (89.4%) achieved a negative pathological circumferential resection margin and 104 (34.6%) had good pathological tumor regression grades. With a median follow-up of 32.4 months, IPRFS, DMFS, and OS rates at 5-years were 88.6%, 78.0%, and 91.2%, respectively. In the subgroup analysis by RT dose, the boost group included more advanced clinical stages of patients. For the non-boost group and boost group, 5-year IPRFS rates were 90.3% and 87.0% (p = 0.242), 5-year DMFS rates were 82.0% and 71.3% (p = 0.105), and 5-year OS rates were 93.0% and 80.6% (p = 0.439), respectively. Treatment related toxicity was comparable between the two groups (p = 0.211).

CONCLUSION

Although this retrospective study failed to confirm the efficacy of dose-escalated NCRT, favorable IPRFS and pathological complete response was achieved with NCRT followed by TME. Further studies combining patient customized RT dose with systemic therapies are needed.

Predictors for temporary stomas non-closure among non-metastatic rectal cancer patients undergoing curative resection: a retrospective analysis

BACKGROUND

The primary treatment for non-metastatic rectal cancer is curative resection. However, sphincter-preserving surgery may lead to complications. This study aims to develop a predictive model for stoma non-closure in rectal cancer patients who underwent curative-intent low anterior resection.

METHODS

Consecutive patients diagnosed with non-metastatic rectal cancer between January 2005 and December 2017, who underwent low anterior resection, were retrospectively included in the Chang Gung Memorial Foundation Institutional Review Board. A comprehensive evaluation and analysis of potential risk factors linked to stoma non-closure were performed.

RESULTS

Out of 956 patients with temporary stomas, 10.3% (n = 103) experienced non-closure primarily due to cancer recurrence and anastomosis-related issues. Through multivariate analysis, several preoperative risk factors significantly associated with stoma non-closure were identified, including advanced age, anastomotic leakage, positive nodal status, high preoperative CEA levels, lower rectal cancer presence, margin involvement, and an eGFR below 30 mL/min/1.73m2. A risk assessment model achieved an AUC of 0.724, with a cutoff of 2.5, 84.5% sensitivity, and 51.4% specificity. Importantly, the non-closure rate could rise to 16.6% when more than two risk factors were present, starkly contrasting the 3.7% non-closure rate observed in cases with a risk score of 2 or below (p < 0.001).

CONCLUSION

Prognostic risk factors associated with the non-closure of a temporary stoma include advanced age, symptomatic anastomotic leakage, nodal status, high CEA levels, margin involvement, and an eGFR below 30 mL/min/1.73m2. Hence, it is crucial for surgeons to evaluate these factors and provide patients with a comprehensive prognosis before undergoing surgical intervention.

Predicting the Feasibility of Curative Resection in Low Rectal Cancer: Insights from a Prospective Observational Study on Preoperative Magnetic Resonance Imaging Accuracy

Background and Objectives: A positive pathological circumferential resection margin is a key prognostic factor in rectal cancer surgery. The point of this prospective study was to see how well different MRI parameters could predict a positive pathological circumferential resection margin (pCRM) in people who had been diagnosed with rectal adenocarcinoma, either on their own or when used together. Materials and Methods: Between November 2019 and February 2023, a total of 112 patients were enrolled in this prospective study and followed up for a 36-month period. MRI predictors such as circumferential resection margin (mCRM), presence of extramural venous invasion (mrEMVI), tumor location, and the distance between the tumor and anal verge, taken individually or combined, were evaluated with univariate and sensitivity analyses. Survival estimates in relation to a pCRM status were also determined using Kaplan-Meier analysis. Results: When individually evaluated, the best MRI predictor for the detection of a pCRM in the postsurgical histopathological examination is mrEMVI, which achieved a sensitivity (Se) of 77.78%, a specificity (Sp) of 87.38%, a negative predictive value (NPV) of 97.83%, and an accuracy of 86.61%. Also, the best predictive performance was achieved by a model that comprised all MRI predictors (mCRM+ mrEMVI+ anterior location+ < 4 cm from the anal verge), with an Se of 66.67%, an Sp of 88.46%, an NPV of 96.84%, and an accuracy of 86.73%. The survival rates were significantly higher in the pCRM-negative group (p < 0.001). Conclusions: The use of selective individual imaging predictors or combined models could be useful for the prediction of positive pCRM and risk stratification for local recurrence or distant metastasis.

Robotic beyond total mesorectal excision (TME) for locally advanced or recurrent rectal cancer: a systematic review protocol

INTRODUCTION

The surgical treatment for locally advanced or recurrent rectal cancer requires oncological clearance with a pelvic exenteration or a beyond total mesorectal excision (TME). The aim of this systematic review is to explore the safety and feasibility of robotic surgery in locally advanced and recurrent rectal cancer by evaluating perioperative outcomes, oncological clearance rates, and survival and recurrence rates postrobotic beyond TME surgery.

METHODS

The systematic review will include studies published until the end of December 2023. The MEDLINE, EMBASE and Scopus databases will be searched. The screening process, study selection, data extraction, quality assessment and analysis will be performed by two independent reviewers. Discrepancies will be resolved by consensus with a third independent reviewer. The risk of bias will be assessed with validated scores. The primary outcomes will be oncological clearance, overall and disease-free survival, and local and systemic recurrence rates post robotic or robot-assisted beyond TME surgery for locally advanced or recurrent rectal cancer. Secondary outcomes will include perioperative outcomes.

ETHICS AND DISSEMINATION

No ethical approval is required for this systematic review as no individual patient cases are studied requiring access to individual medical records. The results of the systematic review will be disseminated with conference presentations and peer-reviewed paper publications.

PROSPERO REGISTRATION OF THE STUDY

CRD42023408098.

Real-time classification of tumour and non-tumour tissue in colorectal cancer using diffuse reflectance spectroscopy and neural networks to aid margin assessment

BACKGROUND

Colorectal cancer is the third most commonly diagnosed malignancy and the second leading cause of mortality worldwide. A positive resection margin following surgery for colorectal cancer is linked with higher rates of local recurrence and poorer survival. We investigated diffuse reflectance spectroscopy (DRS) to distinguish tumour and non-tumour tissue in ex vivo colorectal specimens, to aid margin assessment and provide augmented visual maps to the surgeon in real-time.

METHODS

Patients undergoing elective colorectal cancer resection surgery at a London-based hospital were prospectively recruited. A hand-held DRS probe was used on the surface of freshly resected ex vivo colorectal tissue. Spectral data was acquired for tumour and non-tumour tissue. Binary classification was achieved using conventional machine learning classifiers and a convolutional neural network (CNN), which were evaluated in terms of sensitivity, specificity, accuracy and the area under the curve.

RESULTS

A total of 7692 mean spectra were obtained for tumour and non-tumour colorectal tissue. The CNN-based classifier was the best performing machine learning algorithm, when compared to contrastive approaches, for differentiating tumour and non-tumour colorectal tissue, with an overall diagnostic accuracy of 90.8% and area under the curve of 96.8%. Live on-screen classification of tissue type was achieved using a graduated colourmap.

CONCLUSION

A high diagnostic accuracy for a DRS probe and tracking system to differentiate ex vivo tumour and non-tumour colorectal tissue in real-time with on-screen visual feedback was highlighted by this study. Further in vivo studies are needed to ensure integration into a surgical workflow.

Robotic Lateral Pelvic Lymph Node Dissection in Rectal Cancer: A Feasibility Study from a European Centre

INTRODUCTION

The role of robotic lateral pelvic lymph node dissection (LPLND) for lateral pelvic nodal disease (LPND) in rectal cancer has yet to be investigated in the Western hemisphere. This study aims to investigate the safety and feasibility of robotic LPLND by utilising a well-established totally robotic TME protocol.

METHODS

We conducted a retrospective study on 17 consecutive patients who underwent robotic LPLND for LPND ± TME for rectal cancer between 2015 and 2021. A single docking totally robotic approach from the left hip with full splenic mobilisation was performed using the X/Xi da Vinci platform. All patients underwent a tri-compartmental robotic en bloc excision of LPND with preservation of the obturator nerve and pelvic nerve plexus, leaving a well-skeletonised internal iliac vessel and its branches.

RESULTS

The median operative time was 280 min, which was 40 min longer than our standard robotic TME. The median BMI was 26, and there were no conversions. The median inpatient stay was 7 days with no Clavien-Dindo > 3 complications. One patient (6%) developed local recurrence and metastatic disease within 5 months. The proportion of histologically confirmed LPND was 41%, of which 94% were well to moderately differentiated adenocarcinoma. Median pre-operative lateral pelvic node size was significantly higher in positive nodes (14 mm vs. 8 mm (p = 0.01)). All patients had clear resection margins on histology.

DISCUSSION

Robotic LPLND is safe and feasible with good peri-operative and short-term outcomes, with the ergonomic advantages of a robotic TME docking protocol readily transferrable in LPLND.

Does robotic TME bring difference in lymph node yield and quality of TME?

BACKGROUNDS

Oncological outcomes of the robotic low anterior rectal resection with total mesorectal excision (TME) are still under discussion. Few studies have proven that robotic TME (rTME) is a safe and equivalent method for treatment of rectal carcinoma. But there is almost no comparison between the rTME and conventional TME in terms of the number of lymph nodes obtained and the quality of the TME.

METHODS

A single institution retrospective study was designed in a cohort of 261 patients. Cohort was divided into two groups depending on the type of surgery (rTME versus TME) and within these two groups, patients were divided according to whether they underwent neoadjuvant chemoradiation (nCHRT) or did not. The primary objective of the study was to compare obtained number of the lymph nodes in specimen. Secondary objectives were comparison of the quality of the TME and the number of positive circumferential resection margins.

RESULTS

Results of the study have shown no significant difference in number of the lymph nodes obtained by the rTME and TME. There was no difference in the quality of the TME, neither in the group with the previous nCHRT nor in the group without a nCHRT.

CONCLUSION

With results from the study we consider the rTME to be non-inferior to the conventional TME. Therefore, at least identical oncological results can be expected in patients treated by the rTME.

Diagnostic Performance of Rectal CT for Staging Rectal Cancer: Comparison with Rectal MRI and Histopathology

Purpose

To compare the diagnostic performance of rectal CT with that of high-resolution rectal MRI and histopathology in assessing rectal cancer.

Materials and Methods

Sixty-seven patients with rectal cancer who underwent rectal CT with rectal distension using sonographic gel and high-resolution MRI were enrolled in this study. The distance from the anal verge/anorectal junction, distance to the mesorectal fascia (MRF), extramural depth (EMD), extramesorectal lymph node (LN) involvement, extramural venous invasion (EMVI), and T/N stages in rectal CT/MRI were analyzed by two gastrointestinal radiologists. The CT findings of 20 patients who underwent radical surgery without concurrent chemoradiotherapy were compared using histopathology. Interclass correlations and kappa statistics were used.

Results

The distance from the anal verge/anorectal junction showed an excellent intraclass correlation between CT and MRI for both reviewers. For EMD, the distance to the MRF, presence of LNs, extramesorectal LN metastasis, EMVI, T stage, and intermodality kappa or weighted kappa values between CT and MRI showed excellent agreement. Among the 20 patients who underwent radical surgery, T staging, circumferential resection margin involvement, EMVI, and LN metastasis on rectal CT showed acceptable concordance rates with histopathology.

Conclusion

Dedicated rectal CT may be on par with rectal MRI in providing critical information to patients with rectal cancer.

Intensification of Local Therapy With High Dose Rate, Intraoperative Radiation Therapy (HDR-IORT) and Extended Resection for Locally Advanced and Recurrent Colorectal Cancer

BACKGROUND

We report our long-term experience with high dose rate intraoperative radiotherapy (HDR-IORT) in a single, quaternary institution.

PATIENTS/METHODS

From 2004 to 2020, 60 HDR-IORT procedures for locally advanced colorectal cancer (LACC) and 81 for locally recurrent colorectal cancer (LRCC) were done in our institution. Preoperative radiotherapy was done prior to majority of the resections (89%, 125/141). Sixty-nine percent (58/84) of the resections involving pelvic exenterations had >3 en bloc organs resected. HDR-IORT was delivered using a Freiburg applicator. A single 10 Gy fraction was delivered. Margin status was R0 and R1 in 54% (76/141) and 46% (65/141) of the resections, respectively.

RESULTS

With a median follow-up time of 4 years, 3-, 5-, and 7- year, overall survival (OS) rates were 84%, 58%, and 58% for LACC and 68%, 41%, and 37% for LRCC, respectively. Local progression-free survival (LPFS) rates were 97%, 93%, and 93% for LACC and 80%, 80%, 80% for LRCC, respectively. For the LRCC group, an R1 resection was associated with worse OS, LPFS, and progression-free survival (PFS), preoperative EBRT was associated with improved LPFS and PFS, and ≥2 years disease-free interval was associated with improved PFS. The most common severe adverse events were postoperative abscess (n = 25) and bowel obstruction (n = 11). There were 68 grade 3 to 4 and no grade 5 adverse events.

CONCLUSIONS

Favorable OS and LPFS can be achieved for LACC and LRCC with intensive local therapy. In patients with risk factors for poorer outcomes, optimization of EBRT and IORT, surgical resection, and systemic therapy are required.

Implication of MRI Risk Stratification System on the Survival Benefits of Adjuvant Chemotherapy After Neoadjuvant Chemoradiotherapy in Patients With Locally Advanced Rectal Cancer

RATIONALE AND OBJECTIVES

To investigate the implication of a Magnetic resonance imaging (MRI) risk stratification system on the selection of patients with locally advanced rectal cancer (LARC) who can benefit from adjuvant chemotherapy (ACT) after neoadjuvant chemoradiotherapy (NCRT).

MATERIALS AND METHODS

This retrospective study included 328 patients with LARC who underwent NCRT and surgery. The median follow-up duration was 79 months (Interquartile range, 66-94 months). Cox logistic regression analysis was used to identify MRI risk factors and develop a risk stratification system to stratify patients into groups with high and low risks. Kaplan-Meier curves of distant metastasis-free survival (DMFS) and overall survival (OS) were used to show the benefits of ACT and stratify results based on the MRI risk stratification system and postoperative pathological staging.

RESULTS

An MRI risk stratification system was built based on four MRI risk factors, including MRI-identified T3b-T4 stage, N1-N2 stage, extramural venous invasion, and tumor deposits. 74 (22.6%) patients with 3-4 MRI risk factors were classified into the MRI high-risk group. ACT could significantly improve 5-year DMFS (19.2% versus 52.1%; p < 0.001) and OS (34.6% versus 75.0%; p < 0.001) for patients in the MRI high-risk group, while ACT had no survival benefit for patients in the MRI low-risk group. The benefits of ACT were not observed in patients with any pathological staging subgroups (ypT0-2N0, ypT3-4N0, and ypN+).

CONCLUSION

Patients in the MRI high-risk group could benefit from ACT, regardless of postoperative pathological staging. Baseline MRI should be considered more in ACT decision-making.

Transanal total mesorectal excision versus laparoscopic intersphincteric resection for low rectal cancer: a propensity score matching analysis

BACKGROUND

Anus-preserving surgery for low rectal cancer has always been a serious difficulty for surgeons. Transanal total mesorectal excision (TaTME) and laparoscopic intersphincteric resection (ISR) are commonly used Anus-preserving surgeries for low rectal cancer. The aim of this study was to compare the clinical use of two surgical methods.

METHODS

A total of 152 patients with low rectal cancer were treated with taTME in 75 cases and ISR in 77 cases. After propensity score matching, 46 patients in each group were included in the study. Perioperative outcomes, anal function scores (Wexner incontinence score) and quality of life scores (EORTC QLQ C30, EORTC QLQ CR38) at least 1 year after surgery were compared between the two groups.

RESULTS

There were no significant differences between the two groups in terms of surgical outcomes, pathological examination of surgical specimens, postoperative recovery, and postoperative complications, except for patients in the taTME group who had their indwelling catheters removed later. Anal Wexner incontinence score was lower in taTME group than ISR group (P < 0.05). On the EORTC QLQ-C30 scale, the physical function and role function scores in the ISR group were lower than those in the taTME group (P < 0.05), while the fatigue, pain symptoms, and constipation scores in the ISR group were higher than those in the taTME group (P < 0.05). On the EORTC QLQ-CR38 scale, the scores of gastrointestinal symptoms and defecation problems in the ISR group were higher than those in the taTME group (P < 0.05).

CONCLUSION

Compared with ISR surgery, taTME surgery is comparable in terms of surgical safety and short-term efficacy, and has better long-term anal function and quality of life. From the perspective of long-term anal function and quality of life, taTME surgery is a better surgical method for the treatment of low rectal cancer.

Morphology of the anterior mesorectum: a new predictor for local recurrence in patients with rectal cancer

BACKGROUND

Pre-operative assessment with high-resolution magnetic resonance imaging (MRI) is useful for assessing the risk of local recurrence (LR) and survival in rectal cancer. However, few studies have explored the clinical importance of the morphology of the anterior mesorectum, especially in patients with anterior cancer. Hence, the study aimed to investigate the impact of the morphology of the anterior mesorectum on LR in patients with primary rectal cancer.

METHODS

A retrospective study was performed on 176 patients who underwent neoadjuvant treatment and curative-intent surgery. Patients were divided into two groups according to the morphology of the anterior mesorectum on sagittal MRI: (1) linear type: the anterior mesorectum was thin and linear; and (2) triangular type: the anterior mesorectum was thick and had a unique triangular shape. Clinicopathological and LR data were compared between patients with linear type anterior mesorectal morphology and patients with triangular type anterior mesorectal morphology.

RESULTS

Morphometric analysis showed that 90 (51.1%) patients had linear type anterior mesorectal morphology, while 86 (48.9%) had triangular type anterior mesorectal morphology. Compared to triangular type anterior mesorectal morphology, linear type anterior mesorectal morphology was more common in females and was associated with a higher risk of circumferential resection margin involvement measured by MRI (35.6% [32/90] vs . 16.3% [14/86], P   =  0.004) and a higher 5-year LR rate (12.2% vs . 3.5%, P   =  0.030). In addition, the combination of linear type anterior mesorectal morphology and anterior tumors was confirmed as an independent risk factor for LR (odds ratio = 4.283, P  = 0.014).

CONCLUSIONS

The classification established in this study was a simple way to describe morphological characteristics of the anterior mesorectum. The combination of linear type anterior mesorectal morphology and anterior tumors was an independent risk factor for LR and may act as a tool to assist with LR risk stratification and treatment selection.

Incidence, predictors and prognostic implications of positive circumferential resection margin in colon cancer: A retrospective study in a Chinese high-volume cancer center

Positive circumferential resection margin (CRM) was associated with a higher recurrence rate and worse survival in rectal cancer. Predictors of CRM in rectal cancer have widely been investigated. Our study aims to determine the incidence, predictors and prognostic implications of positive CRM following colon cancer (CC) surgery in a Chinese high-volume cancer center. The clinicopathological features and oncological outcomes of CC patients undergoing surgery between January 2008 and December 2018 were identified from Fudan University Shanghai Cancer Center database. Positive CRM was defined as resection margin ≤1 mm. A total of 5268 stage I-IV CC patients were identified in our study, 108 (2.05%) of whom had positive CRM. Multivariate logistic analysis found that advanced N stage, distant metastases and poorly differentiated tumor had increased risk of positive CRM. After propensity score matching, the 5-year overall survival rates of the patients with positive and negative CRM were 33.2% and 39.8% (P=0.005), respectively. Multivariable COX regression model showed that positive CRM was an independent prognostic factor for OS in CC patients. The overall rate of positive CRM in our center is lower than that in western population. Several adverse pathological parameters deserve more attention to identify CC patients at a high risk of positive CRM. Adoption of appropriate surgical techniques and multidisciplinary treatment planning are expected to improve oncological outcomes for high selected CC patients with “high-risk” CRM involvement.

The value of diffusion kurtosis imaging and intravoxel incoherent motion quantitative parameters in predicting synchronous distant metastasis of rectal cancer

BACKGROUND

The incidence and mortality rate of rectal cancer are still high, the metastasis of rectal cancer are main causes of death. The control of the distant metastasis is one of the main concerns in the treatment of locally advanced rectal cancer, but there are few studies on predicting synchronous distant metastasis (SDM) of rectal cancer.

METHOD

The data of patients with rectal adenocarcinoma confirmed by endoscopic biopsy or postoperative pathology from September 2015 to May 2020 in hospital A (center 1) and hospital B (center 2) were analyzed retrospectively, including age, sex, carcinoembryonic antigen, carbohydrate antigen 19-9, tumor location, tumor length, image staging and characteristics. The average age of the 169 patients consisting of 105 males and 64 females in study is 61.2 years. All patients underwent rectal routine rectal MRI, DKI and IVIM examinations on a 3.0-T scanner. Two radiologists sketched regions of interest (ROIs) on b = 1000 s/mm² DKI and IVIM images to obtain quantitative parameters with FireVoxel manually. We evaluated the difference of histogram analysis, clinical and image data between SDM group and non-SDM group, and evaluated the efficacy of each index in predicting SDM of rectal cancer.

RESULTS

The 90th percentile of f values in the SDM group is lower than that in the non-SDM group (29.4 ± 8.4% vs. 35 ± 17.8%, P = 0.005). CA19-9 in the SDM group is higher than that in the non-SDM group (P = 0.003). Low and high rectal cancer are more likely to develop SDM than middle rectal cancer (P = 0.05 and P = 0.047). The combination of these three indexes has a greater area under the curve (AUC) than any one index (0.801 vs. 0.685 (f (90th percentile)) and 0.627 (CA19-9), P = 0.0075 and 0.0058, respectively), and its specificity and sensitivity are 80.0% and 71.6%, respectively. When this combination is incorporated into the predictive nomogram model, the c-index is 0.801 (95% confidence interval (CI): 0.730-0.871).

CONCLUSIONS

IVIM quantitative parameters combine with CA19-9 and tumor location can better predict the risk of SDM of rectal cancer.

Assessment of mesorectal fascia status in MRI compared with circumferential resection margin after total mesorectal excision and predictors of involved margins

BACKGROUND

Circumferential resection margin is an important prognosticator for total mesorectal excision outcome. We investigated the status of mesorectal fascia on magnetic resonance imaging compared with circumferential resection margin on pathology and factors associated with status change.

METHODS

This was a retrospective analysis of a prospective database of rectal cancer patients who underwent surgery. Mesorectal fascia status on magnetic resonance imaging done before neoadjuvant therapy and circumferential resection margin status on pathology were compared. The study outcomes were factors associated with a margin status conversion between magnetic resonance imaging and pathology, and predictors of involved circumferential resection margin.

RESULTS

In total, 244 patients (average follow-up of 25.4 months) were included. Eighty-one (33.2%) patients had potentially involved mesorectal fascia in magnetic resonance imaging and 12 (4.9%) had involved circumferential resection margin in pathology. A total of 2.8% of patients had a conversion of clear mesorectal fascia in magnetic resonance imaging to involved circumferential resection margin. Abdominoperineal resection was significantly associated with this status change (odds ratio: 25, 95% confidence interval: 2.4-255.8, P = .007). In total, 7.4% of patients with potentially involved mesorectal fascia had persistently involved circumferential resection margin. Lack of total neoadjuvant therapy was associated with higher, yet statistically insignificant, odds of persistently involved circumferential resection margin (odds ratio: 12, 95% confidence interval: 0.65-220.8, P = .09). The significant independent predictors of involved circumferential resection margin were body mass index (odds ratio: 1.2, P = .016) and abdominoperineal resection (odds ratio: 4.22, P = .04).

CONCLUSION

Change of clear mesorectal fascia in magnetic resonance imaging to an involved circumferential resection margin in pathology was recorded in 2.8% of patients; abdominoperineal resection might be associated with this change. Approximately 7% of patients had persistent involvement of circumferential resection margin as determined by pathology. Omission of total neoadjuvant therapy might be associated with persistent margin involvement.

Robotic Surgery in Rectal Cancer: Potential, Challenges, and Opportunities

The current standard treatment for locally advanced rectal cancer is based on a multimodal comprehensive treatment combined with preoperative neoadjuvant chemoradiation and complete surgical resection of the entire mesorectal cancer. For ultra-low cases and cases with lateral lymph node metastasis, due to limitations in laparoscopic technology, the difficulties of operation and incidence of intraoperative complications are always difficult to overcome. Robotic surgery for the treatment of rectal cancer is an emerging technique that can overcome some of the technical drawbacks posed by conventional laparoscopic approaches, improving the scope and effect of radical operations. However, evidence from the literature regarding its oncological safety and clinical outcomes is still lacking. This brief review summarized the current status of robotic technology in rectal cancer therapy from the perspective of several mainstream surgical methods, including robotic total mesorectal excision (TME), robotic transanal TME, robotic lateral lymph node dissection, and artificial intelligence, focusing on the developmental direction of robotic approach in the field of minimally invasive surgery for rectal cancer in the future.

Pathological Evaluation of Rectal Cancer Specimens Using Micro-Computed Tomography

Whole-block imaging (WBI) using micro-computed tomography (micro-CT) allows the nondestructive reconstruction of a three-dimensional view of tissues, implying that WBI may be used for accurate pathological evaluation of patients with rectal cancer. HOWEVER, the clinical impact of this approach is unclear. We aimed to clarify the efficacy of WBI in the whole-mount specimens of locally advanced rectal cancer. A total of 237 whole-mount formalin-fixed paraffin-embedded blocks from 13 patients with rectal cancer who underwent surgical treatment were enrolled and scanned with micro-CT to generate three-dimensional images. WBI was evaluated following the conventional pathological review of the corresponding whole-slide imaging (WSI). WBI identified all tumor sites detected using WSI. Furthermore, WBI revealed one additional tumor site, which was not detected using WSI. Tumor resection margin was significantly closer to the soft-tissue edge when measured using WBI (7.7 mm vs. 6.6 mm, p < 0.01). Seventy-six percent of tumor deposits on WSI were changed according to the evidence of tumor interaction with the surrounding tissues confirmed using WBI. Furthermore, WBI revealed 25 additional lymph nodes, six of which were metastatic. The combination of conventional hematoxylin and eosin-stained imaging and WBI may contribute to an accurate pathological assessment.

Bayesian network structure for predicting local tumor recurrence in rectal cancer patients treated with neoadjuvant chemoradiation followed by surgery

Background and Purpose

Tumor recurrence, a characteristic of malignant tumors, is the biggest concern for rectal cancer survivors. The epidemiology of the disease calls for a pressing need to improve healthcare quality and patient outcomes. Prediction models such as Bayesian networks, which can probabilistically reason under uncertainty, could assist caregivers with patient management. However, some concerns are associated with the standard approaches to developing these structures in medicine. Therefore, this study aims to compare Bayesian network structures that stem from these two techniques.

Patients and Methods

A retrospective analysis was performed on 6754 locally advanced rectal cancer (LARC) patients enrolled in 14 international clinical trials. Local tumor recurrence at 2, 3, and 5-years was defined as the endpoints of interest. Five rectal cancer treating physicians from three countries elicited the expert structure. The algorithmic structure was inferred from the data with the hill-climbing algorithm. Structural performance was assessed with calibration plots and area under the curve values.

Results

The area under the curve for the expert structure on the training and validation data was above 0.9 and 0.8, respectively, for all the time points. However, the algorithmic structure had superior predictive performance over the expert structure for all time points of interest.

Conclusion

We have developed and internally validated a Bayesian networks structure from experts' opinions, which can predict the risk of a LARC patient developing a tumor recurrence at 2, 3, and 5 years. Our result shows that the algorithmic-based structures are more performant and less interpretable than expert-based structures.

Pathological Features and Prognostication in Colorectal Cancer

The prognostication of colorectal cancer (CRC) has traditionally relied on staging as defined by the Union for International Cancer Control (UICC) and American Joint Committee on Cancer (AJCC) TNM staging classifications. However, clinically, there appears to be differences in survival patterns independent of stage, suggesting a complex interaction of stage, pathological features, and biomarkers playing a role in guiding prognosis, risk stratification, and guiding neoadjuvant and adjuvant therapies. Histological features such as tumour budding, perineural invasion, apical lymph node involvement, lymph node yield, lymph node ratio, and molecular features such as MSI, KRAS, BRAF, and CDX2 may assist in prognostication and optimising adjuvant treatment. This study provides a comprehensive review of the pathological features and biomarkers that are important in the prognostication and treatment of CRC. We review the importance of pathological features and biomarkers that may be important in colorectal cancer based on the current evidence in the literature.

Rapid tumor-labeling kinetics with a site-specific near-infrared anti-CEA nanobody in a patient-derived orthotopic xenograft mouse model of colon cancer

BACKGROUND/OBJECTIVES

Nanobodies are the smallest biologic antigen-binding fragments derived from camelid-derived antibodies. Nanobodies effect a peak tumor signal within minutes of injection and present a novel opportunity for fluorescence-guided surgery (FGS). The present study demonstrates the efficacy of an anti-CEA nanobody conjugated to near-infrared fluorophore LICOR-IRDye800CW for rapid intraoperative tumor labeling of colon cancer.

METHODS

LS174T human colon cancer cells or fragments of patient-derived colon cancer were implanted subcutaneously or orthotopically in nude mice. Anti-CEA nanobodies were conjugated with IRDye800CW and 1-3 nmol were injected intravenously. Mice were serially imaged over time. Peak fluorescence signal and tumor-to-background ratio (TBR) were recorded.

RESULTS

Colon cancer tumors were detectable using fluorescent anti-CEA nanobody within 5 min of injection at all three doses. Maximal fluorescence intensity was observed within 15 min-3 h for all three doses with TBR values ranging from 1.3 to 2.3. In the patient-derived model of colon cancer, fluorescence was detectable with a TBR of 4.6 at 3 h.

CONCLUSIONS

Fluorescent anti-CEA nanobodies rapidly and specifically labeled colon cancer in cell-line-based and patient-derived orthotopic xenograft (PDOX) models. The kinetics of nanobodies allow for same day administration and imaging. Anti-CEA-nb-800 is a promising and practical molecule for FGS of colon cancer.

Impact of Surgical Approach on Surgical Resection Quality in Mid- and Low Rectal Cancer, A Bayesian Network Meta-Analysis

AIM

To evaluate the evidence concerning the quality of surgical resection in laparoscopic (LapTME), robotic (RobTME) and transanal (TaTME) total mesorectal excision for mid-/low rectal cancer.

METHODS

A systematic literature search of the PubMed, EMBASE and Cochrane Central Register of Controlled Trials databases was performed. A Bayesian network meta-analysis was utilized to compare surgical resection involved in these 3 surgical techniques by using ADDIS software. Rates of positive circumferential resection margins (CRMs) were the primary endpoint.

RESULTS

A total of 34 articles, 2 randomized clinical trials (RCTs) and 32 non-RCTs, were included in this meta-analysis. Pooled data showed CRM positivity in 114 of 1763 LapTME procedures (6.5%), 54 of 1051 RobTME procedures (5.1%) and 60 of 1276 TaTME procedures (4.7%). There was no statistically significant difference among these 3 surgical approaches in terms of CRM involvement rates and all other surgical resection quality outcomes. The incomplete mesorectal excision rates were 9.6% (69/720) in the LapTME group, 1.9% (11/584) in the RobTME group and 5.6% (45/797) in the TaTME group. Pooled network analysis observed a higher but not statistically significant risk of incomplete mesorectum when comparing both LapTME with RobTME (OR = 1.99; 95% CI = 0.48-11.17) and LapTME with TaTME (OR = 1.90; 95% CI = 0.99-5.25). By comparison, RobTME was most likely to be ranked the best or second best in terms of CRM involvement, complete mesorectal excision, rate of distal resection margin (DRM) involvement and length of DRMs. In addition, RobTME achieved a greater mean tumor distance to the CRM than TaTME. It is worth noting that TaTME was most likely to be ranked the worst in terms of CRM involvement for intersphincteric resection of low rectal cancer.

CONCLUSION

Overall, RobTME was most likely to be ranked the best in terms of the quality of surgical resection for the treatment of mid-/low rectal cancer. TaTME should be performed with caution in the treatment of low rectal cancer.

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.

Characteristics of Patients Presented With Metastases During or After Completion of Chemoradiation Therapy for Locally Advanced Rectal Cancer: A Case Series

PURPOSE

Locally advanced rectal cancer (LARC) is managed by chemoradiotherapy (CRT), followed by surgery. Herein we reported patients with metastases during or after CRT.

METHODS

Data of patients with LARC who received CRT from 2008 to 2017 were reviewed. Patients with metastases after CRT were included. Those with metastatic tumors at the initial diagnosis were excluded.

RESULTS

Fourteen patients (1.3%) of 1,092 who received CRT presented with metastases. Magnetic resonance circumferential resection margin (mrCRM) and mesorectal lymph nodes (LNs) were positive in 12 patients (85.7%). Meanwhile, magnetic resonance extramural vascular invasion (mrEMVI) was positive in 10 patients (71.4%). Magnetic resonance tumor regression grade (mrTRG) 4 and mrTRG5 was detected in 5 and 1 patient respectively. Ten patients (71.4%) underwent combined surgery and 3 (21.4%) received palliative chemotherapy.

CONCLUSION

Patients with metastases after CRT showed a higher rate of positive mrCRM, mrEMVI, mesorectal LNs, and poor tumor response. Further studies with a large number of patients are necessary for better survival outcomes in LARC.

The Emerging Role of Robotics in Pelvic Exenteration Surgery for Locally Advanced Rectal Cancer: A Narrative Review

Pelvic exenteration surgery for locally advanced rectal cancers is a complex and extensive multivisceral operation, which is associated with high perioperative morbidity and mortality rates. Significant technical challenges may arise due to inadequate access, visualisation, and characterisation of tissue planes and critical structures in the spatially constrained pelvis. Over the last two decades, robotic-assisted technologies have facilitated substantial advancements in the minimally invasive approach to total mesorectal excision (TME) for rectal cancers. Here, we review the emerging experience and evidence of robotic assistance in beyond TME multivisceral pelvic exenteration for locally advanced rectal cancers where heightened operative challenges and cumbersome ergonomics are likely to be encountered.

Comparison of Survival between Single-Access and Conventional Laparoscopic Surgery in Rectal Cancer

Introduction

Innovative laparoscopic surgery for rectal cancer can be classified into 2 types: firstly, new instruments such as robotic surgery and secondly, new technique such as single-access laparoscopic surgery (SALS) and transanal total mesorectal excision (TaTME). Most reports of SALS for rectal cancer have shown pathologic outcomes comparable to those of conventional laparoscopic surgery (CLS); however, SALS is considered to be superior to CLS in terms of lower levels of discomfort and faster recovery rates. This study aimed to compare the survival outcomes of the two approaches.

Methods

From 2011 to 2014, 84 cases of adenocarcinoma of the rectum and anal canal were enrolled. The operations were anterior, low anterior, intersphincteric, and abdominoperineal resections. Data collected included postoperative outcomes. The oncological outcomes recorded included 3-year and 5-year survival, local recurrence, and metastasis.

Results

SALS was performed on 41 patients, and CLS was utilized in 43 cases. The demographic data of the two groups were similar. Intraoperative volumes of blood loss and conversion rates were similar, but operative time was longer in the SALS group. There were no significant differences in postoperative complications or pathological outcomes. The oncologic results were similar in terms of 3-year survival (100% and 97.7%; p = 1.00), 5-year survival (78.0% and 86.0%; p = 0.401), local recurrence rates (19.5% vs 11.6%, p = 0.376), and metastasis rates (19.5% vs 11.6%; p = 0.376) for SALS and CLS, respectively.

Conclusion

SALS and CLS for rectal and anal cancer had comparable pathological and survival results, but SALS showed some superior benefits in the early postoperative period.

Neoadjuvant Chemoradiotherapy Does Not Contribute to Worse Survival in Pathological Node-Negative Rectal Cancer

Purpose: The prognostic significance of ypN0 rectal cancer with comparison to pN0 disease still remains poorly defined. This study aimed to compare the prognosis of ypN0 and pN0 rectal cancer.

Methods: Eligible patients were identified from the SEER18 registries research database (the latest data up to date was on April 15, 2019). Propensity score (PS) matching was usually performed to reduce the imbalance and potential confounding that were introduced by inherent differences between the groups. The cause-specific survival (CSS) was analyzed to evaluate the prognostic prediction of ypN0 and pN0 groups using the Kaplan–Meier method with the log-rank test. Cox proportional hazard model was also used to identify independent prognostic variables.

Results: In total, 26,832 patients diagnosed with pN0 or ypN0 rectal cancer were confirmed as the final cohort, including 7,237 (27.0%) patients with radiation and 19,595 (73.0%) patients without radiation prior to surgery. The median follow-up time was up to 81 months. After adjusting for other prognostic factors, neoadjuvant radiotherapy was not an independent prognostic variable of CSS (HR = 1.100, 95%CI = 0.957–1.265, P = 0.180, using pN0 group as the reference).

Conclusions: ypN0 rectal cancer was strongly associated with worse pathological diagnoses compared with pN0 rectal cancer, contributing to worse oncologic outcomes. However, the receipt of neoadjuvant chemoradiotherapy was not an independent prognostic factor of worse prognosis in pathological node-negative patients. Our study could give guidance to the treatment of ypN0 rectal cancer.

The Effect of Formalin Fixation on Resection Margins in Colorectal Cancer

Resection margins in colorectal cancer carry clinical significance with regard to disease recurrence risk and selection for multimodal adjuvant therapy, especially with circumferential resection margins in rectal cancer. Colorectal cancer specimens are routinely fixed in formalin, which results in specimen and tumor-free margin shrinkage. However, the effects of shrinkage have not traditionally been taken into account when analyzing tumor-free margins. In this prospective study, 46 colorectal cancer specimens were measured in the fresh state and subsequently after formalin fixation for total specimen length, distal resection margin, and radial margin (circumferential resection margin for rectal cancer). The mean reduction after formalin fixation was 17.48 mm (14.7%) for distal resection margin and 1.20 mm (10.5%) for radial margin. For rectal cancer, circumferential resection margin reduction was 0.88 mm (11.8%); this was not affected by neoadjuvant chemoradiotherapy. Duration of formalin fixation did not significantly affect the extent of margin shrinkage. This is the first study to evaluate the effect of formalin fixation on radial resection margins, specifically as it relates to rectal cancer, and it demonstrates that shrinkage from formalin fixation should be a consideration in decision-making where the magnitude of tumor-free margins is small.

Circumferential resection margin as a prognostic factor after rectal cancer surgery: A large population-based retrospective study

AIM

This study aimed to investigate circumferential resection margin (CRM) as a prognostic factor for long-term oncologic survival after rectal cancer surgery.

METHODS

Patients diagnosed with malignant rectal cancer between 1 January 2010 and 31 December 2014, from the Surveillance, Epidemiology, and End Results (SEER) program were identified for this study. The patients were divided into five CRM groups to compare the baseline characteristics and assess cancer-specific survival (CSS): 0-1 mm, 1.1-2.0 mm, 2.1-5.0 mm, 5.1-10.0 mm, and >10 mm. The main endpoint was CSS.

RESULTS

Circumferential resection margin ≤1 mm was independently associated with 99% increased risk of cancer-specific mortality in rectal cancer [hazard ratio (HR) = 1.990, 95% confidence interval (CI) = 1.613-2.454, P < 0.001, using CRM (1.1-2.0 mm) as a reference]. CRM (5.1-10.0 mm) was independently associated with 29.2% decreased risk of cancer-specific mortality [HR = 0.708, 95% CI = 0.525-0.954, P = 0.152, using group (2.1-5.0 mm) as reference]. CRM ≤2 mm or ≤0.4 mm was not obviously associated with CSS.

CONCLUSIONS

circumferential resection margin is an independent prognostic factor in rectal cancer. Surgeons should try to maximize the CRM. Rectal cancer patients with CRM ≤1 mm should receive more postoperative attention depending on individual situation. Also, CRM should be accurately measured in millimeters in a preoperative magnetic resonance imaging or pathological report, rather than simply described as "involved" or "clear."