Prognostic importance of circumferential resection margin in the era of evolving surgical and multidisciplinary treatment of rectal cancer: A systematic review and meta-analysis

Safety and efficacy of flexible articulated instrument (ArtiSential®) in laparoscopic surgery for rectal cancer

BACKGROUND

Laparoscopic surgery for rectal cancer remains challenging because of limited joint motion during dissection in the deep and narrow pelvis. Handheld multiarticulated instruments have been developed to address these limitations. This study aimed to assess the safety and efficacy of a flexible articulated instrument, the ArtiSential® (Livsmed Co, Korea), at reducing the duration of laparoscopic rectal cancer surgery.

STUDY DESIGN

We retrospectively reviewed patients who underwent laparoscopic low or ultralow anterior resection for primary mid to low rectal cancer (tumor distance from anal verge, ≤ 10 cm) performed by a single surgeon in 2012-2022. Patients were divided into groups based on the use of ArtiSential® or straight device, and their clinical characteristics, surgical procedures, pathological findings, postoperative complications, and survival outcomes were analyzed.

RESULTS

The study included 93 patients (articulating group, 32; straight group, 61). Low anterior resection was predominant in both groups, while operative time was significantly shorter in the articulating group (148.08 ± 49.72 vs. 188.13 ± 57.86; p = 0.003). Total mesorectal excision quality and resection margin status did not differ between groups. Postoperative complications, including anastomotic leakage, length of hospital stay, 3-year recurrence-free survival rate (90.6% vs. 88.5%, p = 0.760), and overall survival rate (100% vs. 85.2%, p = 0.092), did not differ between groups.

CONCLUSION

Use of the flexible articulated instrument (ArtiSential®) can reduce operative time without impairing surgical quality or oncologic outcomes. These results suggest that laparoscopic rectal cancer surgery can be performed safely and effectively using a flexible articulated instrument.

CLINICAL TRIAL NUMBER

Not applicable.

How robotic platforms are revolutionizing colorectal surgery techniques: a comparative review

INTRODUCTION

In the last two decades, robotic technology has fundamentally transformed the field of colorectal surgery by providing surgeons with unprecedented levels of precision and control. Nevertheless, robotic surgery presents certain challenges such as prolonged operating times, high costs, limited accessibility, and the necessity for specialized training.

AREAS COVERED

This comparative review analyzes the impact of robotic platforms on colorectal surgery and its outcomes, with the expanding market of this technology. The major databases including PubMed, Scopus, and Google Scholars were searched using the key term 'robotic assisted surgery,' 'robotic platforms,' and 'colorectal surgery' to identify relevant articles as of August 2024. The most utilized robotic platforms currently available on the market - Da Vinci, Versius, Senhance, and Revo-I - are compared through their peri- and post-operative outcomes, including operative duration, blood loss, hospitalization period, oncological outcomes, and cost, providing a comprehensive insight into the future of robotic-assisted colorectal surgery.

EXPERT OPINION

Robotic surgery significantly improves patient outcomes, including shorter postoperative recovery times and effective cancer resection margins. However, challenges faced with these platforms include longer intraoperative times, arm clashing, the need for bedside assistance, and cost. Nevertheless, with the evolution toward managing more complex rectal cancer cases and more challenging dissection planes, the need for robotic platforms will only grow.

MRI of the Rectum: A Decade into DISTANCE, Moving to DISTANCED

Over the past decade, advancements in rectal cancer research have reshaped treatment paradigms. Historically, treatment for locally advanced rectal cancer has focused on neoadjuvant long-course chemoradiotherapy, followed by total mesorectal excision. Interest in organ preservation strategies has been strengthened by the introduction of total neoadjuvant therapy with improved rates of complete clinical response. The administration of systemic induction chemotherapy and consolidation chemoradiotherapy in the neoadjuvant setting has introduced a new dimension to the treatment landscape and patients now face a more intricate decision-making process, given the expanded therapeutic options. This complexity underlines the importance of shared decision-making and brings to light the crucial role of radiologists. MRI, especially high-spatial-resolution T2-weighted imaging, is heralded as the reference standard for rectal cancer management because of its exceptional ability to provide staging and prognostic insights. A key evolution in MRI interpretation for rectal cancer is the transition from the DISTANCE mnemonic to the more encompassing DISTANCED-DIS, distal tumor boundary; T, T stage; A, anal sphincter complex; N, nodal status; C, circumferential resection margin; E, extramural venous invasion; D, tumor deposits. This nuanced shift in the mnemonic captures a wider range of diagnostic indicators. It also emphasizes the escalating role of radiologists in steering well-informed decisions in the realm of rectal cancer care.

Incomplete Resection Is Twice as Likely in Locally Advanced Mucinous Compared to Nonmucinous Rectal Adenocarcinoma: A National Propensity-Matched Analysis

BACKGROUND AND OBJECTIVES

Rectal mucinous adenocarcinoma (MA) has poor response to neoadjuvant chemoradiation (NCR) and higher involved radial surgical margin rates than nonmucinous rectal adenocarcinoma (NMA).

METHODS

The National Cancer Database (2010-2018) was queried for adult patients with clinical stage II and III rectal cancer. Patients with MA and NMA treated with NCR and total mesorectal excision (TME) were identified. We sought to evaluate differences in pathologic downstaging and completeness of resection between MA and NMA rectal adenocarcinoma.

RESULTS

We identified 13 294 patients, 12 655 (95.2%) NMA and 639 (4.8%) MA. After 3:1 propensity score matching for pathologic outcomes, 1707 NMA and 569 MA patients were included. MA patients had more involved distal (2.1% vs. 1.1%, p = 0.047) and radial (29% vs. 15%, p < 0.001) margins, and less pathologic downstaging (49% vs. 55%, p = 0.015). Among MA patients, minimally invasive resection had higher distal (2.1% vs. 1.4%, p = 0.65) and radial margin involvement (35% vs. 26%, p = 0.09) compared to open resection. Incomplete resection rates were similar between low anterior and abdominoperineal resection.

CONCLUSIONS

TME of locally advanced rectal MA treated with NCR resulted in nearly double the involved radial surgical margins compared to NMA. Operative approach should be carefully considered. Extended or extra-mesorectal resection may reduce the risk of incomplete resection.

The mode of circumferential margin involvement in rectal cancer determines its impact on outcomes: A population-based study

BACKGROUND

The clinical value of different modes of CRM involvement in rectal cancer patients is unclear. This study aims to determine the clinical impact of different modes of circumferential resection margin (CRM) involvement in patients with a locally advanced rectal carcinoma.

PATIENTS AND METHODS

A cohort of patients who were diagnosed with stage III rectal cancer between June 2014 and June 2020 was selected from the prospective Dutch nationwide pathology databank (PALGA). Histopathological and clinical data were analyzed according to the nature of CRM involvement (via primary tumor invasion, lymph node metastasis, tumor deposit, multiple factors) and analyses on recurrence and overall survival (OS) were performed.

RESULTS

3020 patients were included, of whom 12.4 % had a positive CRM. The majority of these patients (63.2 %) had CRM involvement by primary tumor invasion and in 9 % of patients multiple factors caused the positive CRM. The rates of local recurrence and distant metastasis were related to the nature of the CRM involvement, with lowest rate for lymph node metastasis and highest rate for multiple factors. On multivariate analysis, CRM involvement by primary tumor invasion, tumor deposits and multiple factors, but not by lymph node metastasis, were associated with poor OS.

CONCLUSION

This nationwide population based study highlights the clinical importance of reporting the nature of CRM involvement in rectal cancer patients. Lymph node metastasis involving the CRM does not bear the same risks for local recurrence, distant metastases and OS as CRM involvement by primary tumor invasion or CRM involvement by multiple factors.

Robotic surgery is associated with a decreased risk of circumferential resection margin positivity compared with conventional laparoscopic surgery in patients with rectal cancer undergoing mesorectal excision: A systematic review and meta-analysis

OBJECTIVE

To investigate whether robotic surgery (RS) decreases the risk of circumferential resection margin (CRM) positivity compared with conventional laparoscopic surgery (LS) in patients with rectal cancer (RC) undergoing mesorectal excision (ME).

BACKGROUND

Although it is well known that CRM positivity affects postoperative outcomes in patients with RC undergoing ME, few studies have investigated whether RS is superior to conventional LS for the risk of CRM positivity.

METHODS

We performed a comprehensive electronic search of the literature up to December 2022 to identify studies that compared the risk of CRM positivity between patients with RC undergoing robotic and conventional laparoscopic surgery. A meta-analysis was performed using random-effects models to calculate risk ratios (RRs) and 95 % confidence intervals (CIs), and heterogeneity was analyzed using I2 statistics.

RESULTS

Eighteen studies, consisting of 4 randomized controlled trials (RCTs) and 14 propensity score matching (PSM) studies, involved a total of 9203 patients with RC who underwent ME were included in this meta-analysis. The results demonstrated that RS decreased the overall risk of CRM positivity (RR, 0.82; 95 % CI, 0.73-0.92; P = 0.001; I2 = 0 %) compared with conventional LS. Results of a meta-analysis of the 4 selected RCTs also showed that RS decreased the risk of CRM positivity (RR, 0.62; 95 % CI, 0.43-0.91; P = 0.01; I2 = 0 %) compared with conventional LS.

CONCLUSIONS

This meta-analysis revealed that RS is associated with a decreased risk of CRM positivity compared with conventional LS in patients with RC undergoing ME.

Risk Factors for Recurrence After Surgery for Rectal Cancer in a Modern, Nationwide Population-Based Cohort

BACKGROUND

The success of modern multimodal treatment in rectal cancer is dependent on risk prediction. Better knowledge of the risk of locoregional and distant recurrence, in relation to preoperative treatment, pathological stage, and commonly used risk factors, is needed when deciding on adjuvant therapy and surveillance.

METHODS

The Swedish ColoRectal Cancer Registry was used to identify patients diagnosed with rectal adenocarcinoma between 2011 and 2018. Readily available variables, including patient, tumor, and treatment factors were exposures. Cox proportional hazard models were used to identify important risk factors for recurrence and calculate recurrence risks.

RESULTS

A total of 9428 curatively resected patients were included and followed for a median of 72 months. Eighteen percent had distal recurrence and 3% had locoregional recurrence at 5 years. Risk factors with major impact on distal recurrence were pT4a (hazard ratio [HR] 5.1, 95% confidence interval [CI] 3.3-8.0), pN2b (HR 3.4, 95% CI 2.7-4.2), tumor deposit (HR 1.7, 95% CI 1.5-1.9), lymph node yield (HR 1.5, 95% CI 1.3-1.8), and tumor level 0-5 cm (HR 1.5, 95% CI 1.3-1.8). Pathologic stage and number of risk factors identified groups with markedly different recurrence risks in all neoadjuvant treatment groups.

CONCLUSIONS

Readily available risk factors, as a complement to stage, are still valid and robust in all neoadjuvant treatment groups. Tumor deposit is important, while circumferential resection margin might no longer be important with improved oncological treatments and high-quality TME surgery. Tailored surveillance is possible in selected groups using risk stratification based on stage and risk factors.

Visualization of cecal tumor by near-infrared laparoscopy and intraoperative colonoscopy

BACKGROUND

In laparoscopic colorectal surgery, accurate localization of a tumor is essential for ensuring an adequate ablative margin. Therefore, a new method, near-infrared laparoscopy combined with intraoperative colonoscopy, was developed for visualizing the contour of a cecal tumor from outside of the bowel. The method was used after it was verified on a model that employed a silicone tube.

CASE PRESENTATION

The patient was a 77-year-old man with a cecal tumor near the appendiceal orifice. Laparoscopy was used to clamp of the terminal ileum, and a colonoscope was then inserted through the anus to the cecum. The laparoscope in the normal light mode could not be used to identify the cecal tumor. However, a laparoscope in the near-infrared ray mode could clearly visualize the contour of the cecal tumor from outside of the bowel, and the tumor could be safely resected by a stapler. The histopathological diagnosis of the resected specimen was adenocarcinoma with an invasion depth of M and a clear negative margin.

CONCLUSIONS

This is the first report of the laparoscopic detection of the contour of a cecal tumor from outside the bowel. This technique is useful and safe for contouring tumors in laparoscopic colorectal surgery and can be used in various surgeries that combine endoscopy and laparoscopy.

Disparities in Outcomes following Resection of Locally Advanced Rectal Cancer

Surgical margins following rectal cancer resection impact oncologic outcomes. We examined the relationship between margin status and race, ethnicity, region of care, and facility type. Patients undergoing resection of a stage II-III locally advanced rectal cancer (LARC) between 2004 and 2018 were identified through the National Cancer Database. Inverse probability of treatment weighting (IPTW) was performed, with margin positivity rate as the outcome of interest, and race/ethnicity and region of care as the predictors of interest. In total, 58,389 patients were included. After IPTW adjustment, non-Hispanic Black (NHB) patients were 12% (p = 0.029) more likely to have margin positivity than non-Hispanic White (NHW) patients. Patients in the northeast were 9% less likely to have margin positivity compared to those in the south. In the west, NHB patients were more likely to have positive margins than NHW patients. Care in academic/research centers was associated with lower likelihood of positive margins compared to community centers. Within academic/research centers, NHB patients were more likely to have positive margins than non-Hispanic Other patients. Our results suggest that disparity in surgical management of LARC in NHB patients exists across regions of the country and facility types. Further research aimed at identifying drivers of this disparity is warranted.

Comparison of conventional MRI analysis versus MRI-based radiomics to predict the circumferential margin resection involvement of rectal cancer

BACKGROUND

To compare the application of conventional MRI analysis and MRI-based radiomics to identify the circumferential resection margin (CRM) status of rectal cancer (RC).

METHODS

A cohort of 301 RC patients with 66 CRM invloved status and 235 CRM non-involved status were enrolled in this retrospective study between September 2017 and August 2022. Conventional MRI characteristics included gender, age, diameter, distance to anus, MRI-based T/N phase, CEA, and CA 19 - 9, then the relevant logistic model (Logistic-cMRI) was built. MRI-based radiomics of rectal cancer and mesorectal fascia were calculated after volume of interest segmentation, and the logistic model of rectal cancer radiomics (Logistic-rcRadio) and mesorectal fascia radiomics (Logistic-mfRadio) were constructed. And the combined nomogram (nomo-cMRI/rcRadio/mfRadio) containing conventional MRI characteristics, radiomics of rectal cancer and mesorectal fascia was developed. The receiver operator characteristic curve (ROC) was delineated and the area under curve (AUC) was calculated the efficiency of models.

RESULTS

The AUC of Logistic-cMRI was 0.864 (95%CI, 0.820 to 0.901). The AUC of Logistic-rcRadio was 0.883 (95%CI, 0.832 to 0.928) in the training set and 0.725 (95%CI, 0.616 to 0.826) in the testing set. The AUCs of Logistic-mfRadio was 0.891 (95%CI, 0.838 to 0.936) in the training set and 0.820 (95%CI, 0.725 to 0.905) in the testing set. The AUCs of nomo-cMRI/rcRadio/mfRadio were the highest in both the training set of 0.942 (95%CI, 0.901 to 0.969) and the testing set of 0.909 (95%CI, 0.830 to 0.959).

CONCLUSION

MRI-based radiomics of rectal cancer and mesorectal fascia showed similar efficacy in predicting the CRM status of RC. The combined nomogram performed better in assessment.

Circumferential resection margin positivity due to direct or indirect tumour involvement in rectal cancer - a call for better stratification

BACKGROUND

A positive circumferential resection margin (CRM) after rectal cancer surgery, which can be the result of direct or indirect tumour involvement, has consistently been associated with increased local recurrence and poorer survival. However, little is known of the differential impact of the mode of tumour involvement on outcomes.

METHODS

1460 consecutive patients undergoing rectal cancer resection between 2003 and 2018 were retrospectively assessed. Histopathology reports for patients with a positive CRM were reviewed to determine cases of direct (R1-tumour) or indirect tumour involvement (R1-other). Disease-free survival (DFS) and overall survival (OS) were assessed by Kaplan-Meier analysis. The role of the mode of CRM positivity was examined by univariate and multivariate Cox proportional hazards models.

RESULTS

Eighty-five patients had an R1 resection due to CRM involvement (5.8%). Of those, 69 were due to direct tumour involvement, while 16 were from indirect causes. Kaplan-Meier analysis revealed that R1-other was associated with increased OS (hazard ratio 0.40, log-rank P = 0.006) and DFS (P = 0.043). Multivariate regression confirmed that the mode of CRM positivity was an independent predictor of OS. More interestingly, the patterns of recurrence were different between the two groups, with R1-tumour leading to significantly more local recurrence (P = 0.04).

CONCLUSIONS

Our data strongly suggests that direct tumour involvement of the CRM confers worse prognosis after rectal cancer surgery. Importantly, differences in the site and frequency of recurrences make a case for better stratification of patients with a positive CRM to guide treatment decisions.

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.

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.

Recurrence Patterns and Risk Factors after Curative Resection for Colorectal Cancer: Insights for Postoperative Surveillance Strategies

This study aimed to assess recurrence patterns and related risk factors following curative resection of colorectal cancer (CRC). This retrospective observational study was conducted at a tertiary care center, including 2622 patients with stage I-III CRC who underwent curative resection between 2008 and 2018. Hazard rates of recurrence were calculated using a hazard function. The primary outcome was the peak recurrence time after curative resection and secondary outcomes were prognostic factors associated with recurrence. Over a median follow-up period of 53 months, the overall, locoregional and systemic recurrence rates were 8.9%, 0.7%, and 8.5%, respectively. Recurrence rates were significantly higher for rectal cancer (14.9% overall, 4.4% locoregionally, and 12.3% systemically) than for colon cancer (all p < 0.001). The peak recurrence time was 11 months, with variations in hazard rates and curves depending on the tumor location, stage, and risk factors. Patients with AL or CRM involvement exhibited a distinct pattern, with a high hazard rate in the early postoperative period. Understanding these recurrence patterns and risk factors is crucial for establishing effective postoperative surveillance strategies. Our findings suggested that short-interval surveillance should be considered during the first 2 years post-surgery, particularly for high-risk patients who should receive early attention.

Impact of trans-anal versus laparoscopic total mesorectal excision on the surgical and pathologic outcomes of patients with rectal cancer: meta-analysis of randomized controlled trials

BACKGROUND

Despite its profound impact on the oncologic outcomes of rectal cancer, the most optimal surgical approach to total mesorectal excision (TME) has not been identified yet. All previous meta-analyses on this subject have been based on observational studies. This meta-analysis was conducted to assess the surgical and oncologic outcomes of laparoscopic TME (LaTME) compared to trans-anal TME (TaTME), utilizing only randomized controlled trials.

DESIGN

Systematic review and meta-analysis of randomized controlled trials.

METHODS

We searched electronic databases (MEDLINE, Cochrane CENTRAL, Clinicaltials.gov) from 2010 onwards, for all published clinical trials comparing TaTME to LaTME. Results are presented as risk ratios, with 95% CI, and pooled using the random effects model.

RESULTS

A total of 1691 patients, from 6 eligible randomized controlled trials, were included for analysis. Analyzed data showed no significant difference in morbidity (RR: 0.85, p = 0.15), mortality (RR: 0.50, p = 0.44), conversion to open (RR: 0.40, p = 0.07), or anastomotic leakage (RR: 0.73, p = 0.10) between TaTME and LaTME. There was also no difference in the rate of positive distal resection margin (DRM) (RR: 0.55, p = 0.10) or positive circumferential resection margin (CRM) (RR: 0.67, p = 0.30). Patients undergoing TaTME were more likely to have a complete TME (RR: 1.06, p = 0.002) and shorter hospital stays (RR: - 0.97, p < 0.00001).

CONCLUSIONS

Patients undergoing TaTME for rectal cancer were more likely to have a complete TME when compared to LaTME, though this did not translate into improved distal or circumferential resection margin. Additionally, TaTME and LaTME had similar surgical outcomes except for shorter length of stay with TaTME.

Size and depth of residual tumor after neoadjuvant chemoradiotherapy in rectal cancer - implications for the development of new imaging modalities for response assessment

With the shift towards organ preserving treatment strategies in rectal cancer it has become increasingly important to accurately discriminate between a complete and good clinical response after neoadjuvant chemoradiotherapy (CRT). Standard of care imaging techniques such as CT and MRI are well equipped for initial staging of rectal tumors, but discrimination between a good clinical and complete response remains difficult due to their limited ability to detect small residual vital tumor fragments. To identify new promising imaging techniques that could fill this gap, it is crucial to know the size and invasion depth of residual vital tumor tissue since this determines the requirements with regard to the resolution and imaging depth of potential new optical imaging techniques. We analyzed 198 pathology slides from 30 rectal cancer patients with a Mandard tumor regression grade 2 or 3 after CRT that underwent surgery. For each patient we determined response pattern, size of the largest vital tumor fragment or bulk and the shortest distance from the vital tumor to the luminal surface. The response pattern was shrinkage in 14 patients and fragmentation in 16 patients. For both groups combined, the largest vital tumor fragment per patient was smaller than 1mm for 38% of patients, below 0.2mm for 12% of patients and for one patient as small as 0.06mm. For 29% of patients the vital tumor remnant was present within the first 0.01mm from the luminal surface and for 87% within 0.5mm. Our results explain why it is difficult to differentiate between a good clinical and complete response in rectal cancer patients using endoscopy and MRI, since in many patients submillimeter tumor fragments remain below the luminal surface. To detect residual vital tumor tissue in all patients included in this study a technique with a spatial resolution of 0.06mm and an imaging depth of 8.9mm would have been required. Optical imaging techniques offer the possibility of detecting majority of these cases due to the potential of both high-resolution imaging and enhanced contrast between tissue types. These techniques could thus serve as a complimentary tool to conventional methods for rectal cancer response assessment.

Diffuse reflection spectroscopy at the fingertip: design and performance of a compact side-firing probe for tissue discrimination during colorectal cancer surgery

Optical technologies are widely used for tissue sensing purposes. However, maneuvering conventional probe designs with flat-tipped fibers in narrow spaces can be challenging, for instance during pelvic colorectal cancer surgery. In this study, a compact side-firing fiber probe was developed for tissue discrimination during colorectal cancer surgery using diffuse reflectance spectroscopy. The optical behavior was compared to flat-tipped fibers using both Monte Carlo simulations and experimental phantom measurements. The tissue classification performance was examined using freshly excised colorectal cancer specimens. Using the developed probe and classification algorithm, an accuracy of 0.92 was achieved for discriminating tumor tissue from healthy tissue.

Comparison of three-year oncological results after restorative low anterior resection, non-restorative low anterior resection and abdominoperineal resection for rectal cancer

INTRODUCTION

Oncological outcome might be influenced by the type of resection in total mesorectal excision (TME) for rectal cancer. The aim was to see if non-restorative LAR would have worse oncological outcome. A comparison was made between non-restorative low anterior resection (NRLAR), restorative low anterior resection (RLAR) and abdominoperineal resection (APR).

MATERIALS AND METHODS

This retrospective cohort included data from patients undergoing TME for rectal cancer between 2015 and 2017 in eleven Dutch hospitals. A comparison was made for each different type of procedure (APR, NRLAR or RLAR). Primary outcome was 3-year overall survival (OS). Secondary outcomes included 3-year disease-free survival (DFS) and 3-year local recurrence (LR) rate.

RESULTS

Of 998 patients 363 underwent APR, 132 NRLAR and 503 RLAR. Three-year OS was worse after NRLAR (78.2%) compared to APR (86.3%) and RLAR (92.2%, p < 0.001). This was confirmed in a multivariable Cox regression analysis (HR 1.85 (1.07, 3.19), p = 0.03). The 3-year DFS was also worse after NRLAR (60.3%), compared to APR (70.5%) and RLAR (80.1%, p < 0.001), HR 2.05 (1.42, 2.97), p < 0.001. The LR rate was 14.6% after NRLAR, 5.2% after APR and 4.8% after RLAR (p = 0.005), HR 3.22 (1.61, 6.47), p < 0.001.

CONCLUSION

NRLAR might be associated with worse 3-year OS, DFS and LR rate compared to RLAR and APR.

Transanal Total Mesorectal Excision (TaTME) versus Laparoscopic Total Mesorectal Excision for Lower Rectal Cancer: A Propensity Score-Matched Analysis

Studies have reported positive short-term and histopathological results of transanal total mesorectal excision (TaTME) for mid-low rectal cancer. The long-term oncological outcomes are diverse, and concerns regarding the high local recurrence (LR) rate of TaTME have recently increased. We retrospectively analyzed 298 consecutive patients who underwent Laparoscopic TME (LapTME) or TaTME between January 2015 and December 2019. Propensity score-matching (PSM) was performed with patients matched for demographics and stage. After PSM, 63 patients were included in each group. The TaTME group had a longer mean operative time (394 vs. 333 min, p < 0.001). The blood loss, diverting stoma rate, and conversion rate were similar. Postoperatively, TaTME and LapTME had compatible complications, recovery, and hospital stay. A similar specimen quality was detected in both groups. After a mean follow-up period of 41−47 months, TaTME had less LR than LapTME (9.5% vs. 23.8%, p = 0.031). The 3-year overall survival was 80.3% in the TaTME group and 73.6% in the LapTME group (p = 0.331). The 3-year disease-free survival (DFS) rate was 72.0% in the TaTME group and 56.6% in the LapTME group (p = 0.038). In conclusion, better DFS and fewer LR events were observed after TaTME; thus, TaTME can be considered a safe and feasible approach in patients with low rectal cancer.

The impact of subdivisions of microscopically positive (R1) margins on patterns of relapse in stage III colorectal cancer - A retrospective cohort study

AIM

Microscopically positive (R1) margins are associated with poorer outcomes in patients with colorectal cancer. However, the impact of subdivisions of R1 margins, be they to the primary tumour (R1 tumour) or to lymph node metastases (R1LNM), on patterns of relapse is unknown.

METHODS

Patients treated for stage III colorectal cancer from 01 January 2016 to 31 December 2019 in four specialist centres were identified from the Danish national cancer registry. Patients were stratified into three groups according to margin status (R0 vs. R1 tumour vs. R1LNM). The primary outcomes were local recurrence-free survival (LRFS), distant metastases-free survival (DMFS) and disease-specific survival (DSS).

RESULTS

A total of 1,164 patients were included, with R1 margins found in 237 (20.4%). Irrespective of tumour location, R1 tumour and R1LNM margins were independent prognostic factors for systemic relapse (R1 tumour HR 1.84, CI: 1.17-2.88, p = 0.008; R1LNM HR 1.59, CI: 1.12-2.27, p = 0.009) and disease-related death (R1 tumour HR 2.08, CI: 1.12-3.85, p = 0.020; R1LNM HR 1.84, CI: 1.12-3.02, p = 0.016). Whereas R1 tumour margins were associated with poorer 3-year LRFS in both colon and rectum cancer, R1LNM margins only reduced LRFS in patients with rectal cancer. Patterns of relapse differed between R1 subdivisions, with R1 tumour margins more likely to affect multiple anatomical sites, with a predilection for extra-hepatic/pulmonary metastases.

CONCLUSION

Subdivisions of R1 margins have a distinct impact on the oncological outcomes and patterns of disease relapse in patients with stage III colorectal cancer.

Omission of neoadjuvant radiotherapy for clinical T2/N1 and T3N0/1 middle and low rectal cancers with safe circumferential resection margins

Purpose

For moderately advanced rectal cancers with safe circumferential margins, the oncologic benefit of neoadjuvant radiotherapy must be reconsidered because of the possibility of overtreatment, resulting in complications from radiotoxicity. To evaluate the oncologic safety of the omission of neoadjuvant radiotherapy for moderately advanced rectal cancers, we evaluated and compared the prognoses of patients who underwent radical resection with and without neoadjuvant radiotherapy for T2/N1 and T3N0/1 middle and low rectal cancers with safe circumferential resection margins.

Methods

We retrospectively enrolled 66 patients who underwent radical resection for clinical (c) T2N1 and T3N0/1 middle and low rectal cancers between 2008 and 2014. Patients with distant metastasis; cT4, cN2, or positive lateral pelvic lymph nodes; positive circumferential resection margin; signet-ring cell carcinoma; cT1/2N0; or those who had received adjuvant radiotherapy were excluded. The clinical and pathological characteristics and 5-year oncologic outcomes of the no-radiotherapy (n = 34) and radiotherapy (n = 32) groups were compared.

Results

The rates of abdominoperineal resection and ileostomies and the proportion of patients who received adjuvant chemotherapy were significantly higher in the radiotherapy group. There were no significant differences in tumor location, clinical stage, surgery type, pathologic N stage, anastomotic leakage, or long-term oncologic outcomes including 5-year disease-free survival, overall survival, and local recurrence and distant metastasis rates between both groups.

Conclusion

The oncologic benefit of neoadjuvant radiotherapy for cT2/N1 and T3N0/1 middle and low rectal cancers with safe circumferential resection margins is considered unclear, and it can be omitted to prevent radiotoxicity and facilitate prompt essential treatment.

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.

Quantifying displacement of urogenital organs after abdominoperineal resection for rectal cancer

AIM

This study aimed to quantify displacement of urogenital organs after abdominoperineal resection (APR), and to explore patient and treatment characteristics associated with displacement.

METHOD

Patients from 16 centres who underwent APR for primary or recurrent rectal cancer (2001-2018) with evaluable preoperative and 6-18 months postoperative radiological imaging were included in the study. Anatomical landmarks on sagittal images were related to a coordinate system based on reference lines between fixed bony structures and absolute displacements were calculated using the Pythagorean theorem. Rotation of landmarks was measured relative to a pubic-S5 reference line.

RESULTS

There were 248 patients included of which 171 were men and 77 women. The median displacement of the internal urethral orifice was 25 mm in men (maximum 65), and 17 mm in women (maximum 50). Rotation of the internal urethral orifice was in a caudal direction in 160/170 (94%) of men and 65/73 (89%) of women, with a median of 32 degrees (maximum 85) and 33 degrees (maximum 83), respectively. Displacements of the posterior bladder wall, distal end of prostatic urethra and cervix were significantly correlated with the internal urethral orifice. In linear regression analysis, biological mesh reconstruction of the pelvic floor and visceral interposition were significantly associated with increased displacement of the internal urethral orifice, and female gender and any filling of the presacral space with decreased displacement.

CONCLUSIONS

Substantial absolute displacement and rotation of urogenital organs after APR for rectal cancer were observed, but with high variability among both men and women, and being significantly associated with reconstructive interventions.