The rectosigmoid problem

Rectosigmoid Junction Cancer; The Role of Preoperative and Postoperative Radiation With Novel Nomogram in Predicting Survival in the United States

BACKGROUND

There is controversy and limited data the management of rectosigmoid junction cancer (RSJC), especially the role of radiation. We aim to investigate the role of preoperative and postoperative radiation in RSJC and whether this cancer should be treated as a colon cancer or as a rectal cancer.

METHODS

The data were extracted from the Surveillance, Epidemiology, and End Results (SEER) database and identified from 2000 to 2018.

RESULTS

Of the 50,779 patients, 87% were ≥50 years old, 56.2% were male, 80.8% were White. Regarding tumor characteristics, 76% were Grade II, while 22.7% had distant-stage. 16.4% of patients were treated with multimodal therapy (surgery with chemoradiation), 47.9% surgery alone, 6.5% of patients received preoperative radiation, and 9.9% received postoperative radiation. Regarding prognostic significance of pre-operative and postoperative radiation factors, we evaluated factors, such as age, gender, race, tumor size, histologic variants of adenocarcinoma, and tumor grade. Patients with distant-staged tumors who received preoperative radiation had lower mortality compared to those who received postoperative radiation (95% CI, 0.73 - 0.97, (hazard ratio (HR) = 0.85, p = 0.04). There were no survival differences for localized or regional disease regarding pre and postoperative radiation, or when sub-stratifying for any other significant demographic or tumor characteristics.

CONCLUSION

Surgery with adjuvant chemoradiation had the best prognosis for all demographic and tumor characteristics. Preoperative radiation had a good prognosis only in distant disease. However, further randomized evidence is required to demonstrate the efficacy of pre-and post-operative radiation in rectosigmoid junction cancer.

"Sigmoid take-off" to define recto-sigmoid junction and its impact on rectal cancer classification, staging, and management

AIM

The primary objective of this study was to determine the clinical impact of using sigmoid take-off (STO) in the management of rectal cancer. We also evaluated the inter-observer reliability in the identification of STO.

MATERIAL AND METHODS

This retrospective study reviewed staging MRI of patients with mid and high-rectal cancers performed between January 2019 and December 2022. The location of the tumour was reclassified based on STO as defined by D'Souza et al. (2018) and compared with the location determined based on distance from the anal verge. The proportions of cases that show a change in tumour location from rectal cancer to sigmoid cancer and the potential change in treatment were noted. The interobserver agreement for the location of STO and the location of tumours from STO was studied among four subspecialised abdominal radiologists.

RESULTS

Out of 134 rectal cancer patients included, STO-based assessment resulted in the reclassification of 13.4% (n=18) cases into sigmoid cancer. There was, however, no change in the stage of cancer. Among these 18 patients, there would have been a change in management in 5 patients had the initial assessment been a sigmoid cancer. There was excellent agreement among the radiologists for measuring the distance of STO from the anal verge (ICC = 0.883, p<0.001) and determining the location of the tumour based on STO (K = 0.82, p<0.001).

CONCLUSIONS

Using STO changed the location of tumours in 13.4% of high- and mid-rectal cancers. There was excellent agreement among radiologists regarding determining STO and identifying tumour locations using STO.

Long-Term Outcomes of Sigmoid, Rectosigmoid, and Rectal Cancers: A Matched Analysis

BACKGROUND

To determine a population-based comparative matched overall survival analysis for patients undergoing curative resection for sigmoid, rectosigmoid, and rectal cancers stage by stage.

METHODS

Patients who underwent curative surgery for nonmetastatic adenocarcinoma of the sigmoid, rectosigmoid, and rectum between 2000 and 2020 were identified using the US SEER cancer registry data. Each anatomical subsegment was matched in a 1:1 ratio based on age, sex, time of surgery, grade of differentiation, and histopathological stage. Multivariate (MV) Cox regression analysis was conducted.

RESULTS

A total of 19,607 patients fulfilled the criteria per group. Whereas chemotherapy rates were comparable among groups, radiotherapy rates were significantly higher in the rectum. Compared to the initial time period (2000-2005), there was a significant improvement in 3- and 5-year overall survival rates for each stage in the time period of 2016-2020. During the study period, a 10% improvement was observed for Stage-2 and Stage-3 patients for each site (p < 0.05). MV analysis showed that sex (p < 0.001), primary cancer site (p < 0.001), year category (p < 0.001), age (p < 0.001), stage (p < 0.001), degree of differentiation (p < 0.001), and CTx status (p < 0.001) were independently associated with overall survival.

CONCLUSION

This large population-based, comprehensive registry study demonstrates significant survival differences among sigmoid, rectosigmoid, and rectal cancers. Further studies defining distinct landmarks between rectal and colon cancers may improve treatment approaches, cancer care, and survival.

A method of matching nodes between MRI and pathology with MRI-based 3D node map in rectal cancer

PURPOSE

To propose a node-by-node matching method between MRI and pathology with 3D node maps based on preoperative MRI for rectal cancer patients to improve the yet unsatisfactory diagnostic performance of nodal status in rectal cancer.

METHODS

This methodological study prospectively enrolled consecutive participants with rectal cancer who underwent preoperative MRI and radical surgery from December 2021 to August 2023. All nodes with short-axis diameters of ≥ 3 mm within the mesorectum were regarded as target nodes and were localized in three directions based on the positional relationship on MRI and drawn on a node map with the primary tumor as the main reference, which was used as a template for node-by-node matching with pathological evaluation. Patient and nodal-level analyses were performed to investigate factors affecting the matching accuracy.

RESULTS

545 participants were included, of whom 253 received direct surgery and 292 received surgery after neoadjuvant therapy (NAT). In participants who underwent direct surgery, 1782 target nodes were identified on MRI, of which 1302 nodes (73%) achieved matching with pathology, with 1018 benign and 284 metastatic. In participants who underwent surgery after NAT, 1277 target nodes were identified and 918 nodes (72%) achieved matching, of which 689 were benign and 229 were metastatic. Advanced disease and proximity to primary tumor resulted in matching difficulties.

CONCLUSION

An easy-to-use and reliable method of node-by-node matching between MRI and pathology with 3D node map based on preoperative MRI was constructed for rectal cancer, which provided reliable node-based ground-truth labels for further radiological studies.

MRI for Rectal Cancer: Updates and Controversies-AJR Expert Panel Narrative Review

Rectal MRI is a critical tool in the care of patients with rectal cancer, having established roles for primary staging, restaging, and surveillance. The comprehensive diagnostic and prognostic information provided by MRI helps to optimize treatment decision-making. However, challenges persist in the standardization and interpretation of rectal MRI, particularly in the context of rapidly evolving treatment paradigms, including growing acceptance of nonoperative management. In this AJR Expert Panel Narrative Review, we address recent advances and key areas of contention relating to the use of MRI for rectal cancer. Our objectives include: to discuss concepts regarding anatomic localization of rectal tumors; review the evolving rectal cancer treatment paradigm and implications for MRI assessment; discuss updates and controversies regarding rectal MRI for locoregional staging, restaging, and surveillance; review current rectal MRI acquisition protocols; and discuss challenges in homogenizing and optimizing acquisition parameters.

Impact of the new rectal cancer definition on multimodality treatment and interhospital variability: Results from a nationwide cross-sectional study

AIM

This study aimed to determine the consequences of the new definition of rectal cancer for decision-making in multidisciplinary team meetings (MDT). The new definition of rectal cancer, the lower border of the tumour is located below the sigmoid take-off (STO), was implemented in the Dutch guideline in 2019 after an international Delphi consensus meeting to reduce interhospital variations.

METHOD

All patients with rectal cancer according to the local MDT, who underwent resection in 2016 in the Netherlands were eligible for this nationwide collaborative cross-sectional study. MRI-images were rereviewed, and the tumours were classified as above or on/below the STO.

RESULTS

This study registered 3107 of the eligible 3178 patients (98%), of which 2784 patients had an evaluable MRI. In 314 patients, the tumour was located above the STO (11%), with interhospital variation between 0% and 36%. Based on TN-stage, 175 reclassified patients with colon cancer (6%) would have received different treatment (e.g., omitting neoadjuvant radiotherapy, candidate for adjuvant chemotherapy). Tumour location above the STO was independently associated with lower risk of 4-year locoregional recurrence (HR 0.529; p = 0.030) and higher 4-year overall survival (HR 0.732; p = 0.037) compared to location under the STO.

CONCLUSION

By using the STO, 11% of the prior MDT-based diagnosis of rectal cancer were redefined as sigmoid cancer, with potential implications for multimodality treatment and prognostic value. Given the substantial interhospital variation in proportion of redefined cancers, the use of the STO will contribute to standardisation and comparability of outcomes in both daily practice and trial settings.

Total mesorectal excision in MRI-defined low rectal cancer: multicentre study comparing oncological outcomes of robotic, laparoscopic and transanal total mesorectal excision in high-volume centres

BACKGROUND

The routine use of MRI in rectal cancer treatment allows the use of a strict definition for low rectal cancer. This study aimed to compare minimally invasive total mesorectal excision in MRI-defined low rectal cancer in expert laparoscopic, transanal and robotic high-volume centres.

METHODS

All MRI-defined low rectal cancer operated on between 2015 and 2017 in 11 Dutch centres were included. Primary outcomes were: R1 rate, total mesorectal excision quality and 3-year local recurrence and survivals (overall and disease free). Secondary outcomes included conversion rate, complications and whether there was a perioperative change in the preoperative treatment plan.

RESULTS

Of 1071 eligible rectal cancers, 633 patients with low rectal cancer were identified. Quality of the total mesorectal excision specimen (P = 0.337), R1 rate (P = 0.107), conversion (P = 0.344), anastomotic leakage rate (P = 0.942), local recurrence (P = 0.809), overall survival (P = 0.436) and disease-free survival (P = 0.347) were comparable among the centres. The laparoscopic centre group had the highest rate of perioperative change in the preoperative treatment plan (10.4%), compared with robotic expert centres (5.2%) and transanal centres (2.1%), P = 0.004. The main reason for this change was stapling difficulty (43%), followed by low tumour location (29%). Multivariable analysis showed that laparoscopic surgery was the only independent risk factor for a change in the preoperative planned procedure, P = 0.024.

CONCLUSION

Centres with expertise in all three minimally invasive total mesorectal excision techniques can achieve good oncological resection in the treatment of MRI-defined low rectal cancer. However, compared with robotic expert centres and transanal centres, patients treated in laparoscopic centres have an increased risk of a change in the preoperative intended procedure due to technical limitations.

Evolution of surgical approach to rectal cancer resection: A multinational registry assessment

PURPOSE

Surgical approach to rectal cancer has evolved in recent decades, with introduction of minimally invasive surgery (MIS) techniques and local excision. Since implementation might differ internationally, this study is aimed at evaluating trends in surgical approach to rectal cancer across different countries over the last 10 years and to gain insight into patient, tumour and treatment characteristics.

METHODS

Pseudo-anonymised data of patients undergoing resection for rectal cancer between 2010 and 2019 were extracted from clinical audits in the Netherlands (NL), Sweden (SE), England-Wales (EW) and Australia-New Zealand (AZ).

RESULTS

Ninety-nine thousand five hundred ninety-seven patients were included (38,413 open, 55,155 MIS and 5416 local excision). An overall increase in MIS was observed from 29.9% in 2010 to 72.1% in 2019, with decreasing conversion rates (17.5-9.0%). The MIS proportion was highly variable between countries in the period 2010-2014 (54.4% NL, 45.3% EW, 39.8% AZ, 14.1% SE, P < 0.001), but variation reduced over time (2015-2019 78.8% NL, 66.3% EW, 64.3% AZ, 53.2% SE, P < 0.001). The proportion of local excision for the two periods was highly variable between countries: 4.7% and 11.8% in NL, 3.9% and 7.4% in EW, 4.7% and 4.6% in AZ, 6.0% and 2.9% in SE.

CONCLUSIONS

Application and speed of implementation of MIS were highly variable between countries, but each registry demonstrated a significant increase over time. Local excision revealed inconsistent trends over time.

An updated evaluation of the implementation of the sigmoid take-off landmark 1 year after the official introduction in the Netherlands

PURPOSE

The definition of rectal cancer based on the sigmoid take-off (STO) was incorporated into the Dutch guideline in 2019, and became mandatory in the national audit from December 2020. This study aimed to evaluate the use of the STO in clinical practice and the added value of online training, stratified for the period before (group A, historical cohort) and after (group B, current cohort) incorporation into the national audit.

METHODS

Participants, including radiologists, surgeons, surgical and radiological residents, interns, PhD students, and physician assistants, were asked to complete an online training program, consisting of questionnaires, 20 MRI cases, and a training document. Outcomes were agreement with the expert reference, inter-rater variability, and accuracy before and after the training.

RESULTS

Group A consisted of 86 participants and group B consisted of 114 participants. Familiarity with the STO was higher in group B (76% vs 88%, p = 0.027). Its use in multidisciplinary meetings was not significantly higher (50% vs 67%, p = 0.237). Agreement with the expert reference was similar for both groups before (79% vs 80%, p = 0.423) and after the training (87% vs 87%, p = 0.848). Training resulted in significant improvement for both groups in classifying tumors located around the STO (group A, 69-79%; group B, 67-79%, p < 0.001).

CONCLUSIONS

The results of this study show that after the inclusion of the STO in the mandatory Dutch national audit, the STO was consequently used in only 67% of the represented hospitals. Online training has the potential to improve implementation and unambiguous assessment.

Sigmoid take-off in rectosigmoid cancer as a landmark identifying benefit from neoadjuvant chemoradiation: A retrospective comparative cohort study

INTRODUCTION

There is no standard treatment strategy for rectosigmoid cancer because of the diverse definitions of the proximal rectal origin. This study aimed to evaluate sigmoid take-off compared with other landmarks of the rectosigmoid junction in guiding oncological therapy and outcomes.

MATERIALS AND METHODS

This retrospective, comparative cohort study included patients diagnosed with rectosigmoid carcinoma at our centre between January 2010 and December 2018. The patients were classified into the neoadjuvant treatment group and upfront surgery group. The oncological outcomes were compared between the two groups in relation to the tumor position.

RESULTS

A total of 656 patients (median age 64 years) were included. After propensity score matching, the 3- and 5-year overall survival and disease-free survival in patients in both the groups were comparable. However, when only patients with rectal cancer as defined by the sigmoid take-off point were included, the disease-free survival rate in the upfront surgery group was significantly lower than that in the neoadjuvant treatment group (p = 0.03 in patients who underwent computed tomography, p = 0.03 in patients who underwent magnetic resonance imaging). The turning point of the beneficial hazard ratio of neoadjuvant therapy was compared according to the different definitions of the rectosigmoid junction and the sigmoid take-off was found to be the most effective.

CONCLUSION

The sigmoid take-off point is a suitable landmark for identifying the rectosigmoid junction and is an important defining criterion for assessing the benefit of neoadjuvant therapy. The application of this definition in clinical practice and future trials is warranted.

A postsurgical prognostic nomogram for patients with lymph node positive rectosigmoid junction adenocarcinoma

OBJECTIVE

The definition of rectosigmoid junction (RSJ) is still in debate. The treatment and prognosis of patients with rectosigmoid junction cancer (RSJC) and positive lymph nodes (PLN-RSJCs) are mostly based on the American Joint Committee on Cancer (AJCC) staging system. Our study aims to assist clinicians in creating a more intuitive and accurate nomogram model for PLN-RSJCs for the prediction of patient overall survival (OS) after surgery.

METHODS

Based on the Surveillance, Epidemiology, and End Results (SEER) database, we extracted 3384 patients with PLN-RSJCs and randomly divided them into development (n = 2344) and validation (n = 1004) cohorts at a ratio of 7:3. Using univariate and multivariate COX regression analysis, we identified independent risk factors associated with OS in PLN-RSJCs in the development cohort, which were further used to establish a nomogram model. To verify the accuracy of the model, the concordance index (C-index), receiver operating characteristic (ROC) curves, calibration curves, and an internal validation cohort have been employed. Decision curve analysis (DCA) was used to assess the clinical applicability and benefits of the generated model. Survival curves of the low- and high-risk groups were calculated using the Kaplan-Meier method together with the log-rank test.

RESULTS

Age, marital, chemotherapy, AJCC stage, T and N stage of TNM system, tumor size, and regional lymph nodes were selected as independent risk factors and included in the nomogram model. The C-index of this nomogram in the development (0.751;0.737-0.765) and validation cohorts (0.750;0.764-0.736) were more significant than that of the AJCC 7th staging system (0.681; 0.665-0.697). The ROC curve with the calculated area under the curve (AUC) in the development cohort was 0.845,0.808 and 0.800 for 1-year, 3-year and 5-year OS, AUC in the validation cohort was 0.815,0.833 and 0.814 for 1-year, 3-year and 5-year, respectively. The calibration plots of both cohorts for 1-year,3-year and 5-year OS all demonstrated good agreement between actual clinical observations and predicted outcomes. In the development cohort, the DCA showed that the nomogram prediction model is more advantageous for clinical application than the AJCC 7th staging system. Kaplan-Meier curves in the low and high groups showed significant difference in patient OS.

CONCLUSIONS

We established an accurate nomogram model for PLN-RSJCs, intended to support clinicians in the treatment and follow-up of patients.

Pelvic CT in addition to MRI to differentiate between rectal and sigmoid cancer on imaging using the sigmoid take-off as a landmark

BACKGROUND

The sigmoid take-off (STO) is a recently established landmark to discern rectal from sigmoid cancer on imaging. STO-assessment can be challenging on magnetic resonance imaging (MRI) due to varying axial planes.

PURPOSE

To establish the benefit of using computed tomography (CT; with consistent axial planes), in addition to MRI, to anatomically classify rectal versus sigmoid cancer using the STO.

MATERIAL AND METHODS

A senior and junior radiologist retrospectively classified 40 patients with rectal/rectosigmoid cancers using the STO, first on MRI-only (sagittal and oblique-axial views) and then using a combination of MRI and axial CT. Tumors were classified as rectal/rectosigmoid/sigmoid (according to published STO definitions) and then dichotomized into rectal versus sigmoid. Diagnostic confidence was documented using a 5-point scale.

RESULTS

Adding CT resulted in a change in anatomical tumor classification in 4/40 cases (10%) for the junior reader and in 6/40 cases (15%) for the senior reader. Diagnostic confidence increased significantly after adding CT for the junior reader (mean score 3.85 vs. 4.27; P < 0.001); confidence of the senior reader was not affected (4.28 vs. 4.25; P = 0.80). Inter-observer agreement was similarly good for MRI only (κ=0.77) and MRI + CT (κ=0.76). Readers reached consensus on the classification of rectal versus sigmoid cancer in 78%-85% of cases.

CONCLUSION

Availability of a consistent axial imaging plane - in the case of this study provided by CT - in addition to a standard MRI protocol with sagittal and oblique-axial imaging views can be helpful to more confidently localize tumors using the STO as a landmark, especially for more junior readers.

Adult and Elderly Risk Factors of Mortality in 23,614 Emergently Admitted Patients with Rectal or Rectosigmoid Junction Malignancy

Background: Colorectal cancer, among which are malignant neoplasms of the rectum and rectosigmoid junction, is the fourth most common cancer cause of death globally. The goal of this study was to evaluate independent predictors of in-hospital mortality in adult and elderly patients undergoing emergency admission for malignant neoplasm of the rectum and rectosigmoid junction. Methods: Demographic and clinical data were obtained from the National Inpatient Sample (NIS), 2005−2014, to evaluate adult (age 18−64 years) and elderly (65+ years) patients with malignant neoplasm of the rectum and rectosigmoid junction who underwent emergency surgery. A multivariable logistic regression model with backward elimination process was used to identify the association of predictors and in-hospital mortality. Results: A total of 10,918 non-elderly adult and 12,696 elderly patients were included in this study. Their mean (standard deviation (SD)) age was 53 (8.5) and 77.5 (8) years, respectively. The odds ratios (95% confidence interval, P-value) of some of the pertinent risk factors for mortality for operated adults were 1.04 for time to operation (95%CI: 1.02−1.07, p < 0.001), 2.83 for respiratory diseases (95%CI: 2.02−3.98), and 1.93 for cardiac disease (95%CI: 1.39−2.70), among others. Hospital length of stay was a significant risk factor as well for elderly patients—OR: 1.02 (95%CI: 1.01−1.03, p = 0.002). Conclusions: In adult patients who underwent an operation, time to operation, respiratory diseases, and cardiac disease were some of the main risk factors of mortality. In patients who did not undergo a surgical procedure, malignant neoplasm of the rectosigmoid junction, respiratory disease, and fluid and electrolyte disorders were risk factors of mortality. In this patient group, hospital length of stay was only significant for elderly patients.

Evaluation of the implementation of the sigmoid take-off landmark in the Netherlands

AIM

The sigmoid take-off (STO), the point on imaging where the sigmoid sweeps ventral from the sacrum, was chosen as the definition of the rectum during an international Delphi consensus meeting and has been incorporated into the Dutch guidelines since October 2019. The aim of this study was to evaluate the implementation of this landmark 1 year after the guideline implementation and to perform a quality assessment of the STO training.

METHOD

Dutch radiologists, surgeons, surgical residents, interns, PhD students and physician assistants were asked to complete a survey and classify 20 tumours on MRI as 'below', 'on' or 'above' the STO. Outcomes were agreement with the expert reference, inter-rater variability and accuracy before and after the training.

RESULTS

Eighty-six collaborators participated. Six radiologists (32%) and 11 surgeons (73%) used the STO as the standard landmark to distinguish between rectal and sigmoidal tumours during multidisciplinary meetings. Overall agreement with the expert reference improved from 53% to 70% (p < 0.001) after the training. The positive predictive value for diagnosing rectal tumours was high before and after the training (92% vs. 90%); the negative predictive value for diagnosing sigmoidal tumours improved from 39% to 63%.

CONCLUSION

Approximately half of the represented hospitals have implemented the new definition of rectal cancer 1 year after the implementation of the Dutch national guidelines. Overall baseline agreement with the expert reference and accuracy for the tumours around the STO was low, but improved significantly after training. These results highlight the added value of training in implementation of radiological landmarks to ensure unambiguous assessment.

The growing trend for no primary surgery in colorectal cancer

AIM

In colorectal cancer (CRC), surgery of the primary site is commonly curative. Our aim was to determine estimates of 'no surgery' for primary CRC while identifying common reasons for no surgery.

METHOD

We identified all patients with a diagnosis of colorectal adenocarcinoma from the National Cancer Database between January 2004 and December 2016. Then, we identified patients who did not undergo surgery on the primary tumour and their demographic, tumour and institutional characteristics. Kaplan-Meier and logistic regression analyses were used to evaluate specific factors associated with overall survival as related to no surgery and recommendations against operative management.

RESULTS

A total of 1,208,878 patients with CRC were identified, 14.5% of whom had no surgery of the primary cancer. No surgery was more common in rectal cancer than in colon cancer. Despite a steady incidence of CRC diagnoses, the likelihood of no surgery grew by 170% over the study period. Metastatic disease was noted in 53.7% of the no surgery cohort. Nine per cent of the no surgery patient cohort received a recommendation against surgery despite the absence of metastatic disease, 7.5% refused surgery and only 2% underwent palliative surgery. On multivariable analysis, patients who were not recommended to have surgery were more likely to be older, uninsured, comorbid and receive care at a single hospital. The no surgery patients had significantly lower overall survival.

CONCLUSION

A substantial proportion of patients with CRC do not have surgery. Interventions aimed at expanding access and promoting second opinions at other cancer hospitals might reduce the growing rate of no surgery in CRC.

Rising incidence of colorectal cancer in individuals younger than 50 years and increasing mortality from rectosigmoid cancer in England

AIM

The aim was to describe changes in incidence and mortality from colorectal cancer (CRC) in England by analysing data available from the National Cancer Registration and Analysis Service (NCRAS, 2001-2017).

METHODS

Data analysis was undertaken to interpret trends and patterns in age-standardized incidence and death rates from CRC, including sub-analyses by six age groups (0-24, 25-49, 50-59, 60-69, 70-79, 80+) and three sites of cancer-colonic, rectosigmoid and rectal.

RESULTS

Overall CRC incidence remained relatively stable-70.1 cases per 100 000 individuals (95% CI 69.3-71.0) in 2001 and 68.8 cases (95% CI 68.0-69.5) in 2017. Sub-analysis demonstrates a quarter fewer incidence of rectosigmoid cancer (-27%). This is counterbalanced by a 3% rise in colon cancers. The age-standardized incidence rate of CRC increased by 59% in the 25-49 age group. In the over 50s, CRC incidence remained stable, with reductions seen in rectosigmoid cancer (50-59 years, -19%; 60-69, -26%; 70-79, -39%; 80+, -27%). Overall, mortality improved (-18.7%), primarily as a result of the reduction in deaths from colon (-31.6%) and rectal cancers (-25.1%). Deaths from the small incident number of rectosigmoid cancers, however, demonstrated a significant increase overall (+166.7%). Grouped age-standardized death rate analyses showed increasing death rates in the under 50s (+28.3%) compared to declining rates in the over 50s (-15.8%).

CONCLUSIONS

There is a clear trend in increased incidence and mortality in individuals under 50 years old. There is also a trend to increased mortality from rectosigmoid cancer. These findings should have implications for national screening programme extension to under 50s and a call to arms for appropriate identification, staging and treatment of rectosigmoid cancers.

The sigmoid take-off as a landmark to distinguish rectal from sigmoid tumours on MRI: Reproducibility, pitfalls and potential impact on treatment stratification

PURPOSE

The sigmoid take-off (STO) was recently introduced as a preferred landmark, agreed upon by expert consensus recommendation, to discern rectal from sigmoid cancer on imaging. Aim of this study was to assess the reproducibility of the STO, explore its potential treatment impact and identify its main interpretation pitfalls.

METHODS

Eleven international radiologists (with varying expertise) retrospectively assessed n = 155 patients with previously clinically staged upper rectal/rectosigmoid tumours and re-classified them using the STO as completely below (rectum), straddling the STO (rectosigmoid) or completely above (sigmoid), after which scores were dichotomized as rectum (below/straddling STO) and sigmoid (above STO), being the clinically most relevant distinction. A random subset of n = 48 was assessed likewise by 6 colorectal surgeons. .

RESULTS

Interobserver agreement (IOA) for the 3-category score ranged from κ0.19-0.82 (radiologists) and κ0.32-0.72 (surgeons), with highest scores for the most experienced radiologists (κ0.69-0.76). Of the 155 cases, 44 (28%) were re-classified by ≥ 80% of radiologists as sigmoid cancers; 36 of these originally received neoadjuvant treatment which in retrospect might have been omitted if the STO had been applied. Main interpretation pitfalls were related to anatomical variations, borderline cases near the STO and angulation of axial imaging planes.

CONCLUSIONS

Good agreement was reached for experienced radiologists. Despite considerable variation among less-expert readers, use of the STO could have changed treatment in ±1/4 of patients in our cohort. Identified interpretation pitfalls may serve as a basis for teaching and to further optimize MR protocols.

Mesorectal shape variation in rectal cancer radiotherapy in prone position using a belly board

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Mesorectal shape variation is diverse and largest in the upper-anterior region.

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Derived planning target volume margins for the upper-anterior region were larger in female patients.

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Planning target volume margins are comparable for radiotherapy and chemoradiotherapy groups.

Background and purpose

In rectal cancer patients, radiotherapy in prone position using a belly board can reduce the dose to organs at risk. For this patient group we investigated inter-fraction shape variation of the mesorectal part of the clinical target volume (CTV) and determined planning target volume (PTV) margins.

Materials and methods

Patients with rectal cancer receiving neoadjuvant (chemo)radiotherapy were eligible. For each patient a planning computed tomography (pCT) and five cone-beam CT (CBCT) scans were acquired in prone position using a belly board. The mesorectal CTV was delineated on all scans. Mesorectal shape variation was quantified relative to the pCT. PTV margins were derived locally and averaged for separate subregions of the mesorectal CTV. For each patient a total PTV was constructed using our clinical margins for mesorectal and lymph node CTVs. An artificial dose distribution conforming to this PTV was used to calculate the coverage for the mesorectal CTV using the CBCT delineations.

Results

In 19 rectal cancer patients the derived PTV margins were smallest in the upper-lateral region (6 mm) and largest in the upper-anterior region (16 mm). PTV margins for the upper-anterior region were larger for female patients (19 mm) compared to male patients (14 mm). Clinical margins for the total PTV were sufficient for a coverage of at least 97% of the mesorectal CTV for all patients.

Conclusions

Mesorectal shape variation is heterogeneous and largest in the upper-anterior region, in rectal cancer patients irradiated in prone position and using a belly board.

Comprehensive analysis of lncRNA-associated ceRNA network reveals the novel potential of lncRNA, miRNA and mRNA biomarkers in human rectosigmoid junction cancer

Although accumulating evidence has confirmed the potential biological functions of long non-coding RNAs (lncRNAs) as competitive endogenous RNAs (ceRNAs) in colorectal tumorigenesis and progression, few studies have focused on rectosigmoid junction cancer. In the present study, a comprehensive analysis was conducted to explore lncRNA-mediated ceRNA implications and their potential value for prognosis. lncRNA, microRNA (miR/miRNA) and mRNA expression profiles were downloaded from The Cancer Genome Atlas database. Subsequently, a lncRNA-miRNA-mRNA regulatory network was constructed to evaluate the functions of these differentially expressed genes on overall survival (OS) for rectosigmoid junction cancer. As a result, a rectosigmoid junction cancer-specific ceRNA network was successfully constructed with 7 differentially expressed (DE)lncRNAs, 16 DEmiRNAs and 71 DEmRNAs. Among the network, one DElncRNA (small nucleolar RNA host gene 20) and three mRNAs (sodium- and chloride-dependent taurine transporter, fibroblast growth factor 13 and tubulin polyglutamylase TTLL7) were significantly associated with OS (P<0.05). Additionally, two lncRNAs (KCNQ1OT1 and MIR17HG) interacted with most of the DEmiRNAs. Notably, two top-ranked miRNAs (hsa-miR-374a-5p and hsa-miR-374b-5p) associated networks were identified to be markedly associated with the pathogenesis. Furthermore, four DEmRNAs (caveolin-1, MET, filamin-A and AKT3) were enriched in the Kyoto Encylopedia of Gene and Genomes pathway analysis, as well as being included in the ceRNA network. In summary, the present results revealed that a specific lncRNA-miRNA-mRNA network was associated with rectosigmoid junction cancer, providing several molecules that may be used as novel prognostic biomarkers and therapeutic targets.

Comparison of the sigmoid take-off with other definitions of the rectosigmoid junction: A retrospective comparative cohort analysis

BACKGROUND

The diversity in definitions for the rectosigmoid junction is becoming a major obstacle in standardizing optimal treatment of rectal cancers. The study aimed to determine the average distance of the sigmoid take-off from the anal verge and its association with individual factors.

MATERIALS AND METHODS

Patients diagnosed with rectal and sigmoid colon cancer in our centre from January 2010 to December 2018 were retrospectively enrolled in the cancer group. The results of 200 controls without colorectal disease were also reviewed (normal group). The distance of different landmarks and margins of cancer from the anal verge were retrieved from computed tomography (CT), magnetic resonance imaging (MRI), and endoscopy findings.

RESULTS

The cancer group comprised 635 patients (381 men, median age: 64 years). The average distances of the sigmoid take-off from the anal verge measured in CT and MRI were comparable (P = 0.483). On MRI, the average distance of the sigmoid take-off from the anal verge in the cancer group was comparable with that of the normal group (P = 0.070). Multivariate regression revealed that the distance of the sigmoid take-off from the anal verge was associated with the distances of the sacral promontory (P < 0.001) and peritoneal reflection (P < 0.001) from the anal verge.

CONCLUSION

The cancer distributions of patients varied widely with the application of different definitions. The point of sigmoid take-off is an intuitive landmark influenced by individual factors. The measurement of the sigmoid take-off by different researchers in both CT and MRI revealed good consistency. Further studies regarding the clinical significance of this definition are still needed.

The rectosigmoid junction: are limits important?

The rectosigmoid junction (RSJ) is the limit between the sigmoid colon and the rectum. The limits of this transition zone have been a source of controversy. There are multiple definitions that aim to establish the beginning of the rectum. Some organizations propose the use of more than one definition. Generally, these definitions use either radiological markings, endoscopic measurements or anatomical landmarks. However, no consensus exists currently.

J. Kotte AN, Bol GH, T. van den Berg CA. Clinical implementation of MRI-based organs-at-risk auto-segmentation with convolutional networks for prostate radiotherapy

BACKGROUND

Structure delineation is a necessary, yet time-consuming manual procedure in radiotherapy. Recently, convolutional neural networks have been proposed to speed-up and automatise this procedure, obtaining promising results. With the advent of magnetic resonance imaging (MRI)-guided radiotherapy, MR-based segmentation is becoming increasingly relevant. However, the majority of the studies investigated automatic contouring based on computed tomography (CT).

PURPOSE

In this study, we investigate the feasibility of clinical use of deep learning-based automatic OARs delineation on MRI.

MATERIALS AND METHODS

We included 150 patients diagnosed with prostate cancer who underwent MR-only radiotherapy. A three-dimensional (3D) T1-weighted dual spoiled gradient-recalled echo sequence was acquired with 3T MRI for the generation of the synthetic-CT. The first 48 patients were included in a feasibility study training two 3D convolutional networks called DeepMedic and dense V-net (dV-net) to segment bladder, rectum and femurs. A research version of an atlas-based software was considered for comparison. Dice similarity coefficient, 95% Hausdorff distances (HD95), and mean distances were calculated against clinical delineations. For eight patients, an expert RTT scored the quality of the contouring for all the three methods. A choice among the three approaches was made, and the chosen approach was retrained on 97 patients and implemented for automatic use in the clinical workflow. For the successive 53 patients, Dice, HD95 and mean distances were calculated against the clinically used delineations.

RESULTS

DeepMedic, dV-net and the atlas-based software generated contours in 60 s, 4 s and 10-15 min, respectively. Performances were higher for both the networks compared to the atlas-based software. The qualitative analysis demonstrated that delineation from DeepMedic required fewer adaptations, followed by dV-net and the atlas-based software. DeepMedic was clinically implemented. After retraining DeepMedic and testing on the successive patients, the performances slightly improved.

CONCLUSION

High conformality for OARs delineation was achieved with two in-house trained networks, obtaining a significant speed-up of the delineation procedure. Comparison of different approaches has been performed leading to the succesful adoption of one of the neural networks, DeepMedic, in the clinical workflow. DeepMedic maintained in a clinical setting the accuracy obtained in the feasibility study.

Racial Comparisons in Timeliness of Colon Cancer Treatment in an Equal-Access Health System

BACKGROUND

Non-Hispanic black (NHB) adults with cancer may have longer time-to-treatment than non-Hispanic whites (NHW) in the United States. Unequal access to medical care may partially account for this racial disparity. This study aimed to investigate whether there were racial differences in time-to-treatment and in treatment delays for patients diagnosed with colon cancer in the equal-access Military Health System (MHS).

METHODS

Patients age 18-79 years diagnosed with colon adenocarcinoma between January 1, 1998, and December 31, 2014, were identified in the Department of Defense Central Cancer Registry and the MHS Data Repository-linked databases. Median time-to-treatment (surgery and chemotherapy) and 95% confidence intervals were compared between NHBs and NHWs in multivariable quantile regression models. Odds ratios and 95% confidence intervals of receiving delayed treatment defined by guidelines for NHBs relative to NHWs were estimated using multivariable logistic regression.

RESULTS

Patients (n = 3067) had a mean age at diagnosis of 58.4 (12.2) years and the racial distribution was 76.7% NHW and 23.3% NHB. Median adjusted time-to-treatment was similar for NHB compared to NHW patients. The likelihood of receiving delayed treatment was similar between NHB and NHW patients.

CONCLUSIONS

In the MHS, there was no evidence of treatment delays for NHBs compared to NHWs, suggesting the role of equal access to medical care and insurance coverage in reducing racial disparities in colon cancer treatment.

Imaging and Management of Rectal Cancer

High-resolution phased array external magnetic resonance imaging (MRI) is the first investigation of choice in rectal cancer for local staging, both in the primary and restaging situations. Use of MRI helps differentiate between those with good prognosis, which can be offered upfront surgery and the poor prognostic cases where treatment intensification is needed. MRI identified poor prognostic factors are threatened or involved mesorectal fascia, T3 tumors with >5 mm extramural spread, those with extramural vascular invasion, pelvic sidewall nodes and mucinous tumors. At restaging, use of MRI helps evaluate response and an MR tumor regression grading system is being evaluated. Complete response seen on clinical examination and endoscopy, needs confirmation on MRI using both T2-weighted and diffusion-weighted sequences to justify a "watch and wait" approach. In this subset of patients, MRI also plays a role in monitoring and detecting early regrowth. In those with partial response, MRI helps define surgical margins and can be used as a roadmap to decide between sphincter preserving surgeries and radical sphincter sacrificing surgeries; pelvic exenteration and pelvic sidewall lymph node dissection. Poor responders on MRI may benefit from adjuvant chemotherapy. Use of MRI thus helps in individualizing treatment in rectal cancer.

Ex vivo specimen MRI and pathology confirm a rectosigmoid mesenteric waist at the junction of the mesorectum and mesocolon

AIM

Continuity of the mesentery has recently been established and may provide an anatomical basis for optimal colorectal resectional surgery. Preliminary data from operative specimen measurements suggest there is a tapering in the mesentery of the distal sigmoid. A mesenteric waist in this area may be a risk factor for local recurrence of colorectal cancer. This study aimed to investigate the anatomical characteristics of the mesentery at the colorectal junction.

METHOD

In this cross-sectional study, 20 patients were recruited. After planned colorectal resection, the surgical specimens were scanned in a MRI system and subsequently dissected and photographed as per national pathology guidelines. Mesenteric surface area and linear measurements were compared between MRI and pathology to establish the presence and location of a mesenteric waist.

RESULTS

Specimen analysis confirmed that a narrowing in the mesenteric surface area was consistently apparent at the rectosigmoid junction. Above the anterior peritoneal reflection, the surface area and posterior distance of the mesentery of the upper rectum initially decreased before increasing as the mesentery of the sigmoid colon. These anatomical properties created the appearance of a mesenteric 'waist' at the rectosigmoid junction. Using the anterior reflection as a reference landmark, the rectosigmoid waist occurred at a mean height of 23.6 and 21.7 mm on MRI and pathology, respectively.

CONCLUSION

A rectosigmoid waist occurs at the junction of the mesorectum and mesocolon, and is a mesenteric landmark for the rectum that is present on both radiology and pathology.

The sigmoid take-off: An anatomical imaging definition of the rectum validated on specimen analysis

BACKGROUND

A pre-operative imaging landmark to define the rectum would optimise clinical care of rectal cancer patients and research efforts to improve outcomes. The sigmoid take-off has been suggested as an imaging landmark for the rectosigmoid junction (RSJ). This study aimed to investigate whether this imaging definition of the rectum was validated by surgical specimen analysis.

METHODS

This prospective study recruited 20 patients undergoing surgery and undertook radiological and pathological analysis of their rectal specimens. The radiological landmark of the sigmoid take-off was identified on pre-operative magnetic resonance imaging (MRI), and the distance to the anterior peritoneal reflection was measured by two readers. After surgery, the distance from the beginning of the sigmoid mesocolon to the anterior peritoneal reflection to the beginning of the sigmoid mesocolon on the specimen was measured, and compared to the distance on MRI using Pearson's Correlation Coefficient and Bland-Altman plots.

RESULTS

In 17 patients, the mean distance from the anterior peritoneal reflection to the RSJ on MRI was 20.3 mm and 23.1 mm for two readers, and on pathology was 20.6 mm. The mean differences between MRI and specimen measurements were -0.31 mm (-2.83 to 2.20 mm), and 2.51 mm (95% confidence interval -0.31 to 5.33 mm) for each reader, with correlation coefficients of 0.77 and 0.81.

CONCLUSION

The sigmoid take-off has been validated on specimen analysis to be an imaging landmark that defines the termination of the rectum. This anatomical landmark can be used to classify tumours and guide treatment and research of sigmoid colon and rectal cancer.

Rectal NETs and rectosigmoid junction NETs may need to be treated differently

Neuroendocrine tumors (NETs) are heterogeneous, and the incidence of NETs is rapidly increasing. We observed different survival in patients with rectal NETs and rectosigmoid junction NETs, which are treated similarly. We included patients with rectal and rectosigmoid junction NETs from the SEER database. The 5‐year survival was set as the end‐point. 6675 patients with rectal NETs and 329 patients with rectosigmoid junction NETs, were eligible for the analysis. Initially, the survival analyses suggested that the 5‐year survival significantly differed between the patients with rectal and rectosigmoid junction NETs (HR = 0.82, 95% CI 0.70‐0.95; P = .01). Tumor differentiation, an invasion deeper than T2, and lymph node and distant metastases were still important risk factors affecting survival for both location. While, the males showed better survival (HR = 0.69, 95% CI 0.55‐0.88; P < .01) and primary tumor surgery had no benefits (P = .56) for patients with rectosigmoid junction NETs. The factors that predict regional lymph node metastases varied by location. In rectal NETs, invasion deeper than T1 and a tumor larger than 1 cm could significantly increase the risk of regional lymph node metastases (all OR > 5, P < .01). In rectosigmoid junction NETs, the risk of regional lymph node metastases was considered significantly higher with invasion deeper than T1 (all OR > 5, P < .01) and a tumor larger than 2 cm (OR = 31.32, 95% CI 2.53‐387.57; P < .01). We advocate a clear and consistent definition of the rectosigmoid junction for future studies, and more studies are needed to determine the reason underlying differences between rectum and rectosigmoid junction.

Detailed and applied anatomy for improved rectal cancer treatment

Rectal anatomy is one of the most challenging concepts of visceral anatomy, even though currently there are more than 23,000 papers indexed in PubMed regarding this topic. Nonetheless, even though there is a plethora of information meant to assist clinicians to achieve a better practice, there is no universal understanding of its complexity. This in turn increases the morbidity rates due to iatrogenic causes, as mistakes that could be avoided are repeated. For this reason, this review attempts to gather current knowledge regarding the detailed anatomy of the rectum and to organize and present it in a manner that focuses on its clinical implications, not only for the colorectal surgeon, but most importantly for all colorectal cancer-related specialties.

Value of tumor size as a prognostic factor in metastatic colorectal cancer patients after chemotherapy: a population-based study

Aim: To evaluate the relationship between tumor size and survival in metastatic colorectal cancer (mCRC) patients who received chemotherapy. Materials & methods: SEER database was accessed for eligible patients. Multivariate Cox regression analysis was performed to compare the effect of tumor size on overall survival (OS) and CRC-specific survival (CCSS). Results: Tumor size ≥5 cm was an independent risk factor for OS and CCSS in mCRC patients treated with chemotherapy. Tumor size <5 cm did not show a survival advantage in patients whose primary tumor site was rectosigmoid junction, while tumor size ≥5 cm was associated with poor OS and CCSS in left-and right-sided colorectal cancer. Conclusion: Tumor size ≥5 cm was associated with poor prognosis after receiving chemotherapy treatment and a risk factor for survival of mCRC.