How Should Imaging Direct/Orient Management of Rectal Cancer?

MRI restaging of rectal cancer: The RAC (Response-Anal canal-CRM) analysis joint consensus guidelines of the GRERCAR and GRECCAR groups

PURPOSE

To develop guidelines by international experts to standardize data acquisition, image interpretation, and reporting in rectal cancer restaging with magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Evidence-based data and experts' opinions were combined using the RAND-UCLA Appropriateness Method to attain consensus guidelines. Experts provided recommendations for reporting template and protocol for data acquisition were collected; responses were analysed and classified as "RECOMMENDED" versus "NOT RECOMMENDED" (if ≥ 80% consensus among experts) or uncertain (if < 80% consensus among experts).

RESULTS

Consensus regarding patient preparation, MRI sequences, staging and reporting was attained using the RAND-UCLA Appropriateness Method. A consensus was reached for each reporting template item among the experts. Tailored MRI protocol and standardized report were proposed.

CONCLUSION

These consensus recommendations should be used as a guide for rectal cancer restaging with MRI.

Radiomics and Radiogenomics in Pelvic Oncology: Current Applications and Future Directions

Radiomics refers to the conversion of medical imaging into high-throughput, quantifiable data in order to analyse disease patterns, guide prognosis and aid decision making. Radiogenomics is an extension of radiomics that combines conventional radiomics techniques with molecular analysis in the form of genomic and transcriptomic data, serving as an alternative to costly, labour-intensive genetic testing. Data on radiomics and radiogenomics in the field of pelvic oncology remain novel concepts in the literature. We aim to perform an up-to-date analysis of current applications of radiomics and radiogenomics in the field of pelvic oncology, particularly focusing on the prediction of survival, recurrence and treatment response. Several studies have applied these concepts to colorectal, urological, gynaecological and sarcomatous diseases, with individual efficacy yet poor reproducibility. This article highlights the current applications of radiomics and radiogenomics in pelvic oncology, as well as the current limitations and future directions. Despite a rapid increase in publications investigating the use of radiomics and radiogenomics in pelvic oncology, the current evidence is limited by poor reproducibility and small datasets. In the era of personalised medicine, this novel field of research has significant potential, particularly for predicting prognosis and guiding therapeutic decisions. Future research may provide fundamental data on how we treat this cohort of patients, with the aim of reducing the exposure of high-risk patients to highly morbid procedures.

Determinants of Pre-Surgical Treatment in Primary Rectal Cancer: A Population-Based Study

When preoperative radiotherapy (RT) is best used in rectal cancer is subject to discussions and guidelines differ. To understand the selection mechanisms, we analysed treatment decisions in all patients diagnosed between 2010-2020 in two Swedish regions (Uppsala with a RT department and Dalarna without). Information on staging and treatment (direct surgery, short-course RT, or combinations of RT/chemotherapy) in the Swedish Colorectal Cancer Registry were used. Staging magnetic resonance imaging (MRI) permitted a division into risk groups, according to national guidelines. Logistic regression explored associations between baseline characteristics and treatment, while Cohen's kappa tested congruence between clinical and pathologic stages. A total of 1150 patients without synchronous metastases were analysed. Patients from Dalarna were older, had less advanced tumours and were pre-treated less often (52% vs. 63%, p < 0.001). All MRI characteristics (T-/N-stage, MRF, EMVI) and tumour levels were important for treatment choice. Age affected if chemotherapy was added. The correlation between clinical and pathological T-stage was fair/moderate and poor for N-stage. The MRI-based risk grouping influenced treatment choice the most. Since the risk grouping was modified to diminish the pre-treated proportion, fewer patients were irradiated with time. MRI staging is far from optimal. A stronger wish to decrease irradiation may explain why fewer patients from Dalarna were irradiated, but inequality in health care cannot be ruled out.

Predictors and Outcomes of Upstaging in Rectal Cancer Patients Who Did Not Receive Preoperative Therapy

BACKGROUND

Preoperative chemoradiation is indicated for clinical stage II and III rectal cancers; however, the accuracy of clinical staging with preoperative imaging is imperfect.

OBJECTIVE

The study aimed to better characterize the incidence and management of clinical and pathologic stage discordances in patients who did not receive preoperative chemoradiation.

DESIGN

This was a retrospective cohort analysis.

SETTINGS

The source of data was the National Cancer Database from 2006 to 2015.

PATIENTS

We identified patients who underwent resection with curative intent for clinical stage I rectal adenocarcinoma without preoperative chemotherapy or radiation.

MAIN OUTCOME MEASURES

We evaluated the characteristics of "upstaged" patients-those with T3/T4 tumors found on pathology (pathologic stage II) and/or with positive regional nodes in the resection specimen (pathologic stage III) compared with those patients who were not upstaged (pathologic stage I). We then used a mixed-effects multivariable survival model to compare overall survival between these groups.

RESULTS

Among 7818 clinical stage I rectal cancer patients who did not receive preoperative therapy, tumor upstaging occurred in 819 (10.6%) and nodal upstaging occurred in 1612 (20.8%). Upstaged patients were more likely than those not upstaged to have higher grade tumors and positive margins. Survival was worse in upstaged patients (hazard ratio [HR], 1.64; 95% CI, 1.4-1.9) but improved among those upstaged patients who received either chemotherapy (HR, 0.71; 95% CI, 0.6-0.9) or chemoradiation (HR, 0.62; 95% CI, 0.5-0.7).

LIMITATIONS

In addition to the inherent limitations of a retrospective cohort study, the National Cancer Database does not record functional outcomes, local recurrence, or disease-specific survival, so we are restricted to the evaluation of overall survival as an oncologic outcome.

CONCLUSIONS

Inaccurate preoperative staging remains a common clinical challenge in the management of rectal cancer. Survival among upstaged patients is improved among those who receive recommended postoperative chemotherapy and/or chemoradiation, yet many patients do not receive guideline-concordant care. See Video Abstract at https://links.lww.com/DCR/B999 .

PREDICTORES Y RESULTADOS DE SOBRE ESTADIFICACIN EN PACIENTES CON CNCER DE RECTO QUE NO RECIBIERON TERAPIA PREOPERATORIA

ANTECEDENTES:La quimio radiación preoperatoria está indicada para los estadios clínicos II y III del cáncer rectal; sin embargo, la precisión de la estadificación clínica con imágenes preoperatorias es imperfecta.OBJETIVO:El objetivo fue mejorar la caracterización de la incidencia y el manejo de la discordancia del estadio clínico y patológico en pacientes que no recibieron quimio radiación preoperatoria.DISEÑO:Este fue un análisis de cohorte retrospectivo.CONFIGURACIÓN:La fuente de datos fue de la Base de datos Nacional del Cáncer entre los años 2006-2015.PACIENTES:Identificamos pacientes que fueron sometidos a resección con intención curativa por adenocarcinoma rectal en estadio clínico I, sin quimioterapia o radiación preoperatoria.PRINCIPALES MEDIDAS DE RESULTADO:Evaluamos las características de los pacientes "sobre estadificados": aquellos con tumores T3/T4 encontrados en patología (estadio patológico II) y/o con ganglios regionales positivos en la muestra de resección (estadio patológico III), en comparación con aquellos pacientes que no fueron sobre estadificados (estadio patológico I). Luego usamos un modelo de supervivencia multivariable de efectos mixtos para comparar la supervivencia general entre estos grupos.RESULTADOS:De entre 7818 pacientes con cáncer de recto, en estadio clínico I, y que no recibieron tratamiento preoperatorio, se produjo una sobre estadificación tumoral en 819 (10,6%) y una sobre estadificación ganglionar en 1612 (20,8%). Los pacientes sobre estadificados tenían más probabilidades que los no sobre estadificados de tener tumores de mayor grado y márgenes positivos. La supervivencia fue peor en los pacientes sobre estadificados (HR 1,64, IC del 95% [1,4, 1,9]), pero mejoró entre los pacientes sobre estadificados que recibieron quimioterapia (HR 0,71, IC del 95% [0,6, 0,9]) o quimio radiación (HR 0,62, 95% IC [0,5, 0,7]).LIMITACIONES:Además de las limitaciones inherente a un estudio de cohorte de tipo retrospectivo, la Base de datos Nacional del Cáncer no registra resultados funcionales, la recurrencia local o la supervivencia específica de la enfermedad, por lo que estamos restringidos a la evaluación de la supervivencia general como un resultado oncológico.CONCLUSIONES:La estadificación preoperatoria inexacta sigue siendo un desafío clínico común en el tratamiento del cáncer de recto. La supervivencia entre los pacientes con sobre estadificación mejora en aquellos que reciben la quimioterapia y/o quimio radioterapia postoperatoria recomendada, aunque muchos pacientes no reciben atención acorde con las guías. Consulte Video Resumen en http://links.lww.com/DCR/B999 . (Traducción-Dr. Osvaldo Gauto ).

Diagnostic performance of synthetic magnetic resonance imaging in the prognostic evaluation of rectal cancer

Background

Numerous factors are related to the prognosis of rectal cancer, including T stage, N stage, metastasis, extramural venous invasion (EMVI), circumferential resection margin (CRM), and tumor differentiation. However, it is still a challenge to precisely evaluate them before therapy; therefore, we investigate whether synthetic magnetic resonance imaging and apparent diffusion coefficient (ADC) values could help predict the prognostic factors of rectal cancer.

Methods

Eighty-seven patients (55 men and 32 women; mean age, 59±11 years) with pathologically confirmed rectal cancer were enrolled. Preoperative quantitative metrics, including T1, T2, proton density (PD), and ADC values, were measured with diffusion-weighted imaging (DWI) acquired by a single-shot echo-planar sequence and synthetic magnetic resonance imaging acquired by a multi-dynamic multi-echo sequence at 3.0 T, in patients with rectal cancer by two radiologists. We evaluated the diagnostic performance of synthetic magnetic resonance imaging using the independent sample t-test or Mann-Whitney U test and receiver operating characteristic (ROC) curve and multivariate logistic regression analyses and compared the area under the ROC curve of quantitative values using the DeLong test.

Results

The T2 and PD values showed a significant reduction among patients with poor differentiation and lymph node metastasis in rectal cancer. The area under the ROC curve values of T2 and PD values for predicting magnetic resonance imaging N stage and differentiation were 0.734, 0.682, and 0.673, 0.686, respectively. Moreover, combining T2 and PD values for magnetic resonance imaging N stage slightly improved the area under the ROC curve value of 0.774 (95% CI, 0.673-0.876). In the present study, the ADC and T1 values were not significant in the differentiation or clinical stage of rectal cancer (RC).

Conclusions

Quantitative T2 and PD values obtained by synthetic magnetic resonance imaging might be used for evaluating prognostic factors of rectal cancer noninvasively. Furthermore, combining T2 and PD values further improved the diagnostic performance of magnetic resonance imaging N staging in rectal cancer. The ADC and T1 values were not significant in the differentiation or clinical stage of RC.

Liquid biopsies to monitor and direct cancer treatment in colorectal cancer

Colorectal cancer (CRC) is one of the most prevalent and deadly cancers worldwide. Despite recent improvements in treatment and prevention, most of the current therapeutic options are weighted by side effects impacting patients’ quality of life. Better patient selection towards systemic treatments represents an unmet clinical need. The recent multidisciplinary and molecular advancements in the treatment of CRC patients demand the identification of efficient biomarkers allowing to personalise patient care. Currently, core tumour biopsy specimens represent the gold-standard biological tissue to identify such biomarkers. However, technical feasibility, tumour heterogeneity and cancer evolution are major limitations of this single-snapshot approach. Genotyping circulating tumour DNA (ctDNA) has been addressed as potentially overcoming such limitations. Indeed, ctDNA has been retrospectively demonstrated capable of identifying minimal residual disease post-surgery and post-adjuvant treatment, as well as spotting druggable molecular alterations for tailoring treatments in metastatic disease. In this review, we summarise the available evidence on ctDNA applicability in CRC. Then, we review ongoing clinical trials assessing how liquid biopsy can be used interventionally to guide therapeutic choice in localised, locally advanced and metastatic CRC. Finally, we discuss how its widespread could transform CRC patients’ management, dissecting its limitations while suggesting improvement strategies.

Re-staging and follow-up of rectal cancer patients with MR imaging when "Watch-and-Wait" is an option: a practical guide

In the past nearly 20 years, organ-sparing when no apparent viable tumour is present after neoadjuvant therapy has taken an increasingly relevant role in the therapeutic management of locally-advanced rectal cancer patients. The decision to include a patient or not in a “Watch-and-Wait” program relies mainly on endoscopic assessment by skilled surgeons, and MR imaging by experienced radiologists. Strict surveillance using the same modalities is required, given the chance of a local regrowth is of approximately 25–30%, almost always surgically salvageable if caught early. Local regrowths occur at the endoluminal aspect of the primary tumour bed in almost 90% of patients, but the rest are deep within it or outside the rectal wall, in which case detection relies solely on MR Imaging. In this educational review, we provide a practical guide for radiologists who are, or intend to be, involved in the re-staging and follow-up of rectal cancer patients in institutions with an established “Watch-and-Wait” program. First, we discuss patient preparation and MR imaging acquisition technique. Second, we focus on the re-staging MR imaging examination and review the imaging findings that allow us to assess response. Third, we focus on follow-up assessments of patients who defer surgery and confer about the early signs that may indicate a sustained/non-sustained complete response, a rectal/extra-rectal regrowth, and the particular prognosis of the “near-complete” responders. Finally, we discuss our proposed report template.

Role of Magnetic Resonance Imaging in Patients with Rectal Cancer

In a chapter about rectal cancer there is content about rectal anatomy in relation to magnet-resonanse imaging and TME- surgery (total mesorectal excision). Secondly there is content about imaging methods used in diagnosis and follow-up of rectal cancer. Very important topic is concerning the novel imaging strategies in surgical and radiotherapy planning in the era of individual oncologic approach to the patient. At last there is detailed desctiption and metaanalysis of imaging strategies concerning neoadjuvant and adjuvant radiotherapy and chemotherapy for rectal cancer patients. All imaging markers correspond to substantial oncologic parameters such as survival rates. The connecting bridge is magnet-resonance imaging.

Analysis of core processes of the MRI workflow for improved capacity utilization

PURPOSE

To analyze core processes of the MRI workflow and to evaluate efficiency for improved patient throughput and capacity utilization.

METHOD

Prospective data collection was conducted during a four-week time period and a total sum of 160 working hours for each of the two 1.5 T MRI scanners. Three core processes defined the value stream of patient handling before, during and after the MRI examination: i) Scheduling & Registration, ii) Organization & Preparation, and iii) MR scan. Quantitative data was collected for six essential time intervals of the MRI workflow.

RESULTS

A total of 302 MRI examinations were assessed. The workflow analysis revealed that effective utilization of scan capacity during operating hours varied by scanner (Scanner 1: 77 % / Scanner 2: 85 %). Mean process times for were: patient preparation time 18.9 min (±15.1) p = 0.11, scan preparation time 5.7 min (±4.0) p = 0,015, effective scan time 39.6 min (±18.0) p < 0.0001, scan room occupation time 50.9 min (±21.0) p < 0.0001, clean-up time 5.6 min (±3.2) p = 0.001, total patient handling time 69.7 min (±26.3) p < 0.0001, turnover time 13.4 min (±21.4) p = 0.65.

CONCLUSIONS

This study demonstrates the utility and applicability of a standardized core processes analyses for MRI scanning, which identified underutilization of scanning capacities, related to multiple factors, such as punctuality of patients, the number of same day cancellations, the process of placing an IV access and patient transport contribute to underutilization of MRI scanners. Furthermore, proactive patient management and effective communication with patients and referring physicians might have relevant time saving potential in the scan room.

Radiogenomics in Colorectal Cancer

Simple Summary

Colorectal carcinoma is characterized by intratumoral heterogeneity that can be assessed by radiogenomics. Radiomics, high-throughput quantitative data extracted from medical imaging, combined with molecular analysis, through genomic and transcriptomic data, is expected to lead to significant advances in personalized medicine. However, a radiogenomics approach in colorectal cancer is still in its early stages and many problems remain to be solved. Here we review the progress and challenges in this field at its current stage, as well as future developments.

Abstract

The steady improvement of high-throughput technologies greatly facilitates the implementation of personalized precision medicine. Characterization of tumor heterogeneity through image-derived features—radiomics and genetic profile modifications—genomics, is a rapidly evolving field known as radiogenomics. Various radiogenomics studies have been dedicated to colorectal cancer so far, highlighting the potential of these approaches to enhance clinical decision-making. In this review, a general outline of colorectal radiogenomics literature is provided, discussing the current limitations and suggested further developments.

"Rectal cancer survival: A retrospective analysis of MRI features and their association with prognosis"

PURPOSE

To assess rectal cancer aggressiveness using magnetic resonance (MR) imaging features and to investigate their relationship with patient prognosis.

MATERIALS AND METHODS

Clinical information and Pelvic MR scans of 106 consecutive patients with primary rectal cancer (RC) were analyzed. Clinical symptoms, age, sex, tumor location, and patient´s survival were recorded. The variables investigated by MR were: depth or mural/extramural tumor involvement, distance to mesorectal margin, lymph node involvement, vascular, peritoneal or sphincter complex infiltration. The association between imaging features and disease-free survival (DFS) was also assessed using a Kaplan-Meier model. Differences between survival curves were tested for significance using the Mantel-Cox LogRank test.

RESULTS

The final study population was 106 patients (65 males, 41 females). The median age was 69.5 years (range, 39-92 years). No significant differences were found between death risk and sex, age or tumor location (p>0,05). However, the relative risk (RR) of tumor mortality increased significantly with the presence of the variables: vascular infiltration (×5), T4 tumors (× 4.57), N2 lymph node involvement (more than 3 affected nodes × 4.11) and mesorectal fascia involvement (× 3,77).

CONCLUSION

Tumor extension, number of pathological lymph nodes, mesorectal fascia involvement and vascular infiltration values obtained on initial MR imaging staging showed a significant difference for disease-free survival in RC at six years of control.

Does one size fit all? Risks and benefits of neoadjuvant chemoradiation in patients with clinical stage IIA rectal cancer requiring abdominoperineal resection

BACKGROUND

Neoadjuvant chemoradiotherapy (nCRT) has become the standard of care for locally advanced rectal cancer, decreasing locoregional recurrence, yet with an unclear survival advantage. We aimed to assess the benefit of nCRT on oncologic and perioperative outcomes of patients with clinical stage IIA rectal adenocarcinoma treated with abdominoperineal resection (APR).

METHODS

Patients with clinical T3N0 rectal adenocarcinoma that underwent APR between 1995 and 2014 were included. Patients who received nCRT were compared with patients who did not. Multivariate analysis was conducted to compare oncological and perioperative outcomes between the groups.

RESULTS

127 patients were included, of which 94 received nCRT. Median follow-up was 11.9 years. There was no difference in circumferential margins, postoperative morbidity, and complication rates between the groups. There was no difference in 5-year oncological outcomes between the groups.

CONCLUSIONS

No difference was found in 5-year oncological outcomes between patients with clinical T3N0 rectal adenocarcinoma necessitating an APR who received nCRT and those not receiving nCRT, with similar overall complication rates.

Creation of a rectal cancer registry in Italy by the Advanced International Mini-Invasive Surgery (AIMS) academy clinical research network

Background: The management of rectal cancer is multimodal and involves a multidisciplinary team of cancer specialists with expertise in medical oncology, surgical oncology, radiation oncology and radiology. It is crucial for highly specialized centers to collaborate via networks that aim to maintain uniformity in every aspect of treatment and rigorously gather patients’ data, from the first clinical evaluation to the last follow-up visit.

The Advanced International Mini-Invasive Surgery (AIMS) academy clinical research network aims to create a rectal cancer registry. This will prospectively collect the data of patients operated on for non-metastatic rectal cancer in high volume colorectal surgical units through a well design pre-fashioned database for non-metastatic rectal cancer, in order to take all multidisciplinary aspects into consideration.

Methods/Design: The protocol describes a multicenter prospective observational cohort study, investigating demographics, frailty, cancer-related features, surgical and radiological parameters, and oncological outcomes among patients with non-metastatic rectal cancer who are candidates for surgery with curative intent. Patients enrolled in the present registry will be followed up for 5 years after surgery.

Discussion: Standardization and centralization of data collection for neoplastic diseases is a virtuous process for patient care. The creation of a register will allow the control of the quality of treatments provided and permit prospective and retrospective studies to be carried out on complete and reliable high quality data. Establishing data collection in a prospective and systematic fashion is the only possibility to preserve the enormous resource that each patient represents.

Role of magnetic resonance imaging in organ-preserving strategies for the management of patients with rectal cancer

Total mesorectal excision has been the most effective treatment strategy adopted to reduce local recurrence rates among patients with rectal cancer. The morbidity associated with this radical surgical procedure led surgeons to challenge the standard therapy particularly when dealing with superficial lesions or good responders after neoadjuvant radiotherapy, to which radical surgery may be considered overtreatment. In this subset of patients, less invasive procedures in an organ-preserving strategy may result in good oncological and functional outcomes. In order to tailor the most appropriate treatment option, accurate baseline staging and reassessment of tumor response are relevant. MRI is the most robust tool for the precise selection of patients that are candidates for organ preservation; therefore, radiologists must be familiar with the criteria used to guide the management of these patients. The purpose of this article is to review the relevant features that radiologists should know in order to provide valuable information during the multidisciplinary discussion and ultimate management decision.

CT Staging to Triage Selection of Patients With Poor-Prognosis Rectal Cancer for Neoadjuvant Treatment

OBJECTIVE. The purpose of this study was to evaluate CT as a screening tool for determining high risk of local recurrence of rectal tumors in a scenario of limited MRI availability. MATERIALS AND METHODS. Data were retrospectively analyzed for 180 consecutively registered patients with rectal adenocarcinoma and no previous treatment who underwent baseline CT and MRI staging within 30 days of each other. Two radiologists independently reviewed CT and MR images. CT scans were interpreted in multiplanar reformation. High risk of local recurrence was based on the MRI reference standard: T3cd (more than 5 mm of mesorectal fat infiltration) or T4 disease, N2 nodal status, mesorectal fascia involvement, extramural venous invasion, or positive pelvic sidewall nodes. The performance of CT for determination of high risk of local tumor recurrence was evaluated. RESULTS. Among the 180 patients 128 (71%) met MRI criteria for high risk of local recurrence. CT sensitivity was 84.4% (108/128) and specificity was 78.8% (41/52). The positive predictive value (PPV) of any high-risk CT feature was 90.7% (108/119). When T status was considered, the sensitivity of CT was 75.2% (79/105), specificity was 90.7% (68/75), and PPV was 91.9% (79/86). When tumors within 5.0 cm of the anal verge were excluded, sensitivity was 89.5% (51/57), specificity was 85.7% (24/28), and PPV was 92.7% (51/55). Using CT for disease staging could reduce MRI use by 66%. CONCLUSION. Tumors at high risk of local recurrence can be identified with CT without baseline MRI. Use of CT rather than MRI could markedly reduce costs of baseline staging and shorten time to initiation of neoadjuvant treatment.

[Evidence-based surgery of rectal cancer]

Over the past four decades, the treatment algorithms for rectal cancer have fundamentally changed, which resulted in a considerable improvement of oncological outcomes. In this context, the surgical concept of total mesorectal excision and the implementation of multimodal treatment strategies represent key milestones. These improvements were complemented by a standardized histopathological work-up of the surgical specimen and the introduction of high-resolution magnetic resonance imaging (MRI) diagnostics. In addition, novel surgical techniques have been introduced, such as laparoscopic and robotic rectal resection. Other technological innovations include intraoperative pelvic neuromonitoring and fluorescence imaging. This review highlights the current evidence for selected, sometimes controversially discussed principles of surgical treatment strategies in rectal cancer.

The role of imaging and biopsy in the management and staging of large non-pedunculated rectal polyps

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are often used for benign and Sm1 large non-pedunculated rectal polyps (LNPRPs), although other surgical techniques including transanal endoscopic microsurgery (TEMS) and transanal minimal invasive surgery remain available. This review covers the role of pre-excisional imaging and selective biopsy of LNPRPs. Areas covered: Polyps between 2 and 3 cm with favorable features (Paris 1, Kudo III/IV pit patterns, and non-lateral spreading type [LST]) may have a one-stage EMR without biopsy and imaging, provided adequate expertise is available with other technologies such as magnifying chromoendoscopy. Higher-risk polyps (moderate/severe dysplasia, 0-IIa+c morphology, nongranular LST, Kudo pit pattern V or submucosal carcinoma, or those >3 cm) should have pre-EMR/ESD imaging with magnetic resonance imaging (MRI) and/or endorectal ultrasound (ERUS) ± biopsies and photographs prior to multidisciplinary team discussion. Expert commentary: In some centers, EMR and ESD are considered the primary modality of treatment, with TEMS as a back-up, while elsewhere, TEMS is the main modality for excision of significant polyps and early colorectal cancer lesions. Likewise, the exact roles of ERUS and MRI will depend on availability of local expertise, although it is suggested that the techniques are complementary.