Optimal Imaging Strategies for Rectal Cancer Staging and Ongoing Management. Curr Treat Options Oncol. 2016;17:32. [PMID: 27255100 PMCID: PMC4891388 DOI: 10.1007/s11864-016-0403-7]

Oncological outcomes of local excision versus radical surgery for early rectal cancer in the context of staging and surveillance: A systematic review and meta-analysis

BACKGROUND

Local resection (LR) methods for rectal cancer are generally considered in the palliative setting or for patients deemed a high anaesthetic risk. This systematic review and meta-analysis aimed to compare oncological outcomes of LR and radical resection (RR) for early rectal cancer in the context of staging and surveillance assessment.

METHODS

A literature search of MEDLINE, Embase and Emcare databases was performed for studies that reported data on clinical outcomes for both LR and RR for early rectal cancer from January 1995 to April 2023. Meta-analysis was performed using random-effect models and between-study heterogeneity was assessed. The quality of assessment was assessed using the Newcastle-Ottawa Scale for observational studies and the Cochrane Risk of Bias 2.0 tool for randomised controlled trials.

RESULTS

Twenty studies with 12,022 patients were included: 6,476 patients had LR and 5,546 patients underwent RR. RR led to an improvement in 5-year overall survival (OR 1.84; 95 % CI 1.54-2.20; p < 0.0001; I2 20 %) and local recurrence (OR 3.06; 95 % CI 2.02-4.64; p < 0.0001; I2 39 %) when compared to LR. However, when staging and surveillance methods were clearly adopted in LR cases, there was an improvement in R0 rates (96.7 % vs 85.6 %), 5-year disease-free survival (93.0 % vs 77.9 %) and overall survival (81.6 % vs 79.0 %) compared to when staging and surveillance was not reported/performed.

CONCLUSIONS

LR may be appropriate for selected patients without poor prognostic factors in early rectal cancer. This study also highlights that there is currently no single standardised staging or surveillance approach being adopted in the management of early rectal cancer. A more specified and standardised preoperative staging for patient selection as well as clinical and image-based surveillance protocols is needed.

T2-weighted imaging-based radiomic-clinical machine learning model for predicting the differentiation of colorectal adenocarcinoma

BACKGROUND

The study on predicting the differentiation grade of colorectal cancer (CRC) based on magnetic resonance imaging (MRI) has not been reported yet. Developing a non-invasive model to predict the differentiation grade of CRC is of great value.

AIM

To develop and validate machine learning-based models for predicting the differentiation grade of CRC based on T2-weighted images (T2WI).

METHODS

We retrospectively collected the preoperative imaging and clinical data of 315 patients with CRC who underwent surgery from March 2018 to July 2023. Patients were randomly assigned to a training cohort (n = 220) or a validation cohort (n = 95) at a 7:3 ratio. Lesions were delineated layer by layer on high-resolution T2WI. Least absolute shrinkage and selection operator regression was applied to screen for radiomic features. Radiomics and clinical models were constructed using the multilayer perceptron (MLP) algorithm. These radiomic features and clinically relevant variables (selected based on a significance level of P < 0.05 in the training set) were used to construct radiomics-clinical models. The performance of the three models (clinical, radiomic, and radiomic-clinical model) were evaluated using the area under the curve (AUC), calibration curve and decision curve analysis (DCA).

RESULTS

After feature selection, eight radiomic features were retained from the initial 1781 features to construct the radiomic model. Eight different classifiers, including logistic regression, support vector machine, k-nearest neighbours, random forest, extreme trees, extreme gradient boosting, light gradient boosting machine, and MLP, were used to construct the model, with MLP demonstrating the best diagnostic performance. The AUC of the radiomic-clinical model was 0.862 (95%CI: 0.796-0.927) in the training cohort and 0.761 (95%CI: 0.635-0.887) in the validation cohort. The AUC for the radiomic model was 0.796 (95%CI: 0.723-0.869) in the training cohort and 0.735 (95%CI: 0.604-0.866) in the validation cohort. The clinical model achieved an AUC of 0.751 (95%CI: 0.661-0.842) in the training cohort and 0.676 (95%CI: 0.525-0.827) in the validation cohort. All three models demonstrated good accuracy. In the training cohort, the AUC of the radiomic-clinical model was significantly greater than that of the clinical model (P = 0.005) and the radiomic model (P = 0.016). DCA confirmed the clinical practicality of incorporating radiomic features into the diagnostic process.

CONCLUSION

In this study, we successfully developed and validated a T2WI-based machine learning model as an auxiliary tool for the preoperative differentiation between well/moderately and poorly differentiated CRC. This novel approach may assist clinicians in personalizing treatment strategies for patients and improving treatment efficacy.

An automated deep learning pipeline for EMVI classification and response prediction of rectal cancer using baseline MRI: a multi-centre study

The classification of extramural vascular invasion status using baseline magnetic resonance imaging in rectal cancer has gained significant attention as it is an important prognostic marker. Also, the accurate prediction of patients achieving complete response with primary staging MRI assists clinicians in determining subsequent treatment plans. Most studies utilised radiomics-based methods, requiring manually annotated segmentation and handcrafted features, which tend to generalise poorly. We retrospectively collected 509 patients from 9 centres, and proposed a fully automated pipeline for EMVI status classification and CR prediction with diffusion weighted imaging and T2-weighted imaging. We applied nnUNet, a self-configuring deep learning model, for tumour segmentation and employed learned multiple-level image features to train classification models, named MLNet. This ensures a more comprehensive representation of the tumour features, in terms of both fine-grained detail and global context. On external validation, MLNet, yielding similar AUCs as internal validation, outperformed 3D ResNet10, a deep neural network with ten layers designed for analysing spatiotemporal data, in both CR and EMVI tasks. For CR prediction, MLNet showed better results than the current state-of-the-art model using imaging and clinical features in the same external cohort. Our study demonstrated that incorporating multi-level image representations learned by a deep learning based tumour segmentation model on primary MRI improves the results of EMVI classification and CR prediction with good generalisation to external data. We observed variations in the contributions of individual feature maps to different classification tasks. This pipeline has the potential to be applied in clinical settings, particularly for EMVI classification.

Bowel wall thickness measured by MRI is useful for early diagnosis of bowel endometriosis

OBJECTIVE

To evaluate MRI features of bowel endometriosis (BE) and verify its clinical significance compared with pathological diagnosis.

MATERIALS AND METHODS

Since 2018, patients clinically diagnosed with deep endometriosis (DE) and planned to undergo surgery were enrolled prospectively. MRI parameters including traction, thickening sign of the rectum, obliteration of the Douglas Pouch, sign of adenomyosis, and pelvic adhesion were extracted. Uni- and multi-variate analyses were performed to explore their association with pathological diagnosis of BE. ROC curve was utilized to ascertain the appropriate cutoff value for predicting the presence and assessing the severity of BE.

RESULTS

A total of 226 patients with DE were recruited, and 154 BE cases were pathologically confirmed. Logistic regression analysis revealed that thickness of the rectal wall, traction sign of the rectum, and obliteration of the Douglas Pouch were independent factors to predict the presence of BE with the OR 1.59 (95% CI: 1.29-1.96), 0.24 (95% CI: 0.09-0.67), and 0.17 (95% CI: 0.07-0.40), respectively (p all < 0.01). A cutoff value of 6.0 mm for the thickness of rectal wall resulted in the highest predictive value of BE (specificity: 90.3%; sensitivity: 78.6%). For patients with measured thickness of the rectal wall over 6.0 mm, 72.1% (93/129) was confirmed BE with lesions infiltrated more than muscular layer.

CONCLUSION

This prospective study indicates that based on precise definition of visualized features on MRI images, BE could be recognized pre-operatively. DE patients with thickness of rectal wall exceeding 6.0 mm have a greater probability of BE.

CLINICAL RELEVANCE STATEMENT

Based on precise definition of visualized features and accurate measurement on MRI images, bowel infiltrating among deep endometriosis patients could be recognized pre-operatively.

KEY POINTS

• Precise definition of measurable MRI parameters made it possible for early detection of bowel endometriosis. • Thickening sign, traction sign of the rectum, and obliteration of the Douglas Pouch were typical radiological indicators for bowel endometriosis. • Bowel involvement is more sensitive to be detected among pelvic deep endometriosis patients with the thickness of the rectal wall over 6.0 mm.

Results of a diagnostic imaging audit in a randomised clinical trial in rectal cancer highlight the importance of careful planning and quality control

BACKGROUND

Magnetic resonance (MR) imaging is the modality used for baseline assessment of locally advanced rectal cancer (LARC) and restaging after neoadjuvant treatment. The overall audited quality of MR imaging in large multicentre trials on rectal cancer is so far not routinely reported.

MATERIALS AND METHODS

We collected MR images obtained within the Rectal Cancer And Pre-operative Induction Therapy Followed by Dedicated Operation (RAPIDO) trial and performed an audit of the technical features of image acquisition. The required MR sequences and slice thickness stated in the RAPIDO protocol were used as a reference.

RESULTS

Out of 920 participants of the RAPIDO study, MR investigations of 668 and 623 patients in the baseline and restaging setting, respectively, were collected. Of these, 304/668 (45.5%) and 328/623 (52.6%) MR images, respectively, fulfilled the technical quality criteria. The main reason for non-compliance was exceeding slice thickness 238/668, 35.6% in the baseline setting and 162/623, 26.0% in the restaging setting. In 166/668, 24.9% and 168/623, 27.0% MR images in the baseline and restaging setting, respectively, one or more of the required pulse sequences were missing.

CONCLUSION

Altogether, 49.0% of the MR images obtained within the RAPIDO trial fulfilled the image acquisition criteria required in the study protocol. High-quality MR imaging should be expected for the appropriate initial treatment and response evaluation of patients with LARC, and efforts should be made to maximise the quality of imaging in clinical trials and in clinical practice.

CRITICAL RELEVANCE STATEMENT

This audit highlights the importance of adherence to MR image acquisition criteria for rectal cancer, both in multicentre trials and in daily clinical practice. High-resolution images allow correct staging, treatment stratification and evaluation of response to neoadjuvant treatment.

KEY POINTS

- Complying to MR acquisition guidelines in multicentre trials is challenging. - Neglection on MR acquisition criteria leads to poor staging and treatment. - MR acquisition guidelines should be followed in trials and clinical practice. - Researchers should consider mandatory audits prior to study initiation.

Predicting multiple linear stapler firings in double stapling technique with an MRI-based deep-learning model

Multiple linear stapler firings is a risk factor for anastomotic leakage (AL) in laparoscopic low anterior resection (LAR) using double stapling technique (DST) anastomosis. In this study, our objective was to establish the risk factors for ≥ 3 linear stapler firings, and to create and validate a predictive model for ≥ 3 linear stapler firings in laparoscopic LAR using DST anastomosis. We retrospectively enrolled 328 mid-low rectal cancer patients undergoing laparoscopic LAR using DST anastomosis. With a split ratio of 4:1, patients were randomly divided into 2 sets: the training set (n = 260) and the testing set (n = 68). A clinical predictive model of ≥ 3 linear stapler firings was constructed by binary logistic regression. Based on three-dimensional convolutional networks, we built an image model using only magnetic resonance (MR) images segmented by Mask region-based convolutional neural network, and an integrated model based on both MR images and clinical variables. Area under the curve (AUC), sensitivity, specificity, accuracy, positive predictive value (PPV), and Youden index were calculated for each model. And the three models were validated by an independent cohort of 128 patients. There were 17.7% (58/328) patients received ≥ 3 linear stapler firings. Tumor size ≥ 5 cm (odds ratio (OR) = 2.54, 95% confidence interval (CI) = 1.15-5.60, p = 0.021) and preoperative carcinoma embryonic antigen (CEA) level > 5 ng/mL [OR = 2.20, 95% CI = 1.20-4.04, p = 0.011] were independent risk factors associated with ≥ 3 linear stapler firings. The integrated model (AUC = 0.88, accuracy = 94.1%) performed better on predicting ≥ 3 linear stapler firings than the clinical model (AUC = 0.72, accuracy = 86.7%) and the image model (AUC = 0.81, accuracy = 91.2%). Similarly, in the validation set, the integrated model (AUC = 0.84, accuracy = 93.8%) performed better than the clinical model (AUC = 0.65, accuracy = 65.6%) and the image model (AUC = 0.75, accuracy = 92.1%). Our deep-learning model based on pelvic MR can help predict the high-risk population with ≥ 3 linear stapler firings in laparoscopic LAR using DST anastomosis. This model might assist in determining preoperatively the anastomotic technique for mid-low rectal cancer patients.

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

Purpose

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

Materials and Methods

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

Results

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

Conclusion

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

A radiomics model based on magnetic resonance imaging to predict cytokeratin 7/19 expression and liver fluke infection of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. HCC with liver fluke infection could harbor unique biological behaviors. This study was aimed at investigating radiomics features of HCC with liver fluke infection and establishing a model to predict the expression of cytokeratin 7 (CK7) and cytokeratin 19 (CK19) as well as prognosis at the same time. A total of 134 HCC patients were included. Gadoxetic acid-enhanced magnetic resonance imaging (MRI) images of all patients were acquired. Radiomics features of the tumor were extracted and then data dimensionality was reduced. The radiomics model was established to predict liver fluke infection and the radiomics score (Radscore) was calculated. There were 11 features in the four-phase combined model. The efficiency of the combined model increased significantly compared to each single-phase MRI model. Radscore was an independent predictor of liver fluke infection. It was also significantly different between different expression of CK7/ CK19. Meanwhile, liver fluke infection was associated with CK7/CK19 expression. A cut-off value was set up and all patients were divided into high risk and low risk groups of CK7/CK19 positive expression. Radscore was also an independent predictor of these two biomarkers. Overall survival (OS) and recurrence free survival (RFS) of negative liver fluke infection group were significantly better than the positive group. OS and RFS of negative CK7 and CK19 expression were also better, though not significantly. Positive liver fluke infection and CK19 expression prediction groups harbored significantly worse OS and RFS, survival of positive CK7 expression prediction was unsatisfying as well. A radiomics model was established to predict liver fluke infection among HCC patients. This model could also predict CK7 and CK19 expression. OS and RFS could be foreseen by this model at the same time.

Magnetic resonance imaging accuracy in staging early and locally advanced rectal cancer

INTRODUCTION

Magnetic Resonance Imaging (MRI) is the standard pretreatment staging in patients with rectal cancer. Accurate tumor staging is paramount to determining the appropriate treatment course for patients diagnosed with rectal cancer. The current study aims to re-evaluate the accuracy of pre-operative MRI in staging of both early and locally advanced rectal cancer following completion of neoadjuvant therapy (NAT) compared to the pathologic stage.

METHODS

A retrospective review of patients treated for rectal cancer between 2015 and 2020 at a single academic institution. All patients underwent rectal cancer protocol MRIs before surgical resection. Analysis was carried out in two groups: early rectal cancer: T1/2 N0 tumors with upfront surgical resection (N = 40); and locally advanced disease: T3 or greater or N+ disease receiving NAT, with restaging MRI following NAT (n = 63).

RESULTS

103 patients were included in analysis. MRI accuracy in early tumors was 35% ICC = 0.52 (95% CI 0.25-0.71) T stage and 66% ICC = 0 (95% CI -0.24, 0.29) for 29 patients with nodal data for N stage. There was 28% understaging of T2 tumors and 34% understaging of N0 stage by MRI. Post NAT MRI had 44% accuracy ICC = 0.57 (95% CI -0.15-0.20) T stage and 60% accuracy ICC = 0.32 (95% CI 0.08-0.52) N stage. Tumor invasion was overstaged on MRI: 40% T2, 29% T3, 90% T4. Nodal inaccuracy was due to overstaging, 61% N1, 90% N2.

CONCLUSIONS

In locally advanced rectal cancer MRI overstaged tumors, this could be due to the continued effect of NAT from MRI to resection. This overstaging is of little clinical significance as it doesn't alter the treatment plan, except in cases of complete clinical response. In early rectal cancer, MRI had limited accuracy compared to pathology, understaging a quarter of patients who would benefit from NAT before surgery. Other adjunct imaging modalities should be considered to improve accuracy in staging early rectal cancer and consideration of complete response and enrollment in watch and wait protocols.

Management and Outcomes of Pathologic Upstaging of Clinical Stage I Rectal Cancers: An Exploratory Analysis

BACKGROUND

Preoperative staging of clinical stage I rectal cancer can fail to diagnose T3 or nodal disease. Adjuvant treatment of these upstaged patients remains controversial.

OBJECTIVE

The objective was to identify predictors of clinical stage I rectal cancer upstaging and quantify rates of local and systemic recurrence.

DESIGN

This was a retrospective cohort study.

SETTINGS

The study was conducted using data from the United States Rectal Cancer Consortium, a registry of 1881 rectal cancer resections performed at 6 academic medical centers.

PATIENTS

There were a total of 94 clinical stage I rectal cancer patients who underwent proctectomy without preoperative therapy.

MAIN OUTCOME MEASURES

The primary measures were incidence of pathologic upstaging, recurrence (local and systemic), and overall survival.

RESULTS

Among 94 clinical stage I patients who underwent proctectomy without preoperative therapy, 23 (24.5%) were upstaged by surgical pathology. There were 6 pT3N0 patients, 8 pT1-2N+ patients, and 9 pT3N+ patients. There were no significant differences in demographic or clinical characteristics between upstaged and nonupstaged patients. Of the 6 patients who were upstaged to T3N0 disease, none received adjuvant therapy and none developed recurrence. Of the 17 patients who were upstaged to N+ disease, 14 (82%) received adjuvant chemotherapy and 6 (35%) received adjuvant chemoradiation. None developed a local recurrence, but 4 (24%) developed systemic recurrence, and 2 (12%) died of disease over a mean of 36 months of follow-up. Among the 9 pT3N+ patients, the systemic recurrence rate was 33%, despite 8 of 9 patients receiving adjuvant fluorouracil, leucovorin, and oxaliplatin.

LIMITATIONS

Small sample size hinders the ability to draw significant conclusions.

CONCLUSIONS

One in 4 patients with stage I rectal cancer had unrecognized T3 or nodal disease found on operative pathology. Occult nodal disease was associated with worse outcomes, despite receiving adjuvant therapy. Systemic recurrence was more common than local recurrence. See Video Abstract at http://links.lww.com/DCR/B885 .

MANEJO Y RESULTADOS DEL AUMENTO DEL ESTADIO PATOLGICO DE LOS CNCERES DE RECTO EN ESTADIO CLNICO I UN ANLISIS EXPLORATORIO

ANTECEDENTES:El estadiaje pre-operatorio del cáncer de recto en fase clínica I puede ser erróneo en el diagnóstico T3 o en la diseminación ganglionar. El tratamiento adyuvante de estos pacientes sobre-estadificados ​​sigue siendo controvertido.OBJETIVO:El identificar los factores predictivos en fase clínica I del cáncer de recto y cuantificar las tasas de recurrencia local y sistémica.DISEÑO:Estudio de cohortes retrospectivo.AJUSTE:El estudio se realizó utilizando los datos del Consorcio del Cáncer de Recto de los Estados Unidos, con un registro de 1.881 resecciones oncológicas rectales realizadas en seis centros médicos académicos.PACIENTES:Un total de 94 pacientes con cáncer de recto en fase clínica I fueron sometidos a proctectomía sin terapia preoperatoria.PRINCIPALES MEDIDAS DE RESULTADO:Las medidas primarias fueron la incidencia del sobre-estadiaje histopatológico, la recurrencia (local y sistémica) y la sobrevida general.RESULTADOS:De 94 pacientes en fase clínica I que se sometieron a una proctectomía sin terapia preoperatoria, 23 (24,5%) fueron sobre-estadiados ​​por la histopatología quirúrgica. Hubieron 6 pacientes pT3N0, 8 pT1-2N + y 9 pT3N +. No hubo diferencias significativas en las características demográficas o clínicas entre los pacientes sobre-estadiados ​​y los no sobre-estadiados. De los 6 pacientes que fueron sobre-estadiados en la enfermedad T3N0, ninguno de ellos recibió terapia adyuvante y ninguno recidivó. De los 17 pacientes que fueron sobre-estadiados a la enfermedad N +, 14 (82%) recibieron quimioterapia adyuvante y 6 (35%) recibieron quimio-radioterapia adyuvante. Ninguno desarrolló recidiva local, pero 4 (24%) desarrollaron recidiva sistémica y 2 (12%) murieron a causa de la enfermedad durante el seguimiento medio de 36 meses. Entre los 9 pacientes con pT3N +, la tasa de recidiva sistémica fue del 33%, a pesar de que 8 de 9 pacientes recibieron fluorouracilo, leucovorina y oxaliplatino como quimio-adyuvantes.LIMITACIONES:El tamaño pequeño de la muestra dificulta la capacidad de obtener conclusiones significativas.CONCLUSIONES:Uno de cada cuatro pacientes con cáncer de recto en estadío I presentaba enfermedad ganglionar o T3 no descrita en la histopatología operatoria. La enfermedad ganglionar oculta se asoció con peores resultados, a pesar de recibir terapia adyuvante. La recidiva sistémica fue más común que la recidiva local. Consulte Video Resumen en http://links.lww.com/DCR/B885 . (Traducción-Dr. Xavier Delgadillo ).

Clinical feasibility of the therapeutic strategies total neoadjuvant therapy and "watch and wait" in the treatment of rectal cancer patients with recurrence after clinical complete response

Purpose

In recent years, total neoadjuvant therapy (TNT) has emerged as a new therapeutic strategy against advanced rectal cancer (RC). After administration of TNT, some patients show complete clinical response (cCR) to treatment however, disputes about the effects of TNT and the alternative treatment plans in case of recurrence after cCR still exist.

Methods

A total of 100 patients were included in this paper. CR and non-CR was observed when these patients were administered with TNT at the First Affiliated Hospital of Dalian Medical University, China from May 2015 to June 2021. These patients received different chemotherapeutic regimens, with close monitoring and watch and wait (W&W) strategy being applied by a multidisciplinary team (MDT). According to treatment results, patients were divided into a cCR group and a non-cCR group; according to the recurrence during W&W, they were divided into a recurrence group and a no-local-recurrence group. This study analyzed the factors that may affect the prognosis, and summarized the surgery and treatment after recurrence.

Results

The TNT strategy was effective, and 85% of patients achieved local remission. However, W&W did not affect the survival time of CR patients, nor did it cause new distant metastasis due to local recurrence during the observation period (P > 0.05). However, for patients with positive CRM, we do not recommend W&W as the first choice of treatment (P < 0.05).

Conclusion

(1) Whole-course neoadjuvant therapy was an effective treatment scheme for advanced mid-term rectal cancer. The total local reduction rate of this group of cases was 85.00%, meaning that 25 patients achieved CR. (2) W&W was safe and reliable, and CR patients could receive it as the preferred treatment. (3) CRM was an independent risk factor for local recurrence in CR patients. We do not recommend W&W as the preferred treatment for CR patients with positive CRM.

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 ).

Value of texture analysis based on dynamic contrast-enhanced magnetic resonance imaging in preoperative assessment of extramural venous invasion in rectal cancer

Objective

Accurate preoperative assessment of extramural vascular invasion (EMVI) is critical for the treatment and prognosis of rectal cancer. The aim of our research was to develop an assessment model by texture analysis for preoperative prediction of EMVI.

Materials and methods

This study enrolled 44 rectal patients as train cohort, 7 patients as validation cohort and 18 patients as test cohort. A total of 236 texture features from DCE MR imaging quantitative parameters were extracted for each patient (59 features of Ktrans, Kep, Ve and Vp), and key features were selected by least absolute shrinkage and selection operator regression (LASSO). Finally, clinical independent risk factors, conventional MRI assessment, and T-score were incorporated to construct an assessment model using multivariable logistic regression.

Results

The T-score calculated using the 4 selected key features were significantly correlated with EMVI (p < 0.010). The area under the receiver operating characteristic curve (AUC) was 0.797 for discriminating between EMVI-positive and EMVI-negative patients with a sensitivity of 88.2% and specificity of 70.4%. The conventional MRI assessment of EMVI had a sensitivity of 23.53% and a specificity of 96.30%. The assessment model showed a greatly improved performance with an AUC of 0.954 (sensitivity, 88.2%; specificity, 92.6%) in train cohort, 0.833 (sensitivity, 66.7%; specificity, 100%) in validation cohort and 0.877 in test cohort, respectively.

Conclusions

The assessment model showed an excellent performance in preoperative assessment of EMVI. It demonstrates strong potential for improving the accuracy of EMVI assessment and provide a reliable basis for individualized treatment decisions.

Neoadjuvant FOLFOXIRI prior to chemoradiotherapy for high-risk ("ugly") locally advanced rectal cancer: study protocol of a single-arm, multicentre, open-label, phase II trial (MEND-IT)

Background

The presence of mesorectal fascia (MRF) invasion, grade 4 extramural venous invasion (EMVI), tumour deposits (TD) or extensive or bilateral extramesorectal (lateral) lymph nodes (LLN) on MRI has been suggested to identify patients with indisputable, extensive locally advanced rectal cancer (LARC), at high risk of treatment failure. The aim of this study is to evaluate whether or not intensified chemotherapy prior to neoadjuvant chemoradiotherapy improves the complete response (CR) rate in these patients.

Methods

This multicentre, single-arm, open-label, phase II trial will include 128 patients with non-metastatic high-risk LARC (hr-LARC), fit for triplet chemotherapy. To ensure a study population with indisputable, unfavourable prognostic characteristics, hr-LARC is defined as LARC with on baseline MRI at least one of the following characteristics; MRF invasion, EMVI grade 4, enlarged bilateral or extensive LLN at high risk of an incomplete resection, or TD. Exclusion criteria are the presence of a homozygous DPD deficiency, distant metastases, any chemotherapy within the past 6 months, previous radiotherapy within the pelvic area precluding standard chemoradiotherapy, and any contraindication for the planned treatment. All patients will be planned for six two-weekly cycles of FOLFOXIRI (5-fluorouracil, leucovorin, oxaliplatin and irinotecan) prior to chemoradiotherapy (25 × 2 Gy or 28 × 1.8 Gy with concomitant capecitabine). A resection will be performed following radiological confirmation of resectable disease after the completion of chemoradiotherapy. A watch and wait strategy is allowed in case of a clinical complete response. The primary endpoint is the CR rate, described as a pathological CR or a sustained clinical CR one year after chemoradiotherapy. The main secondary objectives are long-term oncological outcomes, radiological and pathological response, the number of resections with clear margins, treatment-related toxicity, perioperative complications, health-related costs, and quality of life.

Discussion

This trial protocol describes the MEND-IT study. The MEND-IT study aims to evaluate the CR rate after intensified chemotherapy prior to concomitant chemoradiotherapy in a homogeneous group of patients with locally advanced rectal cancer and indisputably unfavourable characteristics, defined as hr-LARC, in order to improve their prognosis.

Trial registration

Clinicaltrials.gov: NCT04838496, registered on 02–04-2021 Netherlands Trial Register: NL9790.

Protocol version

Version 3 dd 11–4-2022.

Endorectal Ultrasound Shear-Wave Elastography of Complex Rectal Adenoma and Early Rectal Cancer

Purpose: To investigate the diagnostic performance of endorectal ultrasound (ERUS), shear-wave elastography (SWE), and magnetic resonance imaging (MRI) in patients with a complex rectal adenoma or an early rectal cancer, i.e., T1 or T2 adenocarcinoma in a clinical setting, and to evaluate the association between SWE and stromal fraction (SF) and apparent diffusion coefficient (ADC) and SF. Method: This prospective study included patients undergoing ERUS and SWE for a rectal tumor subsequently confirmed by histopathology to be an adenoma or a T1 or T2 adenocarcinoma. The accuracy of the imaging methods was assessed by comparing the T category as determined by ERUS and MRI with histopathology, which served as the gold standard. SF was assessed on surgical specimens. Results: A total of 86 patients were included. Of these, 62 patients had adenomas and 24 patients had carcinomas, of which 11 were T1 tumors and 13 were T2 tumors. ERUS and MRI yielded sensitivity, specificity, and accuracy of 0.79 and 0.73, 0.95 and 0.90, and 0.86 and 0.78, respectively, for discrimination between benign and malignant lesions. The area under the receiver operating characteristics curve for SWE was 0.88, and with a cut-off value of 40 kPa the sensitivity, specificity, and accuracy were 0.79, 0.89, and 0.86, respectively. There was a positive correlation between SF and SWE with a p-value of <0.001 and a negative correlation between SF and ADC with a p-value of 0.011. Conclusion: Both ERUS and MRI classified T categories with a high accuracy; however, ERUS classified more adenomas correctly than MRI. In this small population, SWE could differentiate an adenoma from early carcinoma. SF was correlated with both SWE and ADC, as increasing SF tended to yield higher SWE and lower ADC values.

Multimodal Treatment of Rectal Cancer

BACKGROUND

Colorectal cancer is one of the three most common types of cancer in Germany. Approximately 30% of these cancers are located in the rectum, corresponding to about 18 000 new cases per year.

METHODS

This review is based on publications retrieved by a selective search in the PubMed database, including current guidelines and recommendations.

RESULTS

Specialized imaging, particularly magnetic resonance imaging, is essential for treatment planning. In very early stages of this disease, tumors without risk factors can be excised locally. Otherwise, radical surgical resection with lymphadenectomy remains the standard treatment, and can be performed either minimally invasive or open. At present, neoadjuvant treatment plans are evolving in the direction of total neoadjuvant therapy. In addition, recent studies investigate whether the improved efficacy of neoadjuvant therapy might now enable patients with a complete clinical remission to be spared from surgical resection (organ-preserving watch-and-wait strategy).

CONCLUSION

The treatment of rectal cancer is a prime example of an interdisciplinary, multimodal approach. In the past, the focus was mainly on improving oncologic outcomes; at present, increasing attention is being devoted to the patients' quality of life as well and the functional aspects of the various modes of treatment.

Artificial intelligence–based technology for semi-automated segmentation of rectal cancer using high-resolution MRI

Aim

Although MRI has a substantial role in directing treatment decisions for locally advanced rectal cancer, precise interpretation of the findings is not necessarily available at every institution. In this study, we aimed to develop artificial intelligence-based software for the segmentation of rectal cancer that can be used for staging to optimize treatment strategy and for preoperative surgical simulation.

Method

Images from a total of 201 patients who underwent preoperative MRI were analyzed for training data. The resected specimen was processed in a circular shape in 103 cases. Using these datasets, ground-truth labels were prepared by annotating MR images with ground-truth segmentation labels of tumor area based on pathologically confirmed lesions. In addition, the areas of rectum and mesorectum were also labeled. An automatic segmentation algorithm was developed using a U-net deep neural network.

Results

The developed algorithm could estimate the area of the tumor, rectum, and mesorectum. The Dice similarity coefficients between manual and automatic segmentation were 0.727, 0.930, and 0.917 for tumor, rectum, and mesorectum, respectively. The T2/T3 diagnostic sensitivity, specificity, and overall accuracy were 0.773, 0.768, and 0.771, respectively.

Conclusion

This algorithm can provide objective analysis of MR images at any institution, and aid risk stratification in rectal cancer and the tailoring of individual treatments. Moreover, it can be used for surgical simulations.

Minimally Invasive Endoscopic and Surgical Management of Rectal Neoplasia

Rectal cancer demonstrates a characteristic natural history in which benign rectal neoplasia precedes malignancy. The worldwide burden of rectal cancer is significant, with rectal cancer accounting for one-third of colorectal cancer cases annually. The importance of early detection and successful management is essential in decreasing its clinical burden. Minimally invasive treatment of rectal neoplasia has evolved over the past several decades, which has led to reduced local recurrence rates and improved survival outcomes. The approach to diagnosis, staging, and selection of appropriate treatment modalities is a multidisciplinary effort combining interventional endoscopy, surgery, and radiology tools. This review examines the currently available minimally invasive endoscopic and surgical management options of rectal neoplasia.

Endorectal Ultrasonography and Pelvic Magnetic Resonance Imaging Show Similar Diagnostic Accuracy in Local Staging of Rectal Cancer: An Update Systematic Review and Meta-Analysis

Background: Endorectal Ultrasonography (EUS-ERUS) and pelvic magnetic resonance imaging (MRI) are world-wide performed for the local staging of rectal cancer (RC), but no clear consensus on their indications is present, there being literature in support of both. The aim of this meta-analysis is to give an update regarding the diagnostic test accuracy of ERUS and pelvic MRI about the local staging of RC. Materials and methods: A systematic literature search from November 2020 to October 2021 was performed to select studies in which head-to-head comparison between ERUS and MRI was reported for the local staging of rectal cancer. Quality and risk of bias were assessed with the QUADAS-2 tool. Our primary outcome was the T staging accuracy of ERUS and MRI for which pooled accuracy indices were calculated using a bivariable random-effects model. In addition, a hierarchical summary receiver operating characteristic curve (hSROC) was created to characterize the accuracy of ERUS and MRI for the staging of T and N parameters. The area under the hSROC curve (AUC_hSROC) was determined as a measure of diagnostic accuracy. Results: Seven studies and 331 patients were included in our analysis. ERUS and MRI showed a similar accuracy for the T staging, with AUC_hSROC curves of 0.91 (95% C.I., 0.89 to 0.93) and 0.87 (95% C.I., 0.84 to 0.89), respectively (p = 0.409). For T staging, ERUS showed a pooled sensitivity of 0.82 (95% C.I. 0.72 to 0.89) and pooled specificity of 0.91 (95% C.I. 0.77–0.96), while MRI had pooled sensitivity and specificity of 0.69 (95% C.I. 0.55–0.81) and 0.88 (95% C.I. 0.79–0.93), respectively. ERUS and MRI showed a similar accuracy in the N staging too, with AUC_hSROC curves of 0.92 (95% C.I., 0.89 to 0.94) and 0.93 (95% C.I., 0.90 to 0.95), respectively (p = 0.389). Conclusions: In conclusion, ERUS and MRI are comparable imaging techniques for the local staging of rectal cancer.

Transanal Minimally-Invasive Surgery (TAMIS): Experience with No Closure of the Rectal Defect

Background In transanal minimally-invasive surgery (TAMIS), the closure of the rectal defect is controversial, and endoluminal suture is one of the most challenging aspects. The goal of the present study is to evaluate the short- and medium-term complications of a consecutive series of patients with extraperitoneal rectal injuries who underwent TAMIS without closure of the rectal defect.

Materials and Methods A prospective, longitudinal, descriptive study conducted between August 2013 and July 2019 in which all patients with extraperitoneal rectal lesions, who were operated on using the TAMIS technique, were consecutively included. The lesions were: benign lesions ≥ 3 cm; neuroendocrine tumors ≤ 2 cm; adenocarcinomas in stage T1N0; and adenocarcinomas in stage T2N0, with high surgical risk, or with the patients reluctant to undergo radical surgery, and others with doubts about complete remission after the neoadjuvant therapy. Bleeding, infectious complications, rectal stenosis, perforations, and death were evaluated.

Results A total of 35 patients were treated using TAMIS without closure of the defect. The average size of the lesions was of 3.68 ± 2.1 cm (95% confidence interval [95%CI]: 0.7 cm to 9 cm), their average distance from the anal margin was of 5.7 ± 1.48 cm, and the average operative time was of 39.2 ± 20.5 minutes, with a minimum postoperative follow-up of 1 year. As for the pathologies, they were: 15 adenomas; 3 carcinoid tumors; and 17 adenocarcinomas. In all cases, the rectal defect was left open.

The overall morbidity was of 14.2%. Two patients (grade II in the Clavien-Dindo classification) were readmitted for pain treatment, and three patients (grade III in the Clavien-Dindo classification) were assisted due to postoperative bleeding, one of whom required reoperation.

Conclusion The TAMIS technique without closure of the rectal defect yields good results, and present a high feasibility and low complication rate.

Neoadjuvant chemotherapy in locally advanced colon cancer: a systematic review and meta-analysis

BACKGROUND

There is increasing evidence to support the use of neoadjuvant chemotherapy (NAC) in locally advanced colon cancer (LACC). However, its safety, efficacy and side effect profile is yet to be completely elucidated. This review aims to assess NAC regimens, duration, compare completion rates, intra-operative and post-operative complication profiles and oncological outcomes, in order to provide guidance for clinical practice and further research.

METHODS

PubMed, EMBASE and MEDLINE were searched for a systematic review of the literature from 2000 to 2020. Eight eligible studies were included, with a total of 1213 patients, 752 (62%) of whom received NAC. Of the eight studies analysed, two were randomised controlled trials comparing neoadjuvant chemotherapy followed by oncological resection to upfront surgery and adjuvant chemotherapy, three were prospective single-arm phase II trials analysing neoadjuvant chemotherapy followed by surgery only, one was a retrospective study comparing neoadjuvant chemotherapy followed by surgery versus surgery first followed by adjuvant chemotherapy and the remaining two were single-arm retrospective studies of neoadjuvant chemotherapy followed by surgery.

RESULTS

All cases of LACC were determined and staged by computed tomography; majority of the studies defined LACC as T3 with extramural depth of 5 mm or more, T4 and/or nodal positivity. NAC administered was either folinic acid, fluorouracil and oxaliplatin (FOLFOX) or capecitabine and oxaliplatin (XELOX) with the exception of one study which utilised 5-fluorouracil and mitomycin. Most studies had NAC completion rates of above 83% with two notable exceptions being Zhou et al. and The Colorectal Cancer Chemotherapy Study Group of Japan who both recorded a completion rate of 52%. Time to surgery from completion of NAC ranged on average from 16 to 31 days. The anastomotic leak rate in the NAC group ranged from 0 to 4.5%, with no cases of postoperative mortality. The R0 resection rate in the NAC group was 96.1%. Meta-analysis of both RCTs included in this study showed that neoadjuvant chemotherapy increased the likelihood of a negative resection margin T3/4 advanced colon cancer (pooled relative risk of 0.47 with a 95% confidence interval) with no increase in adverse consequence of anastomotic leak, wound infection or return to theatre.

CONCLUSIONS

Our systematic review and meta-analysis show that NAC is safe with an acceptable side effect profile in the management of LACC. The current data supports an oncological benefit for tumour downstaging and increased in R0 resection rate.

Oncologic comparison between nonradical management and total mesorectal excision in good responders after chemoradiotherapy in patients with mid-to-low rectal cancer

Purpose

This study was performed to compare the oncologic outcomes between nonradical management and total mesorectal excision in good responders after chemoradiotherapy.

Methods

We analyzed 75 patients, who underwent 14 watch-and-wait, 30 local excision, and 31 total mesorectal excision, in ycT0-1N0M0 based on magnetic resonance imaging after chemoradiotherapy for advanced mid-to-low rectal cancer in 3 referral hospitals. The nonradical management group underwent surveillance with additional sigmoidoscopy and rectal magnetic resonance imaging every 3-6 months within the first 2 years.

Results

Nonradical management group had more low-lying tumors (P < 0.001) and less lymph node metastasis based on magnetic resonance imaging (P = 0.004). However, cT stage, ycT, and ycN stage were not different between the 2 groups. With a median follow-up period of 64.7 months, the 5-year locoregional failure rate was higher in the nonradical management group than in the total mesorectal excision group (16.7% vs. 0%, P = 0.013). However, the 5-year overall survival and disease-free survival rates of the nonradical management and total mesorectal excision groups were not different (95.2% vs. 93.5%, P = 0.467; 76.4% vs. 83.6%, P = 0.665; respectively).

Conclusion

This study shows that nonradical management for ycT0-1N0 mid-to-low rectal cancer may be an alternative treatment to total mesorectal excision under proper surveillance and management for oncologic events.

The Clinical Value of the Combined Detection of Enhanced CT, MRI, CEA, and CA199 in the Diagnosis of Rectal Cancer

Background

To explore the clinical value of enhanced computed tomography (enhanced CT), magnetic resonance imaging (MRI), carcinoembryonic antigen (CEA), and cancer antigen 199 (CA199) in the diagnosis of rectal cancer (RC).

Methods

A total of 156 patients with RC confirmed by postoperative pathology admitted to the Affiliated Yantai Yuhuangding Hospital of Qingdao University from March 2018 to November 2020 were included in the malignant group, and 52 patients with chronic proctitis in the benign control group. All patients underwent preoperative enhanced CT, MRI scans, and serum CEA and CA199 tests. The accuracy, sensitivity, and specificity of single and combined enhanced CT, MRI, CEA, and CA199 tests for the clinical staging of RC were calculated.

Results

The postoperative pathological diagnosis showed that 35 cases of 156 RC patients were at T1 stage, 29 cases were at T2 stage, 24 cases were at T3 stage, 11 cases were at T4 stage, 23 cases were at N0 stage, 21 cases were at N1 stage, 8 cases were at N2 stage, 3 cases were at M0 stage, and 2 cases were at M1 stage. The positive rate of MRI in the diagnosis of RC was higher than that of enhanced CT. Serum CEA and CA199 levels in the malignant group were significantly increased compared with the benign group. The sensitivity, specificity, and accuracy of the combined detection were significantly higher than those of the single detection.

Conclusion

Compared with enhanced CT, MRI has a higher detection rate of T and N stage in patients with RC. Combined enhanced CT, MRI, CEA, and CA199 can provide more accurate diagnosis and preoperative staging of RC patients.

Emerging applications of radiomics in rectal cancer: State of the art and future perspectives

Rectal cancer (RC) is the third most commonly diagnosed cancer and has a high risk of mortality, although overall survival rates have improved. Preoperative assessments and predictions, including risk stratification, responses to therapy, long-term clinical outcomes, and gene mutation status, are crucial to guide the optimization of personalized treatment strategies. Radiomics is a novel approach that enables the evaluation of the heterogeneity and biological behavior of tumors by quantitative extraction of features from medical imaging. As these extracted features cannot be captured by visual inspection, the field holds significant promise. Recent studies have proved the rapid development of radiomics and validated its diagnostic and predictive efficacy. Nonetheless, existing radiomics research on RC is highly heterogeneous due to challenges in workflow standardization and limitations of objective cohort conditions. Here, we present a summary of existing research based on computed tomography and magnetic resonance imaging. We highlight the most salient issues in the field of radiomics and analyze the most urgent problems that require resolution. Our review provides a cutting-edge view of the use of radiomics to detect and evaluate RC, and will benefit researchers dedicated to using this state-of-the-art technology in the era of precision medicine.

Endoscopic Ultrasound Elastography in the Assessment of Rectal Tumors: How Well Does It Work in Clinical Practice?

Endorectal ultrasound applications in the evaluation of rectal tumors could be a useful tool in achieving proper staging of rectal cancer. The purpose of this study was to compare the efficacy of rectal tumor staging by flexible endoscopic ultrasound (EUS) with real-time elastography (RTE) using the gold standard post-surgery histological analysis of the resected tissue as the control. The second aim of our research was to establish cutoff values for the EUS-RTE strain ratio corresponding to stages by independently comparing the stiffness values obtained with histology and EUS-RTE staging in order to minimize observation bias. We evaluated the records of 130 patients with a rectal tumor confirmed by biopsy. EUS was used in 70 patients, EUS-RTE-in the other 60. We found no statistically significant differences in staging accuracy when comparing EUS to EUS-RTE. Through a correspondence method between staging assessment and the EUS-RTE stain ratio, we identified cutoff intervals for T2, T3, and T4 staging that were nonoverlapping and proved to be statistically significant in terms of EUS-RTE values (significantly different ascending values from one interval to the other). We found that EUS-RTE offers slightly better, although not statistically significant sensitivity and specificity for T and N stage predictions compared to 2D EUS. Our results showed that EUS-RTE offers slightly higher sensitivity and specificity compared to EUS. Reliable cutoff intervals were found for strain rate elastography, previously available only for shear wave elastography (SWE) which is currently unavailable on any EUS system. Thus, these commonly available EUS-RTE systems can serve as a complementary tool in the staging of rectal tumors.

MRI-based nomogram analysis: recognition of anterior peritoneal reflection and its relationship to rectal cancers

Background

This study is aimed to explore the factors influencing the visualization of the anterior peritoneal reflection (APR) and evaluated the feasibility of measuring the distance from the anal verge to APR (AV-APR), the tumor height on MRI and the accuracy of determining the tumor location with regard to APR.

Methods

We retrospectively analyzed 110 patients with rectal cancer. A univariate and multivariate logistic regression was performed to identify the independent factors (age, sex, T stage, the degree of bladder filling, pelvic effusion, intraoperative tumor location, BMI, uterine orientation, the distance from seminal vesicle/uterus to rectum) associated with the visualization of the APR on MRI. The nomogram diagram and receiver operating characteristic curve (ROC curve) were established. Intraclass correlation coefficient (ICC) was used to evaluate the consistency of the distance of AV-APR. The Pearson correlation coefficient was used to characterize the agreement between measurements of the tumor height by colonoscopy and MRI. The Kappa statistics was used to evaluate the value of MRI in the diagnosis of the tumor location with regard to the APR.

Results

Multivariate logistic regression showed that BMI (P = 0.031, odds ratio, OR = 1.197), pelvic effusion (P = 0.020, OR = 7.107) and the distance from seminal vesicle/uterus to the rectum (P = 0.001, OR = 3.622) were correlated with the visualization of APR. The cut-off point of BMI and the distance from seminal vesicle/uterus to the rectum is 25.845 kg/m² and 1.15 cm. The area under curve (AUC) (95% Confidence Interval, 95% CI) of the combined model is 0.840 (0.750–0.930). The favorable calibration of the nomogram showed a non-significant Hosmer–Lemeshow test statistic (P = 0.195). The ICC value (95% CI) of the distance of AV-APR measured by two radiologists was 0.981 (0.969–0.989). The height measured by MRI and colonoscopy were correlated with each other (r = 0.699, P < 0.001). The Kappa value was 0.854.

Conclusions

BMI, pelvic effusion, and the distance from seminal vesicle/uterus to rectum could affect the visualization of APR on MRI. Also, it’s feasible to measure the distance of AV-APR, the tumor height, and to evaluate the tumor location with regard to APR using MRI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12880-021-00583-7.

Establishment and clinical application value of an automatic diagnosis platform for rectal cancer T-staging based on a deep neural network

BACKGROUND

Colorectal cancer is harmful to the patient's life. The treatment of patients is determined by accurate preoperative staging. Magnetic resonance imaging (MRI) played an important role in the preoperative examination of patients with rectal cancer, and artificial intelligence (AI) in the learning of images made significant achievements in recent years. Introducing AI into MRI recognition, a stable platform for image recognition and judgment can be established in a short period. This study aimed to establish an automatic diagnostic platform for predicting preoperative T staging of rectal cancer through a deep neural network.

METHODS

A total of 183 rectal cancer patients' data were collected retrospectively as research objects. Faster region-based convolutional neural networks (Faster R-CNN) were used to build the platform. And the platform was evaluated according to the receiver operating characteristic (ROC) curve.

RESULTS

An automatic diagnosis platform for T staging of rectal cancer was established through the study of MRI. The areas under the ROC curve (AUC) were 0.99 in the horizontal plane, 0.97 in the sagittal plane, and 0.98 in the coronal plane. In the horizontal plane, the AUC of T1 stage was 1, AUC of T2 stage was 1, AUC of T3 stage was 1, AUC of T4 stage was 1. In the coronal plane, AUC of T1 stage was 0.96, AUC of T2 stage was 0.97, AUC of T3 stage was 0.97, AUC of T4 stage was 0.97. In the sagittal plane, AUC of T1 stage was 0.95, AUC of T2 stage was 0.99, AUC of T3 stage was 0.96, and AUC of T4 stage was 1.00.

CONCLUSION

Faster R-CNN AI might be an effective and objective method to build the platform for predicting rectal cancer T-staging.

TRIAL REGISTRATION

chictr.org.cn: ChiCTR1900023575; http://www.chictr.org.cn/showproj.aspx?proj=39665.

Persistent extramural vascular invasion positivity on magnetic resonance imaging after neoadjuvant chemoradiotherapy predicts poor outcome in rectal cancer

BACKGROUND

In rectal cancer, extramural vascular invasion (EMVI) is the presence of tumour cells in blood vessels outside the muscular layer, which is associated with poor prognosis. Regression of EMVI on MRI following neoadjuvant chemoradiotherapy or its persistence may have prognostic implications.

METHODS

This retrospective study included 52 patients with rectal cancer who underwent total mesorectal excision following long-course neoadjuvant chemoradiotherapy (CRT). EMVI assessments were done on previous pelvic MRIs obtained before neoadjuvant CRT and eight weeks after the completion of neoadjuvant chemoradiotherapy in initially EMVI positive cases.

RESULTS

Persistently EMVI positive patients had worse overall survival and disease-free survival compared to initially EMVI negative patients and patients who returned to negative (p < 0.001 for both). Multivariate analysis identified persistent EMVI positivity after neoadjuvant treatment (HR, 102.9; p = 0.003) as significant independent predictor of worse overall survival; and persistent EMVI positivity (HR, 17.0; p = 0.002), mesorectal fascia involvement after neoadjuvant treatment (HR, 8.0; p = 0.017), and poor differentiation (HR, 10.3, p = 0.012) as significant independent predictors of worse disease-free survival.

CONCLUSION

Persistent EMVI positivity after neoadjuvant therapy appears to be an independent factor for poor overall survival; and persistent EMVI positivity as well as mesorectal fascia involvement on post neoadjuvant therapy MRI and poor differentiation appears to be important predictors of poor disease-free survival in rectal cancer patients.

"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.

Prognostic value of CT radiomics in evaluating lymphovascular invasion in rectal cancer: Diagnostic performance based on different volumes of interest

OBJECTIVES

This study aims to evaluate diagnostic performance of radiomic analysis using computed tomography (CT) to identify lymphovascular invasion (LVI) in patients diagnosed with rectal cancer and assess diagnostic performance of different lesion segmentations.

METHODS

The study is applied to 169 pre-treatment CT images and the clinical features of patients with rectal cancer. Radiomic features are extracted from two different volumes of interest (VOIs) namely, gross tumor volume and peri-tumor tissue volume. The maximum relevance and the minimum redundancy, and the least absolute shrinkage selection operator based logistic regression analyses are performed to select the optimal feature subset on the training cohort. Then, Rad and Rad-clinical combined models for LVI prediction are built and compared. Finally, the models are externally validated.

RESULTS

Eighty-three patients had positive LVI on pathology, while 86 had negative LVI. An optimal multi-mode radiology nomogram for LVI estimation is established. The area under the receiver operating characteristic curves of the Rad and Rad-clinical combined model in the peri-tumor VOI group are significantly higher than those in the tumor VOI group (Rad: peri-tumor vs. tumor: 0.85 vs. 0.68; Rad-clinical: peri-tumor vs. tumor: 0.90 vs 0.82) in the validation cohort. Decision curve analysis shows that the peri-tumor-based Rad-clinical combined model has the best performance in identifying LVI than other models.

CONCLUSIONS

CT radiomics model based on peri-tumor volumes improves prediction performance of LVI in rectal cancer compared with the model based on tumor volumes.

Application of ultrasound in the diagnosis of gastrointestinal tumors

Gastrointestinal tumors are common tumors in the digestive system. Early diagnosis of gastrointestinal tumors is the key to improve prognosis and curative effect of patients with tumors. Compared with other methods of examination and diagnosis, ultrasound examination has the advantages of simple operation, non-invasive, economical, and repeatable operation. With the advancement of ultrasound technology and the development of ultrasound contrast agents, ultrasound examination is more and more applied to gastrointestinal examination. Ultrasound cannot only observe the gastrointestinal wall, but also evaluate the surrounding lesions and metastases, as well as preoperative analysis and postoperative follow-up of gastrointestinal tumors. We reviewed the diagnostic applications of ultrasound in gastrointestinal tumors.

Magnetic Resonance of Rectal Cancer Response to Therapy: An Image Quality Comparison between 3.0 and 1.5 Tesla

Purpose

To evaluate signal intensity (SI) differences between 3.0 T and 1.5 T on T2-weighted (T2w), diffusion-weighted imaging (DWI), and apparent diffusion coefficient (ADC) in rectal cancer pre-, during, and postneoadjuvant chemoradiotherapy (CRT).

Materials and Methods

22 patients with locally advanced rectal cancer were prospectively enrolled. All patients underwent T2w, DWI, and ADC pre-, during, and post-CRT on both 3.0 T MRI and 1.5 T MRI. A radiologist drew regions of interest (ROIs) of the tumor and obturator internus muscle on the selected slice to evaluate SI and relative SI (rSI). Additionally, a subanalysis evaluating the SI before and after-CRT (∆SI pre-post) in complete responder patients (CR) and nonresponder patients (NR) on T2w, DWI, and ADC was performed.

Results

Significant differences were observed for T2w and DWI on 3.0 T MRI compared to 1.5 T MRI pre-, during, and post-CRT (all P < 0.001), whereas no significant differences were reported for ADC among all controls (all P > 0.05). rSI showed no significant differences in all the examinations for all sequences (all P > 0.05). ∆SI showed significant differences between 3.0 T and 1.5 T MRI for DWI-∆SI in CR and NR (188.39 ± 166.90 vs. 30.45 ± 21.73 and 169.70 ± 121.87 vs. 22.00 ± 31.29, respectively, all P 0.02) and ADC-∆SI for CR (−0.58 ± 0.27 vs. −0.21 ± 0.24P value 0.02), while no significant differences were observed for ADC-∆SI in NR and both CR and NR for T2w-∆SI.

Conclusion

T2w-SI and DWI-SI showed significant differences for 3.0 T compared to 1.5 T in all three controls, while ADCSI showed no significant differences in all three controls on both field strengths. rSI was comparable for 3.0 T and 1.5 T MRI in rectal cancer patients; therefore, rectal cancer patients can be assessed both at 3.0 T MRI and 1.5 T MRI. However, a significant DWI-∆SI and ADC-∆SI on 3.0 T in CR might be interpreted as a better visual assessment in discriminating response to therapy compared to 1.5 T. Further investigations should be performed to confirm future possible clinical application.

Adherence to Clinical Practice Guidelines and Colorectal Cancer Survival: A Retrospective High-Resolution Population-Based Study in Spain

Colorectal cancer (CRC) is the third most common cancer worldwide. Population-based, high-resolution studies are essential for the continuous evaluation and updating of diagnosis and treatment standards. This study aimed to assess adherence to clinical practice guidelines and investigate its relationship with survival. We conducted a retrospective high-resolution population-based study of 1050 incident CRC cases from the cancer registries of Granada and Girona, with a 5-year follow-up. We recorded clinical, diagnostic, and treatment-related information and assessed adherence to nine quality indicators of the relevant CRC guidelines. Overall adherence (on at least 75% of the indicators) significantly reduced the excess risk of death (RER) = 0.35 [95% confidence interval (CI) 0.28–0.45]. Analysis of the separate indicators showed that patients for whom complementary imaging tests were requested had better survival, RER = 0.58 [95% CI 0.46–0.73], as did patients with stage III colon cancer who underwent adjuvant chemotherapy, RER = 0.33, [95% CI 0.16–0.70]. Adherence to clinical practice guidelines can reduce the excess risk of dying from CRC by 65% [95% CI 55–72%]. Ordering complementary imagining tests that improve staging and treatment choice for all CRC patients and adjuvant chemotherapy for stage III colon cancer patients could be especially important. In contrast, controlled delays in starting some treatments appear not to decrease survival.

Dynamic contrast-enhanced MRI differentiates hepatocellular carcinoma from hepatic metastasis of rectal cancer by extracting pharmacokinetic parameters and radiomic features

The aim of the present study was to explore how dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) may differentiate hepatocellular carcinoma (HCC) from hepatic metastasis of rectal cancer (HMRC) by extracting pharmacokinetic parameters and radiomic features. A total of 75 patients, including 41 cases with HCC and 34 cases with HMRC, underwent DCE-MRI examination. Dual-input two-compartment extended Tofts tracer kinetic model attached to a specialized image post-processing software package from OmniKinetics; GE Healthcare was used to calculate the values of the pharmacokinetic parameters and radiomic features, which were extracted from the lesions at the same region of interest. These values were evaluated using Student's t-test and receiver operating characteristic curves, and discriminant models were built to differentiate between HCC and HRMC. The results identified statistically significant differences in the values of the pharmacokinetic parameters hepatic perfusion index (HPI), endothelial transfer constant (K^trans), initial area under the gadolinium concentration curve during the first 60 sec (IAUC) between the HCC and HRMC groups. In addition, statistically significant differences in 17 radiomic features were observed between the two groups (P<0.05). The areas under the receiver operating characteristic (ROC) curves of the pharmacokinetic parameters K^trans, IAUC and HPI were 0.73, 0.77 and 0.67, respectively. The range of the areas under the ROC curves of the 17 radiomic features with statistical differences was 0.63-0.79. In addition, when pharmacokinetic parameters and radiomic features were incorporated, the area under the ROC curve was 0.86. The accuracy of Fisher's discriminant analysis model based on radiomic features was 89.3%, and the leave-one-out cross-validation accuracy was 80.0%. In conclusion, DCE-MRI was demonstrated to be useful in the differential diagnosis of HCC and HMRC by extracting pharmacokinetic parameters and radiomic features, and incorporation of the two paths improved the diagnostic efficacy. A discriminant model based on radiomic features further enhanced the identification of HCC and HMRC.

The multidisciplinary management of rectal cancer

Rectal cancer treatment has evolved during the past 40 years with the use of a standardized surgical technique for tumour resection: total mesorectal excision. A dramatic reduction in local recurrence rates and improved survival outcomes have been achieved as consequences of a better understanding of the surgical oncology of rectal cancer, and the advent of adjuvant and neoadjuvant treatments to compliment surgery have paved the way for a multidisciplinary approach to disease management. Further improvements in imaging techniques and the ability to identify prognostic factors such as tumour regression, extramural venous invasion and threatened margins have introduced the concept of decision-making based on preoperative staging information. Modern treatment strategies are underpinned by accurate high-resolution imaging guiding both neoadjuvant therapy and precision surgery, followed by meticulous pathological scrutiny identifying the important prognostic factors for adjuvant chemotherapy. Included in these strategies are organ-sparing approaches and watch-and-wait strategies in selected patients. These pathways rely on the close working of interlinked disciplines within a multidisciplinary team. Such multidisciplinary forums are becoming standard in the treatment of rectal cancer across the UK, Europe and, more recently, the USA. This Review examines the essential components of modern-day management of rectal cancer through a multidisciplinary team approach, providing information that is essential for any practising colorectal surgeon to guide the best patient care.

Pathways of spread in rectal cancer: a reappraisal of the true routes to distant metastatic disease

Rectal cancer can spread in a number of ways which have been previously recognised and validated as prognostic markers. These routes of spread are not adequately recognised in the stage grouping of the tumour-node-metastasis system, which focuses predominantly on the depth of invasion and nodal status, thus limiting its prognostic accuracy. Tumour spread involving veins occurs in 40% of patients. Venous channels have greater direct access to distant sites by means of a vascular 'anatomical highway'. This rapid spread of tumour cells to distant metastatic sites by veins cannot occur by means of lymph node pathways. Thus, lymph nodes have been overestimated in their importance. Distinction between local tumour spread (lymph node metastases, perineural and lymphatic invasion) and tumour spread mediated by a direct vascular pathway to distant dissemination (extramural venous invasion and tumour deposits) must be made as the implications for prognosis and choice of treatment are not likely to be equal. Improved precision of radiological and pathological assessment is needed to scrutinise and carefully document each route of tumour spread. Only with this accurate information will it be possible to correctly weight each feature and develop a more prognostically accurate staging method that would allow separation of true high- and low-risk groups and subsequent improvements in patient care.

Multiparametric MRI of rectal cancer-repeatability of quantitative data: a feasibility study

PURPOSE

In this study, we aimed to analyze the repeatability of quantitative multiparametric rectal magnetic resonance imaging (MRI) parameters with different measurement techniques.

METHODS

All examinations were performed with 3 T MRI system. In addition to routine sequences for rectal cancer imaging protocol, small field-of-view diffusion-weighted imaging and perfusion sequences were acquired in each patient. Apparent diffusion coefficient (ADC) was used for diffusion analysis and ktrans was used for perfusion analysis. Three different methods were used in measurement of these parameters; measurements were performed twice by one radiologist for intraobserver and separately by three radiologists for interobserver variability analysis. ADC was measured by the lowest value, the value at maximum wall thickness, and freehand techniques. Ktrans was measured at the slice with maximum wall thickness, by freehand drawn region of interest (ROI), and at the dark red spot with maximum value.

RESULTS

A total of 30 patients with biopsy-proven rectal adenocarcinoma were included in the study. The mean values of the parameters measured by the first radiologist on the first and second measurements were as follows: mean lowest ADC, 721.31±147.18 mm2/s and 718.96±135.71 mm2/s; mean ADC value on the slice with maximum wall thickness, 829.90±144.24 mm2/s and 829.48±149.23 mm2/s; mean ADC value measured by freehand ROI on the slice with maximum wall thickness, 846.56±136.31 mm2/s and 848.23±144.15 mm2/s; mean ktrans value on the slice with maximum wall thickness, 0.219±0.080 and 0.214±0.074; mean ktrans by freehand ROI technique (including as much tumoral tissue as possible), 0.208±0.074 and 0.207±0.069; mean ktrans measured from the dark red foci, 0.308±0.109 and 0.311±0.105. Intraobserver agreement was very good among diffusion and perfusion parameters obtained with all three measurement techniques. Interobserver agreement was very good, except for one of the measurement techniques. As far as interobserver variability is considered, only ADC value measured on the slice with maximum wall thickness differed significantly.

CONCLUSION

Multiparametric MRI of rectum, using ADC as the diffusion and ktrans as the perfusion parameter is a repeatable technique. This technique may potentially be used in prediction and evaluation of neoadjuvant treatment response. New studies with larger patient groups are needed to validate the role of multiparametric MRI.

Neoadjuvant chemoradiation improves oncologic outcomes in low and mid clinical T3N0 rectal cancers

BACKGROUND

Controversial data exists in the current literature in regard to the use of neoadjuvant chemoradiation (nCRT) in patients with clinical T3N0 (cT3N0) rectal cancers, specifically based on location and relation to peritoneal reflection. We aimed to analyze the impact of nCRT on oncologic outcomes among cT3N0 rectal cancers, depending on the tumor height from anal verge (AV).

METHODS

A retrospective analysis of patients with cT3N0 rectal cancers was included from a query of a prospectively maintained rectal cancer database from 1980 to 2016. Patients were divided into 3 groups based on the tumor height: low (1-5 cm from AV), mid (6-10 cm from AV), and upper (11-15 cm from AV). Patients were stratified by use of nCRT.

MAIN OUTCOMES

5-year overall survival (OS), disease-free survival (DFS), cancer-specific survival (CSS), and local recurrence (LR) using Kaplan-Meier curves.

RESULTS

Five hundred ninety-two patients were included. Overall, 364 (61.4%) patients received nCRT and 228 (38.6%) patients did not. There were 251 (43%) patients with low, 302 (51%) with mid, and 39 (7%) with upper rectal cancer. Patients with low and mid rectal cancers received nCRT more frequently than those with upper rectal cancers (68.5% and 61.2% vs 43.6%, p = 0.007). The 5-year OS was 78% and 63%, DFS-88% and 73%, LR-1% and 8% in nCRT followed by resection vs. surgery alone (p < 0.001). In regard to cancer location after nCRT compared with surgery alone, low and mid cancers had better OS, DFS, and CSS, compared with upper ones.

CONCLUSION

nCRT prolongs survival among patients with rectal cancer below 10 cm from AV; however, it has no effect on 5-year oncologic survival of patients with upper rectal cancer located below peritoneal reflection.

Executive Summary of the American Radium Society Appropriate Use Criteria for Local Excision in Rectal Cancer

The goal of treatment for early stage rectal cancer is to optimize oncologic outcome while minimizing effect of treatment on quality of life. The standard of care treatment for most early rectal cancers is radical surgery alone. Given the morbidity associated with radical surgery, local excision for early rectal cancers has been explored as an alternative approach associated with lower rates of morbidity. The American Radium Society Appropriate Use Criteria presented in this manuscript are evidence-based guidelines for the use of local excision in early stage rectal cancer that include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) used by a multidisciplinary expert panel to rate the appropriateness of imaging and treatment procedures. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment. These guidelines are intended for the use of all practitioners and patients who desire information regarding the use of local excision in rectal cancer.

Translational Potential of MicroRNAs for Preoperative Staging and Prediction of Chemoradiotherapy Response in Rectal Cancer

Colorectal cancer is the third most common cancer and the second cause of cancer-related deaths. Rectal cancer presents roughly one-third of all colorectal cancer cases and differs from it on both anatomical and molecular levels. While standard treatment of colon cancer patients is radical surgery, rectal cancer is usually treated with pre-operative chemoradiotherapy followed by total mesorectal excision, which requires precise estimation of TNM staging. Unfortunately, stage evaluation is based solely on imaging modalities, and they often do not correlate with postoperative pathological findings. Moreover, approximately half of rectal cancer patients do not respond to such pre-operative therapy, so they are exposed to its toxic effects without any clinical benefit. Thus, biomarkers that could precisely predict pre-operative TNM staging, and especially response to therapy, would significantly advance rectal cancer treatment—but till now, no such biomarker has been identified. In cancer research, microRNAs are emerging biomarkers due to their connection with carcinogenesis and exceptional stability. Circulating miRNAs are promising non-invasive biomarkers that could allow monitoring of a patient throughout the whole therapeutic process. This mini-review aims to summarize the current knowledge on miRNAs and circulating miRNAs involved in the prediction of response to treatment and pre-operative staging in rectal cancer patients.

PET/MRI and PET/CT hybrid imaging of rectal cancer - description and initial observations from the RECTOPET (REctal Cancer trial on PET/MRI/CT) study

Purpose

The role of hybrid imaging using ¹⁸F-fluoro-2-deoxy-D-glucose positron-emission tomography (FDG-PET), computed tomography (CT) and magnetic resonance imaging (MRI) to improve preoperative evaluation of rectal cancer is largely unknown. To investigate this, the RECTOPET (REctal Cancer Trial on PET/MRI/CT) study has been launched with the aim to assess staging and restaging of primary rectal cancer. This report presents the study workflow and the initial experiences of the impact of PET/CT on staging and management of the first patients included in the RECTOPET study.

Methods

This prospective cohort study, initiated in September 2016, is actively recruiting patients from Region Västerbotten in Sweden. This pilot study includes patients recruited and followed up until December 2017. All patients had a biopsy-verified rectal adenocarcinoma and underwent a minimum of one preoperative FDG-PET/CT and FDG-PET/MRI examination. These patients were referred to the colorectal cancer multidisciplinary team meeting at Umeå University Hospital. All available data were evaluated when making management recommendations. The clinical course was noted and changes consequent to PET imaging were described; surgical specimens underwent dedicated MRI for anatomical matching between imaging and histopathology.

Results

Twenty-four patients have so far been included in the study. Four patients were deemed unresectable, while 19 patients underwent or were scheduled for surgery; one patient was enrolled in a watch-and-wait programme after restaging. Consequent to taking part in the study, two patients were upstaged to M1 disease: one patient was diagnosed with a solitary hepatic metastasis detected using PET/CT and underwent metastasectomy prior to rectal cancer surgery, while one patient with a small, but metabolically active, lung nodulus experienced no change of management. PET/MRI did not contribute to any recorded change in patient management.

Conclusions

The RECTOPET study investigating the role of PET/CT and PET/MRI for preoperative staging of primary rectal cancer patients will provide novel data that clarify the value of adding hybrid to conventional imaging, and the role of PET/CT versus PET/MRI.

Trial registration

NCT03846882.

Differences in prognostic relevance of rectal magnetic resonance imaging findings before and after neoadjuvant chemoradiotherapy

This retrospective study was designed to compare prognostic relevance of magnetic resonance imaging (MRI) findings before and after neoadjuvant chemoradiotherapy (CRT). From 2002 to 2010, 399 patients who underwent surgery after CRT for rectal cancer (≥T3) and had adequate pre-CRT (mr) and post-CRT (ymr) MRI findings were examined. Factors examined included tumour (T), lymph node (N), mesorectal fascia (MRF), extramural venous invasion (EMVI), and tumour regression grade (TRG). Two Cox proportional hazard models were created using mr and ymr findings separately for overall survival (OS), disease-free survival (DFS), and local recurrence rate (LRR). Among mr findings, only mrEMVI was a significant prognostic factor for OS and DFS. Among ymr findings, ymrN, ymrMRF, and ymrEMVI were significant prognostic factors for OS and DFS, whereas ymrMRF and ymrEMVI were significant prognostic factors for LRR. C-indices tended to be higher for ymr findings than for mr findings (OS, 0.682 vs. 0.635; DFS, 0.660 vs. 0.631; LRR, 0.701 vs. 0.617). Survival outcomes of patients having all ymr risk factors were significantly poor (5-year OS, 52.4%; 5-year DFS, 38.1%; 5-year LRR, 27.7%). ymr findings showed better prognostic significance than mr findings. Among ymr findings, ymrN, ymrMRF, and ymrEMVI were independent prognostic factors for oncologic outcomes.

Rectal Endoscopic Ultrasound in Clinical Practice

PURPOSE OF REVIEW

Endoscopic ultrasound (EUS) is routinely utilized for evaluation of disorders of the lower gastrointestinal tract. In this review, we summarize the current status of rectal EUS in clinical practice and describe recent developments in diagnostic and therapeutic rectal EUS.

RECENT FINDINGS

Recent guidelines recommend rectal EUS for rectal cancer staging as a second line modality in cases where MRI is contraindicated. Forward-viewing echoendoscopes and through the scope EUS miniprobes allow for EUS imaging of lesions through the entire colon and for evaluation beyond stenoses or luminal narrowings. EUS can be used to assess perianal disease and drain pelvic abscess associated with IBD, along with newer applications currently under investigation. For rectal varices, EUS can confirm the diagnosis, assess the optimal site for banding, guide therapy placement with sclerotherapy and/or coils, and assess response to treatment by confirming absence of flow. Therapeutic rectal EUS is emerging as a promising modality for drainage of pelvic fluid collection drainage and fiducial placement for rectal or prostatic cancer. Drug delivery mechanisms and substances that may increase the scope of therapy with rectal EUS are in varying stages of development. Rectal EUS continues to be an important modality for evaluation of benign and malignant disorders of the lower gastrointestinal tract, although its use as a cancer staging modality has declined due to improvements in MRI technology. Various technologies to enhance ultrasound imaging and for therapeutics have been developed that have or may contribute to expanded indications for rectal EUS.

[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.