Prognostic stratification by extramural depth of tumor invasion of primary rectal cancer based on the Radiological Society of North America proposal. AJR Am J Roentgenol. 2014;202:1238-1244. [PMID: 24848820 DOI: 10.2214/ajr.13.11311]

Prediction of Synchronous Serum CEA Expression Status Based on Baseline MRI Features of Primary Rectal Cancer Lesions Pre-treatment: A Retrospective Study

This study aimed to investigate the correlation between baseline MRI features and baseline carcinoembryonic antigen (CEA) expression status in rectal cancer patients. A training cohort of 168 rectal cancer patients from Center 1 and an external validation cohort of 75 rectal cancer patients from Center 2 were collected. A nomogram was constructed based on the training cohort and validated using the external validation cohort to predict high baseline CEA expression in rectal cancer patients. The nomogram's discriminative ability and clinical utility were tested using the receiver operating characteristic (ROC) curve, and decision curve analysis (DCA). The baseline CEA high-expression group had significantly higher MRI-detected metastatic lymph node (mLN), MRI-detected extramural vascular invasion (mEMVI), infiltrating tumor border configuration (iTBC), peritoneal invasion, annular infiltration, maximum extramural depth (MED), and tumor length than the normal CEA group (P < 0.05). Among them, MED [odds ratio (OR):1.19 (1.03-1.38), P = 0.016] and annular infiltration [OR:2.36 (1.06-5.25), P = 0.036] were independently predicting factors for high baseline CEA expression. The trained and validated model for predicting high baseline CEA expression in the training and external validation cohorts had the area under the curves (AUC) of 0.787 (95% CI 0.716-0.859) and 0.799 (95% CI 0.698-0.899), respectively. The calibration curves of both cohorts demonstrated good agreement between predicted and observed outcomes. Decision curve analysis indicated the clinical value of the nomogram. We developed a visual nomogram to predict high baseline CEA expression for patients with rectal cancer, enabling clinicians to conduct a personalized risk assessment and therapy.

The importance of preoperative T3 stage substaging by 3D endorectal ultrasonography for the prognosis of middle and low rectal cancer

OBJECTIVE

The study aimed to validate the role of 3D-endorectal ultrasonography in prognosis and recurrence for patients with T3-stage rectal cancer by evaluating the preoperative extramural depth of tumor invasion.

METHODS

In this study, we investigated the medical records of rectal cancer patients who were admitted to Changhai Hospital's Colorectal Surgery Division. The sample group was categorized into three subgroups (T3a, T3b, and T3c) based on the extent of tumor progression (<5 mm, 5-10 mm, and >10 mm) to assess the endorectal ultrasonography diagnostic performance. The 5-year disease-free survival and overall survival were assessed using the Kaplan-Meier method and a log rank test. Cox regression analysis verified the tumor invasion depth's significance as a prognostic predictor, and it was also utilized to evaluate other independent risk variables for recurrence after surgery.

RESULTS

The study included 72 individuals with low and middle rectal cancer from January 2014 to November 2019. Twenty-two individuals had stage T3a, 22 had stage T3b, and 28 had stage T3c based on preoperative endorectal ultrasonography. Endorectal ultrasonography had 88.0%, 86.8%, and 76.2% overall accuracy for stratifying subgroups, respectively. According to the Kaplan-Meier curve, 5-year OS was 100%, 83.5%, and 92.9% for T3a, T3b, and T3c (p = 0.172), and 5-year disease-free survival was 100%, 80.8%, and 72.9% for T3a, T3b, and T3c, respectively (p = 0.014). A distinct risk factor for 5-year disease-free survival was the degree of tumor infiltration (p = 0.039).

CONCLUSION

Preoperative T3 stage subdivision allows for categorization of prognosis and survival. Endorectal ultrasonography reports should make explicit declarations of T3a, T3b, and T3c scales.

Interobserver variability in MRI measurements of mesorectal invasion depth in rectal cancer

PROPOSE

To assess the interobserver variability in MRI measurements of mesorectal invasion depth (MID) in rectal adenocarcinomas primarily staged as T3, by determining the level of interobserver agreement in the differentiation of individual T3 substages and of T3a-b vs. T3c-d disease, between readers with different levels of expertise.

METHODS

A retrospective analysis of 60 patients classified by MRI as having T3 rectal cancers was performed. Each patient underwent MR examination in a 1.5 T machine and the standard imaging protocol included a high-resolution axial T2-weighted sequence in which the measurements were determined by independent radiologists (readers A and B, with 15 years and 1 year of experience, respectively). The rectum was further divided into quadrants and each reader selected the quadrant where the measurement was taken. The patients were grouped according to the MID (T3a < 1 mm; T3b 1-5 mm; T3c > 5-15 mm; T3d > 15 mm) and the interobserver reliability was tested using Cohen's kappa.

RESULTS

Population included 40 males and 20 females with a median age of 65.9 years. Interobserver agreement on individual substage differentiation (T3 a, b, c and d) was moderate (K = 0.428) and in the quadrant evaluation the level of agreement was also moderate (K = 0.414). Nevertheless, the interobserver reliability for the differentiation between stages T3a-b vs. T3c-d was substantial (K = 0.697).

CONCLUSIONS

There is no considerable interobserver variability when distinguishing T3a-b from T3c-d tumors, regardless of the quadrant where the MID is measured. Therefore, assessment of MID, for that purpose, is a reproducible MR parameter, irrespectively of the readers' experience.

Correlation Between the Distance to Mesorectal Fascia and Prognosis of cT3 Rectal Cancer: Results of a Multicenter Study From China

BACKGROUND

The cT3 substage criteria based on extramural depth of tumor invasion in rectal cancer have several limitations.

OBJECTIVE

This study proposed that the distance between the deepest tumor invasion and mesorectal fascia on pretherapy MRI can distinguish the prognosis of patients with cT3 rectal cancer.

DESIGN

This is a cohort study.

SETTING

This study included a prospective, single-center, observational cohort and a retrospective, multicenter, independent validation cohort.

PATIENT

Patients who had cT3 rectal cancer with negative mesorectal fascia undergoing neoadjuvant chemoradiotherapy followed by radical surgery were included in 4 centers in China from January 2013 to September 2014.

INTERVENTION

Baseline MRI with the distance between the deepest tumor invasion and mesorectal fascia, extramural depth of tumor invasion, and mesorectum thickness were measured.

MAIN OUTCOME MEASURES

The cutoff of the distance between the deepest tumor invasion and mesorectal fascia was determined by time-dependent receiver operating characteristic curves, supported by a 5-year progression rate from the prospective cohort, and was then validated in a retrospective cohort.

RESULTS

There were 124 and 274 patients included in the prospective and independent validation cohorts. The distance between the deepest tumor invasion and mesorectal fascia was the only predictor for cancer-specific death (HR, 0.1; 95% CI, 0.0-0.7) and was also a significant predictor for distant recurrence (HR, 0.4; 95% CI, 0.2-0.9). No statistically significant difference was observed in prognosis between patients classified as T3a/b and T3c/d.

LIMITATIONS

The sample size is relatively small, and the study focused on cT3 rectal cancers with a negative mesorectal fascia.

CONCLUSIONS

A cutoff of 7 mm of the distance between the deepest tumor invasion and mesorectal fascia on baseline MRI can distinguish cT3 rectal cancer from a different prognosis. We recommend using the distance between the deepest tumor invasion and mesorectal fascia on baseline MRI for local and systemic risk assessment and providing a tailored schedule of neoadjuvant treatment. See Video Abstract at http://links.lww.com/DCR/B682.CORRELACIÓN ENTRE LA DISTANCIA DE LA FASCIA MESORRECTAL Y EL PRONÓSTICO DEL CÁNCER DE RECTO cT3: RESULTADOS DE UN ESTUDIO MULTICÉNTRICO DE CHINAANTECEDENTES:Los criterios de subestadificación cT3 basados en la profundidad extramural de invasión tumoral en el cáncer de recto tienen varias limitaciones.OBJETIVO:Este estudio propuso que la distancia entre la invasión tumoral más profunda y la fascia mesorrectal en la resonancia magnética preterapia puede distinguir el pronóstico de los pacientes con cT3.DISEÑO:Estudio de cohorte.ENTORNO CLINICO:El estudio incluyó una cohorte observacional, prospectiva, unicéntrica, y una cohorte de validación retrospectiva, multicéntrica e independiente.PACIENTE:Se incluyeron pacientes con cáncer de recto cT3 con fascia mesorrectal negativa sometidos a quimio-radioterapia neoadyuvante seguida de cirugía radical en cuatro centros de China desde enero de 2013 hasta septiembre de 2014.INTERVENCIÓN:Imágenes de resonancia magnética de referencia fueron medidas con la distancia entre la invasión tumoral más profunda y la fascia mesorrectal; la profundidad extramural de la invasión tumoral y el grosor del mesorrecto.PRINCIPALES MEDIDAS DE VALORACION:El límite de la distancia entre la invasión tumoral más profunda y la fascia mesorrectal se determinó mediante curvas características operativas del receptor dependientes del tiempo y se apoyó en la tasa de progresión a 5 años de la cohorte prospectiva, y luego se validó en una cohorte retrospectiva.RESULTADOS:Se incluyeron 124 y 274 pacientes en la cohorte de validación prospectiva e independiente, respectivamente. La distancia entre la invasión tumoral más profunda de la fascia mesorrectal fue el único predictor de muerte específica por cáncer (Hazard ratio: 0.1, 95% CI, 0,0-0,7); y también fue un predictor significativo de recurrencia distante Hazard ratio: 0,4, 95% CI, 0,2-0,9). No se observaron diferencias estadísticamente significativas en el pronóstico entre los pacientes clasificados como T3a/b y T3c/d.LIMITACIONES:El tamaño de la muestra es relativamente pequeño y el estudio se centró en los cánceres de recto cT3 con fascia mesorrectal negativa.CONCLUSIONES:Un límite de 7 mm de distancia entre la invasión tumoral más profunda y la fascia mesorrectal en la resonancia magnética de referencia puede distinguir el cáncer de recto cT3 de diferentes pronósticos. Recomendamos la distancia entre la invasión tumoral más profunda y la fascia mesorrectal en la resonancia magnética de referencia para la evaluación del riesgo local y sistémico, proporcionando un programa personalizado de tratamiento neoadyuvante. Consulte Video Resumen en http://links.lww.com/DCR/B682. (Traducción- Dr. Francisco M. Abarca-Rendon).

Selection of patients with rectal cancer for neoadjuvant therapy using pre-therapeutic MRI - Results from OCUM trial

PURPOSE

No consensus is available on the appropriate criteria for neoadjuvant chemoradiotherapy selection of patients with rectal cancer. The purpose was to evaluate the accuracy of MRI staging and determine the risk of over- and undertreatment by comparing MRI findings and histopathology.

METHOD

In 609 patients of a multicenter study clinical T- and N categories, clinical stage and minimal distance between the tumor and mesorectal fascia (mrMRF) were determined using MRI and compared with the histopathological categories in resected specimen. Accuracy, sensitivity, specificity, positive predictive, and negative predictive value (NPV) were calculated. Overstaging was defined as the MRI category being higher than the histopathological category. mrMRF and circumferential resection margin (CRM) were judged as tumor free at a minimal distance > 1 mm. The chi-squared test or Fisher's exact test were used. P < 0.05 was considered significant.

RESULTS

The T category was correct in 63.5% (386/608) of patients; cT was overstaged in 22.9% (139/608) and understaged in 13.5% (82/608). MRI accuracy for lymph node involvement was 56.5% (344/609); 22.2% (28/126) of patients with clinical stage II and 28.1% (89/317) with clinical stage III disease were diagnosed by histopathology as stage I. The accuracy for tumor free CRM was 86.5% (527/609) and the NPV was 98.1% (514/524). In 1.7% (9/524) mrMRF was false negative.

CONCLUSION

MRI prediction of the tumor-free margin is more reliable than the prediction of tumor stage. MRF status as determined MRI should therefore be prioritized for decision making.

Better prognostic determination of cT3 rectal cancer through measurement of distance to mesorectal fascia: A multicenter study

Objective

To forward the magnetic resonance imaging (MRI) based distance between the deepest tumor invasion and mesorectal fascia (DMRF), and to explore its prognosis differentiation value in cT3 stage rectal cancer with comparison of cT3 substage.

Methods

This was a retrospective, multicenter cohort study including cT3 rectal cancer patients undergoing neoadjuvant chemoradiotherapy followed by radical surgery from January 2013 to September 2014. DMRF and cT3 substage were evaluated from baseline MRI. The cutoff of DMRF was determined by disease progression. Multivariate cox regression was used to test the prognostic values of baseline variables.

Results

A total of 804 patients were included, of which 226 (28.1%) developed progression. A DMRF cutoff of 7 mm was chosen. DMRF category, the clock position of the deepest position of tumor invasion (CDTI) and extramural venous invasion (EMVI) were independent predictors for disease progression, and hazard ratios (HRs) were 0.26 [95% confidence interval (95% CI), 0.13−0.56], 1.88 (95% CI, 1.33−2.65) and 1.57 (95% CI, 1.13−2.18), respectively. cT3 substage was not a predictor for disease progression.

Conclusions

The measurement of DMRF value on baseline MRI can better distinguish cT3 rectal cancer prognosis rather than cT3 substage, and was recommended in clinical evaluation.

Textural differences based on apparent diffusion coefficient maps for discriminating pT3 subclasses of rectal adenocarcinoma

BACKGROUND

The accuracy of discriminating pT3a from pT3b-c rectal cancer using high-resolution magnetic resonance imaging (MRI) remains unsatisfactory, although texture analysis (TA) could improve such discrimination.

AIM

To investigate the value of TA on apparent diffusion coefficient (ADC) maps in differentiating pT3a rectal adenocarcinomas from pT3b-c tumors.

METHODS

This was a case-control study of 59 patients with pT3 rectal adenocarcinoma, who underwent diffusion-weighted imaging (DWI) between October 2016 and December 2018. The inclusion criteria were: (1) Proven pT3 rectal adenocarcinoma; (2) Primary MRI including high-resolution T2-weighted image (T2WI) and DWI; and (3) Availability of pathological reports for surgical specimens. The exclusion criteria were: (1) Poor image quality; (2) Preoperative chemoradiation therapy; and (3) A different pathological type. First-order (ADC values, skewness, kurtosis, and uniformity) and second-order (energy, entropy, inertia, and correlation) texture features were derived from whole-lesion ADC maps. Receiver operating characteristic curves were used to determine the diagnostic value for pT3b-c tumors.

RESULTS

The final study population consisted of 59 patients (34 men and 25 women), with a median age of 66 years (range, 41-85 years). Thirty patients had pT3a, 24 had pT3b, and five had pT3c. Among the ADC first-order textural differences between pT3a and pT3b-c rectal adenocarcinomas, only skewness was significantly lower in the pT3a tumors than in pT3b-c tumors. Among the ADC second-order textural differences, energy and entropy were significantly different between pT3a and pT3b-c rectal adenocarcinomas. For differentiating pT3a rectal adenocarcinomas from pT3b-c tumors, the areas under the curves (AUCs) of skewness, energy, and entropy were 0.686, 0.657, and 0.747, respectively. Logistic regression analysis of all three features yielded a greater AUC (0.775) in differentiating pT3a rectal adenocarcinomas from pT3b-c tumors (69.0% sensitivity and 83.3% specificity).

CONCLUSION

TA features derived from ADC maps might potentially differentiate pT3a rectal adenocarcinomas from pT3b-c tumors.

Clinical TNM staging for esophageal, gastric, and colorectal cancers in the era of neoadjuvant therapy: A systematic review of the literature

AIM

Clinical staging is vital for selecting appropriate candidates and designing neoadjuvant treatment strategies for advanced tumors. The aim of this review was to evaluate diagnostic abilities of clinical TNM staging for gastrointestinal, gastrointestinal cancers.

METHODS

We conducted a systematic review of recent publications to evaluate the accuracy of diagnostic modalities on gastrointestinal cancers. A systematic literature search was performed in PubMed/MEDLINE using the keywords "TNM staging," "T4 staging," "distant metastases," "esophageal cancer," "gastric cancer," and "colorectal cancer," and the search terms used in Cochrane Reviews between January 2005 to July 2020. Articles focusing on preoperative diagnosis of: (a) depth of invasion; (b) lymph node metastases; and (c) distant metastases were selected.

RESULTS

After a full-text search, a final set of 55 studies (17 esophageal cancer studies, 26 gastric cancer studies, and 12 colorectal cancer studies) were used to evaluate the accuracy of clinical TNM staging. Positron emission tomography-computed tomography (PET-CT) and/or magnetic resonance imaging (MRI) were the best modalities to assess distant metastases. Fat and fiber mode of CT may be useful for T4 staging of esophageal cancer, CT was a partially reliable modality for lymph node staging in gastric cancer, and CT combined with MRI was the most reliable modality for liver metastases from colorectal cancer.

CONCLUSION

The most reliable diagnostic modality differed among gastrointestinal cancers depending on the type of cancer. Therefore, we propose diagnostic algorithms for clinical staging for each type of cancer.

Quantitative T2*-Weighted Imaging and Reduced Field-of-View Diffusion-Weighted Imaging of Rectal Cancer: Correlation of R2* and Apparent Diffusion Coefficient With Histopathological Prognostic Factors

Purpose

To assess T2*-weighted imaging (T2*WI) and reduced field-of-view diffusion-weighted Imaging (rDWI) derived parameters and their relationships with histopathological factors in patients with rectal cancer.

Methods

Fifty-four patients with pathologically-proven rectal cancer underwent preoperative T2*-weighted imaging and rDWI in this retrospective study. R2* values from T2*-weighted imaging and apparent diffusion coefficient (ADC) values from rDWI were compared in terms of different histopathological prognostic factors using student’s t-test or Mann-Whitney U-test. The correlations of R2* and ADC with prognostic factors were assessed by Spearman correlation analysis. The diagnostic performances of R2* and ADC were analyzed by receiver operating characteristic curves (ROC) separately and jointly.

Results

Significant positive correlation was found between R2* values and T stage, lymph node involvement, histological grades, CEA level, the presence of EMVI and tumor deposit (r = 0.374 ~ 0.673, p = 0.000–0.006), with the exception of CA19-9 level, CRM status and tumor involvement in the circumference lumen (TIL). Meanwhile, ADC values negatively correlated with almost all the prognostic factors (r = −0.588 to −0.299, p = 0.000–0.030), except CA19-9 level. The AUC range was 0.724–0.907 for R2* and 0.674–0.887 for ADC in discrimination of different prognostic factors. While showing the highest AUC of 0.913 (0.803–1.000) in differentiation of T stage, combination of R2* and ADC with reference to different prognostic factors did not significantly improve the diagnostic performance in comparison with individual R2*/ADC parameter.

Conclusions

R2* and ADC were associated with important histopathological prognostic factors of rectal cancer. R2* might act as additional quantitative imaging marker for tumor characterization of rectal cancer.

Prognostic risk factors and survival models for T3 locally advanced rectal cancer: what can we learn from the baseline MRI?

OBJECTIVES

To evaluate the baseline MRI characteristics for predicting survival outcomes and construct survival models for risk stratification to facilitate personalized treatment and follow-up strategies in patients with MRI-defined T3 (mrT3) locally advanced rectal cancer (LARC).

METHODS

We retrospectively reviewed 256 mrT3 LARC patients evaluated between 2008 and 2012 in our institution, with an average follow-up period of 6.8 ± 1.2 years. The baseline MRI characteristics, clinical data, and follow-up information were evaluated. The patients were randomized into a training cohort (TC, 186 patients) and validation cohort (VC, 70 patients). The TC dataset was used to develop multivariate nomograms for disease-free survival (DFS) and overall survival (OS), while the VC dataset was used for independent validation of the models. Harrell concordance (C) indices and Hosmer-Lemeshow calibration were used to evaluate the performances of the models.

RESULTS

Baseline mrT3 substage, extramural venous invasion (EMVI) grading, mucinous adenocarcinoma, mesorectal fascia involvement, elevated pretreatment carcinoembryonic antigen level, and neoadjuvant chemoradiotherapy (NCRT) were independent predictors of DFS. T3 substage, EMVI grading, and NCRT were also independent predictors of OS. The nomograms constructed permitted the individualized prediction of 3-year and 5-year DFS and 5-year OS with high discrimination (C-index range, 0.833-0.892) and good calibration in the TC and VC.

CONCLUSIONS

We have identified baseline MRI characteristics that help independently predict survival outcomes in patients with mrT3 LARC. The survival models based on these characteristics allow for the individualized pretreatment risk stratification in patients with mrT3 LARC.

KEY POINTS

• Baseline MRI characteristics can independently stratify risk and predict survival outcomes in patients with mrT3 LARC. • The nomograms built using selected baseline MRI characteristics facilitate the individualized pretreatment risk stratification and help with clinical decision-making in patients with mrT3 LARC. • MR-defined risk factors should, therefore, be carefully reported in the baseline MRI evaluation.

Preoperative concurrent chemoradiotherapy MRI characteristics favouring pathologic complete response in patients with rectal cancer: Usefulness of MR T2-stage as an ancillary finding for predicting pathologic complete response

INTRODUCTION

This study sought to assess preoperative concurrent chemoradiotherapy (CRT) magnetic resonance imaging (MRI)-based findings according to a structured MRI report template for primary staging of rectal cancer, and to evaluate the prognostic relevance of the pre-CRT MRI-based findings in patients with rectal cancer after CRT.

METHODS

We retrospectively evaluated pre- and post-CRT MRI data of patients with pathologically proven rectal adenocarcinoma, between January 2008 and October 2019. Image interpretation was performed independently by two radiologists and each reviewer assessed the cancer characteristics on MRI, based on the structured MRI report for primary staging. MRI-based findings associated with pathologic complete tumour regression grade (TRG) after CRT were analysed by univariate and multivariate analysis. Significant factors from pre-CRT MRI were weighted to score mrTRG in post-CRT MRI.

RESULTS

On univariate analysis, MR T-stage, tumour infiltration, mesorectal fascia involvement, extramural vascular invasion and serum carcinoembryonic antigen level correlated significantly with pathologic complete response (pCR). Multivariate analysis identified that only MR T-stage was independently associated with pCR (odds ratio, 3.89, 95% confidence interval, 1.18-12.84; P = 0.0278). Adding MRI-based T2-stage as an ancillary finding to mrTRG statistically significantly improved the sensitivity as compared to using only mrTRG for considering a CR. T2_mrTRG was significantly different in terms of the time to tumour progression between the CR and non-CR group.

CONCLUSIONS

The MR T2-stage was independently associated with pCR after CRT in patients with rectal cancer and was helpful as ancillary predictive factor, adding to mrTRG for prediction of pCR.

Evaluation of the Extent of Mesorectal Invasion and Mesorectal Fascia Involvement in Patients with T3 Rectal Cancer With 2-D and 3-D Transrectal Ultrasound: A Pilot Comparison Study With Magnetic Resonance Imaging Findings

The aim of this study was to determine the value of 2-D and 3-D transrectal ultrasound (TRUS) in assessing the extent of mesorectal invasion (EMI) and mesorectal fascia involvement (MRF+) in patients with T3 rectal tumours. We retrospectively evaluated 80 patients with T3 stage rectal cancer who were pre-operatively evaluated by 2-D and 3-D TRUS before neoadjuvant chemoradiotherapy by using magnetic resonance imaging (MRI) as a reference standard. The T3 stage was subdivided into T3 ab (EMI ≤5 mm) and T3 cd (EMI >5 mm). The consistency assessment of the T3 sub-staging and MRF+ was compared between 2-D and 3-D TRUS using Cohen's kappa statistic. The concordance of the T3 sub-staging based on EMI was excellent between the 3-D TRUS and MRI (κ = 0.84) and good between the 2-D TRUS and MRI (κ = 0.67). For the assessment of MRF+ (κ = 0.82), 3-D TRUS and MRI showed excellent concordance. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 3-D TRUS for MRF+ assessment was 95.3%, 86.5%, 89.1% and 94.1%, respectively. The agreement between 3-D TRUS and MRI for the assessment of T3 sub-staging and MRF status was better in low rectal cancer (both κ = 0.85) than in middle (κ = 0.79 and 0.77) rectal cancer. Compared with MRI, 3-D TRUS has more advantages in the sub-staging of T3 rectal cancer and the assessment of MRF+ than those of 2-D TRUS, especially in low rectal cancer. For patients with T3 rectal cancer, 3-D TRUS may well complement MRI for selecting the appropriate treatment.

Potential image-based criteria of neoadjuvant chemotherapy for colon cancer: multireaders' diagnostic performance

PURPOSE

The objective was to assess which image-based criteria can be best accurately determined at MDCT and which results in least overtreatment.

MATERIALS AND METHODS

A total of 110 consecutive patients, who underwent curative surgery for colon cancer, were included in this retrospective study. Five radiologists independently assessed the longitudinal diameter of cancer as well as T- and N-categories. The five image-based criteria (T3cd/T4, T3/T4, T3/T4 or N+, T3cd/T4 or N2, and T3/T4 with ≥ 4 cm) were evaluated in terms of diagnostic accuracy, interreader agreement, and overtreatment risk using pooled receiver-operating curve and Fleiss kappa analyses. Pathologic high-risk stage II or III was used as a reference standard for assessment of overtreatment risk.

RESULTS

The diagnostic accuracy of multireaders was in the acceptable range (pooled area under curve (AUC): 0.751-0.829). T3/T4 showed the highest AUC (0.829) in terms of diagnostic accuracy. T3/T4 with ≥ 4 cm showed the highest kappa value (κ = 0.695) followed by T3/T4 (κ = 0.623), indicating substantial agreement. The other three criteria revealed moderate agreement (κ = 0.558-0.577). In terms of overtreatment ratio, T3cd/T4 and T3cd/T4 or N2 showed relatively lower ratios (T3cd/T4, 2.2%; T3cd/T4 or N2, 2.9%), whereas T3/T4 and T3/T4 or N+ revealed higher ratios (T3/T4, 8.7%; T3/T4 or N+, 9.5%).

CONCLUSIONS

T3/T4 was the best criterion in terms of diagnostic accuracy. However, in terms of interreader agreement and overtreatment risk, T3/T4 with ≥ 4 cm and T3cd/T4 were better as potential image-based criteria of neoadjuvant chemotherapy for colon cancer.

Additional value of MRI-detected EMVI scoring system in rectal cancer: applicability in predicting synchronous metastasis

INTRODUCTION

Extramural vascular invasion (EMVI) has been recommended as an independent prognostic factor for poor overall survival rate in rectal cancer and can be used as a potential biomarker. Early prediction of prevalence of synchronous metastasis can elevate the disease-free survival rate. We aimed to evaluate the magnetic resonance imaging (MRI)-detected EMVI (mrEMVI) scoring system in predicting distant metastasis in T3 rectal cancer.

METHODS

Patients with postoperative histopathologically confirmed T3 rectal cancer without previous treatment from July 2014 to December 2015 were enrolled in this study. Two blinded radiologists evaluated mrEMVI status. mrEMVI was categorized as EMVI-positive or EMVI-negative in T2-weighted images using an mrEMVI scoring system. The results, along with other clinical characteristics (age, sex, tumor location, MRI-detected distance of mesorectal extension, lymphatic invasion, perineural invasion, mrEMVI score, and carcinoembryonic antigen [CEA]), were then correlated with synchronous metastases to determine the risk factors using univariate and multivariate analysis.

RESULTS

Of 180 patients, 38 were confirmed to be mrEMVI-positive, 142 mrEMVI-negative. There were 34 patients with synchronous metastasis, of whom 25 were mrEMVI-positive and 9 were mrEMVI-negative. Three factors were significantly associated with synchronous metastasis: mrEMVI (p = 0.001; odds ratio = 8.665), histopathologic lymphatic invasion (p = 0.001; odds ratio = 12.940), and preoperative CEA (p = 0.026; odds ratio = 4.124). mrEMVI score 4 was more likely for synchronous metastasis (p = 0.044; odds ratio = 9.429) than mrEMVI score 3 in rectal cancer.

CONCLUSIONS

mrEMVI positivity is an independent risk factor for synchronous distant metastasis in rectal cancer. mrEMVI score 4 is a stronger risk factor for synchronous metastasis than mrEMVI score 3 in rectal cancer.

Characterizing MRI features of rectal cancers with different KRAS status

BACKGROUND

To investigate whether MRI findings, including texture analysis, can differentiate KRAS mutation status in rectal cancer.

METHODS

Totally, 158 patients with pathologically proved rectal cancers and preoperative pelvic MRI examinations were enrolled. Patients were stratified into two groups: KRAS wild-type group (KRAS^wt group) and KRAS mutation group (KRAS^mt group) according to genomic DNA extraction analysis. MRI findings of rectal cancers (including texture features) and relevant clinical characteristics were statistically evaluated to identify the differences between the two groups. The independent samples t test or Mann-Whitney U test were used for continuous variables. The differences of the remaining categorical polytomous variables were analyzed using the Chi-square test or Fisher exact test. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminatory power of MRI features. The area under the ROC curve (AUC) and the optimal cut-off values were calculated using histopathology diagnosis as a reference; meanwhile, sensitivity and specificity were determined.

RESULTS

Mean values of six texture parameters (Mean, Variance, Skewness, Entropy, gray-level nonuniformity, run-length nonuniformity) were significantly higher in KRAS^mt group compared to KRAS^wt group (p < 0.0001, respectively). The AUC values of texture features ranged from 0.703~0.813. In addition, higher T stage and lower ADC values were observed in the KRAS^mt group compared to KRAS^wt group (t = 7.086, p = 0.029; t = - 2.708, p = 0.008).

CONCLUSION

The MRI findings of rectal cancer, especially texture features, showed an encouraging value for identifying KRAS status.

MRI morphologic and clinicopathologic characteristics for predicting outcomes in patients with locally advanced rectal cancer

PURPOSE

The aim of this study was to investigate the value of MRI morphologic and clinicopathologic factors for predicting 3-year disease-free survival (DFS) in patients with locally advanced rectal cancer (LARC).

METHOD

In this retrospective study, pre- and post-neoadjuvant chemoradiotherapy (nCRT) MRI morphologic (e.g., pre-nCRT MRI-detected extramural venous invasion) and clinicopathologic variabilities (e.g., pathological complete response) were evaluated in all patients. Three-year DFS was estimated using Kaplan-Meier product-limit method, and Cox proportional hazards models were used to determine associations between morphologic or clinicopathologic variabilities and survival outcomes.

RESULTS

A total of 115 patients (39 females and 76 males; median age, 54 years; age range, 28-82 years) with LARC treated with nCRT were enrolled. With a median follow-up of 48.0 months, the 3-year DFS was 79.0% for all patients. During follow-up, 18 patients died, 28 patients experienced relapse (26 distant, one local, and one both), and 69 patients were censored. MRI-detected extramural venous invasion (mrEMVI) was the only significantly independent factor of long-term survival, while HR was 2.308 (95% CI 1.151-4.629, P = 0.018) on univariate and 2.495 (95% CI 1.243-5.012, P = 0.010) on multivariate analysis. The 3-year cumulative survival rate in patients with mrEMVI negativity compared with positivity were 86.6% versus 65.0% (P = 0.015), respectively.

CONCLUSION

In conclusion, pre-nCRT mrEMVI status was the independent significant risk factor for long-term outcomes in LARC patients treated with nCRT, while the other morphologic and clinicopathologic characteristics were not related to the patient survival.

Current concepts in imaging for local staging of advanced rectal cancer

Imaging of rectal cancer has an increasingly pivotal role in the diagnosis, staging, and treatment stratification of patients with the disease. This is particularly true for advanced rectal cancers where magnetic resonance imaging (MRI) findings provide essential information that can change treatment. In this review we describe the rationale for the current imaging standards in advanced rectal cancer for both morphological and functional imaging on the baseline staging and reassessment studies. In addition the clinical implications and future methods by which radiologists may improve these are outlined relative to TNM8.

Feasibility of relatively low neoadjuvant radiation doses for locally advanced rectal cancer: A propensity score-matched analysis

BACKGROUND

Neoadjuvant chemoradiation therapy is part of the standard treatment of locally advanced rectal cancer (LARC). Although various options for modifying preoperative radiotherapy protocols have been researched and proposed, there is still no consensus as to the most appropriate dose regimen of neoadjuvant therapy for this disease.

AIM

To evaluate the effects of relatively low-dose radiation regimens on tumor regression and clinical outcomes in rectal cancer patients treated with neoadjuvant CRT followed by mesorectal excision.

METHODS AND RESULTS

We retrospectively analyzed patients with LARC who underwent neoadjuvant concurrent chemoradiation (CCRT) in our hospital from June 2010 to December 2015. A total of 259 consecutive patients were enrolled, receiving 42 to 44 Gy (RLD, n = 31), 46 Gy (SD1, n = 69), or 50 Gy (SD2, n = 159) of CRT, combined with either capecitabine/oxaliplatin or capecitabine only or mFOLFOX6, followed by total mesorectal excision. A 1:4 propensity score matching was employed, and all patients in the RLD group were matched with 124 patients in the SD2 group. Rates of pCR, 3-year local/regional recurrence (LRR), overall survival (OS), and disease-free survival (DFS) in the RLD group were all not significantly different (0.313 for pCR; 0.884 for LRR; and 0.762 for OS; 0.101 for DFS) from those in SD1 and SD2 groups. The RLD group showed a lower incidence of grade 3 to 4 hematologic toxicity than SD2 group (0.019). A propensity score analysis demonstrated no significant differences in the pCR rates and 3-year outcomes between the RLD and SD2 group.

CONCLUSION

Relatively low-dose regimen (≤44 Gy) of neoadjuvant CRT combined with standard concurrent chemotherapy appears to be both safe and effective in Chinese patients with LARC. Further testing by prospective randomized trials is needed.

Diagnostic performance of MRI- versus MDCT-categorized T3cd/T4 for identifying high-risk stage II or stage III colon cancers: a pilot study

PURPOSE

The aim of this study was to determine the diagnostic performance of magnetic resonance imaging (MRI)-categorized T3cd/T4 tumors for identifying high-risk stage II or stage III cancer in patients with curatively resectable colon cancer in comparison to that of multidetector computed tomography (MDCT).

MATERIALS AND METHODS

Thirty-eight patients with histopathologically indicated adenocarcinomas prospectively underwent MRI of the colon. Two radiologists independently and retrospectively assessed for T-category, including T3 substage (≤ T3ab vs. ≥ T3cd). The diagnostic accuracies and interreader agreements between assessments using each modality were compared using a pairwise comparison of receiver-operating characteristic curves and a weighted κ statistic, respectively.

RESULTS

Twenty-nine patients (76.3%) were histopathologically diagnosed with high-risk stage II or stage III colon cancer. The false-positive rate with MRI was lower than that with MDCT (0% vs. 7.9% for reader 1, 2.6% vs. 10.6% for reader 2). The diagnostic performance of MRI was better than that of MDCT across both readers (AUC: 0.707 vs. 0.506 [P = 0.032] for reader 1, 0.651 vs. 0.485 [P = 0.055] for reader 2). Moreover, MRI interreader agreement for the assessment of T3cd/T4 was significantly better than that of MDCT (κ = 0.821 vs. 0.391 [P = 0.017]).

CONCLUSION

The diagnostic performance of MR imaging of the colon may be better than that of MDCT for identifying high-risk stage II or stage III cases. Particularly, colon MRI reduced the false-positive rate and improved the interreader agreement, although further studies with a larger sample size are required.

Standardised reports with a template format are superior to free text reports: the case for rectal cancer reporting in clinical practice

PURPOSE

Rectal cancer staging with magnetic resonance imaging (MRI) allows accurate assessment and preoperative staging of rectal cancers. Therefore, complete MRI reports are vital to treatment planning. Significant variability may exist in their content and completeness. Template-style reporting can improve reporting standards, but its use is not widespread. Given the implications for treatment, we have evaluated current clinical practice amongst specialist gastrointestinal (GI) radiologists to measure the quality of rectal cancer staging MRI reports.

MATERIALS AND METHODS

Sixteen United Kingdom (UK) colorectal cancer multi-disciplinary teams (CRC-MDTs) serving a population over 5 million were invited to submit up to 10 consecutive rectal cancer primary staging MRI reports from January 2016 for each radiologist participating in the CRC-MDT. Reports were compared to a reference standard based on recognised staging and prognostic factors influencing case management RESULTS: Four hundred ten primary staging reports were submitted from 41 of 42 (97.6%) eligible radiologists. Three hundred sixty reports met the inclusion criteria, of these, 81 (22.5%) used a template. Template report usage significantly increased recording of key data points versus non-template reports for extra-mural venous invasion (EMVI) status (98.8% v 51.6%, p < 0.01) and circumferential resection margin (CRM) status (96.3% v 65.9%, p < 0.01). Local tumour stage (97.5% v 93.5%, NS) and nodal status (98.8% v 96.1%, NS) were reported and with similar frequency.

CONCLUSION

Rectal cancer primary staging reports do not meet published standards. Template-style reports have significant increases in the inclusion of key tumour descriptors. This study provides further support for their use to improve reporting standards and outcomes in rectal cancer.

KEY POINTS

• MRI primary staging of rectal cancer requires detailed tumour descriptions as these alter the neoadjuvant and surgical treatments. • Currently, rectal cancer MRI reports in clinical practice do not provide sufficient detail on these tumour descriptors. • The use of template-style reports for primary staging of rectal cancer significantly improves report quality compared to free-text reports.

Clinical significance of the EMD/mesorectum ratio of T3 mid-low rectal cancer: A retrospective observational study

Previous studies suggested that the extramural distance (EMD) should be considered in therapeutic decision-making of rectal cancer because it can be used as an indicator of the T3 subclassification; however, reports of impact of EMD/mesorectum ratio on prognosis are rare.The objectives of this study were to evaluate the feasibility of the extramural distance EMD/mesorectum ratio as a maker of the T3 subclassification for T3 mid-low rectal cancer and find the potential radiological marker on MRI for neoadjuvant chemoradiotherapy (nCRT).From December 2012 to December 2016, 287 consecutive patients with MRI-staged T3 mid-low rectal cancer were enrolled. The EMD was defined as the distance from the outer edge of the muscularis propria to the outer edge of tumor, and the mesorectum was measured as the distance from outer edge of muscularis propria to mesorectal fascia (MRF) in the same layer. The association of the EMD/mesorectum ratio and other MRI or clinicopathological factors with survival was analyzed. The independent prognostic factors were estimated by Cox regression analysis.The mean EMD/mesorectum ratio was 0.43. Based on ROC analysis, we chose a EMD/mesorectum ratio of 0.3 for further analyses. Of 287 patients, 163 (56.8%) had a EMD/mesorectum ratio ≥ 0.3. Patients with an EMD/mesorectum ratio ≥ 0.3 had a decreased recurrence free survival (RFS) and overall survival (OS) (P < .001; P = .034, respectively). Of the 163 patients, patients with nCRT had a higher RFS than patients without nCRT (P = .001). Multivariate analysis showed that the EMD/mesorectum ratio was the only independent prognostic factors for RFS.Our study provided evidence that the EMD/mesorectum ratio could be used for T3 subclassification, the optimal cut-off value of EMD/mesorectum ratio was 0.3 when the ratio was applied to classify T3 mid-low rectal cancer patients, and nCRT should be performed for these patients when the EMD/mesorectum ratio is ≥ 0.3.

Intravoxel Incoherent Motion MRI of Rectal Cancer: Correlation of Diffusion and Perfusion Characteristics With Prognostic Tumor Markers

OBJECTIVE

The objective of our study was to evaluate the intravoxel incoherent motion (IVIM)-DWI derived parameters and their relationships with tumor prognostic markers using 3-T MRI in patients with rectal cancer.

SUBJECTS AND METHODS

Fifty-two patients with histopathologically proven rectal cancer who underwent preoperative pelvic MRI were prospectively enrolled in this study. Diffusion and perfusion parameters including the apparent diffusion coefficient (ADC), pure diffusion coefficient, perfusion fraction, and pseudodiffusion coefficient derived from IVIMDWI were independently measured by two radiologists. Comparisons of IVIM-DWI-derived parameters in patients with different tumor prognostic markers were made using the independent-samples t test, ANOVA, and Mann-Whitney U test. The correlations between IVIM-DWI-derived parameters and tumor grade and tumor stage were further evaluated using Spearman correlation analysis. Interobserver agreement was evaluated using the intraclass correlation coefficient (ICC).

RESULTS

Excellent interobserver reproducibility was obtained for the IVIM-DWI-derived parameters (range of ICCs with 95% limits of agreement = 0.9309-0.9948, which is narrow). ADC, pseudodiffusion coefficient, and perfusion fraction tended to rise with greater tumor differentiation (r = 0.520, p < 0.001; r = 0.447, p = 0.001; r = 0.354, p = 0.010, respectively). The pure diffusion coefficient and pseudodiffusion coefficient showed a trend of decreasing with increasing tumor stages (r = 0.479, p < 0.001; r = 0.517, p < 0.001). The group of patients with extramural vascular invasion (EMVI) showed lower pseudodiffusion coefficient values than the group of patients with no EMVI (p < 0.05).

CONCLUSION

IVIM-DWI-derived parameters in patients with rectal cancer, especially the pseudodiffusion coefficient, are associated with tumor grade and tumor stage and show statistically significant differences between subjects with EMVI and those without EMVI. IVIM-DWI-derived parameters would be helpful in predicting tumor aggressiveness and prognosis.

Whole-lesion Apparent Diffusion Coefficient First- and Second-Order Texture Features for the Characterization of Rectal Cancer Pathological Factors

OBJECTIVE

The objective of this study was to explore the value of whole-volume apparent diffusion coefficient (ADC) features in characterizing pathologic features of rectal cancer.

METHODS

A total of 50 patients who were diagnosed with rectal cancer via biopsy underwent 3-T pretreatment diffusion-weighted imaging. Apparent diffusion coefficient features, including mean, 10th-90th percentile, Entropy and Entropy(H), derived from whole-lesion volumes were compared between pathologic T1-2 and T3 stages, perineural invasion (PNI) present and absent, lymphangiovascular invasion present and absent, and pathological N0 and N+ stage groups.

RESULTS

Entropy and Entropy(H) were significantly lower in rectal cancers at T1-2 stages than T3. The 90th percentile of rectal cancers with PNI was significantly lower than that of those without PNI. All P < 0.05.

CONCLUSIONS

Whole-lesion ADC Entropy and Entropy(H) have potential in evaluating different T stages, and 90th percentile can be helpful for determining PNI presence of rectal cancers.

How Should Imaging Direct/Orient Management of Rectal Cancer?

Modern rectal cancer management is dependent on preoperative staging, and radiological assessment is a crucial part of this process. Imaging must provide sufficient information to guide preoperative decision-making that is reliable and reproducible. Different methods have been used for local staging; however, magnetic resonance imaging (MRI) has shown to be the most reliable tool for this purpose. MRI offers prognostic information about the patients and guides the decision between neoadjuvant treatment and total mesorectal excision alone. Also, not only the initial staging but also restaging by MRI can provide significant information regarding tumor response that is essential when considering alternative approaches.

T3 subclassification using the EMD/mesorectum ratio predicts neoadjuvant chemoradiation outcome in T3 rectal cancer patients

OBJECTIVE

To evaluate the feasibility of the EMD (extramural depth)/mesorectum ratio as a marker for T3 rectal cancer and its ability to predict tumour response to neoadjuvant chemoradiation and survival.

METHODS

From 2010 to 2016, 284 T3 rectal cancer patients who underwent high resolution MRI before neoadjuvant chemoradiation were enrolled. The EMD was defined as the distance from the outer edge of the muscularis propria to the outermost edge of the tumour. The measurement of the tumour EMD and mesorectum was in the same layer and their ratio was calculated. Receiver operating characteristic analysis and relative area under the curve statistics were used to choose the cut-off value. The association of the EMD/mesorectum ratio and other MRI or clinical factors with the tumour regression grade (TRG) was analysed. Cox regression analysis was used to estimate independent risk factors for disease-free survival (DFS) and overall survival (OS).

RESULTS

The mean EMD/mesorectum ratio was 0.47 ± 0.3. We chose an EMD/mesorectum ratio of 0.5 in further analyses after receiver operating characteristic analysis. Of 284 patients, 177 (62.3%) had an EMD/mesorectum ratio ≤ 0.5. Patients with an EMD/mesorectum ratio ≤ 0.5 had a higher TRG 0-1 rate than patients with a ratio >0.5 (53.1% vs 36.4%, p = 0.006). A multivariate analysis identified that an EMD/mesorectum ratio >0.5 [hazard ratio (HR) 2.020; p = 0.028] and ypTNM II-III (HR 3.550; p = 0.017) were independent prognostic factors to indicate decreased DFS. For OS, only patients with TRG 2-3 had decreased OS compared with patients with TRG 0-1 (HR 2.959; p = 0.035).

CONCLUSION

When the EMD/mesorectum ratio was applied to categorize T3 rectal cancer patients, the ratio of 0.5 can be used as a cut-off value for T3 rectal cancer. Patients with a ratio ≤ 0.5 had a higher response rate and better DFS. However, further validation is needed in a larger sample of patients. Advances in knowledge: The EMD/mesorectum ratio may serve to predict tumour response to neoadjuvant chemoradiation and survival in T3 rectal cancer patients.

Value of endorectal ultrasonography in measuring the extent of mesorectal invasion and substaging of T3 stage rectal cancer

The present study aimed to determine the value of endorectal ultrasound (ERUS) and magnetic resonance imaging (MRI) for T3 rectal cancer, and substaging of T3 rectal cancer by measuring the extent of mesorectal invasion (EMI). The clinical data of patients with rectal cancer who were admitted to the general surgical department of Peking Union Medical College Hospital (Beijing, China) were reviewed and analyzed. Two ultrasound practitioners independently measured the EMI on ERUS, and a radiologist measured the EMI on MRI. The consistency of ERUS measurements between the two doctors was assessed using intraclass consistency (ICC) analysis. T3 stages were subdivided into T3a (EMI ≤5 mm) and uT3b (EMI >5 mm). The accuracy of MRI and ERUS in T3 rectal cancer, and T3 substaging of rectal cancer was assessed and compared according to the pathological results. The Bland-Altman scatter plot demonstrated good consistency between the ERUS measurement and pathology measurement. Furthermore, the consistency of the ERUS measurement between the two doctors was good (ICC, 0.9344; 95% confidence interval, 0.8789-0.9645). The diagnostic accuracies for T3 rectal cancer, for the two ultrasound doctors and for MRI were 86.9% (53/61), 85.2% (52/61), and 90.2% (55/61), respectively. The accuracy, sensitivity and specificity for the two individual ultrasound doctors in the substaging of T3 tumors were 79.1% (34/43), 66.7% (10/15), and 85.7% (24/28), compared with 67.4% (31/43), 60% (9/15), and 82.1% (23/28), respectively. The accuracy of MRI in the substaging of T3 tumors was 86.0% (37/43), which was not statistically higher compared with those of ERUS (P>0.05). In conclusion, ERUS is a valuable tool for measuring the EMI and substaging T3 rectal cancer, and thus, can be complementary to MRI in selecting the appropriate treatment for rectal cancer.

Magnetic resonance imaging for diagnosis and neoadjuvant treatment evaluation in locally advanced rectal cancer: A pictorial review

High-resolution pelvic magnetic resonance imaging (MRI) is the primary method for staging rectal cancer. MRI is highly accurate in the primary staging of rectal cancer; however, it has not proven to be effective in re-staging, especially in complete response evaluation after neoadjuvant therapy. Neoadjuvant chemoradiotherapy produces many changes in rectal tumors and on adjacent area, as a result, local tumor extent may not be accurately determined. However, adding diffusion-weighted sequences to the standard approach can improve diagnostic accuracy. In this pictorial review, an overview of the situation of MRI in the staging and re-staging of rectal cancer is exhibited as a pictorial assay. An experience- and literature-based discussion of limitations and difficulties in interpretation are also presented.

Total Mesorectal Excision Versus Local Excision After Favorable Response to Preoperative Chemoradiotherapy in "Early" Clinical T3 Rectal Cancer: A Propensity Score Analysis

PURPOSE

To compare oncological outcomes of total mesorectal excision (TME) and local excision (LE) in patients with "early" clinical T3 rectal cancer who received preoperative chemoradiotherapy (PCRT).

METHODS AND MATERIALS

"Early" clinical T3 rectal cancer was radiologically defined as tumors with extramural extension of <5 mm without mesorectal fascia involvement and lateral lymph node metastasis. Patients with "early" clinical T3 rectal cancer who received PCRT followed by TME or LE between January 2007 and December 2013 were retrospectively analyzed. Propensity scores were generated using patient and tumor characteristics, and a one-to-one case-matched analysis was conducted. Local recurrence-free survival (LRFS), disease-free survival (DFS), and overall survival (OS) were compared between the TME and LE groups.

RESULTS

Of the 406 enrolled patients, 351 received TME and 55 received LE. The median follow-up period was 45 months. Following propensity score matching, each group contained 55 patients. Among 103 patients evaluable for pathologic tumor response, 82 patients (79.6%) showed complete response or near-complete response. No significant differences were observed between the TME and LE groups in LRFS (3-year LRFS 98.1% vs 94.4%, P=.312), DFS (3-year DFS 92.1% vs 90.8%, P=.683), and OS (3-year OS 98.2% vs 100.0%, P=.895).

CONCLUSIONS

In "early" clinical T3 rectal cancer, PCRT followed by LE showed comparable oncologic outcomes to TME. Because most of the matched cohort consisted of good responders to PCRT, the present results should be applied to a limited population.

Long-term outcomes of surgery alone versus surgery following preoperative chemoradiotherapy for early T3 rectal cancer: A propensity score analysis

Recently, a few studies have raised the question of whether preoperative chemoradiotherapy (PCRT) is essential for all T3 rectal cancers. This case-matched study aimed to compare the long-term outcomes of surgery alone with those of PCRT + surgery for magnetic resonance imaging (MRI)-assessed T3ab (extramural depth of invasion ≤5 mm) and absent mesorectal fascia invasion (clear MRF) in mid/lower rectal cancer patients.From January 2006 to November 2012, 203 patients who underwent curative surgery alone (n = 118) or PCRT + surgery (n = 85) were enrolled in this retrospective study. A 1:1 propensity score-matched analysis was performed to eliminate the inherent bias. Case-matching covariates included age, sex, body mass index, histologic grade, carcinoembryonic antigen, operation method, follow-up period, tumor height, and status of lymph node metastasis. The end-points were the 5-year local recurrence (LR) rate and disease-free-survival (DFS).After propensity score matching, 140 patients in 70 pairs were included. Neither the 5-year LR rate nor the DFS was significantly different between the 2 groups (the 5-year LR rate, P = 0.93; the 5-year DFS, P = 0.94). The 5-year LR rate of the surgery alone was 2% (95% confidence interval [CI] 0.2%-10.9%) versus 2% (95% CI 0.2%-10.1%) in the PCRT + surgery group. The 5-year DFS of the surgery alone was 87% (95% CI 74.6%-93.7%) versus 88% (95% CI 77.8%-93.9%) in the PCRT + surgery group.In patients with MRI-assessed T3ab and clear MRF mid/lower rectal cancer, the long-term outcomes of surgery alone were comparable with those of the PCRT + surgery. The suggested MRI-assessed T3ab and clear MRF can be used as a highly selective indication of surgery alone in mid/lower T3 rectal cancer. Additionally, in those patients, surgery alone can be tailored to the clinical situation.

Essential Items for Structured Reporting of Rectal Cancer MRI: 2016 Consensus Recommendation from the Korean Society of Abdominal Radiology

High-resolution rectal MRI plays a crucial role in evaluating rectal cancer by providing multiple prognostic findings and imaging features that guide proper patient management. Quality reporting is critical for accurate effective communication of the information among multiple disciplines, for which a systematic structured approach is beneficial. Existing guides on reporting of rectal MRI are divergent on some issues, largely reflecting the differences in overall management of rectal cancer patients between the United States and Europe. The Korean Society of Abdominal Radiology (KSAR) study group for rectal cancer has developed an expert consensus recommendation regarding essential items for structured reporting of rectal cancer MRI using a modified Delphi method. This recommendation aims at presenting an up-to-date, evidence-based, practical, structured reporting template that can be readily adopted in daily clinical practice. In addition, a thorough explanation of the clinical and scientific rationale underlying the reporting items and their formats is provided. This KSAR recommendation may serve as a useful tool to help achieve more standardized optimal care for rectal cancer patients using rectal MRI.

The degree of extramural spread of T3 rectal cancer: an appeal to the American Joint Committee on Cancer

The T3 category of the TNM classification includes over 60% of all rectal tumours and encompasses the greatest variance in cancer-specific end-points than any other T category. The most recent edition of the cancer staging handbook of the American Joint Committee on Cancer (AJCC) dated 2010 does not divide T3 tumours into subgroups which reflect cancer-specific outcome more sensitively. The original aim of the present study was to review the literature to assess the influence of the degree of extramural extent of T3 rectal cancer on local recurrence and survival. An article written by the authors was accepted for publication but was withdrawn immediately after they became aware of the publication of the 4th edition of the TNM Supplement by the Union for International Cancer Control dated 2012, which was not accessible by the search system used. This article dealt with the subdivision of the T3 category although this was not included in the most up-to-date AJCC guidelines and was stated to be 'entirely optional'. Medline, PubMed and Cochrane Library searches were performed to identify all studies that investigated the degree of extramural spread and its relationship to survival and local recurrence. Twenty-two studies were identified of which 12 assessed the degree of histopathological extramural spread measured in millimetres. In 18 of the 22 studies the degree of extramural spread was a statistically significant prognostic factor for survival and local recurrence. Analysis of the studies indicated that the subdivision of category T3 rectal cancer into two subgroups of extramural spread ≤ 5 mm or more than 5 mm resulted in markedly different survival and local recurrence rates. The data were insufficient to allow validation of any greater subdivision. Measurement of the extent of extramural spread by MRI before any treatment agreed with the histopathological measurement in the surgical specimen to within 1 mm. The extent of extramural spread in T3 rectal cancer measured in millimetres is a powerful prognostic factor. A subdivision of T3 into T3a and T3b of less than or equal to or more than 5 mm appears to give the greatest discrimination of local recurrence and survival. Preoperative T3 subdivision by MRI has the same sensitivity as histopathological examination of the resected specimen. Given the clinical need for the pretreatment classification of the T3 category for oncological management planning, the evidence strongly indicates that the subdivision of the T3 category by MRI should be formally considered as part of the TNM staging system for rectal cancer.

Preoperative diffusion-weighted imaging value of rectal cancer: preoperative T staging and correlations with histological T stage

PURPOSE

To assess the ability of diffusion-weighted imaging (DWI) for evaluating T stage and correlation with histological T stage of rectal cancer.

METHOD

The diagnostic accuracy, sensitivity, and specificity of T2WI and DWI combined with T2WI for T stage were evaluated. Mean tumor apparent diffusion coefficient (ADC) was compared with histological T stage.

RESULT

There were no significant differences in the diagnostic accuracy, sensitivity, and specificity no matter what kind of T stage was concerned. The difference between ADC values and histological T stage were significantly different.

CONCLUSION

DWI was useful for evaluating T stage of rectal cancer. The ADC may predict the histological grade.

Can tumor regression grade influence survival outcome in ypT3 rectal cancer?

PURPOSE

Locally advanced rectal cancer (LARC) patients achieving ypT3 status following neoadjuvant chemoradiation are considered to have poor response with minimal downstaging. However, residual cancer cell amounts vary in the subserosa/perirectal fat. Tumor regression grading (TRG) is an evaluation method based on the proportion of fibrosis and residual cancer cells. The aim of this study is to assess the influence of TRG in ypT3 rectal cancer patients who received neoadjuvant chemoradiation.

METHODS

We retrospectively reviewed 325 LARC patients who received neoadjuvant chemoradiation and surgery. TRG scores were recorded by two independent pathologists. Among these patients, 143 were staged as ypT3. We analyzed TRG and other clinicopathological factors and their relationship with survival outcome including overall survival (OS) and disease-free survival (DFS).

RESULTS

Among 143 ypT3 patients, 44 (30.8 %) were TRG1, 84 (58.7 %) were TRG2 and 15 (10.5 %) were TRG3. Seventy-nine (55.3 %) of these patients had metastatic lymph nodes. In univariate analysis, TRG was not associated with DFS (TRG2 vs TRG1, P = 0.852; TRG3 vs TRG1, P = 0.593) or OS (TRG2 vs TRG1, P = 0.977; TRG3 vs TRG1, P = 0.665). Palliative surgery (HR 3.845; 95 % CI 1.670-8.857; P = 0.002) and metastatic lymph nodes after surgery (HR 5.894; 95 % CI 1.142-3.48; P = 0.015) were significantly associated with decreased DFS, while palliative surgery was the only factor associated with worse OS (HR 6.011; 95 % CI 2.150-16.810; P = 0.001). Palliative surgery (HR 3.923; 95 % CI 1.696-9.073; P = 0.001) and metastatic lymph nodes (HR 2.011; 95 % CI 1.152-3.512; P = 0.014) also showed prognostic significance for DFS in multivariate analysis.

CONCLUSIONS

Residual cancer cells evaluated by TRG score after neoadjuvant chemoradiation do not influence survival outcome in ypT3 rectal cancer patients. However, lymph node status is a significant prognostic factor in ypT3 patients.

Current imaging of rectal cancer

Recent advances in rectal cancer surgery and treatment as well as new developments in magnetic resonance imaging (MRI) technique have led to extensive research in the field of preoperative imaging of rectal cancer and to an abundant literature. Pelvic MRI has indeed become an important part of the decision-making process for patients with rectal cancer. The aim of this article is to give current guidelines in terms of which imaging method to perform and also to review the role of imaging, with emphasis on MRI, not only for tumor primary staging but also for reevaluation of the tumor after neoadjuvant therapy, highlighting the role of new so-called "functional MR techniques". Future trends are also discussed.