How reliable is current imaging in restaging rectal cancer after neoadjuvant therapy?

Comparison of preoperative magnetic resonance imaging with postoperative pathology results in rectal cancer patients undergoing neoadjuvant therapy

BACKGROUND

Locally advanced rectal cancer often requires neoadjuvant treatment (NAT) before surgical intervention. This study aimed to assess the concordance between preoperative magnetic resonance imaging (MRI) findings and postoperative pathology results after NAT in rectal cancer patients.

METHOD

A retrospective analysis of 52 patients who underwent NAT and subsequent surgery at Ankara Bilkent City Hospital between May 2019 and May 2023 was conducted. Demographics, preoperative MRIs, time intervals between NAT, MRI, and surgery, and postoperative pathology were assessed.

RESULTS

The median age of the cohort was 59 years, with a male predominance (76.9%). Tumour T stage (κ = 0.157), lymph node stage (κ = 0.138), and circumferential resection margin (κ = 0.138) concordance showed poor agreement between post-neoadjuvant treatment (PNT) MRI and pathology. PNT MRI demonstrated a limited correlation with postoperative pathology.

CONCLUSIONS

While preoperative MRI is commonly used for restaging after NAT in rectal cancer, our study highlights its limited concordance with postoperative pathology. The sensitivity and specificity metrics, although reported in the literature, should be interpreted alongside concordance assessments for a comprehensive evaluation.

Fluorescence guidance using near-infrared fluorescent clips in robotic rectal surgery: a case series

PURPOSE

Tattoo markings are often used as preoperative markers for colorectal cancer. However, scattered ink markings adversely affect tumor site recognition intraoperatively; therefore, interventions for rectal cancer may lead to an inaccurate distal resection margin (DRM) and incomplete total mesorectal excision (TME). This is the first case series of fluorescence-guided robotic rectal surgery in which near-infrared fluorescence clips (NIRFCs) were used to localize rectal cancer lesions.

METHODS

We enrolled 20 consecutive patients who underwent robotic surgery for rectal cancer between December 2022 and December 2023 in the current study. The primary endpoints were the rate of intraoperative clip detection and its usefulness for marking the tumor site. Secondary endpoints were oncological assessments, including DRM and the number of lymph nodes.

RESULTS

Clip locations were confirmed in 17 of 20 (85%) patients. NIRFCs were not detected in 3 out of 7 patients who underwent preoperative chemoradiation therapy. No adverse events, including bleeding or perforation, were observed at the time of clipping, and no clips were lost. The median DRM was 55 mm (range, 22-86 mm) for rectosigmoid (Rs), 33 mm (range, 16-60 mm) for upper rectum (Ra), and 20 mm (range, 17-30 mm) for low rectum (Rb). The median number of lymph nodes was 13 (range, 10-21).

CONCLUSION

The rate of intraoperative clip detection, oncological assessment, including DRM, and the number of lymph nodes indicate that the utility of fluorescence-guided methods with NIRFCs is feasible for rectal cancer.

Predictors of Nodal Disease in Rectal Cancer Patients with Complete Mucosal Response to Neoadjuvant Therapy

BACKGROUND

Some patients with locally advanced rectal cancer (LARC) achieve complete mucosal response following neoadjuvant therapy (NAT) and may be candidates for watch and wait strategy. This study aimed to identify predictors of nodal disease in patients with LARC who had a complete mucosal response to NAT.

METHODS

This case-control study included patients with LARC who were treated with NAT in the National Cancer Database between 2004 and 2019. Patients with complete mucosal response, defined as pathologic T0, were identified and classified according to the status of the pathologic N stage into complete response (pT0, pN0) and complete mucosal response with positive nodal disease (pT0, pN +). The two groups were compared regarding baseline demographics and tumor characteristics to determine the predictors of nodal disease after NAT.

RESULTS

A total of 5529 patients (59.7% male) with a mean age of 59.6 ± 12.2 years had a complete mucosal response following NAT. Nodal disease was detected in 443 (8%) patients with a complete mucosal response. Independent predictors of nodal disease were clinical N + stage (OR: 1.87, p < 0.001), mucinous histology (OR: 3.8, p = 0.003), and lymphovascular invasion (OR = 4.01, p < 0.001). The clinical T stage was inversely related to the risk of nodal disease.

CONCLUSIONS

Despite having a complete mucosal response following NAT, 8% of patients had nodal disease. Clinical evidence of nodal involvement on preoperative assessment, mucinous tumor histology, and lymphovascular invasion predicted nodal disease after NAT. These findings should be considered when making a decision on watch and wait strategy in patients with clinical complete response.

The CT-based intratumoral and peritumoral machine learning radiomics analysis in predicting lymph node metastasis in rectal carcinoma

Background

To construct clinical and machine learning nomogram for predicting the lymph node metastasis (LNM) status of rectal carcinoma (RC) based on radiomics and clinical characteristics.

Methods

788 RC patients were enrolled from January 2015 to January 2021, including 303 RCs with LNM and 485 RCs without LNM. The radiomics features were calculated and selected with the methods of variance, correlation analysis, and gradient boosting decision tree. After feature selection, the machine learning algorithms of Bayes, k-nearest neighbor (KNN), logistic regression (LR), support vector machine (SVM), and decision tree (DT) were used to construct prediction models. The clinical characteristics combined with intratumoral and peritumoral radiomics was taken to develop a radiomics and machine learning nomogram. The relative standard deviation (RSD) was used to predict the stability of machine learning algorithms. The area under curves (AUCs) with 95% confidence interval (CI) were calculated to evaluate the predictive efficacy of all models.

Results

To intratumoral radiomics analysis, the RSD of Bayes was minimal compared with other four machine learning algorithms. The AUCs of arterial-phase based intratumoral Bayes model (0.626 and 0.627) were higher than these of unenhanced-phase and venous-phase ones in both the training and validation group.The AUCs of intratumoral and peritumoral Bayes model were 0.656 in the training group and were 0.638 in the validation group, and the relevant Bayes-score was quantified. The clinical-Bayes nomogram containing significant clinical variables of diameter, PNI, EMVI, CEA, and CA19-9, and Bayes-score was constructed. The AUC (95%CI), specificity, and sensitivity of this nomogram was 0.828 (95%CI, 0.800-0.854), 74.85%, and 77.23%.

Conclusion

Intratumoral and peritumoral radiomics can help predict the LNM status of RCs. The machine learning algorithm of Bayes in arterial-phase conducted better in consideration of terms of RSD and AUC. The clinical-Bayes nomogram achieved a better performance in predicting the LNM status of RCs.

Utility of Restaging MRI Following Neoadjuvant Chemoradiotherapy for Stage II-III Rectal Adenocarcinoma

Background

Magnetic resonance imaging (MRI) is currently utilized for the pretreatment staging of locally advanced rectal cancer; however, there is no consensus regarding the utility of repeat MRI for restaging following neoadjuvant chemoradiotherapy (CRT). In this study, we aimed to investigate the clinical utility of restaging MRI after CRT in patients with clinical stage II-III rectal cancer.

Methodology

We performed a retrospective observational study at a tertiary care hospital. Our study population included patients with clinical stage II-III rectal cancer treated with neoadjuvant CRT who underwent both pre- and post-CRT MRI followed by surgical resection from 2012 to 2017. MRIs were reviewed by radiologists with an interest in rectal cancer MRI imaging using a standardized template. The utility of post-CRT MRI was evaluated by assessing its impact on change in surgical planning, concordance with pathologic staging, and prediction of surgical margins.

Results

A total of 30 patients were included in the study; 67% had clinical stage III and 33% had stage II disease based on pre-CRT MRI. Post-CRT MRI findings did not lead to a change in the originally outlined surgical plan in any patient. Compared to pre-CRT MRI, post-CRT MRI was not significantly more accurate in predicting T stage (k = 0.483), N stage (k = 0.268), or positive surgical margins (k = 0.839).

Conclusions

Due to poor concordance with pathologic staging, inability to more accurately predict surgical margin status and the absence of a demonstrable change in surgical treatment, post-CRT restaging with MRI, in its current form, appears to be of limited clinical utility.

Reduced field-of-view versus full field-of-view diffusion-weighted imaging for the evaluation of complete response to neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer

PURPOSE

To determine whether reduced field-of-view (rFOV) DWI sequences can improve image quality and diagnostic performance compared with conventional full FOV (fFOV) DWI in the prediction of complete response (CR) to neoadjuvant chemoradiotherapy (CRT) in patients with locally advanced rectal cancers.

METHODS

Between September 2015 and December 2017, seventy-three patients with locally advanced rectal cancers (≥ T3 or lymph node positive) who underwent CRT and subsequent surgery were included in this retrospective study. All patients had tumor located no more than 10 cm from the anal verge, and underwent rectal MRI including fFOV b-1000 DWI and rFOV b-1000 DWI at 3 T before and after CRT. Image quality and diagnostic performance in predicting CR were compared between rFOV DWI and fFOV DWI sets by two reviewers.

RESULTS

Based on a 12-point scale, rFOV DWI provided better image quality scores than fFOV DWI (9.1 ± 1.7 vs. 8.4 ± 1.0, respectively, P < 0.001). Diagnostic accuracy (A_z) in evaluating CR was better with the rFOV DWI set than with the fFOV DWI set for both reviewers: reviewer 1, 0.78 vs. 0.57 (P = .004); reviewer 2, 0.72 vs. 0.61 (P = .031).

CONCLUSION

rFOV DWI of rectal cancer can provide better overall image quality, and its addition to conventional rectal MRI may provide better diagnostic accuracy than fFOV DWI in the evaluation of CR to neoadjuvant CRT in patients with locally advanced rectal cancer.

Risk Stratification Using Neoadjuvant Rectal Score in the Era of Neoadjuvant Chemoradiotherapy: Validation With Long-term Outcome Data

BACKGROUND

Despite the widespread use of neoadjuvant chemoradiotherapy, there is no prognostic surrogate marker established in locally advanced rectal cancer.

OBJECTIVE

This study evaluated the role of neoadjuvant rectal score as a prognostic factor to stratify individual-level risks of survival and tumor recurrence.

DESIGN

This is a retrospective study.

SETTINGS

This study was conducted at the Seoul National University Hospital.

PATIENTS

A total of 397 patients who underwent chemoradiotherapy plus total mesorectal excision were analyzed.

INTERVENTIONS

There was no intervention.

MAIN OUTCOME MEASURES

Harrell C statistic and receiver operating characteristic analysis, as well as Cox regression analysis, were used to assess the prognostic strength.

RESULTS

The low (<8), intermediate (8-16), and high (>16) neoadjuvant rectal score groups included 91 (23%), 208 (52%), and 98 patients (25%). A high neoadjuvant rectal score was independently associated with inferior overall survival and disease-free survival (p = 0.011 and 0.008). Regarding the prognostic models adjusted for neoadjuvant rectal score (I) and ypT/N stage (II), the c-index was higher in model I (0.799 and 0.787, p = 0.009 for overall survival; 0.752 and 0.743, p = 0.093 for disease-free survival). The predictive ability of the neoadjuvant rectal score was superior to tumor regression grade, ypT, and ypN in the receiver operating characteristic analyses (p < 0.05 for all). Adjuvant chemotherapy was associated with better overall and disease-free survival (p = 0.003 and 0.052) in the high neoadjuvant rectal score group.

LIMITATIONS

Potential selection bias attributed to the retrospective study design was a limitation.

CONCLUSIONS

We verified the applicability of the neoadjuvant rectal score to stratify the relapse risk at the individual level for patients with stage II/III rectal cancer undergoing neoadjuvant chemoradiotherapy. Additional studies are needed to validate the usability of neoadjuvant rectal score levels as a determinant of adjuvant strategy. See Video Abstract at http://links.lww.com/DCR/B354. ESTRATIFICACIÓN DE RIESGO UTILIZANDO LA PUNTUACIÓN RECTAL NEOADYUVANTE EN LA ERA DE LA QUIMIORRADIOTERAPIA NEOADYUVANTE: VALIDACIÓN CON DATOS DE RESULTADOS A LARGO PLAZO: A pesar del uso generalizado de la quimiorradioterapia neoadyuvante, no existe un marcador subrogado pronóstico establecido en el cáncer de recto localmente avanzado.Este estudio evaluó el papel de la puntuación rectal neoadyuvante como factor pronóstico para estratificar los riesgos a nivel individual de supervivencia y recurrencia tumoral.Este es un estudio retrospectivo.Este estudio se realizó en el Hospital de la Universidad Nacional de Seúl.Se analizaron un total de 397 pacientes que se sometieron a quimiorradioterapia más escisión mesorrectal total.No hubo intervención.El análisis estadístico C de Harrell y las características operativas del receptor, así como el análisis de regresión de Cox, se utilizaron para evaluar la fuerza pronóstica.Los grupos de puntaje rectal neoadyuvante bajo (<8), intermedio (8-16) y alto (> 16) incluyeron 91 (23%), 208 (52%) y 98 (25%) pacientes, respectivamente. Una puntuación rectal neoadyuvante alta se asoció independientemente con una supervivencia general y una supervivencia libre de enfermedad inferiores (p = 0.011 y 0.008, respectivamente). Con respecto a los modelos pronósticos ajustados por la puntuación rectal neoadyuvante (I) y el estadio ypT/N (II), el índice c fue mayor en el modelo I (0.799 y 0.787, p = 0.009 para la supervivencia general; 0.752 y 0.743, p = 0.093 para supervivencia libre de enfermedad). La capacidad predictiva de la puntuación rectal neoadyuvante fue superior al grado de regresión tumoral, ypT y ypN en los análisis de características operativas del receptor (p <0.05 para todos). La quimioterapia adyuvante se asoció con una mejor supervivencia global y libre de enfermedad (p = 0.003 y 0.052, respectivamente) en el grupo de puntaje rectal neoadyuvante alto.El sesgo de selección potencial debido al diseño retrospectivo del estudio fue la limitación.Verificamos la aplicabilidad de la puntuación rectal neoadyuvante para estratificar el riesgo de recurrencia a nivel individual para pacientes con cáncer rectal en estadio II/III sometidos a quimiorradioterapia neoadyuvante. Se necesitan más estudios para validar la usabilidad de los niveles de puntuación rectal neoadyuvante como determinante de la estrategia adyuvante. Consulte Video Resumen en http://links.lww.com/DCR/B354.

Watch and wait approach in rectal cancer: Current controversies and future directions

According to the main international clinical guidelines, the recommended treatment for locally-advanced rectal cancer is neoadjuvant chemoradiotherapy followed by surgery. However, doubts have been raised about the appropriate definition of clinical complete response (cCR) after neoadjuvant therapy and the role of surgery in patients who achieve a cCR. Surgical resection is associated with significant morbidity and decreased quality of life (QoL), which is especially relevant given the favourable prognosis in this patient subset. Accordingly, there has been a growing interest in alternative approaches with less morbidity, including the organ-preserving watch and wait strategy, in which surgery is omitted in patients who have achieved a cCR. These patients are managed with a specific follow-up protocol to ensure adequate cancer control, including the early identification of recurrent disease. However, there are several open questions about this strategy, including patient selection, the clinical and radiological criteria to accurately determine cCR, the duration of neoadjuvant treatment, the role of dose intensification (chemotherapy and/or radiotherapy), optimal follow-up protocols, and the future perspectives of this approach. In the present review, we summarize the available evidence on the watch and wait strategy in this clinical scenario, including ongoing clinical trials, QoL in these patients, and the controversies surrounding this treatment approach.

Radiomic Texture and Shape Descriptors of the Rectal Environment on Post-Chemoradiation T2-Weighted MRI are Associated with Pathologic Tumor Stage Regression in Rectal Cancers: A Retrospective, Multi-Institution Study

(1) Background: The relatively poor expert restaging accuracy of MRI in rectal cancer after neoadjuvant chemoradiation may be due to the difficulties in visual assessment of residual tumor on post-treatment MRI. In order to capture underlying tissue alterations and morphologic changes in rectal structures occurring due to the treatment, we hypothesized that radiomics texture and shape descriptors of the rectal environment (e.g., wall, lumen) on post-chemoradiation T2-weighted (T2w) MRI may be associated with tumor regression after neoadjuvant chemoradiation therapy (nCRT). (2) Methods: A total of 94 rectal cancer patients were retrospectively identified from three collaborating institutions, for whom a 1.5 or 3T T2w MRI was available after nCRT and prior to surgical resection. The rectal wall and the lumen were annotated by an expert radiologist on all MRIs, based on which 191 texture descriptors and 198 shape descriptors were extracted for each patient. (3) Results: Top-ranked features associated with pathologic tumor-stage regression were identified via cross-validation on a discovery set (n = 52, 1 institution) and evaluated via discriminant analysis in hold-out validation (n = 42, 2 institutions). The best performing features for distinguishing low (ypT0-2) and high (ypT3-4) pathologic tumor stages after nCRT comprised directional gradient texture expression and morphologic shape differences in the entire rectal wall and lumen. Not only were these radiomic features found to be resilient to variations in magnetic field strength and expert segmentations, a quadratic discriminant model combining them yielded consistent performance across multiple institutions (hold-out AUC of 0.73). (4) Conclusions: Radiomic texture and shape descriptors of the rectal wall from post-treatment T2w MRIs may be associated with low and high pathologic tumor stage after neoadjuvant chemoradiation therapy and generalized across variations between scanners and institutions.

Limited Role for Routine Restaging After Neoadjuvant Therapy in Locally Advanced Rectal Cancer

BACKGROUND

Although many patients with locally advanced rectal cancer undergo restaging imaging after neoadjuvant chemoradiotherapy and before surgery, the benefit of this practice is unclear. The purpose of this study was to examine the impact of reimaging on outcomes.

MATERIALS AND METHODS

We performed a retrospective analysis of consecutive patients with stage 2 and 3 rectal adenocarcinoma treated with neoadjuvant chemoradiotherapy between May 2005 and April 2018. Patient and disease characteristics, imaging, treatment, and oncologic outcomes were compared between those who underwent restaging and those who went directly to surgery. Predictors of outcomes and cost effectiveness of restaging were determined.

RESULTS

Of 224 patients, 146 underwent restaging. Six restaged patients had findings leading to a change in management. There was no difference in freedom from recurrence (P = 0.807) and overall survival (P = 0.684) based on restaging. Pretreatment carcinoembryonic antigen level >3 ng/mL (P = 0.010), clinical T stage 4 (P = 0.016), and pathologic T4 (P = 0.047) and N2 (P = 0.002) disease increased the risk of death, whereas adjuvant chemotherapy decreased the risk of death (P < 0.001) on multivariate analysis. Disease recurrence was lower with pelvic exenteration (P = 0.005) and in females (P = 0.039) and higher with pathologic N2 (P = 0.003) and N3 (P = 0.002) disease. The average cost of reimaging is $40,309 per change in management; however, $45 is saved per patient when downstream surgical costs are considered.

CONCLUSIONS

Imaging restaging after neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer rarely changes treatment and does not improve survival. In a subset of patients at higher risk for worse outcome, reimaging may be beneficial.

Accuracy of high-resolution rectal magnetic resonance imaging re-staging with histopathology in locally advanced rectal cancer after neoadjuvant chemoradiotherapy

BACKGROUND/OBJECTIVE

Re-staging of locally advanced rectal cancer (LARC) following neoadjuvant chemoradiotherapy (NCRT) is a crucial step in surgical decision-making. Currently, MRI is the imaging of choice for evaluation of LARCs, however, the diagnostic accuracy of this modality is inconsistent. In this study, we evaluated the diagnostic accuracy of MRI in LARC and analyzed the factors that influenced the accuracy.

METHODS

The records of 133 patients diagnosed with LARC who were operated on during 2011-2018 were retrospectively reviewed. All patients received NCRT followed by re-staging based on high-resolution rectal MRI. The MRI results were analyzed for their yT and yN accuracy and anal sphincter involvement and compared with the related histopathological studies after definitive surgery.

RESULTS

Re-staging MRIs gave overall accuracy in both the yT stage and yN evaluation of 85% (K 0.45 and 0.21, respectively). The MRI tended to overstaging for tumor invasion and understaging for lymph node involvement (sign test p-values = 0.017 and 0.022, respectively.) The highest accuracy of the yT stage was yT4b (93%, K 0.71). The study found that larger tumors (>3 cm) were associated with significantly higher accuracy in the yT readings while lack of lymphovascular invasion was associated with higher accuracy in the yN readings. The negative predictive value for anal sphincter involvement was 100%.

CONCLUSION

MRI has limited accuracy in post-NCRT re-staging in LARC, tending to give overstaged yT readings and understaged yN readings. An MRI exclusion of sphincteric involvement is highly reliable.

Radiomics-Based Preoperative Prediction of Lymph Node Status Following Neoadjuvant Therapy in Locally Advanced Rectal Cancer

Background and Purpose: Lymph node status is a key factor for the recommendation of organ preservation for patients with locally advanced rectal cancer (LARC) following neoadjuvant therapy but generally confirmed post-operation. This study aimed to preoperatively predict the lymph node status following neoadjuvant therapy using multiparametric magnetic resonance imaging (MRI)-based radiomic signature.

Materials and Methods: A total of 391 patients with LARC who underwent neoadjuvant therapy and TME were included, of which 261 and 130 patients were allocated to the primary cohort and the validation cohort, respectively. The tumor area, as determined by preoperative MRI, underwent radiomics analysis to build a radiomic signature related to lymph node status. Two radiologists reassessed the lymph node status on MRI. The radiomic signature and restaging results were included in a multivariate analysis to build a combined model for predicting the lymph node status. Stratified analyses were performed to test the predictive ability of the combined model in patients with post-therapeutic MRI T1-2 or T3-4 tumors, respectively.

Results: The combined model was built in the primary cohort, and predicted lymph node metastasis (LNM+) with an area under the curve of 0.818 and a negative predictive value (NPV) of 93.7% were considered in the validation cohort. Stratified analyses indicated that the combined model could predict LNM+ with a NPV of 100 and 87.8% in the post-therapeutic MRI T1-2 and T3-4 subgroups, respectively.

Conclusion: This study reveals the potential of radiomics as a predictor of lymph node status for patients with LARC following neoadjuvant therapy, especially for those with post-therapeutic MRI T1-2 tumors.

Guidelines for MR imaging in rectal cancer: Europe versus United States

The aim of this study was to compare and contrast recently published guidelines for staging and reporting of MR imaging in rectal cancer from the European Society of Gastrointestinal and Abdominal Radiology and the North American Society of Abdominal Radiology. These guidelines were assessed on the presence of consensus and disagreement. Items were compared by two reviewers, and items with agreement and disagreement between the guidelines were identified and are presented in the current paper. Differences between guidelines are discussed to offer insights in practice variations between both continents and among expert centers, which to some extent may explain the differences between guidelines.

Primary and post-chemoradiotherapy staging using MRI in rectal cancer: the role of diffusion imaging in the assessment of perirectal infiltration

PURPOSE

To analyze changes in MRI diagnostic accuracy in main rectal tumor (T) evaluation resulting from the use of diffusion-weighted imaging (DWI), according to the degree of experience of the radiologist.

METHODS

This is a cross-sectional study of a database including one hundred 1.5 T MRI records (2011-2016) from patients with biopsy-proven rectal cancer, including primary staging and post-chemoradiotherapy follow-up. All cases were individually blindedly reviewed by ten radiologists: three experienced in rectal cancer, three specialized in other areas, and four residents. Each case was assessed twice to detect perirectal infiltration: first, evaluating just high-resolution T2-weighted sequences (HRT2w); second, evaluation of DWI plus HRT2w sequences. Results were pooled by experience, calculating accuracy (area under ROC curve), sensitivity and specificity, predictive values, likelihood ratios, and overstaging/understaging. Histology of surgical specimens provided the reference standard.

RESULTS

DWI significantly improved specificity by experienced radiologists in primary staging (63.2% to 75.9%) and, to a lesser extent, positive likelihood ratio (2.06 to 2.87); minimal changes were observed post-chemoradiotherapy, with a slight decrease of accuracy (0.657 to 0.626). Inexperienced radiologists showed a similar pattern, but with slight enhancement post-chemoradiotherapy (accuracy 0.604 to 0.621). Residents experienced small changes, with increased sensitivity/decreased specificity in both primary (69% to 72%/67.2% to 64.7%) and post-chemoradiotherapy (68.1% to 73.6%/47.3% to 44.6%) staging.

CONCLUSIONS

Adding DWI to HRT2w significantly improved specificity for the detection of perirectal infiltration at primary staging by experienced radiologists and also by inexperienced ones, although to a lesser extent. In the post-neoadjuvant treatment subgroup, only minimal changes were observed.

Prediction of tumor response of rectal cancer cells via 3D cell culture and in vitro cytotoxicity assay before initiating preoperative chemoradiotherapy

The aim of the present study was to investigate the utility of 3D cell culture and in vitro cytotoxicity assays, performed using cells derived from biopsies obtained prior to the initiation of preoperative chemoradiotherapy (preop-CRT), in predicting tumor response to chemoradiotherapy following preop-CRT in rectal cancer. Biopsies were obtained from 49 patients with locally advanced rectal cancer that underwent preop-CRT between August 2015 and March 2017. Tumor tissue was obtained before initiating preop-CRT. The response to chemoradiation was assessed by in vitro cytotoxicity assay following 3D cell culture and radiation treatment. The associations between the results from the cytotoxicity assay, and tumor regression grade (TRG) and yp node (ypN) positivity were investigated. Among 49 patients, 26 patients were available for analysis. Cytotoxicity ranged from 25.5-72.6% (median, 47.6%). There was no difference in cytotoxicity according to the TRGs 1-5 (P=0.940), or good tumor response (TRGs 1-2 vs. TRGs 3-5; P=0.729). However, there was a significant difference in cytotoxicity between the ypN-negative and -positive groups (53.2±14.1 and 38.7±10.1, respectively; P=0.021). Following dichotomization of patients with 45% cut-off value, the cytotoxicity assay was the only factor that predicted ypN positivity in multivariate analysis (odds ratio, 13; 95% confidence interval, 1.2-133.2; P=0.031). In conclusion, the cytotoxicity assay using the 3D cell culture method can be used to predict tumor response, particularly ypN positivity, in patients with rectal cancer who are scheduled for preop-CRT.

Nodal staging in the rectal cancer follow-up MRI after chemoradiotherapy: use of morphology, size, and diffusion criteria

AIM

To analyse changes in post-neoadjuvant follow-up magnetic resonance imaging (MRI) staging accuracy for malignant adenopathies in rectal cancer, by comparing size criteria with morphological criteria using high-resolution T2-weighted sequences, as well as variations when adding diffusion-weighted imaging.

METHODS AND MATERIALS

The present study was a cross-sectional study of a database including 46 1.5-T MRI examinations (2011-2016) from patients with biopsy-proven rectal cancer and chemoradiotherapy treatment before surgery. All cases were reviewed by three radiologists individually, who were blinded to any clinical information. The radiologists were experienced in rectal cancer (3-6 years) and evaluated the presence of malignant nodes in each patient. Malignancy was determined using morphological, size (5 mm), and diffusion criteria separately, as well as morphology plus diffusion. Each case was assessed four times: (1) evaluation of morphological criteria; (2) size criteria; (3) evaluation only using diffusion (b-values 50, 400, and 800); and (4) diffusion plus morphological criteria. Histological staging of surgical specimens was the reference standard. Statistical analysis included accuracy (area under the receiver operating characteristic [ROC] curve [AUC]), sensitivity, specificity, and positive/negative predictive values (PPV/NPV) for each radiologist, and group agreement (Fleiss' kappa).

RESULTS

Mean values using morphological criteria were: AUC 0.78, sensitivity 77.7%, specificity 73.8%, PPV 66.1%, NPV 85.2%. Using size criterion: AUC 0.75, sensitivity 62.9%, specificity 83.2%, PPV 74.1%, NPV 80%. Added diffusion yielded no improvement, and yielded worse results by itself.

CONCLUSIONS

Although morphological criteria showed better results in accuracy, sensitivity, and NPV, size criterion yielded the best specificity and PPV. Adding diffusion did not demonstrate a clear advantage over the criteria by themselves. Thus, mixed size-morphology criteria could have the greatest diagnostic value for follow-up N-staging.

Dynamically prognosticating patients with hepatocellular carcinoma through survival paths mapping based on time-series data

Patients with hepatocellular carcinoma (HCC) always require routine surveillance and repeated treatment, which leads to accumulation of huge amount of clinical data. A predictive model utilizes the time-series data to facilitate dynamic prognosis prediction and treatment planning is warranted. Here we introduced an analytical approach, which converts the time-series data into a cascading survival map, in which each survival path bifurcates at fixed time interval depending on selected prognostic features by the Cox-based feature selection. We apply this approach in an intermediate-scale database of patients with BCLC stage B HCC and get a survival map consisting of 13 different survival paths, which is demonstrated to have superior or equal value than conventional staging systems in dynamic prognosis prediction from 3 to 12 months after initial diagnosis in derivation, internal testing, and multicentric testing cohorts. This methodology/model could facilitate dynamic prognosis prediction and treatment planning for patients with HCC in the future.

Nodal Disease in Rectal Cancer Patients With Complete Tumor Response After Neoadjuvant Chemoradiation: Danger Below Calm Waters

BACKGROUND

A subset of patients with rectal cancer who undergo neoadjuvant chemoradiation therapy will develop a complete pathologic tumor response. Complete nodal response is not universal in these patients and is difficult to assess clinically. Quantifying the risk of nodal disease would allow for targeted therapy with either radical resection or "watchful waiting."

OBJECTIVE

This study aimed to identify risk factors for residual nodal disease in ypT0 rectal adenocarcinoma.

DESIGN

This is a retrospective case control study.

SETTINGS

The National Cancer Database 2006 to 2014 was used to identify patients for this study.

PATIENTS

Patients with stage II/III rectal adenocarcinoma who completed chemoradiation therapy followed by resection and who had ypT0 tumors were included. Patients with metastatic disease and <2 lymph nodes evaluated were excluded. Patients were divided into 2 groups: node positive and node negative.

MAIN OUTCOME MEASURES

The main outcome was nodal disease. The secondary outcome was overall survival.

RESULTS

A total of 42,257 patients with stage II/III rectal cancer underwent chemoradiation therapy and radical resection; 4170 (9.9%) patients had ypT0 tumors and 395 (9.5%) were node positive. Of patients with clinically node-negative disease (ie, pretreatment imaging), 6.2% were node positive after chemoradiation therapy and resection. In multivariable analysis, factors predictive of nodal disease included increasing (pretreatment) clinical N-stage, high tumor grade (3/4), perineural invasion, and lymphovascular invasion. Higher clinical T-stage was inversely associated with residual nodal disease. Overall 5-year survival was significantly different between patients with ypN0, ypN1, and ypN2 disease (87.4%, 82.2%, and 62.5%, p = 0.002).

LIMITATIONS

This study was limited by the lack of clinical detail in the database and the inability to assess recurrence.

CONCLUSIONS

Ten percent of patients with ypT0 tumors had positive nodes after chemoradiation therapy and resection. Factors associated with residual nodal disease included clinical nodal disease at diagnosis and poor histologic features. Patients with any of these features should consider radical resection regardless of tumor response. Others could be suitable for "watchful waiting" strategies. See Video Abstract at http://links.lww.com/DCR/A458.

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.

Re-Staging Following Long-Course Chemoradiotherapy For Rectal Cancer: Does It Influence Management?

BACKGROUND

In patients with locally advanced or low rectal cancers, long-course chemoradiotherapy (LCCRT) is recommended prior to surgical management.¹ The need for restaging afterwards has been questioned as it may be difficult to interpret imaging due to local tissue effects of chemoradiotherapy. The purpose of this study was to determine if restaging affected the management of patients receiving long-course chemoradiotherapy for rectal cancer.

METHODS

A retrospective review of patients with rectal cancer discussed at the South Eastern Health and Social Care Trust Lower Gastrointestinal Multi-Disciplinary Team Meeting (LGIMDT) in 2013 who had received long-course chemoradiotherapy was performed. Patients were identified from the Trust Audit Department, LGIMDT notes and patient records. Imaging results and outcomes from meetings were obtained through the Northern Ireland Picture Archiving and Communications System^® (NIPACS) and Electronic Care Record^® (ECR). Data including patient demographics, initial radiological staging and LGIMDT discussion, restaging modality and result, outcome from post-treatment LGIMDT discussion and recorded changes in management plans were documented using a proforma.

RESULTS

Seventy-one patients with rectal cancer were identified as having LCCRT in 2013 (M:F 36:35; age range 31 - 85 years). Fifty-nine patients were restaged following long-course treatment with computed tomography (CT) and magnetic resonance imaging (MRI). Twelve patients did not undergo restaging. Data was not available for 6 patients, one patient underwent emergency surgery, two patients were not fit for treatment, one failed to attend for restaging and two patients died prior to completion of treatment. Of the 59 patients restaged, 19 patients (32%) had their management plan altered from that which had been proposed at the initial LGIMDT discussion. The most common change in plan was not to operate. Ten patients had a complete clinical and radiological response to treatment and have undergone intensive follow-up. Nine patients had disease progression, with 3 requiring palliative surgery and 6 referred for palliative care.

CONCLUSION

Of those patients who were restaged, 32% had their management plan altered from that recorded at the initial LGIMDT discussion. Seventeen per cent of patients in this group had a complete clinical and radiological response to treatment. Fifteen percent demonstrated disease progression. We recommend, therefore, that patients with rectal cancer be restaged with CT and MRI following long-course chemoradiotherapy as surgery may be avoided in up to 27% of cases.

A Nomogram to Predict Lymph Node Positivity Following Neoadjuvant Chemoradiation in Locally Advanced Rectal Cancer

BACKGROUND

Patients with locally advanced rectal cancer typically receive neoadjuvant chemoradiation followed by total mesorectal excision. Other treatment approaches, including transanal techniques and close surveillance, are becoming increasingly common following positive responses to chemoradiation. Lack of pathologic lymph node staging is one major disadvantage of these novel strategies.

OBJECTIVE

The purposes of this study were to determine clinicopathologic factors associated with positive lymph nodes following neoadjuvant chemoradiation for rectal cancer and to create a nomogram using these factors to predict rates of lymph node positivity.

DESIGN

This is a retrospective cohort analysis.

SETTINGS

This study used the National Cancer Database.

PATIENTS

Patients aged 18 to 90 with clinical stage T3/T4, N0, M0 or Tany, N1-2, M0 adenocarcinoma of the rectum who underwent neoadjuvant chemoradiation before total mesorectal excision from 2010 to 2012 were identified.

MAIN OUTCOME MEASURES

The primary outcome measure was lymph node positivity after neoadjuvant chemoradiation for locally advanced rectal cancer. Bivariate and multivariate analyses were used to determine the associations of clinicopathologic variables with lymph node positivity.

RESULTS

Eight thousand nine hundred eighty-four patients were included. Young age, lower Charlson score, mucinous histology, poorly differentiated and undifferentiated tumors, the presence of lymphovascular invasion, elevated CEA level, and clinical lymph node positivity were significantly predictive of pathologic lymph node positivity following neoadjuvant chemoradiation. The predictive accuracy of the nomogram is 70.9%, with a c index of 0.71. There was minimal deviation between the predicted and observed outcomes.

LIMITATIONS

This study is retrospective, and it cannot be determined when in the course of treatment the data were collected.

CONCLUSIONS

We created a nomogram to predict lymph node positivity following neoadjuvant chemoradiation for locally advanced rectal cancer that can serve as a valuable complement to imaging to aid clinicians and patients in determining the best treatment strategy.

Interobserver agreement of radiologists assessing the response of rectal cancers to preoperative chemoradiation using the MRI tumour regression grading (mrTRG)

AIM

To investigate whether the magnetic resonance imaging (MRI) tumour regression grading (mrTRG) scale can be taught effectively resulting in a clinically reasonable interobserver agreement (>0.4; moderate to near perfect agreement).

MATERIALS AND METHODS

This study examines the interobserver agreement of mrTRG, between 35 radiologists and a central reviewer. Two workshops were organised for radiologists to assess regression of rectal cancers on MRI staging scans. A range of mrTRGs on 12 patient scans were used for assessment.

RESULTS

Kappa agreement ranged from 0.14-0.82 with a median value of 0.57 (95% CI: 0.37-0.77) indicating good overall agreement. Eight (26%) radiologists had very good/near perfect agreement (κ>0.8). Six (19%) radiologists had good agreement (0.8≥κ>0.6) and a further 12 (39%) had moderate agreement (0.6≥κ>0.4). Five (16%) radiologists had a fair agreement (0.4≥κ>0.2) and two had poor agreement (0.2>κ). There was a tendency towards good agreement (skewness: 0.92). In 65.9% and 90% of cases the radiologists were able to correctly highlight good and poor responders, respectively.

CONCLUSIONS

The assessment of the response of rectal cancers to chemoradiation therapy may be performed effectively using mrTRG. Radiologists can be taught the mrTRG scale. Even with minimal training, good agreement with the central reviewer along with effective differentiation between good and intermediate/poor responders can be achieved. Focus should be on facilitating the identification of good responders. It is predicted that with more intensive interactive case-based learning a κ>0.8 is likely to be achieved. Testing and retesting is recommended.

Surgery for Locally Advanced T4 Rectal Cancer: Strategies and Techniques

Locally advanced T4 rectal cancer represents a complex clinical condition that requires a well thought-out treatment plan and expertise from multiple specialists. Paramount in the management of patients with locally advanced rectal cancer are accurate preoperative staging, appropriate application of neoadjuvant and adjuvant treatments, and, above all, the provision of high-quality, complete surgical resection in potentially curable cases. Despite the advanced nature of this disease, extended and multivisceral resections with clear margins have been shown to result in good oncological outcomes and offer patients a real chance of cure. In this article, we describe the assessment, classification, and multimodality treatment of primary locally advanced T4 rectal cancer, with a focus on surgical planning, approaches, and outcomes.

Rectal cancer with complete clinical response after neoadjuvant chemoradiotherapy, surgery, or "watch and wait"

PURPOSE

The purpose of this study was to compare the outcomes of patients treated with chemoradiotherapy with a complete clinical response followed by either a "watch and wait" strategy or a total mesorectal excision.

METHODS

This was an observational retrospective study from a single institute. Patients with locally advanced rectal cancer following chemoradiotherapy with a complete clinical response from January 1, 2007 to December 31, 2014 were included.

RESULTS

The study population consisted of 18 patients who opted for a "watch and wait" policy and 26 patients who underwent radical surgery after achieving a complete clinical response. Patients had no documented treatment complications under the watch and wait policy, while 13 patients who underwent radical surgery experienced significant morbidity. There were two local recurrences in the watch and wait group; both were treated with salvage resection and had no associated mortality. In the radical surgery group, 1 patient showed an incomplete pathologic response (ypT0N1), and the remaining 25 patients showed complete pathologic responses; 1 had a distant recurrence, which was managed non-operatively, and 2 patients died of unrelated causes. The 5-year overall survival rate and median disease-free survival time were 100% and 69.78 months in the watch and wait group and 92.30% and 89.04 months in the radical surgery group.

CONCLUSIONS

A watch and wait policy avoids the morbidity associated with radical surgery and preserves oncologic outcomes in our retrospective study from a single institute. It could be considered a therapeutic option in patients with locally advanced rectal cancer following chemoradiotherapy with a complete clinical response.

Diffusion-weighted imaging: Apparent diffusion coefficient histogram analysis for detecting pathologic complete response to chemoradiotherapy in locally advanced rectal cancer

PURPOSE

To investigate the usefulness of apparent diffusion coefficient (ADC) values derived from histogram analysis of the whole rectal cancer as a quantitative parameter to evaluate pathologic complete response (pCR) on preoperative magnetic resonance imaging (MRI).

MATERIALS AND METHODS

We enrolled a total of 86 consecutive patients who had undergone surgery for rectal cancer after neoadjuvant chemoradiotherapy (CRT) at our institution between July 2012 and November 2014. Two radiologists who were blinded to the final pathological results reviewed post-CRT MRI to evaluate tumor stage. Quantitative image analysis was performed using T2 -weighted and diffusion-weighted images independently by two radiologists using dedicated software that performed histogram analysis to assess the distribution of ADC in the whole tumor.

RESULTS

After surgery, 16 patients were confirmed to have achieved pCR (18.6%). All parameters from pre- and post-CRT ADC histogram showed good or excellent agreement between two readers. The minimum, 10th, 25th, 50th, and 75th percentile and mean ADC from post-CRT ADC histogram were significantly higher in the pCR group than in the non-pCR group for both readers. The 25th percentile value from ADC histogram in post-CRT MRI had the best diagnostic performance for detecting pCR, with an area under the receiver operating characteristic curve of 0.796.

CONCLUSION

Low percentile values derived from the ADC histogram analysis of rectal cancer on MRI after CRT showed a significant difference between pCR and non-pCR groups, demonstrating the utility of the ADC value as a quantitative and objective marker to evaluate complete pathologic response to preoperative CRT in rectal cancer. J. Magn. Reson. Imaging 2016;44:212-220.

The accuracy of endorectal ultrasonography in rectal cancer staging

Background and aims

The incidence of rectal cancer in the European Union is about 35% of the total colorectal cancer incidence. Staging rectal cancer is important for planning treatment. It is essential for the management of rectal cancer to have adequate preoperative imaging, because accurate staging can influence the therapeutic strategy, type of resection, and candidacy for neoadjuvant therapy. The aim of this work is to evaluate the accuracy of endorectal ultrasound (ERUS) in rectal cancer staging.

Methods

A retrospective study was performed to assess the accuracy of ERUS by analyzing patients discharged from Regional Institute of Gastroenterology and Hepatology (IRGH) Cluj-Napoca, Romania, diagnosed with rectal cancer between 01 January 2011 and 31 December 2013. Patients who were preoperatively staged by other imaging methods and those who had ERUS performed in another service were excluded from the analysis. As inclusion criteria remained ERUS performed for patients with rectal cancer in IRGH Cluj-Napoca where they were also operated. We analyzed preoperative T stage obtained by ERUS and it was compared with the histopathology findings.

Results

The number of patients discharged with a diagnosis of rectal cancer were 200 (operated – 157) in 2011, 193 (operated – 151) in 2012, and 198 (operated – 142) in 2013. We analyzed a total of 51 cases diagnosed with rectal cancer who performed ERUS in IRGH Cluj-Napoca. The results according to the T stage obtained by ERUS and histopathology test were:

Conclusions

ERUS is a method of staging rectal cancer which is human dependent. ERUS is less accurate for T staging of stenotic tumours, but the accuracy may still be within acceptable limits. Surgeons use ERUS to adopt a treatment protocol, knowing the risk of under-staging and over-staging of this method. The accuracy of ERUS is higher in diagnosing rectal cancer in stages T1, T2 and even in stage T3 with malignant tumor which is not occlusive. ERUS is less accurate for T staging of locally advanced and stenotic tumours.

Multidisciplinary treatment of rectal cancer in 2014: Where are we going?

In the present review we discuss the recent developments and future directions in the multimodal treatment of locally advanced rectal cancer, with respect to staging and re-staging modalities, to the current role of neoadjuvant chemo-radiation and to the conservative and more limited surgical approaches based on tumour response after neoadjuvant combined therapy. When initial tumor staging is considered a high accuracy has been reported for T pre-treatment staging, while preoperative lymph node mapping is still suboptimal. With respect to tumour re-staging, all the current available modalities still present a limited accuracy, in particular in defining a complete response. The role of short vs long-course radiotherapy regimens as well as the optimal time of surgery are still unclear and under investigation by means of ongoing randomized trials. Observational management or local excision following tumour complete response are promising alternatives to total mesorectal excision, but need further evaluation, and their use outside of a clinical trial is not recommended. The preoperative selection of patients who will benefit from neoadjuvant radiotherapy or not, as well as the proper identification of a clinical complete tumour response after combined treatment modalities,will influence the future directions in the treatment of locally advanced rectal cancer.