The potential of restaging in the prediction of pathologic response after preoperative chemoradiotherapy for rectal cancer

Texture analysis of apparent diffusion coefficient maps: can it identify nonresponse to neoadjuvant chemotherapy for additional radiation therapy in rectal cancer patients?

Background

Neoadjuvant chemotherapy (NCT) alone can achieve comparable treatment outcomes to chemoradiotherapy in locally advanced rectal cancer (LARC) patients. This study aimed to investigate the value of texture analysis (TA) in apparent diffusion coefficient (ADC) maps for identifying non-responders to NCT.

Methods

This retrospective study included patients with LARC after NCT, and they were categorized into nonresponse group (pTRG 3) and response group (pTRG 0-2) based on pathological tumor regression grade (pTRG). Predictive texture features were extracted from pre- and post-treatment ADC maps to construct a TA model using RandomForest. The ADC model was developed by manually measuring pre- and post-treatment ADC values and calculating their changes. Simultaneously, subjective evaluations based on magnetic resonance imaging assessment of TRG were performed by two experienced radiologists. Model performance was compared using the area under the curve (AUC) and DeLong test.

Results

A total of 299 patients from two centers were divided into three cohorts: the primary cohort (center A; n = 194, with 36 non-responders and 158 responders), the internal validation cohort (center A; n = 49, with 9 non-responders) and external validation cohort (center B; n = 56, with 33 non-responders). The TA model was constructed by post_mean, mean_change, post_skewness, post_entropy, and entropy_change, which outperformed both the ADC model and subjective evaluations with an impressive AUC of 0.997 (95% confidence interval [CI], 0.975-1.000) in the primary cohort. Robust performances were observed in internal and external validation cohorts, with AUCs of 0.919 (95% CI, 0.805-0.978) and 0.938 (95% CI, 0.840-0.985), respectively.

Conclusions

The TA model has the potential to serve as an imaging biomarker for identifying nonresponse to NCT in LARC patients, providing a valuable reference for these patients considering additional radiation therapy.

Magnetic resonance imaging for assessment of rectal cancer nodes after chemoradiotherapy: A single center experience

BACKGROUND

Accurate nodal restaging is becoming clinically more important in patients with locally advanced rectal cancer (LARC) with the emergence of organ-preserving treatment after a good response to neoadjuvant chemoradiotherapy (nCRT).

PURPOSE

To evaluate the accuracy of MRI in identifying negative N status (ypN0 patients) in LARC after nCRT.

MATERIAL AND METHODS

191 patients with LARC underwent MRI before and 6-8 weeks after nCRT and subsequent total mesorectal excision. Short-axis diameter of mesorectal lymph nodes was evaluated on the high resolution T2-weighted images to compare MRI restaging with histopathology..

RESULTS

146 and 45 patients had a negative N status (ypN0) and positive N status (ypN + ), respectively. On restaging MRI, the 70 % reduction in size of the largest node was associated with an area under the curve (AUC) of 0.818 to predict ypN0 stage, with a sensitivity of 93.3 % and a negative predictive value (NPV) of 95.4 %. No nodes were observed in 38 pts (37 pts ypN0 and 1 patient ypN + ), with sensitivity and NPV of nodes disappearance for ypN0 stage of 93.3 % and 92.5 % respectively. A 2.2 mm cut-off in short-axis diameter was associated with an AUC of 0.83 for the prediction of ypN0 nodal stage, with sensitivity and NPV of 79,5% and 91.1 % respectively.

CONCLUSION

A reduction in size of 70 % of the largest limph-node on MRI at rectal cancer restaging has high sensitivity and NPV for prediction of ypN0 stage after nCRT. The high NPV of node disappearance and of a ≤ 2.2 mm short-axis diameter is confirmed.

The experience of the COMRE group (REctal COMmittee): can magnetic resonance imaging and endosonography really help the clinical pathway after NCRT in rectal cancer?

BACKGROUND

MRI and rectal endosonography (EUS) are routinely used for preoperative tumor staging and assessment of response to therapy in patients with rectal cancer. This study aimed to evaluate the accuracy of the two techniques in predicting the pathological response compared to the resected specimen and the agreement between MRI and EUS and to define the factors that could affect the ability of EUS and MRI to predict pathological responses.

MATERIALS AND METHODS

This study included 151 adult patients with middle or low rectal adenocarcinoma treated with neoadjuvant chemoradiotherapy, followed by curative intent elective surgery in the Oncologic Surgical Unit of a hospital in the north of Italy between January 2010 and November 2020. All patients underwent MRI and rectal EUS.

RESULTS

The accuracy of EUS to evaluate the T stage was 67.48%, and for the N stage was 75.61%; the accuracy of MRI to evaluate the T stage was 75.97%, and that for the N stage was 51.94%. The agreement in detecting the T stage between EUS and MRI was 65.14% with a Cohen's kappa of 0.4070 and that for the evaluation of the lymph nodes between EUS and MRI was 47.71% with a Cohen's kappa of 0.2680. Risk factors that affect the ability of each method to predict pathological response were also investigated using logistic regression.

CONCLUSIONS

EUS and MRI are accurate tools for rectal cancer staging. However, after Radiotherapy - Chemotherapy RT-CT, neither method is reliable for establishing the T stage. EUS seems significantly better than MRI for assessing the N stage. Both methods can be used as complementary tools in the preoperative assessment and management of rectal cancer, but their role in the assessment of residual rectal tumors cannot predict the complete clinical response.

ERCC1 Overexpression Increases Radioresistance in Colorectal Cancer Cells

Simple Summary

The 20–30% of locally advanced rectal cancer patients undergoing preoperative concurrent chemoradiotherapy had no expected efficacy, and ERCC1 overexpression was found in these tumor tissue patients. In the interest of confirming and adding details to our understanding of that correlation, The Tet-on gene expression system was used to examine ERCC1 functionality and stability. Our data from regulatable HCT116-Tet-on and COLO205-Tet-on cell lines verified the increased radioresistance in colorectal cancer cells that are associated with ERCC1 overexpression, and they confirmed a high correlation between ERCC1 levels and radiotherapeutic efficiency. Furthermore, overexpression of ERCC1 also increases cell migration under radiation exposure. Additional data from ERCC1 expression regulation in vivo confirmed that the overexpression of increased cancer radiation resistance suggests that ERCC1 expression plays a key role.

Abstract

Preoperative concurrent chemoradiotherapy (CCRT) is a standard treatment for locally advanced rectal cancer patients, but 20–30% do not benefit from the desired therapeutic effects. Previous reports indicate that high levels of ERCC1 reduce the effectiveness of cisplatin-based CCRT; however, it remains unclear as to whether ERCC1 overexpression increases radiation resistance. To clarify the correlation between ERCC1 levels and radiation (RT) resistance, we established two cell lines (HCT116-Tet-on and COLO205-Tet-on), induced them to overexpress ERCC1, detected cell survival following exposure to radiation, established HCT116-Tet-on and COLO205-Tet-on heterotopic cancer animal models, and detected tumor volume following exposure to radiation. We found that ERCC1 overexpression increased radiation resistance. After regulating ERCC1 levels and radiation exposure to verify the correlation, we noted that increased radiation resistance was dependent on ERCC1 upregulation in both cell lines. For further verification, we exposed HCT116-Tet-on and COLO205-Tet-on heterotopic cancer animal models to radiation and observed that ERCC1 overexpression increased colorectal cancer tumor radioresistance in both. Combined, our results suggest that ERCC1 overexpression may serve as a suitable CCRT prognostic marker for colorectal cancer patients.

Modest agreement between magnetic resonance and pathological tumor regression after neoadjuvant therapy for rectal cancer in the real world

Magnetic Resonance Imaging (MRI) is routinely used for preoperative tumor staging and to assess response to therapy in rectal cancer patients. The aim of this study was to evaluate the accuracy of MRI based restaging after neoadjuvant CRT in predicting pathologic response. This multicenter cohort study included adult patients with histologically confirmed locally advanced rectal adenocarcinoma treated with neoadjuvant CRT followed by curative intent elective surgery between January 2014 and December 2019 at four academic high-volume institutions. Magnetic resonance tumor regression grade (mrTRG) and pathologic tumor regression grade (pTRG) were reviewed and compared for all the patients. The agreement between radiologist and pathologist was assessed with the weighted k test. Risk factors for poor agreement were investigated using logistic regression. A total of 309 patients were included. Modest agreement was found between mrTRG and pTRG when regression was classified according to standard five-tier systems (k=0.386). When only two categories were considered for each regression system, (pTRG 0-3 vs. pTRG 4; mrTRG 2-5 vs. mrTRG 1) an accuracy of 78% (IC 95% 0.73-0.83) was found between radiologic and pathologic assessment with a k value of 0.185.The logistic regression model revealed that "T3 greater than 5mm extent" was the only variable significantly impacting on disagreement (OR 0.33, 95% CI 0.15-0.68, p=0.0034). Modest agreement exhists between mrTRG and pTRG. The chances of appropriate assessment of the regression grade after neoadjuvant CRT appear to be higher in case of a T3 tumor with at least 5mm extension in the mesorectal fat at the pre-treatment MRI. This article is protected by copyright. All rights reserved.

Locally Advanced Rectal Cancer: What We Learned in the Last Two Decades and the Future Perspectives

The advancement in surgical techniques, optimization of systemic chemoradiotherapy, and development of refined diagnostic and imaging modalities have brought a phenomenal shift in the treatment of the locally advanced rectal cancer. Although each therapeutic option has shown substantial progress in their field, it is finding their ideal amalgamation which has baffled the clinician and researchers alike. In the effort to identifying the perfect salutary treatment plan, we have even shifted our attention from the trimodal approach to non-operative "watchful waiting" to more recent individualized care. In this article, we acknowledge the scientific progress in the management of locally advanced rectal cancer and compare the opportunities as well as the obstacles while implementing them clinically. We also explore the current challenges and controversies surrounding the multidisciplinary approach and highlight the new trends and recent advances with an ultimate goal to improve the patients' quality of life.

Diagnostic performance of MRI and endoscopy for assessing complete response in rectal cancer after neoadjuvant chemoradiotherapy: a systematic review of the literature

BACKGROUND

The diagnostic performance of magnetic resonance imaging (MRI) modalities and/or endoscopy for assessing complete response in rectal cancer after neoadjuvant chemoradiotherapy (nCRT) is unclear.

PURPOSE

To summarize existing evidence on the diagnostic performance of diffusion-weighted MRI, perfusion-weighted MRI, T2-weighted MR tumor regression grade, and/or endoscopy for assessing complete tumor response after nCRT.

MATERIAL AND METHODS

MEDLINE and Embase databases were searched. The PRISMA guidelines were followed. Sensitivity, specificity, negative predictive, and positive predictive values were retrieved from included studies.

RESULTS

In total, 81 studies were eligible for inclusion. Evidence suggests that combined use of MRI and endoscopy tends to improve the diagnostic performance compared to single imaging modality. The positive predictive value of a complete response varies substantially between studies. There is considerable heterogeneity between studies.

CONCLUSION

Combined re-staging tends to improve diagnostic performance compared to single imaging modality, but the vast majority of studies fail to offer true clinical value due to the study heterogeneity.

Biomarkers and cell-based models to predict the outcome of neoadjuvant therapy for rectal cancer patients

Rectal cancer constitutes approximately one-third of all colorectal cancers and contributes to considerable mortality globally. In contrast to colon cancer, the standard treatment for localized rectal cancer often involves neoadjuvant chemoradiotherapy. Tumour response rates to treatment show substantial inter-patient heterogeneity, indicating a need for treatment stratification. Consequently researchers have attempted to establish new means for predicting tumour response in order to assist in treatment decisions. In this review we have summarized published findings regarding potential biomarkers to predict neoadjuvant treatment response for rectal cancer tumours. In addition, we describe cell-based models that can be utilized both for treatment prediction and for studying the complex mechanisms involved.

Accuracy of MRI for nodal restaging in rectal cancer: a retrospective study of 166 cases

AIM

Assessing metastatic mesorectal nodal involvement is a challenge in rectal cancer, especially in the post chemoradiation setting. We aim to assess the accuracy of MRI for nodal restaging and the validity of SAR criteria (≥ 5 mm size being metastatic).

MATERIALS AND METHODS

This was an IRB-approved retrospective study of 166 patients with locally advanced rectal cancers, operated after neoadjuvant treatment. Two dedicated oncoradiologists reviewed the 166 post-chemoradiation presurgical MRIs in consensus. Nodal size and morphology (shape, margins, and signal intensity) were noted. The most accurate cut-off for size for predicting positive pN status was determined using the Youden index.

RESULTS

MRI understaged 30/166 (18%) and overstaged 40/166 (24%) patients using the SAR criteria. The most accurate cut-off for node size was 5.5 mm, with a sensitivity of 75%, specificity of 60.2%, PPV of 40.7%, NPV of 86.9% (95% CI:78-92.5%), accuracy of 64.2%, and area under the curve (AUC) 0.657 (95% CI-0.524-0.79). Morphological characteristics were not significant to determine involvement, with positive nodes including 42% of round and 31% of oval nodes, 40% of heterogeneous and 45% of homogeneous nodes, and 31% irregularly marginated and 46% nodes with regular margins being positive on pathology. MRI was accurate in predicting pathology for mucinous nodes in 9/29 (31%) cases. Seven cases which were yN2 on MRI and yN0 on pathology demonstrated mucinous changes on MRI and had acellular mucin on histopathology.

CONCLUSIONS

MRI has good negative predictive value, poor positive predictive value and moderate accuracy in nodal restaging. The cut-off of 5.5 mm demonstrated in our study is close to the SAR cut-off of 5 mm in the post-treatment setting. MRI accuracy is lower in patients with mucinous nodes.

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.

Analysis of influencing factors of no/low response to preoperative concurrent chemoradiotherapy in locally advanced rectal cancer

The aim of this study is to investigate the influencing factors associated with no/low response to preoperative concurrent chemoradiotherapy (CCRT) for locally advanced rectal cancer (LARC) patients. A total of 79 patients were included in this prospective study. Fifteen factors that might affect the resistance to CCRT were included in this logistic regression analysis, these factors include the general clinical data of patients, the expression status of tumor stem cell marker CD44v6 and the volumetric imaging parameters of primary tumor lesions. We found that the no/low response status to preoperative CCRT was positively correlated with the real tumor volume (RTV), the total surface area of tumor (TSA), and CD44v6 expression, whereas negatively correlated with the tumor compactness (TC). According to the results of logistic regression analysis, two formulas that could predict whether or not no/low response to preoperative CCRT were established. The Area Under Curve (AUC) of the two formulas and those significant measurement data (RTV, TC, TSA) were 0.900, 0.858, 0.771, 0.754, 0.859, the sensitivity were 95.8%, 79.17%, 62.50%, 95.83%, 62.5%, the specificity were 70.9%, 74.55%, 83.64%,47.27%, 96.36%, the positive predictive values were 58.96%, 57.58%, 62.51%,44.23%, 88.23%, the negative predictive values were 97.48%, 89.13%, 83.64%, 96.29%, and 85.48%, respectively.

Local excision in rectal cancer patients with major or complete clinical response after neoadjuvant therapy: a case-matched study

PURPOSE

To assess the long-term oncological outcomes in patients with locally advanced rectal cancer who underwent neoadjuvant therapy followed by local or total mesorectal excision.

METHODS

Patients with locally advanced rectal adenocarcinoma who received neoadjuvant therapy from 2005 to 2017 were evaluated. Those with major or complete clinical response underwent a full-thickness local excision. Kaplan-Meier estimates were used to evaluate overall, disease-free, and local recurrence-free survival of patients who underwent local excision (LE group) and were compared with a matched cohort of patients who underwent total mesorectal excision (TME group).

RESULTS

Among 252 patients who received neoadjuvant therapy for rectal cancer, 51 (20.2%) underwent a local excision. At a median follow-up of 61 months, patients who underwent local excision were stoma-free in 88.2% of cases and with rectum preserved in 78.5% of cases, respectively. The estimated 5-year local, disease-free, and overall survival was 91.8% vs 97.6% (95% CI: 79.5-96.8 vs 84.6-99.6), 86.7% vs 86.4% (95% CI: 72.5-93.9 vs 70.1-94.1), and 85% vs 90% (95% CI: 69.0-93.0% vs 75.3-96.2), in the study and matched control group, respectively. None of the differences was statistically significant.

CONCLUSIONS

One-fifth of patients with locally advanced rectal cancer are manageable with a rectum-sparing approach after neoadjuvant therapy. With this strategy, about 80% patients will have their rectum preserved and 90% will be without stoma at long term.

Sensitivity of Various Evaluating Modalities for Predicting a Pathologic Complete Response After Preoperative Chemoradiation Therapy for Locally Advanced Rectal Cancer

PURPOSE

We investigated the sensitivity of various evaluating modalities in predicting a pathologic complete response (pCR) after preoperative chemoradiation therapy (PCRT) for locally advanced rectal cancer (LARC).

METHODS

From a population of 2,247 LARC patients who underwent PCRT followed by surgery at Asan Medical Center, Seoul, Korea from January 2007 to June 2016, we retrospectively analyzed 313 patients (14.1%) who showed a pCR after surgery. Transrectal ultrasound (TRUS), high-resolution magnetic resonance imaging (MRI), abdominopelvic computed tomography (AP-CT), and endoscopy were performed within 2 weeks prior to surgery.

RESULTS

Of the 313 patients analyzed, 256 (81.8%) had a pCR after radical surgery and 57 (18.2%) showed total regression after local excision. Preoperative TRUS, MRI, and AP-CT were performed in 283, 305, and 139 patients, respectively. Among these 3 groups, a prediction of a pCR of the primary tumor was made in 41 (14.5%), 51 (16.7%), and 27 patients (19.4%), respectively, before surgery. A prediction of a clinical N0 stage was made in 204 patients (88.3%) using TRUS, 130 (52.2%) using MRI, and 78 (65.5%) using AP-CT. Of the 211 patients who underwent endoscopy, 87 (41.2%) had a mention of clinical CR in their records. A prediction of a pathologic CR was made for 124 patients (39.6%) through at least one diagnostic modality.

CONCLUSION

The various evaluation methods for predicting a pCR after PCRT show a predictive sensitivity of 0.15-0.41 for primary tumors and 0.52-0.88 for lymph nodes. Endoscopy is a relatively superior modality for predicting the pCR of the primary tumor of LARC patients.

Colorectal cancer: Parametric evaluation of morphological, functional and molecular tomographic imaging

Colorectal cancer (CRC) represents one of the leading causes of tumor-related deaths worldwide. Among the various tools at physicians’ disposal for the diagnostic management of the disease, tomographic imaging (e.g., CT, MRI, and hybrid PET imaging) is considered essential. The qualitative and subjective evaluation of tomographic images is the main approach used to obtain valuable clinical information, although this strategy suffers from both intrinsic and operator-dependent limitations. More recently, advanced imaging techniques have been developed with the aim of overcoming these issues. Such techniques, such as diffusion-weighted MRI and perfusion imaging, were designed for the “in vivo” evaluation of specific biological tissue features in order to describe them in terms of quantitative parameters, which could answer questions difficult to address with conventional imaging alone (e.g., questions related to tissue characterization and prognosis). Furthermore, it has been observed that a large amount of numerical and statistical information is buried inside tomographic images, resulting in their invisibility during conventional assessment. This information can be extracted and represented in terms of quantitative parameters through different processes (e.g., texture analysis). Numerous researchers have focused their work on the significance of these quantitative imaging parameters for the management of CRC patients. In this review, we aimed to focus on evidence reported in the academic literature regarding the application of parametric imaging to the diagnosis, staging and prognosis of CRC while discussing future perspectives and present limitations. While the transition from purely anatomical to quantitative tomographic imaging appears achievable for CRC diagnostics, some essential milestones, such as scanning and analysis standardization and the definition of robust cut-off values, must be achieved before quantitative tomographic imaging can be incorporated into daily clinical practice.

Endoscopy and magnetic resonance imaging-based prediction of ypT stage in patients with rectal cancer who received chemoradiotherapy: Results from a prospective study of 110 patients

Accurate tumor response determination remains inconclusive after preoperative chemoradiation therapy (CRT) for rectal cancer. This study aimed to investigate whether clinical assessment, such as endoscopy and magnetic resonance imaging (MRI), can accurately predict ypT stage and select candidates for pelvic organ-preserving surgery in rectal cancer after preoperative CRT. A total of 110 patients who underwent preoperative CRT followed by curative resection for rectal cancer were prospectively enrolled. Magnetic resonance tumor regression grade (mrTRG) using T2-MRI, endoscopic evaluation, and combination modality (combination of endoscopy and mrTRG) were used to analyze tumor response after preoperative CRT. Endoscopic findings were categorized as 3 grades and the mrTRG was assessed into 5 grades. Twenty-nine patients (26.4%) had achieved pathologic complete response. When predicting ypT0, endoscopy showed significantly higher area under the curve (AUC 0.818) than did mrTRG (AUC 0.568) and combination modality (AUC 0.768) in differentiating good response from poor response (P < .001). Both endoscopy and combination modality showed significantly higher diagnostic performance in sensitivity (79.31%), positive predictive value (PPV 67.65%), negative predictive value (NPV 92.11%), and accuracy (84.55%) than those of MR tumor response (sensitivity 37.93%, PPV 36.67%, NPV 77.50%, and accuracy 66.36%) for the prediction of ypT0 (P < .001). Combination modality showed significantly higher diagnostic performance in sensitivity (56.92%), NPV (56.92%), and accuracy (67.27%) compared with those of mrTRG. Neither endoscopy, nor mrTRG, nor the combination modality had adequate diagnostic performances to be clinically acceptable in selecting candidates for nonoperative treatment strategies. However, endoscopy may be incorporated in clinical restaging strategy in planning the extent of surgical resection in patients with rectal cancer.

Expression of vascular endothelial growth factor as a predictor of complete response for preoperative chemoradiotherapy in rectal cancer

Biomarkers that predict tumor response before surgical treatment are necessary to help select patients for preoperative chemoradiotherapy for rectal cancer. However, no definite predictive biomarker has been established. This study explored programmed death-ligand 1 (PD-L1), epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), p-signal transducer and activator of transcription 3 (p-STAT3), and death-domain associated protein as predictive biomarkers with regard to preoperative chemoradiotherapy in rectal cancer.Formalin-fixed paraffin-embedded cancer tissues from pretreatment biopsies from 31 patients who underwent preoperative chemoradiotherapy were studied. The biomarkers were evaluated by immunohistochemistry.PD-L1 positivity was found in 22.6% of 31 patients and complete response (CR) showed 33.3% and non-CR showed 18.2%. EGFR positivity was found in 71.0% of 31 patients and CR showed 88.9% and non-CR showed 73.6%. VEGF positivity was found in 83.9% of 31 patients and CR showed 88.9% and non-CR showed 81.8%. p-STAT3 positivity was found in 80.6% of 31 patients and CR showed 88.9% and non-CR showed 77.3%. On multiple logistic regression analysis, only VEGF expression was found to be a significant predictive factor for CR (P = .001). VEGF expression in pretreatment biopsies might be a predictive marker for CR after preoperative chemoradiation in rectal cancer.Although there is a restriction of small sample size, our finding suggested that this study can be foundation for a larger further study for biomarkers which can predict neoadjuvant therapy response of specimens obtained for diagnosis before surgery.

Metastatic pattern and new primary tumours after neoadjuvant therapy and surgery in rectal cancer

AIM

Current follow-up guidelines for distant tumour recurrence after rectal cancer surgery are not defined or agreed. The aim was to elucidate the pattern of recurrence over time and provide information that could help direct a strategy for surveillance.

METHOD

In all, 378 patients with locally advanced rectal cancer were treated with preoperative chemoradiotherapy and surgery with curative intent. Patients were followed up with a standard protocol, and data were prospectively collected in a dedicated database. Disease-free survival and overall survival were calculated.

RESULTS

Within a median follow-up time of 75 months, rates of local and distant recurrence were 2.6% and 21.7%, respectively. Risk factors for recurrence were a baseline carcinoembryonic antigen > 5.0 ng/ml, a distance from the anal verge ≤ 5 cm, R1 resection margins, G3 grading, ypT staging > 2, positive lymph node status and a tumour regression grade of 3-5. Disease-free survival did not vary significantly between patients with lung and extra-pulmonary metastases (P = 0.59). The only factor associated with increased risk of lung metastases was a distance of the tumour from the anal verge of ≤ 5 cm (P = 0.01). Most recurrences occurred within the first 3 years after surgery (74.4%). The first site of recurrence was most frequently the lung (52.0%). The most frequent new primary malignancy was lung cancer (22.5%).

CONCLUSIONS

Patients undergoing curative therapy for rectal cancer often experience distant recurrence; the majority of recurrences occur within the first 3 years after surgery and lung metastases are the most common. A predictive factor for pulmonary recurrence is a tumour in the lower rectum.

Non-operative management of rectal cancer: understanding tumor biology

The management of locally-advanced rectal cancer involves a combination of chemotherapy, chemoradiation, and surgical resection to provide excellent local tumor control and overall survival. However, aspects of this multimodality approach are associated with significant morbidity and long-term sequelae. In addition, there is growing evidence that patients with a clinical complete response to chemotherapy and chemoradiation treatments may be safely offered initial non-operative management in a rigorous surveillance program. Weighed against the morbidity and significant sequelae of rectal resection, recognizing how to best optimize non-operative strategies without compromising oncologic outcomes is critical to our understanding and treatment of this disease.

Assessment of remaining tumour involved lymph nodes with MRI in patients with complete luminal response after neoadjuvant treatment of rectal cancer

OBJECTIVE

To assess the accuracy of MRI to predict remaining lymph node metastases in patients with complete pathological luminal response (ypT0) after neoadjuvant therapy.

METHODS

Data from a national registry were used. 19 patients with histopathologically remaining lymph node metastases (ypT0N+) were identified. Another 19 patients without lymph node metastases (ypT0N0) were used as matched controls. Two radiologists blinded to all patient information evaluated staging and restaging MRI that was compared to histopathological findings of the resected specimen.

RESULTS

The average size of the largest lymph node on restaging MRI was significantly larger (4.5 mm) in the ypT0N+ group than in the ypT0N0 group (2.6 mm) (p = 0.04). Presence of ypN+ was correctly predicted by MRI in 7 of 19 patients. In patients without lymph node metastases (ypT0N0), these were correctly classified by MRI in 16 of 19 patients. All patients who had MR-identified lymph nodes larger than 8 mm at restaging were ypTN+. The sensitivity, specificity, positive predictive value and negative for prediction of remaining lymph node metastasis with MRI were 37, 84, 70 and 57%.

CONCLUSION

In patients with ypT0 in rectal cancer after neoadjuvant treatment, remaining regional lymph node metastases cannot safely be predicted by restaging MRI alone using presently known criteria. Presence of a lymph node over 8 mm on restaging MRI strongly indicates yPN+. Advances in knowledge: This is one of the first studies on MRI lymph node assessment after chemo-radiotherapy (CRT) in luminal complete response.

The Optimal Application of Transrectal Ultrasound in Staging of Rectal Cancer Following Neoadjuvant Therapy: A Pragmatic Study for Accuracy Investigation

Background: Transrectal ultrasound (TRUS) is a cost-effective test for preoperative assessment of rectal cancer. However, whether the accuracy of TRUS staging is correlated with tumor location remains obscured. This study is designed to explore their relationship and confirm an optimal application of TRUS in rectal cancer restaging.

Methods: From 2005 to 2011, rectal cancer patients with TRUS data were retrospectively reviewed. Patients were divided into five groups according to tumor-involved rectal segment (SEG) above the anal verge: SEG I 1-3cm, II 3-6cm, III 6-9cm, IV 9-12cm, and V 12-16cm. The accuracy and long-term outcomes of tumor staging were compared between ultrasonographic and pathological stages.

Results: 219 patients were included, with 55 (25.1%) in SEG I, 123 (56.2%) in SEG II, 32 (14.6%) in SEG III, 4 (1.8%) in SEG IV and 5 (2.3%) in SEG V. The overall accuracy of TRUS staging was remarkably superior to clinical staging by CT (64.8% vs. 34.7%, P<0.001), with 70.3% and 82.2% for ultrasonographic T and N stages respectively. The accuracy of TRUS reached its peak value when tumors were located in SEG II. The 5-year overall survival had no significant difference between TRUS and pathology staging for all stages. A cox regression analysis indicated that high levels of CEA and tumor location were risk factors of inaccurate staging.

Conclusions: TRUS is still a valuable examination for restaging of rectal cancer after neoadjuvant therapy. The application of TRUS would be optimal for rectal cancer located 3-6cm above the anal verge.

Cell-free DNA levels and correlation to stage and outcome following treatment of locally advanced rectal cancer

Accurate staging of rectal cancer remains essential for optimal patient selection for combined modality treatment, including radiotherapy, chemotherapy and surgery. We aimed at examining the correlation of cell free DNA with the pathologic stage and subsequent risk of recurrence for patients with locally advanced rectal cancer undergoing preoperative chemoradiation. We examined 75 patients with locally advanced rectal cancer receiving preoperative chemoradiation. Blood samples for translational use were drawn prior to rectal surgery. The level of cell free DNA was quantified by digital droplet PCR and expressed as copy number of beta 2 microglobulin. We found a median level of cell free DNA in the AJCC stages I-III of 3100, 8300, and 10,700 copies/mL respectively. For patients with 12 sampled lymph nodes or above, the median level of cell free DNA were 2400 copies/mL and 4400 copies/mL (p = 0.04) for node negative and node positive disease respectively. The median follow-up was 39 months and 11 recurrences were detected (15%). The median level for patients with recurrent disease was 13,000 copies/mL compared to 5200 copies/mL for non-recurrent patients (p = 0.08). We have demonstrated a correlation between the level of total cell free DNA and the pathologic stage and nodal involvement. Furthermore, we have found a trend towards a correlation with the risk of recurrence following resection of localized rectal cancer.

Prediction of N0 Irradiated Rectal Cancer Comparing MRI Before and After Preoperative Chemoradiotherapy

BACKGROUND

The prediction of lymph node status using MRI has an impact on the management of rectal cancer, both before and after preoperative chemoradiotherapy.

OBJECTIVE

The purpose of this study was to maximize the negative predictive value and sensitivity of mesorectal lymph node imaging after chemoradiotherapy because postchemoradiation node-negative patients may be treated with rectum-sparing approaches.

DESIGN

This was a retrospective study.

SETTINGS

The study was conducted at a tertiary care hospital.

PATIENTS

Sixty-four patients with locally advanced rectal cancer who underwent preoperative chemoradiotherapy and MRI for staging and the assessment of response were evaluated.

MAIN OUTCOME MEASURES

The sums of the sizes of all mesorectal lymph nodes in each patient on both prechemoradiotherapy and postchemoradiotherapy imaging data sets were calculated to determine the lymph node global size reduction rates, taking these to be the outcomes of the histopathologic findings. Other included measures were interobserver agreement regarding the prediction of node status based on morphologic criteria and the diagnostic performance of contrast-enhanced images.

RESULTS

Using a cutoff value of a 70% lymph node global size reduction rate with only 15 node-positive patients on histopathology, the sensitivity in the prediction of nodal status and negative predictive value were 93% (95% CI, 70.2%-98.8%) and 97% (95% CI, 82.9%-99.8%) for observer 1 and 100% (95% CI, 79.6%-100%) and 100% (95% CI, 62.9%-100%) for observer 2. The areas under the receiver operating characteristic curves for the 2 observers were 0.90 (95% CI, 0.82-0.98; p < 0.0001) for observer 1 and 0.65 (95% CI, 0.50-0.79; p = 0.08) for observer 2. The efficacy of the morphologic criteria and contrast-enhanced images in predicting node status was limited after chemoradiotherapy.

LIMITATIONS

This study is limited by its small sample size and retrospective nature.

CONCLUSIONS

Assessing the lymph node global size reduction rate value reduces the risk of undetected nodal metastases and may be helpful in better identifying suitable candidates for the local excision of early stage rectal cancer. See Video Abstract at http://links.lww.com/DCR/A412.

Rectal sparing approach after preoperative radio- and/or chemotherapy (RESARCH) in patients with rectal cancer: a multicentre observational study

BACKGROUND

Rectum-sparing approaches appear to be appropriate in rectal cancer patients with a major (mCR) or complete clinical response (cCR) after neoadjuvant therapy. The aim of the present study is to evaluate the effectiveness of rectum-sparing approaches at 2 years after the completion of neoadjuvant treatment.

STUDY DESIGN

Patients with rectal adenocarcinoma eligible to receive neoadjuvant therapy will be prospectively enrolled. Patients will be restaged 7-8 weeks after the completion of neoadjuvant therapy and those with mCR (defined as absence of mass, small mucosal irregularity no more than 2 cm in diameter at endoscopy and no metastatic nodes at MRI) or cCR will be enrolled in the trial. Patients with mCR will undergo local excision, while patients with cCR will either undergo local excision or watch and wait policy. The main end point of the study is to determine the percentage of rectum preservation at 2 years in the enrolled patients.

CONCLUSION

This protocol is the first prospective trial that investigates the role of both local excision and watch and wait approaches in patients treated with neoadjuvant therapy for rectal cancer. The trial is registered at clinicaltrials.gov (NCT02710812).

Recent advances in the management of rectal cancer: No surgery, minimal surgery or minimally invasive surgery

Over the last decade, with the acceptance of the need for improvements in the outcome of patients affected with rectal cancer, there has been a significant increase in the literature regarding treatment options available to patients affected by this disease. That treatment related decisions should be made at a high volume multidisciplinary tumor board, after pre-operative rectal magnetic resonance imaging and the importance of total mesorectal excision (TME) are accepted standard of care. More controversial is the emerging role for watchful waiting rather than radical surgery in complete pathologic responders, which may be appropriate in 20% of patients. Patients with early T1 rectal cancers and favorable pathologic features can be cured with local excision only, with transanal minimal invasive surgery (TAMIS) because of its versatility and almost universal availability of the necessary equipment and skillset in the average laparoscopic surgeon, emerging as the leading option. Recent trials have raised concerns about the oncologic outcomes of the standard “top-down” TME hence transanal TME (TaTME “bottom-up”) approach has gained popularity as an alternative. The challenges are many, with a dearth of evidence of the oncologic superiority in the long-term for any given option. However, this review highlights recent advances in the role of chemoradiation only for complete pathologic responders, TAMIS for highly selected early rectal cancer patients and TaTME as options to improve cure rates whilst maintaining quality of life in these patients, while we await the results of further definitive trials being currently conducted.

Accuracy of MRI in Restaging Locally Advanced Rectal Cancer After Preoperative Chemoradiation

BACKGROUND

Patients with a locally advanced rectal carcinoma benefit from preoperative chemoradiotherapy. MRI is considered the first choice imaging modality after preoperative chemoradiation, although its reliability for restaging is debatable.

OBJECTIVE

The purpose of this study was to determine the accuracy of MRI in restaging locally advanced rectal cancer after preoperative chemoradiation.

DESIGN

This was a retrospective study.

SETTINGS

The study was conducted in a Dutch high-volume rectal cancer center.

PATIENTS

A consecutive cohort of 48 patients with locally advanced rectal cancer treated with a curative intent was identified.

MAIN OUTCOME MEASURES

Three readers independently evaluated the MRI both for primary staging and for restaging after preoperative chemoradiation and were blinded to results from the other readers as well as histological results. Interobserver variability was determined. Accuracy of the restaging MRI was assessed through the comparison of tumor characteristics on MRI with histopathologic outcomes.

RESULTS

T stage was correctly predicted by the 3 readers in 47% to 68% and N stage in 68% to 70%. Overstaging was more common than understaging. Positive predictive values (PPV) among the 3 readers for T0 were 0%, and negative predictive values (NPVs) varied from 84% to 85%. For T1/2, PPVs and NPVs were 50% to 67% and 72% to 90%, and for T3/4 they were 54% to 62% and 33% to 78%. PPVs and NPVs for N0 stage were 81% to 95% and 58% to 73%. Tumor regression grade on MRI did not correspond with histopathologic tumor regression grade; PPVs for good response (tumor regression grade on MRI 1-2) were 48% to 61%, and NPVs were 42% to 58%. Interobserver agreement was fair to moderate for T stage, N stage, and tumor response (κ = 0.20-0.41) and fair to substantial for the relation with the mesorectal fascia (κ = 0.33-0.77). In none of the patients was the surgical plan changed after the restaging MRI.

LIMITATIONS

This study was limited by its small sample size and retrospective nature.

CONCLUSIONS

MRI has low accuracy for restaging locally advanced rectal cancer after preoperative chemoradiation, and the interobserver variability is significant.

Pathological Assessment of Rectal Cancer after Neoadjuvant Chemoradiotherapy: Distribution of Residual Cancer Cells and Accuracy of Biopsy

We investigated the distribution of residual cancer cells (RCCs) within different layers of the bowel wall in surgical specimens and the value of biopsies of primary rectal lesion after preoperative volumetric modulated arc therapy (VMAT) with concurrent chemotherapy in patients with rectal cancer. Between April 2011 and April 2013, 178 patients with rectal cancer who received preoperative VMAT, concurrent chemotherapy, and surgery were evaluated; 79 of the patients received a biopsy of the primary lesion after chemoradiotherapy and prior to surgery. The distribution of RCCs in the surgical specimens and the sensitivity and specificity of the biopsy of primary rectal lesions for pathological response were evaluated. Fifty-two patients had a complete pathological response in the bowel wall. Of the 120 patients with ypT2-4, the rate of detection of RCCs in the mucosa, submucosa, and muscularis propria was 20%, 36.7%, 69.2%, respectively. The sensitivity and specificity of biopsies of primary rectal lesions was 12.9% and 94.1%, respectively. After chemoradiotherapy, the RCCs were primarily located in the deeper layers of the bowel wall, and the biopsy results for primary rectal lesions were unreliable due to poor sensitivity.

Bowel function and quality of life after local excision or total mesorectal excision following chemoradiotherapy for rectal cancer

BACKGROUND

Local excision for rectal cancer is expected to offer a better functional outcome than conventional surgery. The aim of the present study was to compare quality of life and bowel function in patients with rectal cancer who underwent either local excision or conventional surgery after chemoradiotherapy.

METHODS

This was a retrospective multicentre study. Patients who underwent local excision were compared with those who had mesorectal excision. Quality of life and bowel function were investigated using validated questionnaires (European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30, EORTC QLQ-CR29 and Memorial Sloan-Kettering Cancer Center Bowel Function Instrument) at a median follow-up of 49 (range 13-95) months. Further analysis was undertaken of data from patients who underwent local excision alone compared with those requiring subsequent radical surgery. Statistical significance was set at P < 0·010.

RESULTS

The mean constipation score was significantly better in the local excision group than in the mesorectal excision group (3·8 (95 per cent c.i. 0·3 to 7·2) versus 19·8 (12·1 to 27·4); P < 0·001). Compared with patients who underwent mesorectal excision, those who had local excision had less sensation of incomplete emptying (mean score 3·7 (3·4 to 4·0) versus 2·8 (2·5 to 3·1); P < 0·001) and second bowel movements within 15 min (mean score 3·6 (3·3 to 3·9) versus 3·0 (2·7 to 3·3); P = 0·006). Patients who underwent local excision alone scored better than those who had mesorectal excision, particularly for bowel function, who, in turn, scored better than patients requiring subsequent radical surgery following local excision.

CONCLUSION

Patients who underwent local excision had a better quality of life and bowel function than those who underwent mesorectal excision.

Advances for achieving a pathological complete response for rectal cancer after neoadjuvant therapy

Neoadjuvant therapy has become the standard of care for locally advanced mid-low rectal cancer. Pathological complete response (pCR) can be achieved in 12%–38% of patients. Patients with pCR have the most favorable long-term outcomes. Intensifying neoadjuvant therapy and extending the interval between termination of neoadjuvant treatment and surgery may increase the pCR rate. Growing evidence has raised the issue of whether local excision or observation rather than radical surgery is an alternative for patients who achieve a clinical complete response after neoadjuvant therapy. Herein, we highlight many of the advances and resultant controversies that are likely to dominate the research agenda for pCR of rectal cancer in the modern era.

Definitive Chemoradiotherapy ("Watch-and-Wait" Approach)

Preoperative chemoradiotherapy (CRT) followed by total mesorectal excision has been the standard of care for locally advanced patients with rectal cancer. Some patients achieve a pathologic complete response (pCR) to CRT and the oncologic outcomes are particularly favorable in this group. The role of surgery in patients with a pCR is now being questioned as radical rectal resection is associated with significant morbidity and long-term effects on quality of life. In an attempt to better tailor therapy, there is an interest in a "watch-and-wait" approach in patients who have a clinical complete response (cCR) after CRT with the goal of omitting surgery and allowing for organ preservation. However, a cCR does not always indicate a pCR, and improved clinical and imaging modalities are needed to better predict which patients have achieved a pCR and therefore can safely undergo a "watch-and-wait" approach. This article reviews the current data on nonoperative management and on-going controversies associated with this approach.

Complete radiotherapy response in rectal cancer: A review of the evidence

Complete response to chemoradiotherapy for rectal cancer is becoming a common clinical entity. Techniques to diagnose complete response and how to survey these patients without operative intervention are still unclear. We review the most recent evidence. Barriers to firm conclusions regarding this are heterogeneity of diagnostic definitions, differing surveillance protocols, and a lack of randomised studies.

Influence of Preoperative Chemoradiotherapy on the Surgical Strategy According to the Clinical T Stage of Patients With Rectal Cancer

The aim of this study was to evaluate the pathologic responses and changes to surgical strategies following preoperative chemoradiotherapy (PCRT) in rectal cancer patients according to their clinical T stage (cT).The use of PCRT has recently been extended to less advanced disease.The authors enrolled 650 patients with cT2 to 4 mid and low rectal cancer who received both PCRT and surgical resection. The rate of total regression and the proportion of local excision were compared according to the cT category. The 3-year recurrence-free survival (RFS) rate was compared using the log-rank test according to patient cT category, pathologic stage, and type of surgical treatment.Patients with cT2 were older (P = 0.001), predominately female (P = 0.028), and had low-lying rectal cancer (P = 0.008). Pathologic total regression was achieved most frequently in cT2 patients (54% of cT2 versus 17.6% of cT3 versus 8.2% of cT4; P < 0.001). Local excision was performed on 42 cT2 (42%) and 24 cT3 (5.2%) patients (P < 0.001). The 3-year RFS rates differed according to both cT (P < 0.001) and ypT stage (P < 0.001). Among patients with ypT0 to 1 disease, the 3-year RFS did not differ according to the type of surgical treatment received (P = 0.5).Total regression of the primary tumor and a change in the surgical strategy after PCRT are most commonly seen in cT2 disease. Although PCRT is not generally indicated for cT2 rectal cancer, optimal surgical treatment may be achieved with the tailored use of PCRT.

Watch and wait policy after preoperative radiotherapy for rectal cancer; management of residual lesions that appear clinically benign

BACKGROUND

During an ongoing phase II observational study on watch and wait policy in rectal cancer, a substantial number of patients presented residual lesion after radiotherapy with a clinical benign appearance. This article aims to discuss the clinical significance of such findings.

MATERIALS AND METHODS

Main entry criteria were age ≥70 years and small tumour (≤5 cm and ≤60% of circumferential involvement) located in the low rectum. Patients received chemoradiation (50 Gy, 2 Gy per fraction concomitantly with a 5-Fu bolus and leucovorin) or 5 × 5 Gy if considered unfit for chemotherapy. Patients with clinical complete response (cCR) were observed. Those with persistent tumours underwent transanal endoscopic microsurgery [TEM] if the baseline tumour was ≤3 cm and cN0 or total mesorectal excision.

RESULTS

The watch and wait procedure was used in 11 out of the total 35 patients (31%) with a cCR; 17 patients (49%) with residual tumours that appeared clinically malignant were referred for TEM or abdominal surgery. In the remaining seven (20%), the residual tumour clinically appeared benign. Of these, there were two invasive cancers, four high-grade dysplasias and one low-grade dysplasia. The five patients with dysplasia, underwent local lesion resection without recurrence within a median of 11 months follow-up.

CONCLUSIONS

The majority of lesions that appeared clinically benign after radio(chemo)therapy were also benign on pathological examination. Thus, local excision of such lesions should be considered.

Assessing pathological complete response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer: a systematic review

AIM

Pathological complete response to neoadjuvant chemoradiotherapy is found in 20% of patients with rectal cancer undergoing long-course chemoradiotherapy. Some authors have suggested that these patients do not need to undergo surgery and can be managed with careful follow-up, with surgery only used in the event of clinical failure. Widespread adoption of this regimen is limited by the accuracy of methods to confirm a pathological complete response (pCR).

METHOD

A systematic search of PubMed, Medline and Cochrane databases was conducted to identify clinical, histological and radiological features in those patients with rectal cancer who achieved a pCR following chemoradiotherapy. Searches were conducted with the following keywords and MeSH search terms: 'rectal neoplasm', 'response', 'neoadjuvant', 'preoperative chemoradiation' and 'tumour response'. After review of title and abstracts, 89 articles addressing the assessment of pCR were identified.

RESULTS

Histology and clinical assessment are the most effective methods of assessment of pCR, with histology considered the gold standard. Clinical assessment is limited to low rectal tumours and is open to significant inter-rater variability, while histological examination requires a surgical specimen. Diffusion-weighted MRI and (18) F-fluorodeoxyglucose positron emission tomography/CT demonstrate the greatest potential for the assessment of pCR, but both modalities have limited accuracy.

CONCLUSION

Determination of a pCR is crucial if a nonoperative approach is to be undertaken proactively. Various methods are available, but currently they lack sufficient sensitivity and specificity to define management. This is likely to be an area of further research in the future.

Systematic review and meta-analysis of the accuracy of MRI and endorectal ultrasound in the restaging and response assessment of rectal cancer following neoadjuvant therapy

AIM

Restaging imaging by MRI or endorectal ultrasound (ERUS) following neoadjuvant chemoradiotherapy is not routinely performed, but the assessment of response is becoming increasingly important to facilitate individualization of management.

METHOD

A search of the MEDLINE and Scopus databases was performed for studies that evaluated the accuracy of restaging of rectal cancer following neoadjuvant chemoradiotherapy with MRI or ERUS against the histopathological outcome. A systematic review of selected studies was performed. The methodological quality of studies that qualified for meta-analysis was critically assessed to identify studies suitable for inclusion in the meta-analysis.

RESULTS

Sixty-three articles were included in the systematic review. Twelve restaging MRI studies and 18 restaging ERUS studies were eligible for meta-analysis of T-stage restaging accuracy. Overall, ERUS T-stage restaging accuracy (mean [95% CI]: 65% [56-72%]) was nonsignificantly higher than MRI T-stage accuracy (52% [44-59%]). Restaging MRI is accurate at excluding circumferential resection margin involvement. Restaging MRI and ERUS were equivalent for prediction of nodal status: the accuracy of both investigations was 72% with over-staging and under-staging occurring in 10-15%.

CONCLUSION

The heterogeneity amongst restaging studies is high, limiting conclusive findings regarding their accuracies. The accuracy of restaging imaging is different for different pathological T stages and highest for T3 tumours. Morphological assessment of T- or N-stage by MRI or ERUS is currently not accurate or consistent enough for clinical application. Restaging MRI appears to have a role in excluding circumferential resection margin involvement.

The impact of lymph node size to predict nodal metastasis in patients with rectal cancer after preoperative chemoradiotherapy

PURPOSE

During restaging after preoperative chemoradiotherapy (CRT), the assessment of lymph node (LN) metastasis is vital for selecting further treatment strategies. This study aimed to evaluate the impact of LN size to predict LN metastasis in rectal cancer patients after preoperative CRT.

METHODS

A total of 30 consecutive patients who underwent preoperative CRT followed by curative resection of primary rectal cancer were selected as a study group (CRT group). As a control group (non-CRT group), 30 patients who underwent primary tumor resection were selected using a 1:1 case-match design. Matching criteria were gender, age, and clinical T stage. The size of each LN was measured from the surgical specimen. To clarify optimal cutoff values for node size according to the risk of detecting metastasis, receiving-operator characteristic (ROC) curves were generated.

RESULTS

In the non-CRT group, 39/474 LNs were confirmed to have metastasis. In the CRT group, 29/422 LNs showed metastasis. The median size of metastatic LNs was 6.0 mm in CRT group, which was significantly larger than 4.0 mm in the non-CRT group (p = 0.006). The optimal cutoff value for determining metastasis in the CRT group was 4.5 mm, compared to 3.5 mm in the non-CRT group. The accuracy of the cutoff value was much higher in the CRT group (CRT vs. non-CRT, 77.9 vs. 59.9%).

CONCLUSIONS

LN size is a strong indicator for prediction of regional LN metastasis in rectal cancer patients after preoperative CRT, compared to those without CRT.

Predicting complete response: is there a role for non-operative management of rectal cancer?

Pre-operative chemoradiotherapy followed by a total mesorectal excision (TME) is the standard of care for patients with locally advanced (stage II or III) rectal cancer. Approximately 20% of patients may achieve a pathologic complete response after chemoradiation therapy (CRT), which has been shown to be associated with better oncologic outcomes. Whether surgery can be avoided in this population is an area of active investigation. Recent studies demonstrated feasibility and safety of non-operative management in patients with clinical complete response (cCR) after chemoradiotherapy. In this article, we set out to review the current data on non-operative management and to identify areas requiring further investigation, including improvement in imaging for reassessment after CRT and identifying the optimal time frame for restaging. As the field moves forward with non-operative management in select patients with rectal cancer, there continues to be a need to better understand the prognostic factors and biomarkers that may more accurately characterize patients who are qualified for this "wait-and-see" approach and thereby avoid overtreatment, potentially leading to improvements in long-term quality of life.

Limits of endorectal ultrasound in tailoring treatment of patients with rectal cancer

BACKGROUND

Endorectal ultrasound (ERUS) is considered reliable in staging rectal cancer, but recently some critics have questioned its accuracy. The aim of this study was to evaluate how often an ERUS-based decision leads to an appropriate treatment.

METHODS

Two hundred and twenty patients with rectal cancer staged with ERUS who underwent a surgical resection or a local excision without neoadjuvant therapy from 1997 to 2012 were included. According to ERUS, patients were divided into three groups of indication: (a) local excision (Tis-1 N0), (b) direct surgery (T2 N0), (c) preoperative chemoradiation (T3-4 or N+). Accuracy was explored by the correlation established with the final pathology.

RESULTS

Accuracy for T and N staging was 65 and 64%, respectively. Indication to local excision and to chemoradiation was correct in 97 and 88% of patients staged by ERUS. Accuracy of indication to direct surgery was poor (37%), and 21% of patients were overtreated in this group.

CONCLUSIONS

ERUS seems not able to fulfill all the needs of ideal tailored therapeutic strategies. T2 diagnosis needs to be confirmed by an excisional biopsy before a final decision is made because overstaging of early tumors may occur in a not-so-negligible proportion of patients.

Assessment of a novel, full-thickness incisional biopsy model to restage rectal tumours after neoadjuvant chemoradiotherapy: results of an ex vivo pilot study

BACKGROUND

There is currently no reliable means to restage rectal cancers after neoadjuvant chemoradiation. Recent histological evidence shows that the epicentre for residual cancer cells is focussed directly underneath any residual mucosal abnormality (RMA). This proof-of-concept study aimed to determine the utility of a novel, minimally invasive method of incisional biopsy as a restaging tool. A secondary aim was to compare its performance to clinical response assessment.

METHODS

After surgical resection, 0.5 × 0.5 cm, full-thickness incisional biopsy was performed in 15 rectal cancers. Of these, 13 had RMA and 2 had mucosal cCR but a palpable intramural abnormality. In all patients, a full-thickness incisional biopsy was taken through the centre of these areas. The ypT stage of the incisional biopsy and the final total specimen were compared. Complete mucosal clinical response was deemed to have occurred when either no residual tumour or only a flat mucosal scar remained.

RESULTS

Incisional biopsy correctly identified all patients that had been downstaged to ypT0; however, it also falsely identified 5 of 10 patients (50%) with yp residual disease as ypT0. Overall performance of incisional biopsy to detect residual cancer was 50% sensitivity, 100 % specificity, 100% PPV, and 50% NPV with an accuracy of 66%. A complete mucosal clinical response occurred in only one of five patients downstaged to ypT0 (20% sensitive). It also occurred in one patient, which was ultimately staged as ypT3.

CONCLUSION

This prospective data demonstrates that incisional biopsy is not suitable as a stand-alone method to restage rectal cancer after CRT. Alternate or complementary means of restaging are needed.

Factors affecting the restaging accuracy of magnetic resonance imaging after preoperative chemoradiation in patients with rectal cancer

PURPOSES

We evaluated patient or tumor factors associated with the preoperative restaging accuracy of magnetic resonance imaging (MRI) for determining T and N stages as well as circumferential resection margin (CRM) involvement after chemoradiation (CRT) in patients with locally advanced rectal cancer.

METHODS

Seventy-seven patients with rectal cancer that were treated with preoperative CRT (50.4 Gy) followed by radical resection were included. Post-CRT MRI was performed approximately 4 weeks after preoperative CRT.

RESULTS

The median tumor distance from the anal verge was 6 cm, 48 (62%) of which were anterior and 29 (38%) posterior. The median tumor diameter was 3 cm. A stage-by-stage comparison showed that correct staging occurred in 62%, 43%, and 86% of patients for T staging, N staging, and CRM prediction, respectively. Shorter distance to the anal verge (<5 cm), smaller tumor diameter (<1 cm), and anterior tumor location were associated with incorrect T staging. There were no significant variables in terms of N staging accuracy. Shorter tumor distance and anterior tumor location were associated with incorrect CRM prediction.

CONCLUSIONS

Our findings suggest that specific tumor factors such as small, distal, or anterior rectal tumors are closely associated with the accuracy of MRI after preoperative CRT.

Diffusion-weighted imaging of the male pelvis

Diffusion-weighted (DW) imaging is playing an increasingly important role in disease detection, prognostication, and monitoring of treatment response. Particularly in the realm of oncology, the potential applications for DW imaging continue to expand. In this article, the authors detail the role of DW imaging for pathologic processes involving the male pelvis. The authors describe the current data, new insights, and ongoing controversies regarding DW imaging of the male pelvis with a particular emphasis on oncologic applications. The authors also discuss imaging techniques and common pitfalls for DW imaging in this anatomic region.

Can We Predict Complete or Major Response after Chemoradiotherapy for Rectal Cancer by Noninvasive Methods? Results of a Prospective Study on 61 Patients

Rectal preservation has been proposed as an alternative to radical resection in patients with presumed complete or major response to chemoradiotherapy (CRT). The aim of this prospective study was to evaluate the accuracy of digital rectal examination (DRE) and magnetic resonance imaging (MRI) to predict major or complete rectal cancer response to CRT. Over 2 years, 61 patients underwent radical resection after CRT for rectal cancer. DRE and MRI were carried out before and 6 to 8 weeks after the end of CRT. Data from DRE and MRI post-CRT were compared with pathological examinations. At pathological examination, major/complete responses were recorded for tumors classified ypT1N0 and ypT0N0, respectively. DRE post-CRT showed major/complete response in 26 cases, of which 14 (54%) were confirmed by pathology. The positive (PPV) and negative (NPV) predictive values of DRE to predict major/complete response were 54 and 88 per cent, respectively. MRI post-CRT showed major/complete response in 12 cases, of which nine (75%) were confirmed by pathology. The PPV and NPV of MRI to predict major/complete response were 75 and 82 per cent, respectively. Data from DRE and RMI post-CRT were concordant in 45 patients. The PPV and NPV of concordant DRE and MRI to predict major/complete response were 82 and 91 per cent, respectively. DRE and MRI do not appear to be sufficiently accurate for safe selection of patients appropriate for a rectum-sparing strategy because the risk of leaving an invasive tumor untreated is 18 per cent.