Imaging in rectal cancer: magnetic resonance imaging versus endorectal ultrasonography

Primary staging of rectal cancer on MRI: an updated pictorial review with focus on common pitfalls and current controversies

Magnetic resonance imaging (MRI) plays a pivotal role in primary staging of rectal cancer, enabling the determination of appropriate management strategies and prediction of patient outcomes. However, inconsistencies and pitfalls exist in various aspects, including rectal anatomy, MRI protocols and strategies for artifact resolution, as well as in T- and N-staging, all of which limit the diagnostic value of MRI. This narrative and pictorial review offers a comprehensive overview of factors influencing primary staging of rectal cancer and the role of MRI in assessing them. It highlights the significance of the circumferential resection margin and its relationship with the mesorectal fascia, as well as the prognostic role of extramural venous invasion and tumor deposits. Special attention is given to tumors of the lower rectum due to their complex anatomy and the challenges they pose in MRI staging. The review also addresses current controversies in rectal cancer staging and the need for personalized risk stratification. In summary, this review provides valuable insights into the role of MRI in the primary staging of rectal cancer, emphasizing key aspects for accurate assessment to enhance patient outcomes.

Conjoint analysis of clinical, imaging, and pathological features of schistosomiasis and colorectal cancer

This study aims to examine and compare clinical, radiological, and pathological data between colorectal cancer (CRC) patients with and without schistosomiasis and uncover distinctive CRC characteristics when accompanied by schistosomiasis. This retrospective study is based on data collected from 341 patients diagnosed with CRC post-surgery and pathology. Of these patients, 101 (Group A) were diagnosed with colorectal cancer co-occurring with schistosomiasis (CRC-S), while 240 patients (Group B) were diagnosed with colorectal cancer without concurrent schistosomiasis (CRC-NS). Both groups were compared and analyzed based on their clinical data, imaging-based TNM staging, lymph node metastasis, nerve invasion, vascular cancer thrombus, and histopathological differentiation. A Chi-squared test revealed a significant difference in gender distribution between the patients with CRC-S (Group A) and CRC-NS (Group B), with a p -value of 0.043 and χ2 = 4.115. Specifically, a higher incidence rate was observed among males in Group A. There was a difference in the overall distribution of TNM staging between the two groups (p = 0.034, χ2 = 6.764). After pairwise comparison, a statistically significant difference was observed in the T3 stage (p <0.05). The proportion of the T3 stage in Group A was significantly higher than that in Group B, indicating certain advantages. There was a difference in postoperative histopathological grading between the two groups (p = 0.005, χ2 = 10.626). After pairwise comparison, a statistically significant difference was observed between the well-differentiated adenocarcinoma and the moderately and poorly differentiated adenocarcinoma (p <0.05), with a higher proportion of welldifferentiated patients in Group A compared to Group B. There was no significant difference in age, lymph node metastasis, nerve invasion, and vascular invasion between the two groups of patients (p > 0.05). Among the 101 patients with CRC-S, 87 (86%) showed linear calcification on CT imaging. Patients with CRC-S are mainly male, with tumor staging mostly in the middle stage, high tumor differentiation, and low malignancy. CT imaging can help identify the presence of lumps and linear calcification indicative of schistosome deposits. MRI can early clarify TNM staging and determine the presence of lymph node metastasis and nerve and vascular invasion.

Local excision after neoadjuvant chemoradiotherapy for mid and low rectal cancer: a multicentric French study from the GRECCAR group

AIM

A complete or subcomplete tumour response (CTR) is observed in 10%-25% of patients with mid/low rectal cancer after neoadjuvant chemoradiotherapy (CRT). The aim of our study was to report a multicentric French experience in local excision (LE) after CRT.

METHOD

All patients who underwent LE for mid/low rectal cancer with suspected CTR after CRT, from 2006 to 2019 in seven GRECCAR centres were included. LE was considered adequate if the specimen showed a ypT0/Tis/T1R0 tumour, otherwise, a completion total mesorectal excision (TME) was discussed. Morbi-mortality, functional results and oncological outcomes were studied.

RESULTS

A total of 257 patients were included. LE specimens showed 36% ypT0, 4% ypTis and 19% ypT1. Thus, 108 patients (42%) had theoretical indication of completion TME, which was performed in only 42 patients. Overall, 30-day morbidity after LE was 11%, including 2% Clavien-Dindo grade III or IV complications. After completion TME, 47% described major low anterior resection syndrome versus 5% after LE alone (p < 0.001). After a mean follow-up of 4 years (range 2-6 years), the recurrence rate was 11% after LE, 32% after completion TME and 20% in patients for whom completion TME was indicated but not performed (p = 0.021).

CONCLUSION

TME remains the gold standard for mid/low rectal cancer after CRT. LE in selected patients is safe for operative and functional, but also oncological, results. However, completion TME was indicated in 42% of patients after LE, highlighting the difficulty of the preoperative diagnosis of CTR after CRT.

A model based on endorectal ultrasonography predicts lateral lymph node metastasis in low and middle rectal cancer

PURPOSE

To investigate the risk factors for lymph node (LN) metastasis in low and middle rectal tumors, construct a predictive model and test the model's diagnostic efficacy.

METHODS

The clinical and pathological data of 172 patients with rectal cancer confirmed by surgery were retrospectively evaluated, among whom 61 patients were finally included in this study. Patients were divided into positive groups and negative groups based on LN metastasis, and risk factors that might affect LN metastasis were analyzed. Finally, a risk predictive model was constructed based on the weights of each risk factor.

RESULTS

Compared with pathology, the efficacy of diagnosing LN metastasis only according to conventional endorectal ultrasonography (ERUS) features of LN was not high, with sensitivity 67%, specificity 86%, positive predictive value 76%, negative predictive value 80%, and accuracy 79%. Univariate analysis showed that circumferential angle of the tumor, ultrasonic T- stage (UT stage), conventional ultrasound features diagnosis of LN metastasis, strain ratio (SR) of tumor were risk factors for LN metastasis, while vascular resistance index of rectal tumor was protective factor. Multivariate analysis showed that UT stage (OR = 7.188, p = 0.049), conventional ultrasound features diagnosis of LN metastasis (OR = 8.010, p = 0.025) and SR (OR = 5.022, p = 0.031) were independent risk factors for LN metastasis. These risk factors were included in logistic regression analysis and the model was established, Y = -7.3 + 1.9 X10 + 2.1 X11 + 1.6 X13 (Y = Logit[P], P: LN metastasis rate, X10: UT stage, X11: conventional ultrasound features diagnosis of LN metastasis, X13: SR). The receiver operating characteristic (ROC) curve was used to test the model's predictive efficacy, the area under the curve was 0.95, sensitivity: 95%, specificity: 87%. Hosmer-Lemeshow goodness of fit test showed X2 = 6.015, p = 0.65 (p > 0.05), indicating that the model had a high predictive value.

CONCLUSION

Evaluation of perirectal LN metastasis only based on conventional ERUS features of LN was not effective enough. UT stage of tumor, conventional ultrasound features diagnosis of LN metastasis and SR were independent risk factors for LN metastasis. The predictive model had good assessment efficacy and had certain clinical application value.

Current status of surgical treatment of rectal cancer in China

With the changing lifestyle and the acceleration of aging in the Chinese population, the incidence and mortality of colorectal cancer (CRC) have risen in the last decades. On the contrary, the incidence and mortality of CRC have continued to decline in the USA since the 1980s, which is mainly attributed to early screening and standardized diagnosis and treatment. Rectal cancer accounts for the largest proportion of CRC in China, and its treatment regimens are complex. At present, surgical treatment is still the most important treatment for rectal cancer. Since the first Chinese guideline for diagnosis and treatment of CRC was issued in 2010, the fourth version has been revised in 2020. These guidelines have greatly promoted the standardization and internationalization of CRC diagnosis and treatment in China. And with the development of comprehensive treatment methods such as neoadjuvant chemoradiotherapy, targeted therapy, and immunotherapy, the post-operative quality of life and prognosis of patients with rectal cancer have improved. We believe that the inflection point of the rising incidence and mortality of rectal cancer will appear in the near future in China. This article reviewed the current status and research progress on surgical therapy of rectal cancer in China.

Colorectal Cancer in the Elderly Patient: The Role of Neo-adjuvant Therapy

BACKGROUND

Neoadjuvant chemoradiotherapy has a significant role in downstaging cancer. It improves the local control of the disease and can make conservative resection of rectal cancer possible.

METHODS

We enrolled 114 patients with subperitoneal rectal cancer who underwent neoadjuvant chemoradio-therapy and radical excision with total mesorectal excision (TME). The primary endpoint was oncological outcomes and the secondary endpoint was surgical outcomes.We evaluate the experience of a multidisciplinary team and the role of neoadjuvant chemoradiotherapy in integrated treatment of cancer of the subperitoneal rectum.

RESULTS

Surgical procedures performed were abdominal perineal resection in 4 cases (3.5%), anterior resection in 89 cases (78%), Hartmann's procedure in 5 cases (4.4%), and ultralow resection with coloanal anastomosis and diverting stoma in 16 patients (14%).Local recurrence occurred in 6 patients (5.2%), the overall survival was 71.9% at 5 years and disease-free survival was about 60%.

CONCLUSIONS

The effect of pathological downstaging amounted to 58.8%, including cPR. The pathologic complete remission occurred in 8.8% of cases.The outcomes of neoadjuvant therapy can be achieved when this treatment is associated with correct surgical technique with TME and the prognosis is defined by an anatomopathological examination performed according to Quirke's protocol.

Shear Wave Elastography in Rectal Cancer Staging, Compared with Endorectal Ultrasonography and Magnetic Resonance Imaging

The goal of the study described here was to investigate the value of shear wave elastography (SWE) in pre-operative staging of rectal cancer. Fifty-five patients with rectal cancer underwent pre-operative conventional endorectal ultrasonography (ERUS), SWE and enhanced magnetic resonance imaging (MRI) examinations. Pathologic results were used as the gold standard for cancer staging. The concordance rate with pathologic stage by ERUS and MRI and the stiffness values measured by SWE for tumors in different stages were compared. The concordance rates for cancer staging were 72.7% and 70.9% for conventional ERUS and enhanced MRI, respectively; the difference was not significant (p > 0.05). SWE indicated that the mean and maximum stiffness values of the tumors increased with advance in stage. The differences in stiffness values between T1 and T2, T1 and T3-4, as well as T2 and T3-4, were all statistically significant (p < 0.001). When the maximum stiffness values of 65.0 and 90.7 kPa are used for the diagnosis of T1, T2 and local advanced rectal cancer, the concordance rate of cancer staging was 85.5%, which was slightly higher than those of ERUS and MRI, although the difference was not statistically significant (p > 0.05). SWE is useful in judging the depth of invasion of rectal tumors. The value of tumor stiffness can provide a quantifiable indicator for pre-operative diagnosis of cancer staging and can be used as a supplement to conventional ERUS. Further studies with larger sample sizes are needed.

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.

Radiologic Evaluation of Clinically Benign Rectal Neoplasms May Not Be Necessary Before Local Excision

BACKGROUND

Local excision may be curative for benign and malignant rectal neoplasms. Because many early rectal cancers are discovered incidentally after local excision of clinically benign lesions, it is unclear whether preoperative imaging with transrectal ultrasound or MRI affects management.

OBJECTIVE

The purpose of this study was to determine the diagnostic characteristics and effect of preoperative imaging on the incidence of malignancy in benign rectal lesions undergoing local excision.

DESIGN

Prospective data from 2 institutions were included. Coarsened exact matching created a balanced cohort comparing imaging and no-imaging groups.

SETTING

The study was conducted at high-volume specialist referral hospitals.

PATIENTS

Adult patients undergoing local excision via transanal endoscopic surgery between 1997 and 2016 for clinically benign rectal neoplasms were included.

INTERVENTION

The study intervention included preoperative imaging with transrectal ultrasound and/or MRI.

MAIN OUTCOME MEASURES

We measured the incidence of malignancy and diagnostic accuracy of preoperative imaging.

RESULTS

A total of 620 patients were included (272 with preoperative imaging and 348 without). There were 250 patients undergoing transrectal ultrasound, and 24 patients undergoing MRI (2 patients underwent both). Transrectal ultrasound and MRI correctly identified malignant polyps in 50% (11/22) and 44% (8/18). Overall agreement for benign versus malignant polyps between preoperative imaging and final pathology was κ = 0.30 (95% CI, 0.18-0.41) for transrectal ultrasound and 0.29 (95% CI, 0.01-0.57) for MRI. In both the overall and unmatched cohorts, the incidence of malignancy, margin involvement, and proportion of patients requiring salvage surgery was similar.

LIMITATIONS

Data were obtained from 2 institutions with different equipment over a long time period.

CONCLUSIONS

Preoperative imaging did not accurately identify malignancy in clinically benign rectal lesions and did not affect the incidence of malignancy, margin involvement, or proportion of patients requiring salvage surgery. Therefore, preoperative imaging may not be necessary for clinically benign lesions undergoing local excision. See Video Abstract at http://links.lww.com/DCR/A695.

Colonoscopic and histologic features of rectal masses in dogs: 82 cases (1995-2012)

OBJECTIVE To evaluate colonoscopic and histologic features of rectal masses in dogs. DESIGN Retrospective case series. ANIMALS 82 client-owned dogs with rectal masses that underwent colonoscopy. PROCEDURES Medical records of dogs with rectal masses that underwent colonoscopy were reviewed. History, signalment, clinical signs, results of physical examination, diagnostic imaging findings, and results of colonoscopy (including complications) were recorded. When available, tissue samples obtained during colonoscopy and by means of surgical biopsy were reviewed by a single board-certified pathologist. Histologic features and tumor grade (when applicable) of tissue samples obtained during colonoscopy versus surgical biopsy were compared. RESULTS Multiple rectal masses were observed during colonoscopy in 6 of the 82 dogs, but no lesions were visualized orad to the colorectal junction. Results of histologic evaluation of surgical biopsy specimens were consistent with a diagnosis of epithelial neoplasia in 58 of 64 dogs, of which 71% were classified as benign adenoma or polyp and 29% were classified as adenocarcinoma in situ or adenocarcinoma. Complications of colonoscopy occurred in 3 of 82 dogs but were considered minor. A discrepancy in diagnosis occurred in 5 of 16 dogs for which both colonoscopic and surgical biopsy samples were available for histologic review. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that multiple rectal masses are uncommon in dogs, and secondary lesions orad to the colorectal junction were not found in this study. Colonoscopy was associated with few complications, but the need for colonoscopic assessment of the entire colon in this patient population may merit reevaluation.

Organ-Preserving Strategies for the Management of Near-Complete Responses in Rectal Cancer after Neoadjuvant Chemoradiation

In recent years, organ preservation has been considered a feasible alternative to total mesorectal excision for patients with locally advanced rectal cancer with a clinical complete response to neoadjuvant therapy. However, the degree of tumor response to neoadjuvant therapy is variable. A fraction of the patients who did not achieve a complete response had grossly visible tumors. These patients, with clearly incomplete clinical response, need a total mesorectal excision. In addition, some patients with a significant tumor response still have some abnormalities in the bowel wall, such as superficial ulceration or tissue nodularity, which, while not conclusive for the presence of a tumor, are indicative of the possibility of a residual tumor in the bowel wall or in mesorectal lymph nodes. The management of patients with a so-called near-complete clinical response to neoadjuvant therapy is controversial. In this article, we will review the clinical and radiological criteria that define a clinical response to neoadjuvant therapy, possible treatment strategies, and follow-up protocols. We will also discuss patient and tumor characteristics that in our opinion can be useful in selecting the most appropriate treatment alternative. Although organ preservation and quality of life are important, the primary goal of treatment for these patients should be local tumor control and long-term survival.

Management of rectal cancer: the 2016 French guidelines

AIM

Rectal cancer is a malignant disease requiring multidisciplinary management. In view of the increasing number of studies published over the past decade, a comprehensive update is required to draw recommendations for clinical practice mandated by the French Research Group of Rectal Cancer Surgery and the French National Coloproctology Society.

METHOD

Seven questions summarizing the treatment of rectal cancer were selected. A search for evidence in the literature from January 2004 to December 2015 was performed. A drafting committee and a large group of expert reviewers contributed to validate the statements.

RESULTS

Recommendations include the indications for neoadjuvant therapy, the quality criteria for surgical resection, the management of postoperative disordered function, the role of local excision in early rectal cancer, the place of conservative strategies after neoadjuvant treatment, the management of synchronous liver metastases and the indications for adjuvant therapy. A level of evidence was assigned to each statement.

CONCLUSION

The current clinical practice guidelines are useful for the treatment of rectal cancer. Some statements require a higher level of evidence due to a lack of studies.

Radiological assessment of anal cancer: an overview and update

Anal cancer is uncommon neoplasm with an incidence of 2 new cases per 100,000 per year in the USA, accounting approximately 0.4 % of all tumors and 2.5 % of gastrointestinal malignancies. An early detection of the anal cancer is crucial for the patient management, whereas the diagnosis at an early stage allows conservative management with sphincter sparing, on the contrary a delays in diagnosis might lead to an advance cancer stage at presentation with worst survival. According to National Comprehensive Cancer Network (NCCN) Anal Carcinoma guidelines the patients should be subjected to a careful clinical examination, including a digital rectal examination (DRE), an anoscopic examination, and palpation of inguinal nodes. The guidelines recommended for the assessment of T stage, only a clinical examination, while the role of imaging techniques, as Magnetic Resonance imaging (MRI) is limited to the identification of regional nodes. Instead, the endoanal ultrasound (EAUS) is not recommended. This paper presents an overview and some updates about 3D EAUS and MRI in detection, staging and assessment post therapy of anal cancer patients.

Diagnostic Accuracy of MRI for Assessment of T Category and Circumferential Resection Margin Involvement in Patients With Rectal Cancer: A Meta-Analysis

BACKGROUND

The prognosis of rectal cancer is directly related to the stage of the tumor at diagnosis. Accurate preoperative staging is essential for selecting patients to receive optimal treatment.

OBJECTIVE

The purpose of this study was to evaluate the diagnostic performance of MRI in tumor staging and circumferential resection margin involvement in rectal cancer.

DATA SOURCES

A systematic literature search was performed in MEDLINE, EMBASE, PubMed, Cochrane Database of Systematic Reviews, and Web of Science database.

STUDY SELECTION

Original articles from 2000 to 2016 on the diagnostic performance of MRI in the staging of rectal cancer and/or assessment of mesorectal fascia status were eligible.

MAIN OUTCOME MEASURES

Pooled diagnostic statistics including sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were calculated for invasion of muscularis propria, perirectal tissue, and adjacent organs and for circumferential resection margin involvement through bivariate random-effects modeling. Summary receiver operating characteristic curves were fitted, and areas under summary receiver operating characteristic curves were counted to evaluate the diagnostic performance of MRI for each outcome.

RESULTS

Thirty-five studies were eligible for this meta-analysis. Preoperative MRI revealed the highest sensitivity of 0.97 (95% CI, 0.96-0.98) and specificity of 0.97 (95% CI, 0.96-0.98) for muscularis propria invasion and adjacent organ invasion. Areas under summary receiver operating characteristic curves indicated good diagnostic accuracy for each outcome, with the highest of 0.9515 for the assessment of adjacent organ invasion. Significant heterogeneity existed among studies. There was no notable publication bias for each outcome.

LIMITATIONS

This meta-analysis revealed relatively high diagnostic accuracy for preoperative MRI, although significant heterogeneity existed. Therefore, exploration should be focused on standardized interpretation criteria and optimal MRI protocols for future studies.

CONCLUSIONS

MRI showed relatively high diagnostic accuracy for preoperative T staging and circumferential resection margin assessment and should be reliable for clinical decision making.

Multimodal Rectal Cancer Treatment: In Some Cases, Less May Be More

A series of clinical trials in the last several decades has resulted in the development of multimodality treatment of locally advanced rectal cancer that includes neoadjuvant (preoperative) chemoradiotherapy, total mesorectal excision, and postoperative adjuvant chemoradiotherapy. Owing to this regimen, patients with locally advanced rectal cancer have better survival rates than patients with colon cancer, but at the cost of substantial morbidity and reduced quality of life. The challenge is to identify treatment approaches that maintain or even improve oncologic outcomes while preserving quality of life. We have identified different tumor characteristics that are associated with recurrence and probability of survival for locally advanced rectal cancer. This risk stratification, based on baseline clinical staging and tumor response to chemoradiotherapy, has led us to question whether all patients with locally advanced rectal cancer require every component of the multimodal regimen. In this article, we will review recent evidence that some patients with locally advanced rectal cancer can be spared one or more treatment modalities without compromising long-term oncologic outcomes and while preserving quality of life.

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.

Neoadjuvant chemoradiation therapy and pathological complete response in rectal cancer

The management of rectal cancer has evolved significantly in the last few decades. Significant improvements in local disease control were achieved in the 1990s, with the introduction of total mesorectal excision and neoadjuvant radiotherapy. Level 1 evidence has shown that, with neoadjuvant chemoradiation therapy (CRT) the rates of local recurrence can be lower than 6% and, as a result, neoadjuvant CRT currently represents the accepted standard of care. This approach has led to reliable tumor down-staging, with 15-27% patients with a pathological complete response (pCR)-defined as no residual cancer found on histological examination of the specimen. Patients who achieve pCR after CRT have better long-term outcomes, less risk of developing local or distal recurrence and improved survival. For all these reasons, sphincter-preserving procedures or organ-preserving options have been suggested, such as local excision of residual tumor or the omission of surgery altogether. Although local recurrence rate has been stable at 5-6% with this multidisciplinary management method, distal recurrence rates for locally-advanced rectal cancers remain in excess of 25% and represent the main cause of death in these patients. For this reason, more recent trials have been looking at the administration of full-dose systemic chemotherapy in the neoadjuvant setting (in order to offer early treatment of disseminated micrometastases, thus improving control of systemic disease) and selective use of radiotherapy only in non-responders or for low rectal tumors smaller than 5 cm.

Role of endoscopic ultrasonography in the loco-regional staging of patients with rectal cancer

The prognosis of rectal cancer (RC) is strictly related to both T and N stage of the disease at the time of diagnosis. RC staging is crucial for choosing the best multimodal therapy: patients with high risk locally advanced RC (LARC) undergo surgery after neoadjuvant chemotherapy and radiotherapy (NAT); those with low risk LARC are operated on after a preoperative short-course radiation therapy; finally, surgery alone is recommended only for early RC. Several imaging methods are used for staging patients with RC: computerized tomography, magnetic resonance imaging, positron emission tomography, and endoscopic ultrasound (EUS). EUS is highly accurate for the loco-regional staging of RC, since it is capable to evaluate precisely the mural infiltration of the tumor (T), especially in early RC. On the other hand, EUS is less accurate in restaging RC after NAT and before surgery. Finally, EUS is indicated for follow-up of patients operated on for RC, where there is a need for the surveillance of the anastomosis. The aim of this review is to highlight the impact of EUS on the management of patients with RC, evaluating its role in both preoperative staging and follow-up of patients after surgery.

Evolution of imaging in rectal cancer: multimodality imaging with MDCT, MRI, and PET

Magnetic resonance imaging (MRI), multidetector computed tomography (MDCT), and positron emission tomography (PET) are complementary imaging modalities in the preoperative staging of patients with rectal cancer, and each offers their own individual strengths and weaknesses. MRI is the best available radiologic modality for the local staging of rectal cancers, and can play an important role in accurately distinguishing which patients should receive preoperative chemoradiation prior to total mesorectal excision. Alternatively, both MDCT and PET are considered primary modalities when performing preoperative distant staging, but are limited in their ability to locally stage rectal malignancies. This review details the role of each of these three modalities in rectal cancer staging, and how the three imaging modalities can be used in conjunction.

Transrectal ultrasonography of anorectal diseases: advantages and disadvantages

Transrectal ultrasonography (TRUS) has been widely accepted as a popular imaging modality for evaluating the lower rectum, anal sphincters, and pelvic floor in patients with various anorectal diseases. It provides excellent visualization of the layers of the rectal wall and of the anatomy of the anal canal. TRUS is an accurate tool for the staging of primary rectal cancer, especially for early stages. Although magnetic resonance imaging is a modality complementary to TRUS with advantages for evaluating the mesorectum, external sphincter, and deep pelvic inflammation, three-dimensional ultrasonography improves the detection and characterization of perianal fistulas and therefore plays a crucial role in optimal treatment planning. The operator should be familiar with the anatomy of the rectum and pelvic structures relevant to the preoperative evaluation of rectal cancer and other anal canal diseases, and should have technical proficiency in the use of TRUS combined with an awareness of its limitations compared to magnetic resonance imaging.

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.

Transanal endoscopic surgery with total wall excision is required with rectal adenomas due to the high frequency of adenocarcinoma

BACKGROUND

Colorectal adenomatous polyps are considered premalignant lesions, although a high percentage are already malignant at the time of their removal. Full-thickness excision in patients with adenoma detected in preoperative biopsy enables much more accurate pathology examination and has shown that local surgery is appropriate for T1 adenocarcinoma.

OBJECTIVE

To determine whether full-thickness excision during transanal endoscopic surgery is the treatment of choice for rectal adenoma, and to identify possible predictors of invasive adenocarcinoma associated with this type of lesion.

DESIGN

Prospective, observational study.

SETTING

The study was conducted at a university teaching hospital.

PATIENTS

All patients scheduled for transanal endoscopic surgery after detection of adenoma in a preoperative biopsy between June 2004 and February 2013 entered the study.

MAIN OUTCOME MEASURES

The principal variable was the presence of invasive adenocarcinoma in the pathology study. Other study variables were the epidemiological variables sex and age; the clinical variables tumor size, number of quadrants affected, distance from the anal verge, and tumor location; and the morphological variables tumor aspect, degree of dysplasia, preoperative biopsy (tubulo-villous), endorectal ultrasound, and pelvic MRI stage. Variables found to be related to the risk of malignancy in rectal adenomas were evaluated using univariate and multivariate analysis.

RESULTS

Of 471 patients who underwent surgery, 277 had a preoperative diagnosis of adenoma. Final pathology studies showed 52 (18.8%) invasive adenocarcinomas, among which 27 were pT1 (52%), 16 pT2 (30.7%), and 9 pT3 (17.3%). Factors predictive of invasive adenocarcinoma were sessile morphology (OR 3.2, 95%CI 1.4-7.1), high-grade dysplasia (OR 2.3, 95%CI 1.2-4.8), and endorectal ultrasound stage uT2-T3 (OR 3.8, 95%CI 1.6-9).

LIMITATIONS

The limitations are derived from the observational design.

CONCLUSIONS

In this sample, half of the adenocarcinomas from adenomas were T1 adenocarcinomas. Because a high proportion of rectal adenomas are, in fact, invasive adenocarcinomas, full-thickness excision is appropriate.

Time-intensity curve parameters in rectal cancer measured using endorectal ultrasonography with sterile coupling gels filling the rectum: correlations with tumor angiogenesis and clinicopathological features

The primary aim of this study was to investigate the relationship between contrast-enhanced ultrasonography (CEUS) imaging parameters and clinicopathological features of rectal carcinoma and assess their potential as new radiological prognostic predictors. A total of 66 rectal carcinoma patients were analyzed with the time-intensity curve of CEUS. The parameter arrival time (AT), time to peak enhancement (TTP), wash-in time (WIT), enhanced intensity (EI), and ascending slope (AS) were measured. Microvessel density (MVD) was evaluated by immunohistochemical staining of surgical specimens. All findings were analysed prospectively and correlated with tumor staging, histological grading, and MVD. The mean values of AT, TTP, WIT, EI, and AS value of the rectal carcinoma were 10.84 ± 3.28 s, 20.61 ± 5.52 s, 9.78 ± 2.83 s, 28.68 ± 4.67 dB, and 3.20 ± 1.10, respectively. A positive linear correlation was found between the EI and MVD in rectal carcinoma (r = 0.295, P = 0.016), and there was a significant difference for EI among histological grading (r = -0.264, P = 0.007). EI decreased as T stage increased with a trend of association noted (P = 0.096). EI of contrast enhanced endorectal ultrasonography provides noninvasive biomarker of tumor angiogenesis in rectal cancer. CEUS data have the potential to predict patient prognosis.