Results of EUS in detecting perirectal lymph node metastases of rectal cancer: the pathologist makes the difference

Lymph Node Cluster Dissection After Carbon Nanoparticles Injection Enhances the Retrieval Number in Colorectal Cancer

For colorectal cancer patients, NCCN recommended that at least 12 lymph nodes should be detected since the number and metastases status of lymph nodes played an important role in the treatment and prognostic. Carbon nanoparticles have been proved to be an efficient lymph node tracer. Faced with the clinical problem of insufficient lymph nodes in colorectal cancer, we proposed a lymph node cluster (D3, D2 and D1) dissection method combined with carbon nanoparticle injection. In our study, patients were divided into 2 groups (CNP and control). All lymph nodes of each patient were collected and made into hematoxylin-eosin sections to observe their size, staining appearance and metastasis status under the microscope. As a result, the total lymph nodes in CNP group were greatly higher than control group (51.45 vs. 29.62, P = 0.000), especially micro LNs and positive micro LNs. Compared with D2 and D1 stations, fewer lymph nodes were found in D3, and it was the same for cancer metastasis status. In CNP group, most lymph nodes got black for quick visualization. In conclusion, lymph node cluster dissection combined with carbon nanoparticles could enhance the number of lymph node retrieval.

Double-Contrast Barium Enema and Computerised Tomography in the Pre-Operative Evaluation of Rectal Carcinoma: Are they Still Useful Diagnostic Procedures?

Purpose

In modern management of rectal carcinoma, the preoperative evaluation of disease parameters is important for selection of therapeutic options. Such parameters are currently defined through endorectal ultrasonography or endoscopic ultrasonography. A retrospective analysis of the parameters obtained with double-contrast barium enema (DCBE) and endorectal balloon computed tomography (CT) was conducted to verify the diagnostic reliability of the radiological techniques and to establish whether there is still an indication for their use.

Methods

53 consecutive patients with adenocarcinoma of the distal half of the rectal ampulla underwent double contrast barium enema examination and CT of the pelvis with endorectal balloon. On the basis of the DCBE and CT assessment we evaluated: 1) the distance between the cranial extremity of the anal canal and the distal margin of the neoplasm; 2) the radial diffusion of the tumor; 3) the metastatic involvement of the perirectal and inferior mesenteric lymph nodes.

Results

1) CT and DBCE measurements of the distal margin tended to coincide, but both tended to overestimate the measurement when compared to the pathologic examination; 2) in the identification of neoplastic infiltration of perirectal fat (T3) CT had 100% sensitivity, 78.7% specificity and 86.8% accuracy; 3) the CT sensitivity for detecting lymph node metastasis was 52.6%, specificity 85.3% and accuracy 73.6%.

Conclusions

The diagnostic information provided by the radiological examinations is comparable to that of clinical and instrumental methods currently employed for staging of rectal carcinoma, although the latter are preferred because they are more readily accessible and less costly. DCBE and CT can therefore be usefully employed for staging of cancer of the rectum in those cases in which there are limitations of the current standard methods.

Has the role of EUS in rectal cancer staging changed in the last decade?

The need for effective diagnosis, staging, and treatment of rectal cancer cannot be overstated. Accurate staging of rectal cancer has wide-ranging implications, including therapeutic strategy and prognosis. A change in stage may lead to the need for preoperative neoadjuvant therapy to decrease the risk of recurrence. The modalities commonly used for the primary staging of rectal cancer include EUS, computed tomography, and magnetic resonance imaging. EUS may be accompanied by the use of EUS-fine-needle aspiration to provide cytological confirmation. In this review, we take a deeper look into the role of EUS in the accurate staging of rectal cancer, how it compares to other modalities for the same, and how its role has changed in the last decade.

Diagnostic Value of Endorectal Ultrasound in Preoperative Assessment of Lymph Node Involvement in Colorectal Cancer: a Meta-analysis

BACKGROUND

Nodal invasion by colorectal cancer is a critical determinant in estimating patient survival and in choosing appropriate preoperative treatment. The present meta-analysis was designed to evaluate the diagnostic value of endorectal ultrasound (EUS) in preoperative assessment of lymph node involvement in colorectal cancer.

MATERIALS AND METHODS

We systematically searched PubMed, Web of Science, Embase, and China National Knowledge Infrastructure (CNKI) databases for relevant studies published on or before December 10th, 2014. The sensitivity, specificity, likelihood ratios, diagnostic odds ratio (DOR) and area under the summary receiver operating characteristics curve (AUC) were assessed to estimate the diagnostic value of EUS. Subgroup analysis and meta-regression were performed to explore heterogeneity across studies.

RESULTS

Thirty-three studies covering 3,016 subjects were included. The pooled sensitivity and specificity were 0.69 (95%CI: 0.63-0.75) and 0.77 (95%CI: 0.73-0.82), respectively. The positive and negative likelihood ratios were 3.09 (95%CI: 2.52-3.78) and 0.39 (95%CI: 0.32-0.48), respectively. The DOR was 7.84 (95%CI: 5.56-11.08), and AUC was 0.80 (95%CI: 0.77-0.84).

CONCLUSIONS

This meta-analysis indicated that EUS has moderate diagnostic value in preoperative assessment of lymph node involvement in colorectal cancer. Further refinements in technology and diagnostic criteria are necessary to improve the diagnostic accuracy of EUS.

Primary staging and response assessment postchemoradiotherapy in rectal cancer

SUMMARY Initial assessment of newly diagnosed patients with rectal cancer includes clinical examination, colonoscopy, pelvic MRI and CT scan of the thorax, abdomen and pelvis. Radiological staging can objectively evaluate both surgical and biological prognostic features of rectal cancer. MRI has emerged to be the most useful preoperative prognostic staging tool and it can predict the risk of tumor involvement of surgical circumferential resection margin. An agreed definition of favorable tumor response to chemoradiotherapy is controversial. The importance of detecting and assessing good versus poor responders to chemoradiotherapy is of increasing relevance. MRI has been found to be useful in assessing tumor response postchemoradiotherapy, especially the assessment of potential circumferential resection margin and magnetic resonance tumor regression grade. These imaging markers predict survival outcomes for good and poor responders and provide an opportunity for clinicians to offer additional neoadjuvant and adjuvant treatments to reduce local or distance failure for the poor responders.

Endoanorectal ultrasonography

Endoanorectal ultrasonography (EARUS) may be used for diagnosing various anorectal disorders. EARUS is easy to perform, has a short learning curve, and causes less discomfort than routine digital examination. Anal sphincters can be clearly visualized, and one can easily distinguish between the internal (hypoechoic) and external (hyperechoic) anal sphincters. Other pelvic floor structures, like the puborectalis muscle, can also be visualized. The use of contrast agents can increase the accuracy of EARUS in the assessment of perianal fistulae. In addition, EARUS is an excellent alternative to expensive magnetic resonance imaging. Besides its use in incontinence and perianal sepsis, the presence of slight or massive submucosal invasion in early rectal cancer may be imaged in greater detail. With 3-dimensional EARUS, it is possible to diagnose the anorectal diseases, in multiplane, with high spatial resolution, adding important information about the therapeutic decision. The normal sonographic anatomy of the anorectum, sonographic findings of anorectal diseases, and indications and limitations of endosonography with complementary techniques such as transvaginal and transperineal ultrasound are reviewed in this article.

Rectal cancer: primary staging and assessment after chemoradiotherapy

Rectal cancer staging is based on 2 principles. The first is an anatomic definition of the tumor allowing for surgical planning. The second is prognostic stage grouping. A given prognostic stage carries different risks of both local and distant recurrence, a selective and tailored approach to preoperative therapy is appropriate. Increasingly, selective approaches enable an overall reduction in morbidity from overtreatment, while allowing aggressive treatment of high-risk patients. Therefore, the aim of preoperative staging is to accurately and reproducibly differentiate between good and poor prognosis tumors. In the preoperative setting, superficial and flat rectal cancers are probably best initially staged using endoscopic ultrasound, and where available magnetic resonance imaging is used for all other rectal cancers because of its proven high sensitivity and specificity in identifying poor-risk patients based on circumferential margin status, the depth of extramural spread, extramural venous invasion, and nodal status. Restaging after neoadjuvant therapy is a challenge to all modalities because of radiation-induced changes, namely fibrosis, edema, inflammation, and necrosis. However, emerging data suggest that reassessment using a combination of high-resolution magnetic resonance imaging, diffusion-weighted imaging, and positron emission tomography/computed tomography scanning may help to provide valuable prognostic information before definitive surgery.

Application of endoscopic sonography in preoperative staging of rectal cancer: six-year experience

OBJECTIVES

The aim of this study was to evaluate our experience with the application of endoscopic sonography in preoperative staging of rectal cancer.

METHODS

Between April 2004 and May 2010, 192 patients with rectal cancer first underwent endoscopic sonography and then underwent surgery at our hospital. None of the patients in this study received neoadjuvant therapy. The endoscopic sonographic staging results were compared with those of postoperative pathologic staging.

RESULTS

The accuracy of overall T staging was 86.5%, and for T1, T2, T3, and T4, the accuracy rates were 86.7%, 94.0%, 86.2%, and 65.5%, respectively. The accuracy of T staging for ulcerated lesions was significantly lower than that for nonulcerated lesions (P = .013). The accuracy of T staging between nontraversable stenotic lesions and traversable lesions was also significantly different (P = .002). The accuracy of N staging was 77.8%, and the specificity and sensitivity were 85.6% and 74.2%, respectively.

CONCLUSIONS

Endoscopic sonography is safe and effective for preoperative staging of rectal cancer and should be a routine examination before surgery. As for ulcerated and nontraversable stenotic lesions, however, the results of endoscopic sonographic staging could be doubtful. Moreover, the accuracy of endoscopic sonographic N staging still needs modification by further research.

Does a learning curve exist in endorectal two-dimensional ultrasound accuracy?

BACKGROUND

Aim of the study was to assess adequacy of Colorectal Surgical Society of Australia and New Zealand (CSSANZ) endorectal ultrasound (ERUS) training and whether a subsequent learning curve exists.

METHODS

A prospective audit of ERUS for staging rectal cancer by a single surgeon from commencement of consultant practice was performed. Data were recorded in a prospectively maintained database. The audit commenced on completion of CSSANZ training. T- and N-stage were assessed clinically, then by ERUS prior to treatment and finally by histology over 8 years.

RESULTS

The results were compared over three time periods: the first a single year, then two three-year periods. Two hundred and seventy-two patients were examined. Two hundred and thirty-three were assessable for T-stage (13 no tumour excision, 26 long course pre-operative radiotherapy) and 142 for N-stage (74 endoanal excision, 17 proximal mesorectum un-assessable). Overall accuracy was 82% for T-stage and 73% for N-stage. Accuracy for T- and N-staging did not change significantly over the three time periods (T: 82.1, 82.3, 81.6%, P = 0.14; N: 83.3, 67.9, 74.2%, P = 0.31). The utility of ERUS was demonstrated by clinical assessment not being possible in 32% of cases and where the two modalities disagreed was correct 82% of the time.

CONCLUSIONS

Endorectal ultrasound rectal cancer staging is accurate for T-stage. Competency in ERUS can be achieved in the CSSANZ fellowship and accuracy does not improve with further experience. An ERUS accreditation scheme should be established for future trainees.

Evaluation of gadolinium-enhanced T1-weighted magnetic resonance imaging in the preoperative assessment of local staging in rectal cancer

AIM

The aim of this study was to determine whether gadolinium-enhanced T1-weighted magnetic resonance (MR) sequence is beneficial in the preoperative assessment of tumour and nodal staging in patients with primary rectal cancer.

METHOD

Eighty-eight patients with primary rectal cancer underwent preoperative MR imaging, followed by surgical resection. Two radiologists independently reviewed (i) T2-weighted MR images (T2WI); (ii) gadolinium-enhanced T1-weighted MR images (T1 + Gd); (iii) MR combined with T2WI and T1 + Gd for the prediction of tumour and nodal stage compared with histopathologic findings as the end point. Differences in the diagnostic performance of T2WI only, T1 + Gd image only and combined T2WI and T1 + Gd MR images were analyzed by comparing areas under receiver operating characteristic curves (Az) for each reader. Interobserver agreement was also calculated.

RESULTS

There was no significant difference in the Az values of T2WI only, T1 + Gd image only and combined T2WI and T1 + Gd images for the prediction of tumour staging (Az of T2WI, T1 + Gd and combined MR images for reader 1, 0.80, 0.76 and 0.85; reader 2, 0.83, 0.82 and 0.87) and nodal staging (Az for reader 1, 0.73, 0.73 and 0.81; reader 2, 0.79, 0.80 and 0.83). Interobserver agreement for the prediction of tumour staging was moderate to substantial, while only fair agreement was noted for the prediction of nodal staging.

CONCLUSION

Gadolinium-enhanced T1-weighted MRI did not increase the diagnostic yield for tumour and nodal staging, and may be omitted in the MR protocol for preoperative assessment of primary rectal cancer.

Accuracy of endoscopic ultrasound to diagnose nodal invasion by rectal cancers: a meta-analysis and systematic review

BACKGROUND

Nodal staging in patients with rectal cancer predicts prognosis and directs therapy. Published data on the accuracy of endoscopic ultrasound (EUS) for diagnosing nodal invasion in patients with rectal cancer has been inconsistent.

AIM

To evaluate the accuracy of EUS in diagnosing nodal metastasis of rectal cancers.

METHOD

Study Selection Criteria: Only EUS studies confirmed by surgical histology were selected. Data Collection and Extraction: Articles were searched in Medline, Pubmed, and CENTRAL.

STATISTICAL METHOD

Pooling was conducted by both fixed-effects model and random-effects model.

RESULTS

The initial search identified 3610 reference articles in which 352 relevant articles were selected and reviewed. Data were extracted from 35 studies (N = 2732) that met the inclusion criteria. Pooled sensitivity of EUS in diagnosing nodal involvement by rectal cancers was 73.2% (95% confidence interval [95% CI] 70.6-75.6). EUS had a pooled specificity of 75.8% (95% CI 73.5-78.0). The positive likelihood ratio of EUS was 2.84 (95% CI 2.16-3.72), and negative likelihood ratio was 0.42 (95% CI 0.33-0.52). All the pooled estimates, calculated by fixed- and random-effect models, were similar. SROC curves showed an area under the curve of 0.79. The P for chi-squared heterogeneity for all the pooled accuracy estimates was >.10.

CONCLUSIONS

EUS is an important and accurate diagnostic tool for evaluating nodal metastasis of rectal cancers. This meta-analysis shows that the sensitivity and specificity of EUS is moderate. Further refinement in EUS technologies and diagnostic criteria are needed to improve the diagnostic accuracy.

Impact of biopsy on the accuracy of endorectal ultrasound staging of rectal tumors

PURPOSE

Endorectal ultrasound is a well-established method for the preoperative staging of rectal tumors. This prospective study was performed to establish whether obtaining a biopsy before endorectal ultrasound has an influence on staging accuracy.

METHODS

Between 1990 and 2003, a total of 333 rectal tumors were examined preoperatively by using endorectal ultrasound. All patients underwent rectal resection, and the specimens were sent for histologic evaluation. Thirty-three were not biopsied, the remaining at various times before endorectal ultrasound. The chi-squared test or Fisher's exact test were used for statistical analysis to compare the accuracies.

RESULTS

The overall staging accuracy was 71 percent but differed significantly (P = 0.004) between the groups as a function of time elapsed since biopsy. The best results were seen in tumors that were not biopsied before endorectal ultrasound, which were correctly staged in 85 percent of the cases. The least accurate staging (53 percent) was noted when endorectal ultrasound was performed in the third week after biopsy, mostly as a result of overstaging. Biopsy did not have a significant effect on nodal staging.

CONCLUSIONS

Biopsy before endorectal ultrasound significantly affects its accuracy. To achieve the most accurate staging, biopsy should be performed after endorectal ultrasound. Endorectal ultrasound staging performed in the first week after biopsy is the second best option but should be interpreted with caution in the second or third week.

Imaging and management of rectal cancer

Local staging and management of rectal cancer has evolved during the past decade. Imaging modalities used for staging rectal cancer include CT, endoscopic ultrasound, pelvic phased-array coil MRI, endorectal MRI, and PET. Each modality has its strengths and limitations. Evidence supports the use of both endoscopic ultrasound and CT in staging rectal cancer. MRI is the only reliable tool for determining the status of the circumferential resection margin, which is important for the assessment of the risk of local recurrence.

Preoperative staging of rectal carcinoma by endorectal ultrasound: is there a learning curve?

BACKGROUND AND AIMS

Endorectal ultrasound (ERUS) is becoming an essential tool in the management of rectal cancer. However, accuracy in the assessment of disease staging may be dependent on operator experience. The aim of this study was to determine if a learning curve exists.

MATERIALS AND METHODS

From October 1999 to December 2004, all patients with rectal cancer had a pre-operative ERUS performed by a single radiologist. ERUS staging was compared with post-operative pathology findings using the tumour, node, metastases (TNM) classification. The accuracy of ERUS in tumour (T) and node (N) staging after each additional consecutive ten patients was calculated.

RESULTS

One hundred and thirty one patients were investigated by ERUS, of which 36 were excluded, leaving 95 patients in the study (60 men). Overall accuracy for T staging was 71.6%. No improvement with experience was noted (p > 0.05). With regard to T staging, ERUS tended to overstage more frequently than understage (24.2 versus 4.2%). The sensitivity, specificity, positive predictive value and negative predictive value of uT3 staging were 96.6, 33.3, 70.4 and 85.7%, respectively. Overall accuracy of uN staging was 68.8%. ERUS tended to overstage nodal disease more frequently than understage (16.1 versus 15.1%). Sensitivity, specificity, positive predictive value and negative predictive value were calculated for ultrasound-detected nodal disease (73.2, 62.2, 74.5 and 60.5%, respectively). Nodal staging accuracy improved from 50% after assessment of 10 cases to 77% after 30 cases were examined.

CONCLUSIONS

ERUS is an accurate method for staging rectal cancer pre-operatively. Accurate assessment of tumour stage can be achieved immediately by an experienced radiologist without specific training in ERUS. Nodal staging accuracy tends to improve with experience but reaches a plateau after 30 cases.

Review of endoscopic ultrasound-guided fine-needle aspiration cytology

This review, based on the Hennepin County Medical Center experience and review of the literature, vastly covers the up-to-date role of endoscopic ultrasonography (EUS) and EUS-guided fine-needle aspiration (FNA) in evaluating tumorous lesions of the gastrointestinal tract and adjacent organs. Emphasis is given to the tumoral and nodal staging of esophageal, pulmonary, and pancreatic cancer. This review also discusses technical, pathological, and gastroenterologic aspects and the role of the pathologist and endosonographer in the evaluation of these lesions, as well as the corresponding FNA cytology and differential diagnosis.

Anorectal ultrasound for neoplastic and inflammatory lesions

Accurate staging of rectal and anal carcinoma is crucial for planning surgery and indicating adjuvant therapy. Although, computed tomography and magnetic resonance imaging are very sensitive in detecting metastatic disease, the local staging of rectal cancer with these techniques has been disappointing. Endorectal ultrasound (ERUS) and anal endosonography (AE) remain the most accurate methods for staging rectal and anal cancer. Anal endosonography is also of value in evaluating perianal sepsis: it can assist the surgeon in planning the surgical strategy by delineating the anatomy of fistula tracts, and can aid in puncturing abscesses in the operating room. Continued research and development has made the instrumentation for ERUS and AE more accurate and user-friendly. New techniques that have contributed significantly to the evolution of ERUS include three-dimensional ERUS, high-frequency miniprobes, transrectal ultrasound-guided biopsy techniques and hydrogen peroxide-enhanced endosonography. Further improvements can be expected from contrast enhancement with microbubbles and colour Doppler imaging. In this new millennium, new developments in ERUS and anal endosonography, such as tri-dimensional ERUS and anal endosonography and radial electronic probing, widen the role of ERUS in the staging of rectal and anal carcinoma, as well as for perianal inflammatory conditions.

Endosonographic imaging of anorectal diseases

OBJECTIVE

The normal sonographic anatomy of the anorectum, sonographic findings of anorectal diseases, and indications and limitations of endosonography compared with magnetic resonance imaging are reviewed. Methods. Endosonographic imaging was performed with a Siemens (Erlangen, Germany) FI 400 ultrasound scanner with an end-fire 7.5-MHz biplane endorectal probe and a B-K Medical (Sandhoften, Denmark) scanner with an 1850 axial-type side-fire 5.0- to 10.0-MHz rotating endoscopic probe.

RESULTS

Rectal carcinoma appears on endorectal sonography as a low-echogenicity lesion that abruptly interrupts the normal sequence of layers. The internal anal sphincter is seen very clearly on endoanal sonography, and it is easy to appreciate atrophy and small tears of this sphincter. Endoanal sonography cannot accurately show thinning of the external anal sphincter. Peroxide-enhanced endoanal sonography is especially useful for patients with recurrent perianal fistulas in whom scarring should be distinguished from recurrent fistulas and detection of the internal opening. However, sonography does not provide an adequate deep and global display of all adjacent pelvic and perineal spaces.

CONCLUSIONS

Endosonography can accurately stage primary rectal tumors and assess the internal anal sphincter. Peroxide-enhanced 3-dimensional imaging can increase the utility of endoanal sonography in detection and characterization of perianal fistulas and planning of optimal therapy. However, magnetic resonance imaging can be used a complementary modality to endosonography, especially for evaluation of external anal sphincter atrophy and deep pelvic inflammation.

Preoperative staging of rectal cancer: the MERCURY research project

The development of a surgical technique that removes the tumour and all local draining nodes in an intact package, namely total mesorectal excision (TME) surgery, has provided the impetus for a more selective approach to the administration of preoperative therapy. One of the most important factors that governs the success of TME surgery is the relationship of tumour to the circumferential resection margin (CRM). Tumour involves the CRM in up to 20% of patients undergoing TME surgery, and results in both poor survival and local recurrence. It is therefore clear that the importance of the decision regarding the use of pre-operative therapy lies with the relationship of the tumour to the mesorectal fascia. In addition, a high-spatial-resolution MRI technique will identify tumours exhibiting other poor prognostic features, namely, extramural spread >5 mm, extramural venous invasion by tumour, nodal involvement, and peritoneal infiltration. The potential benefits of a selective approach using MRI-based selection criteria are evident. That is, over 50% of patients can be treated successfully with primary surgery alone without significant risk of local recurrence or systemic failure. Of the remainder, potentially dramatic improvements may be achieved through the use of intensive and targeted preoperative therapy aimed not only at reducing the size of the primary tumour and rendering potentially irresectable tumour resectable with tumour-free circumferential margins, but also at enabling patients at high risk of systemic failure to benefit from intensive combined modality therapy aimed at eliminating micrometastatic disease.

Imaging for Predicting the Risk Factors—the Circumferential Resection Margin and Nodal Disease—of Local Recurrence in Rectal Cancer: A Meta-Analysis

The aim of the present study was to conduct a meta-analysis of English literature on the accuracy of preoperative imaging in predicting the two most important risk factors for local recurrence in rectal cancer, the circumferential resection margin (CRM) and the nodal status (N-status). Articles published between 1985 and August 2004 that report on the diagnostic accuracy of endoluminal ultrasound (EUS), computed tomography (CT), or magnetic resonance imaging (MRI) in the evaluation of lymph node involvement were included. A similar search was done for the assessment of the circumferential resection margin in rectal cancer in the period from January 1985 till January 2005. The inclusion criteria were as follows: (1) more than 20 patients with histologically proven rectal cancer were included, (2) histology was used as the gold standard, and (3) results were given in a 2 x 2 contingency table or this table could otherwise be extracted from the article by two independent readers. Based on the results summary receiver operating characteristic (ROC) curves were constructed. Only 7 articles matching inclusion criteria were found concerning the CRM. The meta-analysis shows that MRI is rather accurate in diagnosing a close or involved CRM. For nodal status 84 articles could be included. The diagnostic odds ratio of EUS is estimated at 8.83. For MRI and CT, the diagnostic odds ratio are 6.53 and 5.86, respectively. The results show that EUS is slightly, but not significantly, better than MRI or CT for identification of nodal disease. There is no significant difference between the different modalities with respect to staging nodal status. At present, MRI is the only modality that predicts the circumferential resection margin with good accuracy, making it a good tool to identify high and low risk patients. Predicting the N-status remains a problem for the radiologist for every modality, although considering the new developments in MR imaging, this may change in the near future.

Endoscopic ultrasound for luminal malignancies

Luminal gastrointestinal (GI) tract cancers are responsible for substantial morbidity and mortality. Since the first pairing of ultrasonography with endoscopy in 1980, technologic advances and the increased availability of trained endosonographers have propelled endoscopic ultrasonography (EUS) to the forefront of luminal GI cancer staging. In this article we discuss the role of EUS for evaluating luminal GI cancers.

Assessment of publication bias in the reporting of EUS performance in staging rectal cancer

INTRODUCTION

Endoscopic ultrasound (EUS) has emerged as a promising diagnostic modality for locoregional staging of rectal cancer. However, as with any new technology, publication bias, the selective reporting of studies featuring positive results, may result in overestimation of the capability of EUS. The aim of this study was to systematically assess for publication bias in the reporting of the accuracy of EUS in staging rectal cancer.

METHODS

A MEDLINE search for all published estimates of EUS accuracy in staging rectal cancer between 1985 and 2003 was performed. All retrieved studies were fully published in the English literature. Published studies were analyzed and the following information was abstracted: accuracy of EUS, year of publication, number of subjects studied, impact factor of journal, and type of journal (gastroenterology, surgery, radiology, other).

RESULTS

Two hundred and two abstracts were reviewed; 41 publications met the stated criteria for inclusion. EUS T-staging accuracy was reported in 40 studies while EUS N-staging accuracy was reported in 27 studies. The experience of 4, 118 subjects was reported with an overall mean T-staging accuracy of 85.2% (median, 87.5%) and N-staging accuracy of 75.0% (median, 76.0%). There was a paucity of smaller studies expressing low EUS accuracy rates. Both T-staging and N-staging accuracy rates also declined over time with the lowest rates reported in more recent literature.

CONCLUSION

The performance of EUS in staging rectal cancer may be overestimated in the literature due to publication bias. This inflated estimate of the capability of EUS may lead to unrealistic expectations of this technology.

High-resolution MR imaging for nodal staging in rectal cancer: are there any criteria in addition to the size?

PURPOSE

MR staging of nodal metastases in patients with rectal cancer using criteria based on size, shape and signal intensity can be difficult, because > or =50% of the nodes are less than 5 mm in size. Therefore new MR criteria were evaluated to see whether it can improve the MR assessment of nodal metastases in rectal cancer patients.

MATERIALS AND METHODS

Ninety-nine patients with primary rectal carcinoma underwent 1.5 T high-resolution MRI with a quadrature phased array coil. Among them, 75 patients who had undergone total mesorectal excision were enrolled in this study. An MR radiologist, blinded for the histological results, randomly recorded the characteristics of each detectable node (LN); common criteria such as short-axis diameter, the ratio of long- to short-axis diameter, and signal intensity on each sequence; new criteria such as the margin (smooth, lobulated, spiculated, indistinct), a homogenous or mottled heterogeneous appearance, gross enhancement and its pattern, the venous encasement, and the dirty perirectal fat signal.

RESULTS

Among 75 patients, 22 (29%) were node-positive. All patients who did not have detectable LN on MR were node-free (n = 15). Presence of LNs > 4 mm was significantly higher in the node-positive group. Presence of LNs > 8 mm was seen only in the node-positive group. Presence of a spiculated border and an indistinct border shows sensitivities of 45 and 36%, and specificities of 100 and 100%, respectively. Presence of a mottled heterogeneic pattern shows a sensitivity of 50%, a specificity of 95%. The presence of these three features were strongly correlated with LN positivity (P < 0.001, respectively). Presence of a venous encasement (n = 4) and dirty perirectal fat signal (n = 3) were also significantly (P < 0.05, respectively) correlated with LN positivity.

CONCLUSION

In addition to size, new criteria such as a spiculated or indistinct border and a mottled heterogeneous appearance could be useful to predict regional lymph node involvement in patients with rectal cancer.

Endoanal and endorectal ultrasound: applications in colorectal surgery

Endoanal and endorectal ultrasound have an important role in colorectal surgery. They can be applied in the management of faecal incontinence, rectal tumours and inflammatory perianal conditions. In faecal incontinence, anal ultrasound will confirm the presence or absence of sphincter defects. This will direct any operative intervention such as direct sphincter repair. Ultrasound in rectal cancer allows staging of the tumour by assessing the depth of invasion through the bowel wall and involvement of mesenteric nodes. Such staging might influence the choice of operation and determine which patients might benefit from preoperative chemotherapy and radiotherapy. Ultrasound has a particular role in recurrent and complex anal fistula and perianal sepsis. Preoperative and perioperative planning with accurate delineation of fistula tracts, extensions and sphincter involvement might help prevent recurrence and impaired continence from sphincter damage after surgery. Correct interpretation of ultrasound images requires training and experience so that the results can be properly correlated with the clinical situation.

ASGE guideline: the role of endoscopy in the diagnosis, staging, and management of colorectal cancer

This is one of a series of statements discussing the utilization of GI endoscopy in common clinical situations. The Standards of Practice Committee of the American Society for Gastrointestinal Endoscopy prepared this text. In preparing this guideline, a MEDLINE literature search was performed, and additional references were obtained from the bibliographies of the identified articles and from recommendations of experts. When little or no data exist from well-designed prospective trials, emphasis is given to results from large series and reports from recognized experts. Guidelines for appropriate utilization of endoscopy are based on a critical review of the available data and expert consensus. Further controlled clinical studies are needed to clarify aspects of this statement and revision needed to clarify aspects of this statement and revision may be necessary as new data appear. Clinical consideration may justify a course of action at variance to the recommendations.

Rectal cancer: local staging and assessment of lymph node involvement with endoluminal US, CT, and MR imaging--a meta-analysis

PURPOSE

To perform a meta-analysis to compare endoluminal ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging in rectal cancer staging.

MATERIALS AND METHODS

Relevant articles published between 1985 and 2002 were included if more than 20 patients were studied, histopathologic findings were the reference standard, and data were presented for 2 x 2 tables; articles were excluded if data were reported elsewhere in more detail. Two reviewers independently extracted data on study characteristics and results. Bivariate random-effects approach was used to obtain summary estimates of sensitivity and specificity for invasion of muscularis propria, perirectal tissue, and adjacent organs and for lymph node involvement. Summary receiver operating characteristic (ROC) curves were fitted for perirectal tissue invasion and lymph node involvement.

RESULTS

Ninety articles fulfilled all inclusion criteria. For muscularis propria invasion, US and MR imaging had similar sensitivities; specificity of US (86% [95% confidence interval [CI]: 80, 90]) was significantly higher than that of MR imaging (69% [95% CI: 52, 82]) (P =.02). For perirectal tissue invasion, sensitivity of US (90% [95% CI: 88, 92]) was significantly higher than that of CT (79% [95% CI: 74, 84]) (P <.001) and MR imaging (82% [95% CI: 74, 87]) (P =.003); specificities were comparable. For adjacent organ invasion and lymph node involvement, estimates for US, CT, and MR imaging were comparable. Summary ROC curve for US of perirectal tissue invasion showed better diagnostic accuracy than that of CT and MR imaging. Summary ROC curves for lymph node involvement showed no differences in accuracy.

CONCLUSION

For local invasion, endoluminal US was most accurate and can be helpful in screening patients for available therapeutic strategies.

Evaluation of a new curved linear array echoendoscopy system for EUS

BACKGROUND

EUS-FNA can be used to accurately diagnose and stage GI and pulmonary neoplasms. This study evaluated the performance characteristics of a new compact linear EUS system during EUS-FNA.

METHODS

A total of 37 patients enrolled in this prospective pilot study underwent clinically indicated EUS-FNA and/or celiac plexus neurolysis with the compact EUS system.

RESULTS

The mean time to perform a radial and linear array EUS with FNA and/or celiac plexus neurolysis was 24 minutes shorter with the compact EUS system compared with that for an historical control procedure in which a conventional linear EUS unit was used (p = 0.0007). The EUS images and visualization of the needle during EUS-FNA were rated good to excellent in greater than 95% of the patients. With respect to ease of esophageal intubation, duodenal intubation, and general maneuverability, the performance of the new linear echoendoscope, compared with a radial scanning videoechoendoscope, was the same or better in, respectively, 85%, 87%, and 100% of procedures. The video image quality of the new linear array echoendoscope was superior to that of the radial scanning videoechoendoscope in all patients. No complications were encountered.

CONCLUSIONS

EUS-FNA and celiac plexus neurolysis can be performed safely with the new compact EUS system. The efficiency of this procedure is enhanced compared with historical experience with other instruments. Although image quality is sufficient for EUS-FNA and celiac plexus neurolysis, the compact unit cannot be used as a "stand-alone" system for routine diagnostic EUS, and its use must be complemented by standard radial imaging.

Morphologic predictors of lymph node status in rectal cancer with use of high-spatial-resolution MR imaging with histopathologic comparison

PURPOSE

To evaluate signal intensity and border characteristics of lymph nodes at high-spatial-resolution magnetic resonance (MR) imaging in patients with rectal cancer and to compare these findings with size in prediction of nodal status.

MATERIALS AND METHODS

Forty-two patients who underwent total mesorectal excision of the rectum to determine if they had rectal carcinoma were studied with preoperative thin-section MR imaging. Lymph nodes were harvested from 42 transversely sectioned surgical specimens. The slice of each lymph node was carefully matched with its location on the corresponding MR images. Nodal size, border contour, and signal intensity on MR images were characterized and related to histologic involvement with metastases. Differences in sensitivity and specificity with border or signal intensity were calculated with CIs by using method 10 of Newcombe.

RESULTS

Of the 437 nodes harvested, 102 were too small (<3 mm) to be depicted on MR images, and only two of these contained metastases. In 15 (68%) of 22 patients with nodal metastases, the size of normal or reactive nodes was equal to or greater than that of positive nodes in the same specimen. Fifty-one nodes were above the area imaged, and seven of these contained metastases. The diameter of benign and malignant nodes was similar; therefore, size was a poor predictor of nodal status. If a node was defined as suspicious because of an irregular border or mixed signal intensity, a superior accuracy was obtained and resulted in a sensitivity of 51 (85%) of 60 (95% CI: 74%, 92%) and a specificity of 216 (97%) of 221 (95% CI: 95%, 99%).

CONCLUSION

Prediction of nodal involvement in rectal cancer with MR imaging is improved by using the border contour and signal intensity characteristics of lymph nodes instead of size criteria.

Comparative study of three-dimensional and conventional endorectal ultrasonography used in rectal cancer staging

BACKGROUND

Three-dimensional (3D) imaging offers improved knowledge of various anatomic structures and tumors by providing 3D images. This prospective study was performed to verify whether 3D endorectal ultrasonography (EUS) enhances the accuracy of rectal cancer staging, as compared with conventional EUS.

METHODS

Using both 3D and conventional EUS, 33 consecutive patients with operable rectal cancer were preoperatively staged. A rigid 3D probe with a scanner was used for 3D EUS, and a rigid endorectal probe with a scanner was used for conventional EUS.

RESULTS

The accuracy of 3D EUS was 90.9% for pT2 and 84.8% for pT3, whereas that of conventional EUS was 84.8% and 75.8%, respectively, thereby showing no difference between these two methods. The lymph node metastasis was accurately predicted by 3D EUS in 28 patients (84.8%), whereas conventional EUS predicted the disorder in 22 patients (66.7%). The difference was not statistically significant. The average infiltration grade of the circumference on transverse 3D EUS scans was associated closely with advancement of the TNM stage (p <0.001-0.006) and lymph node metastasis (p = 0.003). The presence of a cone-shaped surface on the deep tumor border correlated with the infiltration grade shown on all of the sectional displays (p <0.001-0.042) and with advancement of the TNM stage (p = 0.018).

CONCLUSIONS

Although the findings did not show 3D EUS to have a significant advantage over conventional EUS for the accurate evaluation of rectal cancer, a numeric advantage may possibly be statistically significant in a further study with larger cases. Furthermore, stereoscopic visualization provided easier and complete understanding of both focal lesions and lymph nodes.

Endoscopic ultrasound and endoscopic mucosal resection for rectal cancers and villous adenomas

EUS is the most accurate tool for local staging of rectal carcinoma. In addition to providing accurate T- and N-stages, EUS allows assessment of the internal and external anal sphincters. Accurate endosonographic staging directs the optimal method of management of rectal carcinoma, type of resection, and candidacy for neoadjuvant therapy. EMR may be applied to large rectal adenomas as an alternative to surgical resection in selected patients. EUS is important in discriminating lesions suitable for EMR.

Source of errors in the evaluation of early rectal cancer by endoluminal ultrasonography

PURPOSE

Although preoperative evaluation of early rectal cancers can be done by endoluminal sonography and by means of colonoscopic findings, it is still controversial whether endoluminal sonography can effectively discriminate mucosal from submucosal lesions. This study was performed to verify objective causes of errors in the evaluation of early rectal cancer (T0/1) using a review of videotaped endoluminal sonography images.

METHODS

Eighty-nine patients with suspected early rectal cancer on endoluminal sonography were included. Two different scanners with appropriate probes were used according to tumor location, i.e., transrectal ultrasonography was used to scan up to 8 cm of the rectum above the anal verge, whereas endoscopic ultrasonography was used to assess higher lesions. Endoluminal sonography images were correlated with histologic infiltration and were reevaluated carefully to identify sources of errors.

RESULTS

Sensitivity and specificity were 83.1 and 96.5 percent, respectively, for tumor staging, whereas sensitivity was very low compared with specificity (16.7 vs. 90.2 percent) for metastatic lymph nodes. Endoluminal sonography images showed irregularity of the underlying tumor border (P < 0.01) and hypoechoic blurring or cutoff of the inner and outer hypoechoic layers (P < 0.001), all of which closely correlated with histologic infiltration of tumor cells. Overstaging occurred more than twice as often as understaging in tumor reevaluation (14 vs. 5 occurrences). In contrast to tumors, lymph nodes showed a similar amount of both overstaging (four cases) and understaging (five cases). The sources of errors were summarized as five types: false instrumentation, interpretive errors, anatomic defects, imaging failure, and inevitable errors.

CONCLUSIONS

Because false instrumentation, interpretive errors, and anatomic defects were considered preventable, 23 (82.1 percent) of the 28 errors might have been avoided. Therefore, a clear image by endoluminal sonography can effectively distinguish mucosal from submucosal lesions in early rectal cancer.

EUS in patients with benign and malignant lymphadenopathy

BACKGROUND

The EUS appearance of lymph nodes in patients undergoing evaluation for malignancy was studied.

METHODS

In 378 patients EUS characteristics were assessed: size of tumor, largest lymph node size, number of lymph nodes, distance of lymph nodes from the tumor, and on a 5-point visual analogue scale (1 = least malignant to 5 = most malignant), roundness, homogeneity, and echogenicity. A morphology score (sum of roundness, homogeneity, and echogenicity) was calculated. Findings were compared with fine needle aspiration or surgical histopathology in 238 patients.

RESULTS

When using multivariate analysis, only lymph node size (1.4 +/- 0.1 cm vs. 1.7 +/- 0.1 cm, p = 0.001), distance from tumor (3.1 +/- 0.4 cm vs. 1.6 +/- 0.4 cm, p = 0.013), and morphology score (9.9 +/- 0.3 vs. 11.9 +/- 0.3, p = 0.001) for benign versus malignant lymph nodes (mean +/- SEM) were significant. Lymph node size was significant for esophageal cancer (p = 0.006) and other mediastinal lymph nodes (p = 0.007) but not for pancreaticobiliary malignancies (p = 0.1) or celiac lymph nodes (p = 0.4). Distance from the tumor was significant for pancreaticobiliary (p = 0.01) but not esophageal cancers (p = 0.7). Morphology was significant for all sites. The presence of at least one lymph node of 1 cm or greater within 1 cm of the tumor and with a morphology score of 14 or greater had a positive predictive value of 81% (prevalence = 13%). A morphology score of 6 or less had a negative predictive value of 92% (prevalence = 12%).

CONCLUSIONS

Patients with malignant adenopathy have lymph nodes that are larger, closer to the primary tumor, rounder, darker, and more homogeneous than those of patients without malignant adenopathy.

Role of endoscopy in staging colorectal cancer

The treatment of colorectal cancer depends in large measure on the depth of tumor invasion and the extent of lymph node involvement. Endoscopic ultrasonography (EUS) has added a new dimension to the evaluation of tumor invasion and lymph node involvement in gastrointestinal cancer. The overall EUS accuracy for colorectal cancer T-staging is 78%, specificity is 73%, and sensitivity is 94%. In determining the nodal involvement by tumor, EUS has an accuracy of 75%, specificity of 73%, and sensitivity of 74%. Comparison with computerized tomography (CT), magnetic resonance imaging (MRI), and MRI with endorectal coil (MRIEC) shows that EUS is an effective single modality for assessing tumor penetration of the rectal wall. It does not, however, allow the assessment of distant metastatic disease. For assessing lymph node involvement, MRIEC offers the most comprehensive information.