Diagnostics of rectal cancer: endorectal ultrasound

Local Excision for Early-Stage Rectal Adenocarcinomas

ABSTRACT

Although total mesorectal excision (TME) remains the standard of care for rectal cancer, including early-stage T1/T2 rectal adenocarcinoma, local excision may be warranted for these early-stage tumors in a select group of patients who may decline surgery or may be nonoptimal surgical candidates. Operative approaches for transanal local excision include transanal endoscopic microsurgery or transanal minimally invasive surgery for tumors <4 cm, occupying <40% of the rectal circumference and <10 cm from the dentate line. The use of preoperative chemoradiation therapy may help to downstage tumors and allow for more limited resections, and chemoradiation may also be employed postoperatively. Local excision approaches appear to result in improved quality of life compared with TME, but limited resections may also compromise survival rates compared with TME. Multidisciplinary management and shared decision-making can allow for the desired patient outcomes.

Organ preservation in rectal cancer: a synopsis of current guidelines

BACKGROUND

The high morbidity associated with radical resection for rectal cancer is an incentive for surgeons to adopt strategies aimed at organ preservation, particularly for early disease. There are a number of different approaches to achieve this. In this study we have collated current national and international guidelines to produce a synopsis to support this changing practice.

METHODS

The databases PubMed, Embase, Trip database, national guideline clearinghouse, BMJ Best practice were interrogated. Guidelines published before 2010 were excluded. The AGREE-II tool was used for quality assessment.

RESULTS

24 guidelines were drawn from 2278 potential publications. A consensus exists for local excision for "low risk" T1 rectal cancer but there is no agreement how to stratify the risk of treatment failure. There is a low level of agreement for rectal preservation for more advanced disease but when mentioned is recommended for unfit patients or in th context of a clinical trial. Guidelines are inconsistent with respect to surveillance in node negative disease and after, complete response to chemoradiotherapy CONCLUSION: According to current guidelines and consensus statements organ preservation for rectal cancer beyond low risk T1, is still considered experimental and only indicated in patients unsuitable for radical surgery.. Follow up strategies and cN0 staging deserve attention and highlight the need for high quality clinical trials. This article is protected by copyright. All rights reserved.

Adjuvant radiotherapy improves cause specific survival in stage II, not stage III mucinous carcinoma of the rectum

Background

The effect of adjuvant radiotherapy on the survival outcomes of patients with mucinous rectal cancer remains unclear. This study evaluated the 5-year cause specific survival (CSS) of patients with mucinous rectal cancer after surgery to determine whether adjuvant radiotherapy conferred a survival benefit.

Methods

An analysis of the Surveillance, Epidemiology, and End Results (SEER)-registered database was conducted of patients presenting with mucinous rectal cancer between 2004 and 2011. The primary endpoint was 5-year CSS; univariate and multivariate analyses were performed using Cox proportional hazards regression models.

Results

A total of 574 patients were included for analysis with 248 patients in postoperative radiotherapy group and 326 patients in surgery alone group. Preliminary analysis demonstrated that adjuvant radiotherapy was not associated with CSS (χ² = 0.560, P = 0.454). Subgroup analysis indicated that postoperative radiotherapy group had survival advantage in stage II rectal cancer (93.3% vs. 76.6%, χ² = 4.654, P = 0.031), but not in stage III rectal cancer (67.5% vs. 64.7%, χ² = 0.186, P = 0.666). Multivariate analysis demonstrated that postoperative radiotherapy group had a reduced risk of death on survival (HR 0.346; 95%CI 0.129-0.927, P = 0.035)

Conclusion

Postoperative radiotherapy is an independent factor for improvement in CSS in patients with stage II rectal mucinous adenocarcinoma, and it should be routinely recommended in these patients. But for stage III patients, considering the losing of CSS advantage and potential radiotherapy toxicity, postoperative radiotherapy should be recommended with great caution.

Imaging Advances in Colorectal Cancer

The optimal management of rectal cancer is achieved through a shared multidisciplinary decision making process with accurate staging by imaging being critical for treatment planning. Good quality, high-resolution MRI has become the imaging gold standard as it allows consistent staging and stratification of patients into distinct prognostic groups according to MR-findings. Imaging features other than T and N have been proven to influence patient outcomes, and increasingly these features are taken into consideration when determining treatment options: distance of tumour to the potential circumferential margin (CRM), presence of tumour within the extramural rectal vessels (EMVI), discontinuous tumour deposits (N1c), relationship to the intersphincteric plane in low rectal tumours and to pelvic compartments in advanced disease. The presence or absence of proven adverse MR features should be included in the MRI report and shared with the patient when treatment choices are offered. MRI enables the identification of high risk tumours where the use of neoadjuvant therapy is justified and is a robust method of identifying patients with a strong likelihood of complete response after preoperative treatment.

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.

Performance of endoscopic ultrasound in staging rectal adenocarcinoma appropriate for primary surgical resection

BACKGROUND & AIMS

Endoscopic ultrasound (EUS) often is used to stage rectal cancer and thereby guide treatment. Prior assessments of its accuracy have been limited by small sets of data collected from tumors of varying stages. We aimed to characterize the diagnostic performance of EUS analysis of rectal cancer, paying particular attention to determining whether patients should undergo primary surgical resection.

METHODS

We performed a retrospective observational study using procedural databases and electronic medical records from 4 academic tertiary-care hospitals, collecting data on EUS analyses from 2000 through 2012. Data were analyzed from 86 patients with rectal cancer initially staged as T2N0 by EUS. The negative predictive value (NPV) was calculated by comparing initial stages determined by EUS with those determined by pathology analysis of surgical samples. Logistic regression models were used to assess variation in diagnostic performance with case attributes.

RESULTS

EUS excluded advanced tumor depth with an NPV of 0.837 (95% confidence interval [CI], 0.742-0.908), nodal metastasis with an NPV of 0.872 (95% CI, 0.783-0.934), and both together with an NPV of 0.767 (95% CI, 0.664-0.852) compared with pathology analysis. Incorrect staging by EUS affected treatment decision making for 20 of 86 patients (23.3%). Patient age at time of the procedure correlated with the NPV for metastasis to lymph node, but no other patient features were associated significantly with diagnostic performance.

CONCLUSIONS

Based on a multicenter retrospective study, EUS staging of rectal cancer as T2N0 excludes advanced tumor depth and nodal metastasis, respectively, with an approximate NPV of 85%, similar to that of other modalities. EUS has an error rate of approximately 23% in identifying disease appropriate for surgical resection, which is lower than previously reported.

A century of abdominoperineal excision for rectal cancer

SUMMARY Abdominoperineal excision (APE) for rectal cancer was described by Miles over 100 years ago. The technique and approach have undergone a number of modifications, however, the essence of the procedure remains essentially unchanged. Management of rectal cancer has changed significantly over the century as surgery and adjuvant therapies have evolved, with improved outcome and a marked decline in incidence of APE. It has been widely recognized that tumors requiring APE are associated with higher rates of local recurrence and positive resection margins compared with anterior resection. The modern challenge remains in obtaining oncological equivalence for both procedures. This article reviews the history and evolution of APE, assesses its current status and explores modern perspectives on optimizing the surgical approach.

[Diagnostic endoscopic ultrasonography in the gastrointestinal tract]

Endoscopic ultrasonography is a relatively new technology that combines the use of flexible fiberoptic endoscopes with high-resolution ultrasound technology. It proved to be highly accurate and useful in the staging of gastrointestinal malignancies, as well as in characterizing the nature of subepithelial lesions and disorders of the pancreaticobiliary system. In this overview the variety of current evidence based diagnostic options of endoscopic ultrasonography are discussed.

Role of radiation in intermediate-risk rectal cancer

The treatment of rectal cancer has greatly evolved during the last several decades as a result of the understanding of the pathways of cancer spread, natural history of the disease, stages prognosis and prognostic markers. The tendency is clearly to move toward a more personalized approach to these patients based on preoperative staging and response to therapy. Although in the past we have been adding more treatment modalities to surgery to the point that every stage II/III cancer was treated with neoadjuvant chemo and radiotherapy followed by radical surgery by total mesorectal excision with or without sphincter preservation and more chemotherapy to follow, more recently this algorithm has been under discussion and scrutiny. Two of the major topics of controversy are: the use of local excision or even a watch-and-wait approach after a clinical complete response and the need for radiotherapy in the intermediate risk group. In this manuscript we will present the historical perspective that has brought the treatment of rectal cancer to the current standard of care and present the evidence supporting further investigation in the intermediate risk group.

Rectal cancer staging

Rectal cancer staging provides critical information concerning the extent of the disease. The information gained from staging is used to determine prognosis, to guide management, and to assess response to therapy. Accurate staging is essential for directing the multidisciplinary approach to therapy. This article focuses on the evolution of staging systems, the rational for staging, and current methods used to stage rectal cancer.

Preoperative staging of rectal cancer

Preoperative staging is now an essential factor in the multidisciplinary management of rectal cancer because tumor stage is the strongest predictive factor for recurrence. Preoperative staging of rectal cancer can be divided into either local or distant staging. Local staging incorporates the assessment of mural wall invasion, circumferential resection margin involvement, as well as the nodal status for metastasis. Distant staging assesses for evidence of metastatic disease. The aim of this review is to consider the indications and limitations of the current preoperative imaging modalities for rectal cancer staging including clinical examination, endorectal ultrasound, magnetic resonance imaging, computed tomography and positron emission tomography–computed tomography, with respect to local and distant disease.

A simple scoring system based on clinical features to predict locally advanced rectal cancers

PURPOSE

The purpose of this study was to identify clinical risk factors and establish a prediction scoring system for locally advanced rectal cancer.

MATERIALS AND METHODS

Retrospective univariate and multivariate logistic analyses were conducted for 413 curable rectal cancer patients. Clinical factors found to be significantly related with tumor stages were incorporated into a scoring system to predict locally advanced stages, which was validated in an independent cohort of 279 rectal cancer patients.

RESULTS

In the training set, tumor size, differentiation, and serum carcinoembryonic antigen (CEA) level (P < 0.01) were significant predictors of locally advanced rectal cancer in both univariate and multivariate analyses, which were incorporated into a proposed scoring system to predict locally advanced stages. The area under the receiver operating characteristic curve (AUROC) of this scoring system was 0.751 and the prediction accuracy was 78.2%. Patients were categorized into three subsets according to the total score. The low-risk group (score 0) had a smaller chance (18.2%) to have locally advanced rectal cancer, compared to mean 49.2% for the intermediate-risk group (score 1) and mean 83.0% for the high-risk group (score of 2-4; P < 0.05). In the validation set, the AUROC of the scoring system was 0.756 and the prediction accuracy was 75.3%.

CONCLUSIONS

Tumor size more than 2 cm, poor differentiation, and elevated serum CEA level are high-risk factors of locally advanced rectal cancer. A simple scoring system based on these three factors may be valuable to predict locally advanced rectal cancer.

[The value of endorectal ultrasonography in rectal cancer staging]

INTRODUCTION

Preoperative staging of rectal cancer is considered essential to select patients adequately for different therapeutic regimes. The aim of the present study was to evaluate the accuracy of endorectal ultrasonography in preoperative staging of rectal cancer.

MATERIALS AND METHODS

Fifty rectal cancer patients (31 men, 19 women) underwent endorectal ultrasonography with a 7.5-MHz probe. Thirty-eight of these patients had preoperative chemoradiation and in these patients examination was done before and after the radiotherapy treatment. The results of examinations were compared with the histological findings of the resected specimens.

RESULTS

Histopathology showed 4 stage TO, 3 stage T1, 12 stage T2, 30 stage T3, and one stage T4 tumor. Nodal metastases were seen in 17 patients. The overall accuracy of endorectal ultrasonography for determining the depth of invasion (T stage) was 66% (33/50). The accuracy rate of T1 was 100% (1/1), T2 was 45% (9/20), T3 was 79% (22/28), and T4 was 100% (1/1). Overstaging was 18% (9/50) and understaging 16% (8/50). In staging lymph node metastasis, the overall accuracy rate was 70% (18/25) with 18% (9/50) overstaged and 12% (6/50) understaged With regard to nodal involvement, sensitivity was 65% and specificity 73%. Regarding penetration of the rectal wall (stages T1 and T2 vs stages T3 and T4/Dukes' classification A versus B), endorectal sonography showed sensitivity, specificity, and accuracy of 74%, 68%, and 72%, respectively.

CONCLUSION

Endorectal ultrasonography is a valuable diagnostic modality for rectal cancer staging. It is fast, safe, accurate, well tolerated by the patient and cheap procedure and therefore should be used as a diagnostic modality of the first choice in rectal cancer staging although one must take into consideration possible limitations in cases of preoperative chemoradiation.

Preoperative staging and treatment options in T1 rectal adenocarcinoma

BACKGROUND

Major rectal resection for T1 rectal cancer offers more than 95% cancer specific five-year survival to patients surviving the first 30 days after surgery. A significant further improvement by development of the surgical technique may not be possible. Improvements in the total survival rate have to come from a more differentiated treatment modality, taking patient and procedure related risk factors into account. Subgroups of patients have operative mortality risks of 10% or more. Operative complications and long-term side effects after rectum resection are frequent and often severe.

RESULTS

Local treatment of T1 cancers combined with close follow-up, early salvage surgery or later radical resection of local recurrences or with chemo-radiation may lead to fewer severe complications and comparable, or even better, long-term survival. Accurate preoperative staging and careful selection of patients for local or non-operative treatment are mandatory. As preoperative staging, at present, is not sufficiently accurate, strategies for completion, salvage or rescue surgery is important, and must be accepted by the patient before local treatment for cure is initiated.

RECOMMENDATIONS

It is recommended that polyps with low-risk T1 cancers should be treated with endoscopic snare resection in case of Haggitt's stage 1 or 2. TEM is recommended if resection margins are uncertain after snare resection for Haggitt's stage 3 and 4, and for sessile and flat, low-risk T1 cancers. Average risk patients with high-risk T1 cancers should be offered rectum resection, but old and comorbid patients with high-risk T1 cancers should be treated individually according to objective criteria as age, physical performance as well as patient's preference. All patients treated for cure with local resection or non-surgical methods should be followed closely.

The role of minimally invasive treatments in surgical oncology

This article reviews the use of minimally invasive surgical and endoscopic techniques in the field of surgical oncology. It reviews the indications and techniques of the use of minimally invasive surgery for several oncologic indications in general surgery. In particular, it reviews the currently published literature discussing the oncologic outcomes of these techniques.

Local management of rectal neoplasia

The treatment of rectal neoplasia, whether benign or malignant, challenges the surgeon. The challenge in treating rectal cancer is selecting the proper approach for the appropriate patient. In a small number of rectal cancer patients local excision may be the best approach. In an attempt to achieve two goals-cure of disease with a low rate of local failure and maintenance of function and quality of life-multiple approaches can be utilized. The key to obtaining a good outcome for any one patient is balancing the competing factors that impact on these goals. Any effective treatment aimed at controlling rectal cancer in the pelvis must take into account the disease in the bowel wall itself and the disease, or potential disease, in the mesorectum. The major downside of local excision techniques is the potential of leaving untreated disease in the mesorectum. Local management techniques avoid the potential morbidity, mortality, and functional consequences of a major abdominal radical resection and are thus quite effective in achieving the maintenance of function and quality of life goal. The issue for the transanal techniques is how they fare in achieving the first goal-cure of the cancer while keeping local recurrence rates to an absolute minimum. Without removing both the rectum and the mesorectum there is no completely accurate way to determine whether a rectal cancer has moved outside the bowel wall, so any decision on local management of a rectal neoplasm is a calculated risk. For benign neoplasia, the challenge is removing the lesion without having to resort to a major abdominal procedure.

[Management of superficial rectal cancers]

Superficial rectal cancers consist of Tis and T1 tumors as defined by the TNM classification system. Earlier detection of colorectal cancers through endoscopic screening should lead to an increase in the percentage of superficial cancers detected while still superficial; they may eventually represent more than a third of diagnosed rectal cancers. Endorectal ultrasound, ideally performed with a mini-probe, is the best pre-operative study to define the level of penetration into the rectal wall; depth of penetration and grade of differentiation are the major factors to be considered when contemplating local excision as an alternative to radical resection. Local excision can be performed endoscopically or by the classic transanal surgical approach. Each technique has pros and cons and the two are often complementary. Compared to the alternative of radical proctectomy, they have the decided advantages of zero mortality, minimal morbidity, and decreased expense. Pathologic examination of the resected specimen is the final determinant as to whether local resection is adequate therapy. When histologic prognostic factors are favorable (well-differentiated, absence of lymphatic or vascular invasion, superficial invasion of the submucosa (sm1), and clear resection margins), the risk of lymph node spread is negligible. When histologic prognostic factors are not favorable, a completion radical proctectomy should be performed.

cT3N0 rectal cancer: potential overtreatment with preoperative chemoradiotherapy is warranted

PURPOSE

Although combined-modality therapy (CMT) is the preferred treatment for T3 and/or lymph node (LN)-positive rectal cancer, the German rectal cancer study published in 2004 demonstrated that 18% of patients deemed suitable for preoperative CMT by endorectal ultrasound (ERUS) may be overstaged. Because data also suggest that LN-negative rectal cancer after total mesorectal excision may not require radiotherapy, it is reasonable to consider omitting radiotherapy for the cT3N0 subset. We therefore determined the accuracy of pre-CMT ERUS or magnetic resonance imaging (MRI) staging, to explore the validity of a nonpreoperative CMT approach for cT3N0 disease.

PATIENTS AND METHODS

One hundred eighty-eight ERUS-/MRI-staged T3N0 rectal cancer patients received preoperative CMT (fluorouracil based and 45-50.4 Gy) followed by radical resection. Rates of pathologic complete response (pCR) and mesorectal LN involvement were determined.

RESULTS

Tumors were located a median of 5 cm from the anal verge. Sphincter-preserving surgery was performed in 143 patients (76%). Overall pCR was 20%, and 41 patients (22%) had pathologically positive mesorectal LNs. The incidence of positive LNs significantly increased with T stage: ypT0, 3%; ypT1, 7%; ypT2, 20%; ypT3-4, 36% (P = .001).

CONCLUSION

The accuracy of preoperative ERUS/MRI for staging mid to distal cT3N0 rectal cancer is limited because 22% of patients have undetected mesorectal LN involvement despite CMT. Therefore, ERUS-/MRI-staged T3N0 rectal cancer patients should continue to receive preoperative CMT. Although 18% may be overstaged and therefore overtreated, our data suggest that an even larger number would be understaged and require postoperative CMT, which is associated with significantly inferior local control, higher toxicity, and worse functional outcome.

Limitations of early rectal cancer nodal staging may explain failure after local excision

Successful selection of patients with rectal cancer for local excision requires accurate preoperative lymph node staging. Although endorectal ultrasound is capable of detecting locally advanced disease, its ability to correctly identify nodal metastases in early rectal lesions is less well described. This study examines the accuracy of endorectal ultrasound in determining nodal stage based on depth of penetration of the primary lesion (T stage). Between 1998 and 2003, endorectal ultrasound was performed on 938 consecutive patients; 134 had biopsy-proven rectal cancers and were treated with radical resection, without neoadjuvant therapy. Lymph node metastases were measured pathologically and correlated with endorectal ultrasound and clinicopathologic features. Accuracy and specificity of endorectal ultrasound nodal staging was determined. The overall accuracy of endorectal ultrasound nodal staging for the study cohort was 70 percent, with a 16 percent false-positive rate and 14 percent false-negative rate. Endorectal ultrasound was more likely to overlook small metastatic lymph node deposits. The size of lymph node metastasis and accuracy of endorectal ultrasound nodal staging was related to T stage. The specificity of endorectal ultrasound nodal staging, or the ability to identify patients who were node-negative, was dependent on T stage. Early rectal lesions are more likely to have lymph node micrometastases not detected by endorectal ultrasound. The ability of endorectal ultrasound to correctly identify patients without lymph node metastasis is dependent on the T stage of the primary lesion. The limitations of endorectal ultrasound in accurately staging nodal disease in early rectal lesions may, in part, explain the relatively high recurrence rates seen after local excision.

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.

Interpreting missense variants: comparing computational methods in human disease genes CDKN2A, MLH1, MSH2, MECP2, and tyrosinase (TYR)

The human genome contains frequent single-basepair variants that may or may not cause genetic disease. To characterize benign vs. pathogenic missense variants, numerous computational algorithms have been developed based on comparative sequence and/or protein structure analysis. We compared computational methods that use evolutionary conservation alone, amino acid (AA) change alone, and a combination of conservation and AA change in predicting the consequences of 254 missense variants in the CDKN2A (n = 92), MLH1 (n = 28), MSH2 (n = 14), MECP2 (n = 30), and tyrosinase (TYR) (n = 90) genes. Variants were validated as either neutral or deleterious by curated locus-specific mutation databases and published functional data. All methods that use evolutionary sequence analysis have comparable overall prediction accuracy (72.9-82.0%). Mutations at codons where the AA is absolutely conserved over a sufficient evolutionary distance (about one-third of variants) had a 91.6 to 96.8% likelihood of being deleterious. Three algorithms (SIFT, PolyPhen, and A-GVGD) that differentiate one variant from another at a given codon did not significantly improve predictive value over conservation score alone using the BLOSUM62 matrix. However, when all four methods were in agreement (62.7% of variants), predictive value improved to 88.1%. These results confirm a high predictive value for methods that use evolutionary sequence conservation, with or without considering protein structural change, to predict the clinical consequences of missense variants. The methods can be generalized across genes that cause different types of genetic disease. The results support the clinical use of computational methods as one tool to help interpret missense variants in genes associated with human genetic disease.

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

BACKGROUND

We performed this study to prospectively evaluate the postchemoradiotherapy performance of transrectal ultrasonography (TRUS), pelvic computed tomography (CT) scan and magnetic resonance imaging (MRI), and endoscopic biopsies for predicting the pathologic complete response of rectal cancer patients.

METHODS

Four weeks after completion of preoperative chemoradiotherapy, 46 consecutive patients with mid to low rectal cancer were prospectively evaluated by proctoscopy, TRUS, and pelvic CT scan and MRI. On the basis of T and N status, patients were classified as T0 or T1-4 and N-negative or N-positive. For each staging modality used, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated. Findings were compared with the pathologic tumor-node-metastasis stage.

RESULTS

On histopathologic analysis, 12 patients had pT0 and 34 had pT1-4 lesions; out of 45 assessable patients, 9 were N-positive. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in predicting T status (T0 vs. T >or=1) were 77%, 33%, 74%, 36%, and 64%, respectively, for TRUS; 100%, 0%, 74%, not assessable, and 74% for CT; and 100%, 0%, 77%, not assessable, and 77% for MRI. The corresponding figures in predicting N status (N-negative vs. N-positive) were, respectively, 37%, 67%, 21%, 81%, and 61% for TRUS; 78%, 58%, 32%, 91%, and 62% for CT; and 33%, 74%, 25%, 81%, and 65% for MRI.

CONCLUSIONS

Current rectal cancer staging modalities after chemoradiotherapy allow good prediction of node-negative cases, although none of them is able to predict the pathologic complete response on the rectal wall.

Local staging of rectal cancer: the current role of MRI

With the advent of powerful gradient coil systems and high-resolution surface coils, magnetic resonance imaging (MRI) has recently extended its role in the staging of rectal cancer. MRI is superior to endorectal ultrasound, the most widely used staging modality in patients with rectal tumors, in that it visualizes not only the intestinal wall but also the surrounding pelvic anatomy. The crucial advantage of MRI is not that it enables exact T-staging but precise evaluation of the topographic relationship of a tumor to the mesorectal fascia. This fascia is the most important anatomic landmark for the feasibility of total mesorectal excision, which has evolved into the standard operative procedure for the resection of cancer located in the middle or lower third of the rectum. MRI is currently the only imaging modality that is highly accurate in predicting whether or not it is likely that a tumor-free margin can be achieved and thus provides important information for planning of an effective therapeutic strategy, especially in patients with advanced rectal cancer.

The role and value of endorectal ultrasonography in diagnosing T1 rectal tumors

Rectal carcinoma in 50% to 60% of cases is localized in the rectum and, if diagnosed early can be locally excised. The authors evaluated the diagnostic accuracy of the preoperative endorectal ultrasonography (ERUS) in the staging of rectal tumors and the usefulness of the method to assess patients' suitability for local excision. In the retrospective analysis, we analyzed 29 patients with rectal cancer. The depth of invasion into the rectal wall was assessed by ERUS and all patients were qualified for tumor excision with transanal endoscopic microsurgery (TEM). We analyzed overall accuracy of ERUS and the effectiveness of treatment. In the analyzed group, diagnostic accuracy of ERUS in assessing T1 carcinomas was 89.2%, sensitivity 92.3% and specificity 50%. Local excision with TEM was deemed to be curative in 86.2% patients with rectal tumors detected by ERUS. ERUS is an accurate method of preoperative assessment of T1 and T2 carcinomas and its diagnostic accuracy is sufficient to qualify patients for anal-saving operations.

Feasibility and accuracy of TRUS in the pre-treatment staging for rectal carcinoma in general practice

AIMS

Transrectal ultrasonography (TRUS) is the diagnostic tool of choice for local staging of rectal carcinoma. The accuracy in determining of tumour infiltration depth has been reported to reach 95% (on average, 85%). The aim of the study was to analyse the diagnostic accuracy of the TRUS in the clinical routine.

PATIENTS AND METHODS

From 01/01/2000 to 12/31/2003, all patients with rectal carcinoma were enrolled in a prospective multicenter observational study. In case of complete findings of pre-operative TRUS and post-operative histological investigation of the surgical specimen on the tumour infiltration depth, overall accuracy of TRUS was determined.

RESULTS

Overall, 13,610 patients with rectal carcinoma were enrolled in the study. Five thousand and fifty-six subjects (37%) underwent TRUS. In 3,501 patients, TRUS finding (uT-stage) could be compared with the result of the definitive histologic investigation (pT-stage). The accuracy of TRUS in all T-stages was 65.8%. The highest sensitivity was achieved in the T3-stage (74.9%), while in T2, T1, and T4, it was 59.6, 59.0 and 31.1%, respectively. In discriminating tumour growth limited to the rectal wall vs that through the rectal wall into the neighboring tissue, TRUS-associated accuracy was 76.5%. There were no differences between various tumour locations above the anocutaneous line.

CONCLUSIONS

Diagnostic accuracy of TRUS in determining depth of tumour infiltration within or through the rectum wall in the routinuous diagnostic of rectal carcinoma does not reach the excellent published study results. A considerable improvement of the qualitative outcome in using this specific diagnostic tool appears to be recommendable to utilize its advantages such as high accuracy, efficacy, and practicability in the diagnostic process and deriving consequences for a possible neoadjuvant treatment as well as optimal planning of the surgical approach.

Staging of rectal cancer by endorectal ultrasonography

Endorectal ultrasonography is valuable method for accurate local staging of rectal cancer. Precise evaluation of tumor stage is essential for optimal therapy planning in patients with rectal cancer. Furthermore, it has great influence on the resectability and the risk of recurrence following resection. Endorectal ultrasonography has become the most common diagnostic tool for locally staging rectal cancer due to its advantages over magnetic resonance imaging (MRI) and computer tomography (CT). Among these diagnostic modalities ERUS has been known to be most accurate. Moreover, endorectal ultrasonography is inexpensive and quick diagnostic procedure associated with minimal discomfort to the patient. However, the use of CT, MRI, and more recently magnetic resonance imaging with endorectal coil often remains necessary. These modalities may be useful supplements in patients with suspected T4 lesion, when endorectal ultrasonography is technically unsuccessful and in cases of diagnostic dilemma. Major improvements in diagnostic and staging of rectal cancer have led to stage-oriented surgery, planning of therapy individually for each patient, reduce of local recurrences, and better overall survival. This article reviews the current use of endorectal ultrasonography in preoperative staging of rectal cancer as the most practical and accurate diagnostic modality for preoperative locoregional staging of rectal cancer at this time.