Use of preoperative ultrasound staging for treatment of rectal cancer

MRI Radiomics for Prediction of Tumor Response and Downstaging in Rectal Cancer Patients after Preoperative Chemoradiation

Purpose

This study aimed to investigate radiomic features extracted from magnetic resonance imaging (MRI) scans performed before and after neoadjuvant chemoradiotherapy (nCRT) in predicting response of locally advanced rectal cancer (LARC).

Methods and Materials

Thirty-nine patients who underwent nCRT for LARC were included, with 294 radiomic features extracted from MRI that was performed before (pre-CRT) and 6 to 8 weeks after completing nCRT (post-CRT). Based on tumor regression grade (TRG), 26 patients were classified as having a histopathologic good response (GR; TRG 0-1) and 13 as non-GR (TRG 2-3). Tumor downstaging (T-downstaging) occurred in 25 patients. Univariate analyses were performed to assess potential radiomic and delta-radiomic predictors for TRG in pathologic complete response (pCR) versus non-pCR, GR versus non-GR, and T-downstaging. The support vector machine-based multivariate model was used to select the best predictors for TRG and T-downstaging.

Results

We identified 13 predictive features for pCR versus non-pCR, 14 for GR versus non-GR, and 16 for T-downstaging. Pre-CRT gray-level run length matrix nonuniformity, pre-CRT neighborhood intensity difference matrix (NIDM) texture strength, and post-CRT NIDM busyness predicted all 3 treatment responses. The best predictor for GR versus non-GR was pre-CRT global minimum combined with clinical N stage in the multivariate analysis. The best predictor for T-downstaging was the combination of pre-CRT gray-level co-occurrence matrix correlation, NIDM-texture strength, and gray-level co-occurrence matrix variance. The pre-CRT, post-CRT, and delta radiomic-based models had no significant difference in predicting all 3 responses.

Conclusions

Pre-CRT MRI, post-CRT MRI, and delta radiomic-based models have the potential to predict tumor response after nCRT in LARC. These data, if validated in larger cohorts, can provide important predictive information to aid in clinical decision making.

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

AIM

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

METHOD

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

RESULTS

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

CONCLUSION

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

Organ preservation in rectal cancer: current status and future perspectives

With the introduction of population screening initiatives, more patients may be amenable to local, transanal excision (LE) of early-stage rectal cancer. The most important drawback of LE is the risk of understaging node-positive disease. The most powerful predictors of node-positive disease are lymphatic invasion, submucosal invasion depth and width, tumor budding and poor differentiation. Therefore, LE should be reserved for low-risk T1 tumors in those reluctant or unable to undergo major surgery. Neoadjuvant chemoradiation followed by LE for T2 tumors allows adequate local control, and is currently being compared with anterior resection alone in randomized trials. A mere watchful waiting approach has been proposed in clinical complete responders to chemoradiation. However, given the very poor accuracy of current imaging modalities to predict a true pathological complete response, this strategy should not be offered outside of well-controlled trials.

When is local excision appropriate for "early" rectal cancer?

Local excision is increasingly performed for “early stage” rectal cancer in the US; however, local recurrence after local excision has become a controversial issue in Western countries. Local recurrence is considered to originate based on the type of tumor and procedure performed, and in surgical margin-positive cases. This review focuses on the inclusion criteria of “early” rectal cancers for local excision from the Western and Japanese points of view. “Early” rectal cancer is defined as T1 cancer in the rectum. Only the tumor grade and depth of invasion are the “high risk” factors which can be evaluated before treatment. T1 cancers with sm1 or submucosal invasion <1,000 μm are considered to be “low risk” tumors with less than 3.2 % nodal involvement, and are considered to be candidates for local excision as the sole curative surgery. Tumors with a poor tumor grade should be excluded from local excision. Digital examination, endoscopy or proctoscopy with biopsy, a barium enema study and endorectal ultrasonography are useful for identifying “low risk” or excluding “high risk” factors preoperatively for a comprehensive diagnosis. The selection of an initial local treatment modality is also considered to be important according to the analysis of the nodal involvement rate after initial local treatment and after radical surgery.

The accuracy of multi-detector row computerized tomography in staging rectal cancer compared to endoscopic ultrasound

BACKGROUND/AIM

Our aim was to evaluate the diagnostic accuracy of multi-detector row computerized tomography (MDCT) in staging of rectal cancer by comparing it to rectal endoscopic ultrasound (EUS).

MATERIALS AND METHODS

We prospectively included all patients with rectal cancer referred to our gastroenterology unit for staging of rectal cancer from December 2007 until February 2011, 53 patients whose biopsy had proven rectal cancer underwent both MDCT scan of the pelvis and rectal EUS. Both imaging modalities were compared and the agreement between T- and N-staging of the disease was assessed.

RESULTS

We staged 62 patients with rectal cancer during the study period. Of these, 53 patients met the inclusion criteria and were evaluated (25 women and 28 men). The mean age was 57.79 ± 14.99 years (range 21-87). MDCT had poor accuracy compared with EUS in T-staging with a low degree of agreement (kappa = 0.26), while for N-staging MDCT had a better accuracy and a moderate degree of agreement with EUS (kappa = 0.45).

CONCLUSIONS

MDCT has a poor accuracy for predicting tumor invasion compared to EUS for T-staging while it has moderate accuracy for N-staging.

[Impact of endoscopy and endosonography on local staging of rectal carcinoma]

For rectal carcinoma the decision between primary resection, neoadjuvant therapy and local excision depends on an accurate local staging. Local staging includes digital examination, rigid rectoscopy and endorectal ultrasound (EUS). The rectal digitation allows clinical staging according to the mobility of the tumor in relation to the rectal mucosa or the rectal wall. The rigid rectoscopy determines the aboral distance of the tumor from the dentate line or the anal verge. The endorectal ultrasound determines the pre-therapeutic UICC stage on the basis of evaluating the pretherapeutic T and N categories. Results of EUS should be discussed on the background of neoadjuvant therapy including response evaluation and in comparison with the results of magnetic resonance imaging. In addition, there is only little information available concerning evaluation of the circumferential resection margin by EUS. Technical improvements, such as the 3D-EUS, might be appropriate in the future to provide enhancement of EUS staging of rectal tumors.

Progress in rectal cancer treatment

The dramatic improvement in local control of rectal cancer observed during the last decades is to be attributed to attention to surgical technique and to the introduction of neoadjuvant therapy regimens. Nevertheless, systemic relapse remains frequent and is currently insufficiently addressed. Intensification of neoadjuvant therapy by incorporating chemotherapy with or without targeted agents before the start of (chemo)radiation or during the waiting period to surgery may present an opportunity to improve overall survival. An increasing number of patients can nowadays undergo sphincter preserving surgery. In selected patients, local excision or even a "wait and see" approach may be feasible following active neoadjuvant therapy. Molecular and genetic biomarkers as well as innovative imaging techniques may in the future allow better selection of patients for this treatment option. Controversy persists concerning the selection of patients for adjuvant chemotherapy and/or targeted therapy after neoadjuvant regimens. The currently available evidence suggests that in complete pathological responders long-term outcome is excellent and adjuvant therapy may be omitted. The results of ongoing trials will help to establish the ideal tailored approach in resectable rectal cancer.

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.

Can endoscopic ultrasound predict early rectal cancers that can be resected endoscopically? A meta-analysis and systematic review

BACKGROUND

Rectal cancers that are confined to the mucosa (T0) can be resected endoscopically. This can help the patient avoid transabdominal surgery. The published data on accuracy of endoscopic ultrasound (EUS) to predict T0 stage of rectal cancers has been varied.

AIM

To evaluate the accuracy of EUS in T0 staging of rectal cancers. METHOD (STUDY SELECTION CRITERIA): Only EUS studies confirmed by surgery were selected. T0 was defined as tumor confined to the mucosa. DATA COLLECTION AND EXTRACTION: Articles were searched in Medline, PubMed, and CENTRAL.

STATISTICAL METHOD

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

RESULTS

An initial search identified 3,360 reference articles. Of these, 339 relevant articles were selected and reviewed. Eleven studies (N = 1,791) which met the inclusion criteria were included in this analysis. Pooled sensitivity of EUS in diagnosing T0 was 97.3% (95% CI: 93.7-99.1). EUS had a pooled specificity of 96.3% (95% CI: 95.3-97.2). The positive likelihood ratio of EUS was 21.9 (95% CI: 16.3-29.7) and negative likelihood ratio was 0.08 (95% CI: 0.04-0.15). All the pooled estimates, calculated by fixed and random effect models, were similar. The P-value for Chi-squared heterogeneity for all the pooled accuracy estimates was >0.10.

CONCLUSIONS

EUS has excellent sensitivity and specificity, this helps accurately diagnose T0 stage of rectal cancers. Over the past two decades, the sensitivity and specificity of EUS to diagnose T0 stage of rectal cancers has remained high. This can help physicians offer endoscopic treatment to these patients, therefore EUS should be strongly considered for staging of early rectal cancers.

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.

Role of combined-modality therapy in the management of locally advanced rectal cancer

The majority of patients with nonmetastatic rectal cancer are candidates for an aggressive multimodality approach with curative intent. Preoperative staging is critical in determining which patients should be offered neoadjuvant therapy. Available staging tools include digital rectal examination, transrectal ultrasound, computed tomography, positron-emission tomography, and magnetic resonance imaging scans. Magnetic resonance imaging has emerged as the most accurate staging modality in experienced centers. Multidisciplinary preoperative patient evaluation, better staging techniques, neoadjuvant chemoradiation, acceptance of shorter distal rectal margins, and transanal excision of T1 N0 rectal tumors in close proximity to the anal sphincter have resulted in decreased rates of abdominoperineal resections. Total mesorectal excision has been adopted as the standard surgical approach because of a reduction in rates of pelvic relapse. Preoperative and postoperative radiation therapy was shown to decrease the local recurrence rate, but not overall survival, in patients with resectable rectal cancer. The addition of chemotherapy to radiation was consistently shown to improve local control, and in some trials, improved overall survival. Neoadjuvant combined chemotherapy and radiation therapy are superior to adjuvant combined-modality therapy because of higher rates of sphincter preservation, less toxicity, and lower local recurrence rates. For patients with stage II or III disease, neoadjuvant continuous-infusion 5-fluorouracil (5-FU), concurrently with pelvic radiation, followed by postoperative 5-FU-based chemotherapy, remains the standard multimodality approach. Ongoing trials are testing the integration of newer cytotoxic agents such as capecitabine, oxaliplatin, irinotecan, and biologic agents such as cetuximab and bevacizumab to chemoradiation.

Diagnosis and management of recurrent colorectal cancer

Justification for the management of recurrent colorectal cancer begins with proof that the ultimate outcome measured by survival can be influenced. To do this, we must prove there is value to follow-up of colorectal cancer patients. Without followup, the management of recurrent cancer is limited.

How good is endoscopic ultrasound in differentiating various T stages of rectal cancer? Meta-analysis and systematic review

Published data on accuracy of endoscopic ultrasound (EUS) in differentiating T stages of rectal cancers is varied. Study selection criteria were to select only EUS studies confirmed with results of surgical pathology. Articles were searched in Medline and Pubmed. Pooling was conducted by both fixed and random effects models. Initial search identified 3,630 reference articles, of which 42 studies (N = 5,039) met the inclusion criteria and were included in this analysis. The pooled sensitivity and specificity of EUS to determine T1 stage was 87.8% [95% confidence interval (CI) 85.3-90.0%] and 98.3% (95% CI 97.8-98.7%), respectively. For T2 stage, EUS had a pooled sensitivity and specificity of 80.5% (95% CI 77.9-82.9%) and 95.6% (95% CI 94.9-96.3%), respectively. To stage T3 stage, EUS had a pooled sensitivity and specificity of 96.4% (95% CI 95.4-97.2%) and 90.6% (95% CI 89.5-91.7%), respectively. In determining the T4 stage, EUS had a pooled sensitivity of 95.4% (95% CI 92.4-97.5%) and specificity of 98.3% (95% CI 97.8-98.7%). The p value for chi-squared heterogeneity for all the pooled accuracy estimates was > 0.10. We conclude that, as a result of the demonstrated sensitivity and specificity, EUS should be the investigation of choice to T stage rectal cancers. The sensitivity of EUS is higher for advanced disease than for early disease. EUS should be strongly considered for T staging of rectal cancers.

Endorectal ultrasonography versus phased-array magnetic resonance imaging for preoperative staging of rectal cancer

AIM: To compare the diagnostic accuracy of pelvic phased-array magnetic resonance imaging (MRI) and endorectal ultrasonography (ERUS) in the preoperative staging of rectal carcinoma.

METHODS: Thirty-four patients (15 males, 19 females) with ages ranging between 29 and 75 who have biopsy proven rectal tumor underwent both MRI and ERUS examinations before surgery. All patients were evaluated to determine the diagnostic accuracy of depth of transmural tumor invasion and lymph node metastases. Imaging results were correlated with histopathological findings regarded as the gold standard and both modalities were compared in terms of predicting preoperative local staging of rectal carcinoma.

RESULTS: The pathological T stage of the tumors was: pT1 in 1 patient, pT2 in 9 patients, pT3 in 21 patients and pT4 in 3 patients. The pathological N stage of the tumors was: pN0 in 19 patients, pN1 in 9 patients and pN2 in 6 patients. The accuracy of T staging for MRI was 89.70% (27 out of 34). The sensitivity was 79.41% and the specificity was 93.14%. The accuracy of T staging for ERUS was 85.29% (24 out of 34). The sensitivity was 70.59% and the specificity was 90.20%. Detection of lymph node metastases using phased-array MRI gave an accuracy of 74.50% (21 out of 34). The sensitivity and specificity was found to be 61.76% and 80.88%, respectively. By using ERUS in the detection of lymph node metastases, an accuracy of 76.47% (18 out of 34) was obtained. The sensitivity and specificity were found to be 52.94% and 84.31%, respectively.

CONCLUSION: ERUS and phased-array MRI are complementary methods in the accurate preoperative staging of rectal cancer. In conclusion, we can state that phased-array MRI was observed to be slightly superior in determining the depth of transmural invasion (T stage) and has same value in detecting lymph node metastases (N stage) as compared to ERUS.

Comparison between 3-T magnetic resonance imaging and multi-detector row computed tomography for the preoperative evaluation of rectal cancer

OBJECTIVE

To compare prospectively between 3-T magnetic resonance imaging (MRI) and multidetector row computed tomography (MDCT) for the local staging of rectal cancer.

MATERIALS AND METHODS

During a recent 8-month period, both 3-T MRI with a phased array coil and MDCT scanner were used to preoperatively examine 31 consecutive patients. Preoperatively, the 3 experienced reviewers independently assessed the MRI and MDCT findings for the depth of tumor invasion into the rectal wall (T). Regional lymph node metastasis (N) was assessed by the 3 reviewers working in consensus. For T staging, we used a modified T staging (<or=T2, T3, and T4 staging). The results of the MRI and MDCT findings were compared based on the diagnosis of the resected specimens.

RESULTS

At histopathology, T1 was identified in 8 patients, T2 in 6, and T3 in 17 patients. The sensitivity, specificity, and accuracy for T2 staging or less between MRI and MDCT were 93% and 79%, 88% and 76%, and 91% and 77%, respectively. The sensitivity, specificity, and accuracy for T3 between MRI and MDCT were 92% and 73%, 93% and 83%, and 92% and 78%, respectively; there was a statistically significant difference for the T2 and T3 staging or less (P < 0.01). For N staging, MRI and CT can predict accurately in 88% and 77%, respectively (P > 0.05).

CONCLUSIONS

For local staging of rectal cancer, 3-T MRI is more accurate than MDCT for determining the depth of tumor invasion and the extent of lymph node metastasis.

Increased detection rate and potential prognostic impact of disseminated tumor cells in patients undergoing endorectal ultrasound for rectal cancer

BACKGROUND

Hematogenous tumor-cell dissemination during diagnostic and therapeutic procedures in patients with colorectal cancer has been demonstrated.

OBJECTIVE

The aim of this study was to investigate the extent of disseminated tumor cells in blood samples of rectal cancer patients after endorectal ultrasound and to determine its prognostic relevance.

MATERIALS AND METHODS

Peripheral venous blood samples from 45 patients with rectal cancer were taken before and after endorectal ultrasound. Blood samples were examined using a reverse transcriptase-polymerase chain reaction (RT-PCR) assay to amplify cytokeratin 20 transcripts. Overall survival of the patients was calculated by the Kaplan-Meier method.

RESULTS

Disseminated tumor cells were detected in peripheral blood samples of 17 of 45 (38%) patients before and after endorectal ultrasound. Circulating tumor cells were found in 11 of 45 (24%) patients only after endorectal ultrasound (p=0.006). There was a clear trend toward a worse prognosis in patients with tumor cells in blood samples after endorectal ultrasound, but this difference was not statistically significant.

CONCLUSION

This study demonstrates significantly increased hematogenous tumor-cell dissemination after endorectal ultrasound in rectal cancer patients. Patients with tumor cells in blood samples after endorectal ultrasound tend to have a worse prognosis. The potential prognostic impact of this finding is presently unclear and has to be further validated in larger clinical trials.

Local staging of rectal cancer using combined pelvic phased-array and endorectal coil MRI

PURPOSE

To assess the accuracy of MRI, using a pelvic phased-array coil and an endorectal coil, for preoperative local staging of rectal cancer.

MATERIALS AND METHODS

Fifty-one patients (26 males and 25 females) with adenocarcinoma of the rectum underwent preoperative MRI and surgical resection of their tumors. Surgical pathology staging was compared to MRI staging (using the TNM classification) obtained both retrospectively by a reader blinded to surgical findings and prospectively (radiological reports). In addition, patients were stratified according to surgical treatment groups (stage I = T1-2/N0, stage II = T3/N0, stage III = Tx/N1-2).

RESULTS

At pathology, 36 of 51 (68%) tumors were classified as T0-T2, and 15 (32%) were classified as T3. Overall, the sensitivity and specificity of MRI readings for T3 staging were 93% and 86%, respectively (positive predictive value (PPV) = 74%, negative predictive value (NPV) = 97%, accuracy = 88%). MRI correctly predicted lymph node metastases in 11 of 13 patients with a sensitivity of 85% and specificity of 69% (PPV = 58%, NPV = 90%, accuracy = 74%). MRI correctly predicted surgical treatment groups in 33 of 39 (85%) patients. Interobserver agreement between the retrospective and prospective readings was excellent (kappa = 0.85) for prediction of T3 tumor and good (kappa = 0.80) for prediction of nodal involvement.

CONCLUSION

Combined endorectal and pelvic phased-array coil MRI can be used reliably to select which patients should receive preoperative chemoradiotherapy. It is highly predictive in terms of excluding T3 tumors, but still has limitations in predicting lymph node metastasis.

Outcomes for early rectal cancer managed with transanal endoscopic microsurgery: a 5-year follow-up study

BACKGROUND

This study aimed to evaluate the long-term risk of local and distant recurrence as well as the survival of patients with early rectal cancer treated using transanal endoscopic microsurgery (TEM).

METHODS

The study reviewed 69 patients with Tis/T1/T2 rectal cancer treated using full-thickness excision between 1991 and 1999. The pathology T-stages included 25 Tis, 23 T1, and 21 T2. The median follow-up period was 6.5 years (range 5-10.2 years).

RESULTS

The overall local recurrence rate was 8.7%. The 5-year local recurrence rate was 8% for Tis, 8.6% for T1, and 9.5% for T2. All six patients with recurrence were managed surgically. The 5-year disease-specific survival rate was 100% for Tis, 100% for T1, and 70% for T2. The overall cancer-related mortality rate was 7.2%.

CONCLUSIONS

After local excision of early rectal cancer, a substantial local recurrence rate is observed. Patients with recurrent Tis/T1 cancers who undergo a salvage operation may achieve good long-term outcome. Local treatment without adjuvant therapy for T2 rectal cancers appears inadequate.

Surgical Treatment of Rectal Cancer: Local Resection

Local treatment of rectal cancer aims to decrease the morbidity and the functional sequela associated with radical surgery without compromising local tumor control and long-term survival. Local excision is associated with a higher rate of local recurrence compared with radical surgery, and salvage radical surgery cannot guarantee equivalent long-term survival compared with radical surgery as the primary form of therapy. Therefore, strict criteria for patient selection are critical for local excision to be successful. Selecting the optimal therapy for an individual patient with rectal cancer is crucial and requires consideration of both tumor and patient characteristics. Endorectal ultrasonography is essential for the accurate assessment of rectal wall invasion and nodal metastasis. Only patients with well- or moderately differentiated T1 tumors without blood vessel or lymphatic vessel invasion are candidates for curative local excision as the only form of treatment. Tumors penetrating the muscularis propria should not be treated by local excision alone. These patients can be asked to participate in a trial of chemoradiation followed by local excision. Otherwise, they should undergo radical surgery. The tumor should be removed by full-thickness local excision with an adequate normal margin for pathologic evaluation. Final decisions regarding the treatment strategy should be based on the pathology of the surgical specimen. Intense, close follow-up is critical for early diagnosis of local recurrences as many of them may be surgically salvaged by radical resection. Local treatment can also be used for palliation of patients with histological unfavorable or advanced tumors, and those who are medically unfit for radical surgery.

Development of a cost-effective system for digital off-line analysis of transrectal ultrasound

BACKGROUND

Transrectal ultrasound (TRUS) is the most sensitive and accurate technique for preoperative staging and follow-up of rectal cancer. One of the most relevant problems of this technique is that the assessment of TRUS is possible only during real-time examination. Furthermore, interpretation of the ultrasound findings is difficult and requires long experience. We show the development of a new, cost-effective software solution for off-line examination and documentation of transrectal ultrasound.

METHODS

The ultrasound device is connected to a frame-grabber card in a standard PC. Video capturing is done using a freeware software solution and various video codecs. The whole examination course is recorded. The examiner only has to concentrate on producing an artifact-free realization of the examination.

RESULTS

The software solution offers a flexible review of each individual "frame" of the investigation on the personal computer, very similar to CT and MRI scans. Infiltration depth and lymph node status can be assessed at any time, independently of the investigation and the investigator. The picture quality is excellent even if a lossy codec is used. It is not necessary to do definitive assessment of the TRUS during the examination.

CONCLUSIONS

This new technique gives a cost-effective possibility for high-quality off-line staging, re-examination, re-evaluation, and documentation of rectal cancer. TRUS becomes an examiner-independent objective examination technique for staging and follow-up of rectal cancer.

Diagnostics of rectal cancer: endorectal ultrasound

In rectal cancer, accurate preoperative staging is essential to adequately select patients for different therapeutic regimes. Endosonography has been proven to be an accurate staging modality in multiple prospective studies. A recent large retrospective study, however, has cast doubt on the actual accuracy of endorectal ultrasound for staging rectal cancer in everyday clinical routines. The results of endosonographic staging of rectal tumours over a period of 10 years at the Department of Surgery of the University of Heidelberg are presented. In a first time period, 424 patients with rectal cancer were staged by endosonography and the data recorded prospectively. The examinations were exclusively done by four surgeons with high experience and scientific interest in endosonography. The second time period comprises 332 patients with rectal tumours (including adenomas) having undergone endosonography by six different examiners after introduction of this staging method into the clinical routine. The data here were analysed retrospectively. Accuracy, sensitivity, specificity, and positive and negative predictive values were calculated for the T and N classifications for both series. In the second series, eight factors which have been postulated to influence staging accuracy in the literature were included in a regression analysis in order to identify relevant factors for staging inaccuracies. Accuracy for staging of the T classification was 81% in the first series versus 71.7% in the second series. In the regression analysis of the second series, status post-chemoradiation proved to be the most significant factor for staging inaccuracy (p < 0.0002). When excluding all patients having undergone chemoradiation, the accuracy for staging of the T classification rose to 76%. A major problem of endosonography in this second series was overstaging; the T category was overestimated in 76 cases (22.9% of patients). The main error here was overstaging of adenomas as cancerous lesions (45.5% of all adenomas) and T2-cancers as more advanced cancers (42.2% of all T2-cancers). When excluding the adenomas from this analysis, the accuracy increased to 73.5%. Accuracy for staging of the N classification was 76% in the first series versus 71% in the second series. Status post-chemoradiation again was a relevant factor (p < 0.0003); when excluding these patients the accuracy increased to 73%. The accuracy of endosonography for rectal tumours decreases after introduction of the method into the everyday clinical routine. Nonetheless, apart from magnetic resonance imaging with an endorectal coil, rectal endosonography is still the most accurate staging modality for rectal tumours and allows adequate selection of patients for different therapeutic regimes. As the major problem of rectal endosonography is overstaging, more patients are likely to undergo overtreatment rather than undertreatment. Endosonography is inaccurate in staging patients having undergone chemoradiation.

Tumour regression grading in the evaluation of tumour response after different preoperative radiotherapy treatments for rectal carcinoma

BACKGROUND AND AIMS

Preoperative radiotherapy (PRT) for rectal carcinoma has been shown to cause tumour regression and increase local control and patient survival. The aim of this study was to examine the usefulness of tumour regression grading (TRG) in quantifying the effect of PRT.

METHODS

Depending on the tumour stage (uT), as defined by preoperative endorectal ultrasound (ERUS), fixity and distance from the anal verge, 126 patients with rectal cancer underwent either surgery alone, or received short-course 25-Gy radiotherapy or long-course 50-Gy radiotherapy combined with 5-fluorouracil (5-FU) before surgery. TRG in each group was assessed and compared with the downstaging, defined as a change in preoperative uT stage and pathologic stage (pT).

RESULTS

Complete response (no residual tumour, TRG 1) was seen in 7% of the patients (3/44) and total or major regression (TRG 1-3) in 73% of the patients (32/44) treated with 50-Gy chemoradiation. Of those treated with 25-Gy PRT, 21% (9/42) showed major tumour regression. Of the patients who underwent ERUS and PRT, 32% (26/83) were downstaged when comparing uT with pT, but 53% (14/26) of the downstaged tumours showed no response by TRG. In comparison, 50% (28/57) of the tumours with no downstaging showed a marked response by TRG (p=0.05).

CONCLUSIONS

Tumour regression grading offers detailed information of the effect of PRT and shows that tumour regression is more marked after long-term chemoradiation than after short-course radiotherapy (p=0.02). In contrast, T-stage downstaging was similar in both groups and did not correlate with the TRG results (p=0.05).

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.

Preoperative radiotherapy for rectal adenocarcinoma: Which are strong prognostic factors?

PURPOSE

This retrospective 12-year study evaluated the prognostic value of initial and postoperative staging of rectal tumors.

METHODS AND MATERIALS

Between 1985 and 1996, 297 patients were treated with preoperative radiotherapy (39 Gy in 13 fractions) and surgery for Stage T2-T4N0-N1M0 rectal adenocarcinoma. Pretreatment staging included a clinical examination and endorectal ultrasonography (EUS) since 1988. Clinical staging was performed by digital rectal examination and rigid proctoscopy. EUS was performed in 236 patients. Postoperative staging was performed by examination of the pathologic specimen.

RESULTS

The median follow-up was 49 months. The overall 5-year survival rate was 67%, with a local failure rate of 9%. The rate of sphincter preservation was 65%. The clinical examination findings were strong prognostic factor for both cT stage (p < 0.001) and cN stage (p < 0.006) but had poor specificity for cN stage (only 25 lymph nodes detected). In both univariate and multivariate analyses, EUS had a statistically significant prognostic value for uT (p < 0.014) but not for uN (p < 0.47) stage. In contrast, pT and pN stages were strong prognostic factors (p < 0.001 and p < 0.001, respectively).

CONCLUSION

Pretreatment staging, including clinical examination and EUS, seemed accurate enough to present a high prognostic value for the T stage. EUS was insufficient to stage lymph node involvement. Owing to its lack of specificity, uN stage was not a reliable prognostic factor. An improvement in N staging is necessary and essential. Despite downstaging, postoperative staging remained a very strong prognostic factor for both T and N stages.

Effectiveness of gene expression profiling for response prediction of rectal adenocarcinomas to preoperative chemoradiotherapy

PURPOSE

There is a wide spectrum of tumor responsiveness of rectal adenocarcinomas to preoperative chemoradiotherapy ranging from complete response to complete resistance. This study aimed to investigate whether parallel gene expression profiling of the primary tumor can contribute to stratification of patients into groups of responders or nonresponders.

PATIENTS AND METHODS

Pretherapeutic biopsies from 30 locally advanced rectal carcinomas were analyzed for gene expression signatures using microarrays. All patients were participants of a phase III clinical trial (CAO/ARO/AIO-94, German Rectal Cancer Trial) and were randomized to receive a preoperative combined-modality therapy including fluorouracil and radiation. Class comparison was used to identify a set of genes that were differentially expressed between responders and nonresponders as measured by T level downsizing and histopathologic tumor regression grading.

RESULTS

In an initial set of 23 patients, responders and nonresponders showed significantly different expression levels for 54 genes (P < .001). The ability to predict response to therapy using gene expression profiles was rigorously evaluated using leave-one-out cross-validation. Tumor behavior was correctly predicted in 83% of patients (P = .02). Sensitivity (correct prediction of response) was 78%, and specificity (correct prediction of nonresponse) was 86%, with a positive and negative predictive value of 78% and 86%, respectively.

CONCLUSION

Our results suggest that pretherapeutic gene expression profiling may assist in response prediction of rectal adenocarcinomas to preoperative chemoradiotherapy. The implementation of gene expression profiles for treatment stratification and clinical management of cancer patients requires validation in large, independent studies, which are now warranted.

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.

Endorectal ultrasound in the preoperative evaluation of rectal cancer

For rectal cancer, the decisions about neoadjuvant therapy, radical resection, or local excision depend on accurate preoperative staging. Multiple modalities are available to stage rectal cancer, including digital rectal examination, computed tomography, magnetic resonance imaging (MRI), and endorectal ultrasound (ERUS). Digital rectal examination accuracy varies from 58% to 88% for depth of penetration. Computed tomography accuracy varies from 53% to 94% for depth of penetration and from 54% to 70% for lymph node metastases. Magnetic resonance imaging accuracy varies from 66% to 92% for depth of penetration and from 60% to 90% for lymph node metastases. Endorectal ultrasound varies from 62% to 92% for depth of penetration and from 64% to 88% for lymph node metastases. In all radiologic modalities, overstaging and understaging occurs. Endorectal ultrasound has the advantage of being portable and often office-based, requiring only minimal preparation and is well tolerated by the patient. Although MRI with the use of an endorectal coil may have a slightly higher accuracy for detecting lymph nodes, ERUS has been shown to be the most accurate method for the determination of the depth of wall penetration, and is comparable for lymph node metastases. Interpretation varies with operator experience. Three-dimensional (3D) ERUS may further improve staging accuracy. Endorectal ultrasound is an accurate method to preoperatively stage rectal cancers. Although operator-dependent, it can be readily performed at the time of patient evaluation with minimal preparation or patient discomfort. We are prospectively evaluating modifications to the current staging system and the use of 3D ERUS.

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.

The value of endosonographic rectal carcinoma staging in routine diagnostics: a 10-year analysis

BACKGROUND

Endosonography is currently the gold standard for the local staging of rectal carcinoma, but its accuracy varies from 62% to 91%. This study aimed to determine the accuracy of endosonography, to evaluate the interobserver variability, and to compare the performance of the 7.5-MHz and the 10-MHz ultrasound scanners.

METHODS

Between 1990 and 2000, 458 patients with rectal cancer were included in the study. All the patients had undergone rectal endosonography with a 7.5-MHz scan (period 1: 1990-1996) or a 10-MHz scan (period 2: 1997-2000). Endosonographic staging was compared with pathologic staging.

RESULTS

The overall rate for correctly classified patients was 69% with respect to the T category and 68% with respect to the N category. There was no difference between the two scanners. In terms of accuracy, the T3 category tumors were the most (86%) and the T4 tumors the least (36%) accurately classified. Overstaging of tumors (19%) was much more frequent than understaging (12%). A high interobserver variability of 61% to 77% was noted. For pT1 tumors, the 10-MHz scan was almost two times more accurate than the 7.5-MHz scan (71% vs 36%).

CONCLUSIONS

The accuracy of endosonographic staging of rectal carcinoma very much depends on the T category. A high-resolution scanner and an experienced examiner can help to ensure that endosonography remains an important tool in the staging process of patients with rectal carcinoma, especially early carcinoma.

Preoperative chemoradiation for locally advanced rectal cancer: rationale, technique, and results of treatment

Over the past decade, 392 patients with stage II and III rectal cancer have been managed with preoperative chemoradiation and surgery at the M. D. Anderson Cancer Center (MDACC). Aggressive surgical techniques such as total mesorectal excision, proctectomy with coloanal anastamosis, and multivisceral excisions have been used. Initial pelvic chemoradiation is also used in patients who present with metastases. Preoperative chemoradiation followed by surgery has resulted in excellent sphincter preservation (SP) and pelvic control with minimal acute, perioperative, and late morbidity. SP has been achieved in greater numbers of patients over the past 3 years due to the increased use of coloanal anastamosis in very low tumors. There has been no increase in pelvic failure or perioperative morbidity with this practice. Patients with clinical T4 disease have significantly worse pelvic control. An assessment of the impact of CB on pelvic control and survival requires further follow-up. Poor differentiation and poor response to preoperative therapy predict a worse overall survival. Durable symptom control without colostomy has been achieved using initial chemoradiation in patients who present with metastases. Aggressive bowel management and skin care can minimize hospitalization and treatment interruption due to acute toxicity. Multidisciplinary therapy using preoperative chemoradiation and aggressive surgery has resulted in excellent SP and pelvic control. However, more effective systemic therapies are needed, especially for patients who do not respond well to preoperative chemoradiation.

Preoperative T and N staging of colorectal cancer: accuracy of contrast-enhanced multi-detector row CT colonography--initial experience

PURPOSE

To evaluate the accuracy of contrast material-enhanced multi-detector row computed tomographic (CT) colonography for preoperative staging of colorectal cancer.

MATERIALS AND METHODS

Forty-one patients with colorectal carcinoma underwent preoperative contrast-enhanced multi-detector row CT colonography. Images were obtained in the arterial (start delay of 35 seconds) and portal venous (start delay of 70 seconds) phases. The arterial phase was focused on the suspected region of neoplasm, whereas the venous phase included the whole abdomen and pelvis. Two radiologists independently evaluated the depth of tumor invasion into the colorectal wall (T) and regional lymph node involvement (N) on transverse CT images alone and in combination with multiplanar reformations (MPRs). Disagreements were resolved by means of consensus. CT findings were compared with pathologic results, which served as the reference standard. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were assessed. Differences in accuracy for T and N staging were assessed by using the McNemar test.

RESULTS

In T staging, overall accuracy was 73% when transverse images were evaluated alone and 83% when they were evaluated in combination with MPRs. This difference was not significant. N staging was associated with an overall accuracy of 59% with transverse images alone and 80% with combined transverse and MPR images (P <.01).

CONCLUSION

Contrast-enhanced multi-detector row CT colonography is an accurate technique for preoperative local staging of colorectal tumors.

Staging of rectal carcinoma with transrectal ultrasonography

BACKGROUND AND AIMS

Transrectal ultrasonography (TRUS) has proven useful for loco-regional staging of rectal carcinoma in specialised centres, but the investigation is not widely used. The aim of this study was to audit the introduction of TRUS performed by surgeons without previous experience with ultrasonography.

MATERIAL AND METHODS

All patients admitted with rectal carcinoma in the period 1996-2002 entered this prospective, comparative study. TRUS with a stiff endorectal probe was performed preoperatively in 118 consecutive patients, 91 of whom subsequently had rectal resection without preoperative radiotherapy (PRT), and seven who had rectal resection after PRT. Twenty patients did not have resection. The main outcome measures was the feasibility of TRUS in staging of rectal cancer, and the accuracy of T- and N-staging, comparing TRUS with the histopathological examination of resected specimens.

RESULTS

TRUS was successful in 81/91 patients who underwent rectal resection without PRT. The accuracy of T-staging was 74% overall; 40% in five pT1 tumours, 81% in 26 pT2 tumours, 80% in 45 pT3 tumours and 25% in four pT4-tumours. With regard to perirectal tissue invasion, the sensitivity and specificity of TRUS was 82% and 84%, respectively, and the positive and negative predictive values were 89% and 71%, respectively. The accuracy of TRUS for N-staging was 65%. The sensitivity for detection of lymph node metastases was 41% and the specificity 68%. TRUS was unsuccessful in 21/118 patients, in 12/98 who had rectal resection, and in 9/ 20 who did not have resection, because of stenosis or high location of the tumour precluding correct placing of the probe.

CONCLUSIONS

TRUS is often unsuccessful in patients with advanced tumours, especially when the tumour is located in the upper rectum. The predictive values for perirectal tumour invasion were acceptable, but the sensitivity for detection of lymph node metastases was low. These results were obtained by surgeons without previous experience with ultrasonographic examinations.

Adjuvant vs. neoadjuvant radiochemotherapy for locally advanced rectal cancer: the German trial CAO/ARO/AIO-94

AIM

The standard treatment for patients with clinically resectable rectal cancer is surgery. Postoperative radiochemotherapy (RCT) is recommended for advanced disease (pT3/4 or pN+). In recent years, encouraging results of pre-operative radiotherapy have been reported. This prospective randomized phase-III-trial (CAO/ARO/AIO-94) compares the efficacy of neoadjuvant RCT to standard postoperative RCT. We report on the design of the study and first results with regard to toxicity of RCT and postoperative morbidity.

PATIENTS AND METHODS

Patients with locally advanced operable rectal cancer (uT3/4 or uN+, Mason CS III/IV) were randomly assigned to pre or postoperative RCT: A total dose of 50.4 Gy (single dose 1.8 Gy) was applied to the tumour and the pelvic lymph nodes. 5-FU (1000 mg/m2/d) was administered concomitantly in the 1th and 5th week of radiation as 120 h-continuous infusion. Four additional cycles of 5-FU-chemotherapy (500 mg/m2/d, i.v.-bolus) were applied. RCT was identical in both arms except for a small-volume boost of 5.4 Gy postoperatively. The time interval between RCT and surgery was 4-6 weeks in both arms. Techniques of surgery were standardized and included total mesorectal excision. Primary endpoints of the study are 5-year survival and local and distant control. Secondary endpoints include the rate of curative (R0) resection and sphincter saving procedures, toxicity of RCT, surgical complications and quality of life.

RESULTS

As of July 2002, 805 patients were randomized from 26 participating institutions. Acute toxicity (WHO) of RCT was low, with less than 15% of patients experiencing grade 3 or higher toxicity: The principal toxicity was diarrhea, with 12% in the postoperative RCT-arm and 11% in the pre-operative RCT-arm having grade 3-, and 1% in either arm having grade 4-diarrhea. Erythema, nausea and leukopenia were the next common toxicities, with less than 3% of patients in either arm suffering grade 3 or greater leukopenia or nausea. Postoperative complication rates were similar in both arms, with 12% (postop. RCT) and 12% (pre-op. RCT) of patients, respectively, suffering from anastomotic leakage, 3% (postop. RCT) and 3% (pre-op. RCT) from postoperative bleeding, and 6% (postop. RCT) and 4% (pre-op. RCT) from delayed wound healing.

CONCLUSION

The patient accrual to the trial is satisfactory. Neoadjuvant RCT is well tolerated and bears no higher risk for postoperative morbidity.

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.

Flexible endorectal ultrasound for predicting pathologic stage of rectal cancers

BACKGROUND

Endorectal ultrasound (ERUS) is an accurate method for preoperative staging of rectal cancers. Most often, a rigid 360-degree rotating probe is used. We studied whether flexible probes could attain equivalent accuracy for bowel wall penetration.

METHODS

Forty-five patients were prospectively evaluated with flexible devices. Results were compared with 20 rigid and 10 flexible probe studies. To assess learning curves, we used logistic regression analysis and coefficients of correlation on accuracy data to compare ERUS accuracy with the number of examinations.

RESULTS

Level of invasion was correct in 49%. Nodal examinations were correct in 78%. Learning curves leveled out at 100 examinations with 87% accuracy for the rigid probe (R = 0.46) and 77% for the flexible devices (R = 0.31).

CONCLUSIONS

The coefficient of correlation for each method portends a more reliable learning curve for the rigid devices. Flexible devices were less accurate for level of invasion than the literature reported for rigid devices.

Emerging standards of radiotherapy combined with radical rectal cancer surgery

For patients with resectable rectal cancer treated with total mesorectal excision, the routine use of radiotherapy should be omitted for stage I of the disease and for lesions located higher than 10 cm from the anal verge. Preoperative radiotherapy may be considered for all patients with a lesion with deep perirectal fat infiltration located in the lower two thirds of the rectum. The other option is to offer postoperative radiotherapy for patients with a positive surgical margin, N+ stage disease, mesorectal tumour implants, high tumour grade, perineural invasion, extramuscular blood and lymphatic vessel invasion and with inadvertent tumour perforation. The lower risk of small bowel damage and probable higher efficacy are arguments for the use of preoperative radiotherapy instead of postoperative radiotherapy. The impairment of anorectal function appears to be most frequent late postirradiation sequel. The analysis of acute complications (including toxic deaths) compliance, cost and convenience favours 5 x 5 Gy preoperative irradiation with immediate surgery for patients with resectable tumours in comparison to other commonly used schemes of radiotherapy. These advantages should be weighed against approximately 1.5% risk of late neurotoxicity. There is no clear answer to the question whether preoperative conventional radio(chemo)therapy offers an advantage in sphincter preservation. To answer this question, the results of two ongoing randomised trials are awaited. For patients with unresectable cancers, long-term preoperative radio(chemo)therapy with delayed surgery is a preferable scheme. The total mesorectal irradiation should be employed for mid- and low-lying lesions. Therefore, during radiotherapy planning, a contrast enema should be used to identify the anorectal ring, anatomically corresponding with the lowest edge of the mesorectum.

Radiation plus chemotherapy as adjuvant therapy for rectal cancer

The most common neo-adjuvant therapy for rectal cancer is chemotherapy and concurrent radiation therapy. In general, it is delivered pre-operatively for patients with clinical evidence of T(3-4) disease or post-operatively in patients who have undergone surgery and have T(3) and/or N(1-2) disease. This chapter reviews the rationale and results for neo-adjuvant therapy, the selection process for pre-operative versus post-operative treatment, and new approaches and controversies.

Assessing the predictive value of clinical complete response to neoadjuvant therapy for rectal cancer: an analysis of 488 patients

BACKGROUND

Patients with transmural or node-positive rectal cancer benefit from the addition of chemoradiation to surgical resection. Administration of the chemoradiation (combined modality therapy) preoperatively has gained popularity in recent years. Some patients undergo apparent complete tumor regression after preoperative combined modality therapy, and controversy exists about the proper management of these patients. Some investigators have proposed that such patients should simply be observed and not undergo resection.

STUDY DESIGN

The purpose of this study was to determine the significance of clinical complete response to preoperative combined modality therapy. Specifically, we have attempted to determine the frequency with which a clinical complete response (based on the absence of detectable tumor on preoperative digital rectal examination and proctoscopy) correlates with a pathologic complete response (based on the absence of cancer cells in the resected specimen). A retrospective review of the clinical and pathologic characteristics of 488 patients from the Memorial Sloan-Kettering prospective colorectal database who received preoperative chemoradiation followed by resection for primary rectal cancer was performed. The indications for preoperative therapy included clinical or ultrasound T3 or T4 tumors or node-positive disease.

RESULTS

The clinical complete response rate to preoperative therapy was 19%. All patients underwent resection subsequent to preoperative therapy regardless of response. The pathologic complete response rate among all patients was 10%. The pathologic complete response rate among clinical complete responders was 25%. Clinical complete response was a significant predictive factor for pathologic complete response, but the majority (75%) of clinical complete responders had persistent foci of tumor that were not detectable on preoperative examination or proctoscopy.

CONCLUSIONS

Clinical complete response to preoperative therapy as determined by preoperative digital rectal examination and proctoscopy or EUA is not an accurate predictor of pathologic complete response. A significant percentage of clinical complete responders have persistent deep tumors or nodal involvement. We do not recommend making treatment decisions based solely on the absence of clinically palpable or visible tumor after chemoradiation. Our data suggest that all acceptable-risk patients with a diagnosis of primary rectal cancer should undergo resection, regardless of their response to preoperative therapy.

Transit endoscopic ultrasound of colorectal cancer using a 12 MHz catheter probe

The objective of this study was to examine the accuracy of a 12 MHz ultrasound catheter probe in the pre-operative staging of colorectal cancer by assessing the depth of tumour infiltration and involvement of pericolonic lymph nodes. 159 patients with colorectal cancer who underwent ultrasound examination with a 12 MHz catheter probe were studied prospectively. The results of this imaging procedure were compared with the histological findings of the resected specimens. The accuracy of the 12 MHz ultrasound catheter probe for depth of invasion (T category) was 85% (131/154) for all tumours, 87% (46/53) for pT1 tumours, 60% (9/15) for pT2 tumours, 89% (74/83) for pT3 tumours and 67% (2/3) for pT4 tumours. The accuracy for tumours of the rectum and colon was 81% and 89%, respectively. The accuracy of the probe for nodal staging (N category) was 67% (76/114) overall. The sensitivity was 70% (33/47), the specificity 64% (43/67), the positive predictive value 58% (33/57) and the negative predictive value 75% (43/57). Endoscopic ultrasound using a 12 MHz catheter probe accurately assessed tumour stage, although nodal staging remained suboptimal. This method may aid in the selection of treatment for patients with colorectal cancer.

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.

Investigation of colonic disease

Bowel cancer awareness among the general public has heightened in recent years. The promotion of prompt referral and the pressure on early diagnosis will alter our previous strategies on colonic evaluation. This article gives an overview of the colonic investigations currently available.

Preoperative staging of rectal cancer using a 7.5 MHz front-loading US probe

BACKGROUND

Conventional echoendoscopes have disadvantages when used for staging colorectal cancer including the inability to pass the instrument through tight stenosis and limited maneuverability. This study evaluated the preoperative use of a newly developed 7.5 MHz front-loading ultrasound probe (FLUP) for local staging of rectal cancer.

METHODS

A 7.5 MHz FLUP, diameter 7.3 mm, was used in this study. The mechanical shaft portion of the probe can be passed in retrograde fashion through the accessory channel of a standard colonoscope. Thirty-nine patients with rectal cancer underwent ultrasonography with this probe. The tumors were staged using the TNM system, and the results were compared with the histologic findings of the resected specimens.

RESULTS

The FLUP proved to be satisfactory, with respect to maneuverability, for traversing stenosis and accurate recognition of small tumors under direct endoscopic control. The accuracy of the FLUP for T staging was 82% (32 of 39) for all tumors, 90% in pT1, and 79% in pT2 to pT4 tumors. The accuracy of the FLUP for N staging was 72% (23 of 32) overall. The sensitivity was 83%, the specificity was 65%, the positive predictive value was 59%, and the negative predictive value was 87%.

CONCLUSIONS

The 7.5 MHz FLUP appears to be useful for preoperative local staging of rectal cancer. This system makes it technically easier to image small cancers as well as advanced rectal cancers.