Preoperative staging of colorectal cancer by a 15 MHz ultrasound miniprobe

Diagnostic and therapeutic strategies for colorectal tumor with positive muscle-retracting sign

Objectives

Endoscopic submucosal dissection (ESD) for colorectal tumors with positive muscle-retracting (MR) sign often results in incomplete resection or discontinuation owing to the difficulty of submucosal dissection. The present study aimed to evaluate the usefulness of endoscopic ultrasonography (EUS) in diagnosing the MR sign and performing ESD using the pocket-creation method (PCM).

Methods

Thirty-six cases of colorectal tumors with positive MR sign during ESD between January 2015 and December 2021 were retrospectively reviewed. Cases were divided into two groups: 1) the conventional method (CM) group, comprising 29 cases, and 2) the PCM group with seven cases, in which preoperative EUS and ESD using PCM were performed. Treatment outcomes were compared between the groups. The diagnostic yield of EUS for the MR sign was evaluated among large sessile tumors >20 mm in which preoperative EUS was performed.

Results

Histologic diagnosis was adenoma or Tis carcinoma in 12 cases (33%), T1 carcinoma in 18 cases (50%), T2 carcinoma in four cases (11%), and unevaluable in two cases (6%). The sensitivity and specificity of the EUS-MR sign for large sessile tumors were 87.5% and 83.3%, respectively. ESD was achieved in all cases in the PCM group, although it was discontinued in eight cases (28%) in the CM group. There were significant differences between the PCM and CM groups in en bloc resection (100% vs. 48%, p = 0.013) and R0 resection rates (71% vs. 31%, p = 0.049).

Conclusion

The MR sign can be predicted by preoperative EUS, and ESD using PCM allows en bloc resection.

Novel endoscopic ultrasonography classification for assured vertical resection margin (≥500 μm) in colorectal endoscopic submucosal dissection

BACKGROUND AND AIM

The risk of local recurrence might be low in pT1 colorectal carcinoma with a tumor vertical margin (VM) ≥500 μm. We investigated the relationship between endoscopic ultrasonography (EUS) findings and VM in cases with colorectal endoscopic submucosal dissection (ESD) categorized as Type 2B according to the Japan NBI Expert Team (JNET) classification.

METHODS

We analyzed 179 JNET Type 2B colorectal tumors resected by ESD at Hiroshima University Hospital from January 2010 to May 2021. The distance from the tumor invasive front to the muscle layer on EUS was defined as the tumor-free distance (EUS-TFD) and classified as Type I (EUS-TFD ≥1 mm) and II (<1 mm). We investigated the relationship between EUS-TFD and VM and analyzed the predictive factors for VM ≥500 μm.

RESULTS

EUS-TFD Type I was diagnosed in 133 (74.3%) lesions: VM ≥500 μm (114, 85.7%); VM <500 μm (19, 14.3%); and VM positive (VM1) (0, 0%). Type II was diagnosed in 46 (25.7%) lesions: VM ≥500 μm (14, 30.5%); VM <500 μm (22, 47.8%); and VM1 (10, 21.7%). In the EUS-TFD Type I cases, 84.5% and 87.8% were protruded and superficial types; whereas for Type II cases, these were 38.9% and 25%, respectively. EUS-TFD classification (Type I), scope operability (good), submucosal invasion depth (<2000 μm), histology at the deepest invasive portion (favorable), and degree of fibrosis (F0/F1) were significant predictors of VM ≥500 μm.

CONCLUSIONS

In JNET Type 2B lesions, EUS-TFD classification is a novel diagnostic indicator to predict VM ≥500 μm in ESD preoperatively.

Forward-Looking Multimodal Endoscopic System Based on Optical Multispectral and High-Frequency Ultrasound Imaging Techniques for Tumor Detection

We developed a forward-looking (FL) multimodal endoscopic system that offers color, spectral classified, high-frequency ultrasound (HFUS) B-mode, and integrated backscattering coefficient (IBC) images for tumor detection in situ. Examination of tumor distributions from the surface of the colon to deeper inside is essential for determining a treatment plan of cancer. For example, the submucosal invasion depth of tumors in addition to the tumor distributions on the colon surface is used as an indicator of whether the endoscopic dissection would be operated. Thus, we devised the FL multimodal endoscopic system to offer information on the tumor distribution from the surface to deep tissue with high accuracy. This system was evaluated with bilayer gelatin phantoms which have different properties at each layer of the phantom in a lateral direction. After evaluating the system with phantoms, it was employed to characterize forty human colon tissues excised from cancer patients. The proposed system could allow us to obtain highly resolved chemical, anatomical, and macro-molecular information on excised colon tissues including tumors, thus enhancing the detection of tumor distributions from the surface to deep tissue. These results suggest that the FL multimodal endoscopic system could be an innovative screening instrument for quantitative tumor characterization.

Management of colorectal T1 carcinoma treated by endoscopic resection

As a result of recent advances in endoscopic therapeutic technology, the number of endoscopic resections carried out in the treatment of early colorectal carcinomas with little risk of lymph node metastasis has increased. There are no reports of lymph node metastasis in intramucosal (Tis) carcinomas, whereas lymph node metastasis occurs in 6.8-17.8% of submucosal (T1) carcinomas. Three clinical guidelines have been published in Japan and the management strategy for early colorectal tumors has been demonstrated. According to the 2014 Japanese Society for Cancer of the Colon and Rectum (JSCCR) Guidelines for the Treatment of Colorectal Cancer, additional surgery should be done in cases of endoscopically resected T1 carcinoma with a histologically diagnosed positive vertical margin. Additional surgery may also be considered when one of the following histological findings is detected: (i) SM invasion depth ≥1000 µm; (ii) histological type por., sig., or muc.; (iii) grade 2-3 tumor budding; and (iv) positive vascular permeation. A resected lesion that is histologically diagnosed as a T1 carcinoma without any of the above-mentioned findings can be followed up without additional surgery. As for the prognosis of endoscopically resected T1 carcinomas, the relapse ratio of approximately 3.4% (44/1312) is relatively low. However, relapse is associated with a poor prognosis, with 72 cancer-related deaths reported out of 134 relapsed cases (54%). A more detailed stratification of the lymph node metastasis risk after endoscopic resection for T1 carcinomas and the prognosis of relapsed cases will be elucidated through prospective studies. Thereafter, the appropriate indications and safe and secure endoscopic resection for T1 carcinomas will be established.

Diagnostic performance of EUS for evaluating the invasion depth of early colorectal cancers

BACKGROUND

EUS is one technique used to estimate the invasion depth of early colorectal cancer (CRC), but its diagnostic accuracy remains a matter of debate.

OBJECTIVE

To assess the accuracy of EUS for estimating the invasion depth of early CRC.

DESIGN

Retrospective analysis.

SETTING

Tertiary-care academic medical center.

PATIENTS

The invasion depth of early CRC was estimated by EUS from 1989 through 2012.

INTERVENTIONS EUS MAIN OUTCOME MEASUREMENTS

Accuracy of EUS diagnosis, risk factors for misdiagnosis, and characteristics of lesions that were difficult to image.

RESULTS

We estimated the invasion depth of 714 cases of early CRC on EUS. Of the lesions able to be visualized on EUS, the overall diagnostic accuracy of EUS for differentiating between lesions that could be resected endoscopically (Tis and T1a cancers), and those that required colectomy (T1b cancers) was 89%. Submucosal cancer and a macroscopic classification of superficial type were independent risk factors for misdiagnosis. Ninety lesions (13%) were difficult to image. Risk factors for difficulty in imaging were protruding-type morphology and tumor location in the sigmoid colon or from the descending colon to the cecum.

LIMITATIONS

Single center, retrospective. Experienced endoscopists performed EUS.

CONCLUSIONS

Although some lesions that were protruding or located in the proximal colon were difficult to visualize, EUS is considered a useful technique for the diagnosis of invasion depth and the selection of treatment in patients with early CRC.

Mini-probe ultrasonography for the staging of colon cancer: a systematic review and meta-analysis

AIM

With an increasing array of treatment modalities available for colon cancer, it is increasingly important to stage tumours accurately to allocate the appropriate management. This study evaluated the accuracy of mini-probe endoscopic ultrasound (EUS) in assigning clinical stage to colon cancer.

METHOD

An electronic search was performed in January 2013 using the Embase, MEDLINE and Cochrane databases. This was supplemented by a hand search of published abstracts from scientific meetings. Trials evaluating the accuracy of the mini-probe EUS compared with histopathological grade in determining the clinical stage of colon cancer were included in this pooled analysis. The main outcome measures included accuracy, sensitivity and specificity for T and N staging.

RESULTS

Ten studies were identified which compared the mini-probe EUS staging of 642 colon or rectal cancers with the histopathological specimen. The pooled sensitivity and specificity for staging were 0.91 and 0.98 for T1 tumours, 0.78 and 0.94 for T2 tumours, 0.97 and 0.90 for T3/T4 tumours and 0.63 and 0.82 for nodal staging. Eight per cent of T1/T2 tumours were upstaged to T3/T4 tumours and 5% of T3/T4 tumours were downstaged.

CONCLUSION

Mini-probe EUS is highly effective for assigning clinical stage in colon cancer and in identifying patients who may be suitable for nonsurgical treatment including neoadjuvant chemotherapy or endoscopic resection.

Colonoscopic high frequency mini-probe ultrasound is more accurate than conventional computed tomography in the local staging of colonic cancer

AIM

Colonoscopic high frequency mini-probe ultrasound was compared prospectively with CT in the local staging of colonic cancer.

METHOD

Consecutive patients undergoing surgical resection for colonic cancer were recruited. Preoperative 64-slice CT staging with multiplanar reconstruction was compared with colonoscopic high frequency mini-probe ultrasound using 12 MHz and 20 MHz probes. The three methods of staging (CT, 12 MHz ultrasound and 20 MHz ultrasound) were compared with the histological stage of the resected specimen. This was done using weighted kappa coefficients where weights of 0.7-0.8 were given to penalize disagreements of one level in either direction and weights of zero were given to penalize disagreements of more than one level in any direction.

RESULTS

In total, 38 patients with colonic cancer were included. They were located in the sigmoid (n = 20), descending (n = 5), ascending (n = 2) and transverse colon (n = 1) and in the caecum (n = 7) and splenic (n = 2) and hepatic (n = 1) flexure. Histopathological assessment revealed seven pT1, four pT2, 25 pT3 and two pT4 cancers. In relation to the pathology the weighted kappa coefficients were 0.36 (SE = 0.14), 0.81 (SE = 0.16) and 0.81 (SE = 0.17) for CT, ultrasound 12 MHz and ultrasound 20 MHz. Histopathologically 15 (39.5%) patients were lymph node positive. The sensitivity, specificity and kappa coefficient for detection of nodal disease for CT were 80%, 47.8% and 0.25 (SE = 0.14) compared with 80%, 82.5% and 0.62 for 12 MHz ultrasound (SD = 0.14) and 23%, 90.5% and 0.15 (SD = 0.13) for 20 MHz ultrasound.

CONCLUSION

Colonoscopic ultrasound is significantly more accurate than CT for T staging of colonic cancers. With respect to nodal status, 12 MHz ultrasound offers superior accuracy to CT or 20 MHz ultrasound.

High-frequency ultrasound probe sonography staging for colorectal neoplasia with superficial morphology: its utility and impact on patient management

BACKGROUND

This prospective study aimed to evaluate the impact of high-frequency ultrasound probe sonography (HFUPS) staging on the management of patients with superficial colorectal neoplasia (SCN) as determined by the endoscopic characteristics of lesions.

METHODS

Consecutive patients referred for endoscopic treatment of nonpedunculated SCN were enrolled in this study. A lesion was considered high risk if a depressed area or invasive pit pattern was present. The gold standard for final staging included histology from endoscopic or surgical resection. The impact on treatment was defined as any modification of the therapeutic algorithm based on the result of the HFUPS examination compared with that based on endoscopy alone.

RESULTS

In this study, 48 lesions in 48 patients were evaluated. Of these, 28 (58%) were considered high risk, and the remaining 20 (42%) were regarded as low risk. A total of seven lesions (15%) that could not be examined with HFUPS and another non-neoplastic lesion were excluded from final analysis. For the remaining 40 lesions, the overall accuracy of the HFUPS examination to predict the correct T-stage was 90% (95% confidence interval [CI], 77-96%). The HFUPS examination had a positive impact on the treatment of 0 low-risk and 11 high-risk (42%) lesions.

CONCLUSION

The impact of HFUPS on the treatment of SCN depends on their endoscopic characteristics. It is negligible for low-risk SCNs, and these lesions can be treated on the basis of their endoscopic appearance alone. Nevertheless, compared with endoscopy alone, HFUPS changed the subsequent therapeutic approach in a positive way for up to 42% of high-risk lesions, including those with a depressed component and an invasive pit pattern. These endoscopic features can therefore be recommended as the entry criteria for an HFUPS examination.

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.

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.

Intraductal ultrasound in the biliary tract

Although endoscopic ultrasonography (EUS) represents a major advance in endoscopic imaging, endosonography using dedicated echoendoscopes has some serious drawbacks, including the diameter of the echoendoscope (12 to 13 mm), the lack of intraluminal examination of the pancreatobiliary duct system due to the size of the instrument, unsatisfactory image quality and resolution for small lesions, and the need for a second examination separate from the previous routine endoscopy. Recently developed ultrasonographic miniprobes (diameter, about 2 mm; frequency, 12 to 20 MHz) can be passed through the working channel of standard endoscopes to provide high-frequency ultrasound images. These miniprobes may overcome some of the noted drawbacks and add to the safety and convenience of patients. Moreover, in various diseases of the gastrointestinal tract and the pancreatobiliary ductal system, the diagnostic accuracy of miniprobe ultrasonography has been proven to be superior to that of EUS. Miniprobe ultrasonography is a promising tool that adds new capabilities to the armamentarium of gastroenterologic diagnostic assessment.

Role of endoscopy in staging colorectal cancer

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

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.

Preoperative evaluation of colorectal neoplasms by colonoscopic miniprobe ultrasonography

OBJECTIVE

To investigate the value of colonoscopic miniprobe ultrasonography for preoperative staging of colorectal neoplasms.

SUMMARY BACKGROUND DATA

Endoscopic ultrasonography is the most accurate technique for staging colorectal cancer. However, limitations of this technique include the inability to examine stenotic tumors and the difficulty of reaching tumors proximal to the rectum.

METHODS

Miniprobe ultrasonography (12.5 MHz) was performed in 63 patients with tumors of the colon or rectum. The results of imaging were compared with endoscopic assessment of the lesions and histopathologic findings of the resected specimens.

RESULTS

Miniprobe ultrasonography allowed high-resolution imaging of colorectal tumors during routine colonoscopy. The infiltration depth was correctly classified in 22 adenoma, 3 T1, 10 T2, and 22 T3 or T4 tumors. The accuracy for tumors of the rectum and colon was 86% and 92%, respectively (overall accuracy 90%). The small diameter of the probe allowed examination of 21 stenotic tumors with an accuracy of 86%. Miniprobe ultrasonography revealed carcinoma in 5 of 30 broad-based polyps, although adenomas were diagnosed by endoscopy. Correct assessment of lymph node involvement was obtained in 47 of 55 patients. Based on the findings of miniprobe ultrasonography, management was modified in 7 of the 63 patients.

CONCLUSIONS

These preliminary results show that miniprobe ultrasonography improves preoperative staging of stenotic rectal cancer and colonic tumors. This technique can be easily performed during routine colonoscopy and may have considerable impact on surgical therapy.