Transrectal ultrasound and magnetic resonance imaging measurement of extramural tumor spread in rectal cancer

ACR Appropriateness Criteria® Staging of Colorectal Cancer: 2021 Update

Preoperative imaging of rectal carcinoma involves accurate assessment of the primary tumor as well as distant metastatic disease. Preoperative imaging of nonrectal colon cancer is most beneficial in identifying distant metastases, regardless of primary T or N stage. Surgical treatment remains the definitive treatment for colon cancer, while organ-sparing approach may be considered in some rectal cancer patients based on imaging obtained before and after neoadjuvant treatment. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Evaluation of the Extent of Mesorectal Invasion and Mesorectal Fascia Involvement in Patients with T3 Rectal Cancer With 2-D and 3-D Transrectal Ultrasound: A Pilot Comparison Study With Magnetic Resonance Imaging Findings

The aim of this study was to determine the value of 2-D and 3-D transrectal ultrasound (TRUS) in assessing the extent of mesorectal invasion (EMI) and mesorectal fascia involvement (MRF+) in patients with T3 rectal tumours. We retrospectively evaluated 80 patients with T3 stage rectal cancer who were pre-operatively evaluated by 2-D and 3-D TRUS before neoadjuvant chemoradiotherapy by using magnetic resonance imaging (MRI) as a reference standard. The T3 stage was subdivided into T3 ab (EMI ≤5 mm) and T3 cd (EMI >5 mm). The consistency assessment of the T3 sub-staging and MRF+ was compared between 2-D and 3-D TRUS using Cohen's kappa statistic. The concordance of the T3 sub-staging based on EMI was excellent between the 3-D TRUS and MRI (κ = 0.84) and good between the 2-D TRUS and MRI (κ = 0.67). For the assessment of MRF+ (κ = 0.82), 3-D TRUS and MRI showed excellent concordance. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 3-D TRUS for MRF+ assessment was 95.3%, 86.5%, 89.1% and 94.1%, respectively. The agreement between 3-D TRUS and MRI for the assessment of T3 sub-staging and MRF status was better in low rectal cancer (both κ = 0.85) than in middle (κ = 0.79 and 0.77) rectal cancer. Compared with MRI, 3-D TRUS has more advantages in the sub-staging of T3 rectal cancer and the assessment of MRF+ than those of 2-D TRUS, especially in low rectal cancer. For patients with T3 rectal cancer, 3-D TRUS may well complement MRI for selecting the appropriate treatment.

ACR Appropriateness Criteria® Pretreatment Staging of Colorectal Cancer

Colorectal cancers are common tumors in the United States and appropriate imaging is essential to direct appropriate care. Staging and treatment differs between tumors arising in the colon versus the rectum. Local staging for colon cancer is less integral to directing therapy given radical resection is often standard. Surgical options for rectal carcinoma are more varied and rely on accurate assessment of the sphincter, circumferential resection margins, and peritoneal reflection. These important anatomic landmarks are best appreciated on high-resolution imaging with transrectal ultrasound or MRI. When metastatic disease is suspected, imaging modalities that provide a global view of the body, such as CT with contrast or PET/CT may be indicated. Rectal cancer often metastasizes to the liver and so MRI of the liver with and without contrast provides accurate staging for liver metastases. This article focuses on local and distant staging and reviews the appropriateness of different imaging for both variants. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Value of endorectal ultrasonography in measuring the extent of mesorectal invasion and substaging of T3 stage rectal cancer

The present study aimed to determine the value of endorectal ultrasound (ERUS) and magnetic resonance imaging (MRI) for T3 rectal cancer, and substaging of T3 rectal cancer by measuring the extent of mesorectal invasion (EMI). The clinical data of patients with rectal cancer who were admitted to the general surgical department of Peking Union Medical College Hospital (Beijing, China) were reviewed and analyzed. Two ultrasound practitioners independently measured the EMI on ERUS, and a radiologist measured the EMI on MRI. The consistency of ERUS measurements between the two doctors was assessed using intraclass consistency (ICC) analysis. T3 stages were subdivided into T3a (EMI ≤5 mm) and uT3b (EMI >5 mm). The accuracy of MRI and ERUS in T3 rectal cancer, and T3 substaging of rectal cancer was assessed and compared according to the pathological results. The Bland-Altman scatter plot demonstrated good consistency between the ERUS measurement and pathology measurement. Furthermore, the consistency of the ERUS measurement between the two doctors was good (ICC, 0.9344; 95% confidence interval, 0.8789-0.9645). The diagnostic accuracies for T3 rectal cancer, for the two ultrasound doctors and for MRI were 86.9% (53/61), 85.2% (52/61), and 90.2% (55/61), respectively. The accuracy, sensitivity and specificity for the two individual ultrasound doctors in the substaging of T3 tumors were 79.1% (34/43), 66.7% (10/15), and 85.7% (24/28), compared with 67.4% (31/43), 60% (9/15), and 82.1% (23/28), respectively. The accuracy of MRI in the substaging of T3 tumors was 86.0% (37/43), which was not statistically higher compared with those of ERUS (P>0.05). In conclusion, ERUS is a valuable tool for measuring the EMI and substaging T3 rectal cancer, and thus, can be complementary to MRI in selecting the appropriate treatment for rectal cancer.

The degree of extramural spread of T3 rectal cancer: an appeal to the American Joint Committee on Cancer

The T3 category of the TNM classification includes over 60% of all rectal tumours and encompasses the greatest variance in cancer-specific end-points than any other T category. The most recent edition of the cancer staging handbook of the American Joint Committee on Cancer (AJCC) dated 2010 does not divide T3 tumours into subgroups which reflect cancer-specific outcome more sensitively. The original aim of the present study was to review the literature to assess the influence of the degree of extramural extent of T3 rectal cancer on local recurrence and survival. An article written by the authors was accepted for publication but was withdrawn immediately after they became aware of the publication of the 4th edition of the TNM Supplement by the Union for International Cancer Control dated 2012, which was not accessible by the search system used. This article dealt with the subdivision of the T3 category although this was not included in the most up-to-date AJCC guidelines and was stated to be 'entirely optional'. Medline, PubMed and Cochrane Library searches were performed to identify all studies that investigated the degree of extramural spread and its relationship to survival and local recurrence. Twenty-two studies were identified of which 12 assessed the degree of histopathological extramural spread measured in millimetres. In 18 of the 22 studies the degree of extramural spread was a statistically significant prognostic factor for survival and local recurrence. Analysis of the studies indicated that the subdivision of category T3 rectal cancer into two subgroups of extramural spread ≤ 5 mm or more than 5 mm resulted in markedly different survival and local recurrence rates. The data were insufficient to allow validation of any greater subdivision. Measurement of the extent of extramural spread by MRI before any treatment agreed with the histopathological measurement in the surgical specimen to within 1 mm. The extent of extramural spread in T3 rectal cancer measured in millimetres is a powerful prognostic factor. A subdivision of T3 into T3a and T3b of less than or equal to or more than 5 mm appears to give the greatest discrimination of local recurrence and survival. Preoperative T3 subdivision by MRI has the same sensitivity as histopathological examination of the resected specimen. Given the clinical need for the pretreatment classification of the T3 category for oncological management planning, the evidence strongly indicates that the subdivision of the T3 category by MRI should be formally considered as part of the TNM staging system for rectal cancer.

Beyond Histologic Staging: Emerging Imaging Strategies in Colorectal Cancer with Special Focus on Magnetic Resonance Imaging

Imaging plays an increasingly important role in the staging and management of colorectal cancer. In recent years, magnetic resonance imaging (MRI) has supplanted transrectal ultrasound as the preferred modality for the locoregional staging of rectal cancer. Furthermore, the advent of both diffusion-weighted imaging and hepatobiliary contrast agents has significantly enhanced the ability of MRI to detect colorectal liver metastases. In clinical practice, MRI routinely provides prognostic information, helps to guide surgical strategy, and determines the need for neoadjuvant therapies related to both the primary tumor and metastatic disease. Expanding on these roles for MRI, positron emission tomography (PET)/MRI is the newest clinical hybrid imaging modality and combines the metabolic information of PET with the high soft tissue contrast of MRI. The addition of PET/MRI to the clinical staging armamentarium has the potential to provide comprehensive state-of-the-art colorectal cancer staging in a single examination.

Endoscopic ultrasound for staging of colonic cancer proximal to the rectum: A systematic review and meta-analysis

Background and Objectives:

Treatment of colonic cancer patients is highly dependent on the depth of tumor invasion (T-stage) as well as the extension of lymph node involvement (N-stage). We aimed to systematically review the accuracy of endoscopic ultrasound (EUS) for staging of colonic cancer proximal to the rectum.

Patients and Methods:

Men and women with colonic adenocarcinomas were included in the study. EUS staging was compared to histopathology as the gold standard. Outcome measures were T- and N-staging accuracies. Articles were searched in PubMed, Web of Science, The Cochrane Library, and EMBASE.

Results:

Six studies were identified comparing EUS staging of colonic cancer to histopathology. The pooled-staging sensitivity and specificity were 0.90 and 0.98 for T1 tumors, 0.67 and 0.96 for T2 tumors, and 0.97 and 0.83 for T3/T4 tumors, respectively. Sensitivity and specificity for N + disease were 0.59 and 0.78, respectively.

Conclusions:

EUS is a feasible method for T-staging of cancers of the colon proximal to the rectum. The accuracy of lymph node staging needs to be verified by prospective multicenter studies including larger patient populations.

The accuracy of endorectal ultrasonography in rectal cancer staging

Background and aims

The incidence of rectal cancer in the European Union is about 35% of the total colorectal cancer incidence. Staging rectal cancer is important for planning treatment. It is essential for the management of rectal cancer to have adequate preoperative imaging, because accurate staging can influence the therapeutic strategy, type of resection, and candidacy for neoadjuvant therapy. The aim of this work is to evaluate the accuracy of endorectal ultrasound (ERUS) in rectal cancer staging.

Methods

A retrospective study was performed to assess the accuracy of ERUS by analyzing patients discharged from Regional Institute of Gastroenterology and Hepatology (IRGH) Cluj-Napoca, Romania, diagnosed with rectal cancer between 01 January 2011 and 31 December 2013. Patients who were preoperatively staged by other imaging methods and those who had ERUS performed in another service were excluded from the analysis. As inclusion criteria remained ERUS performed for patients with rectal cancer in IRGH Cluj-Napoca where they were also operated. We analyzed preoperative T stage obtained by ERUS and it was compared with the histopathology findings.

Results

The number of patients discharged with a diagnosis of rectal cancer were 200 (operated – 157) in 2011, 193 (operated – 151) in 2012, and 198 (operated – 142) in 2013. We analyzed a total of 51 cases diagnosed with rectal cancer who performed ERUS in IRGH Cluj-Napoca. The results according to the T stage obtained by ERUS and histopathology test were:

Conclusions

ERUS is a method of staging rectal cancer which is human dependent. ERUS is less accurate for T staging of stenotic tumours, but the accuracy may still be within acceptable limits. Surgeons use ERUS to adopt a treatment protocol, knowing the risk of under-staging and over-staging of this method. The accuracy of ERUS is higher in diagnosing rectal cancer in stages T1, T2 and even in stage T3 with malignant tumor which is not occlusive. ERUS is less accurate for T staging of locally advanced and stenotic tumours.

Paradigm shift in the management of rectal cancer

Surgery for rectal cancer in the pre-Total Mesorectal Excision (TME) era was associated with high local recurrence rates. The widespread adoption of the TME technique together with the addition of neoadjuvant oncological therapies have reduced local failure rates and improved survival for patients with rectal cancer. Advances in our knowledge, better understanding of tumour biology and refinement in minimal access techniques and equipment have significantly changed the management of rectal cancer. This paper reviews these changes and proposes a paradigm shift in how rectal cancer management is conceptualised and treated, such that the treatment of rectal cancer is separated into early tumours (potentially suitable for local excison), TME tumours (optimally managed by TME) and beyond TME tumours (optimally managed by multivisceral resection outside the TME plane).

Palliative care and end-stage colorectal cancer management: The surgeon meets the oncologist

Colorectal cancer (CRC) is a common neoplasia in the Western countries, with considerable morbidity and mortality. Every fifth patient with CRC presents with metastatic disease, which is not curable with radical intent in roughly 80% of cases. Traditionally approached surgically, by resection of the primitive tumor or stoma, the management to incurable stage IV CRC patients has significantly changed over the last three decades and is nowadays multidisciplinary, with a pivotal role played by chemotherapy (CHT). This latter have allowed for a dramatic increase in survival, whereas the role of colonic and liver surgery is nowadays matter of debate. Although any generalization is difficult, two main situations are considered, asymptomatic (or minimally symptomatic) and severely symptomatic patients needing aggressive management, including emergency cases. In asymptomatic patients, new CHT regimens allow today long survival in selected patients, also exceeding two years. The role of colonic resection in this group has been challenged in recent years, as it is not clear whether the resection of primary CRC may imply a further increase in survival, thus justifying surgery-related morbidity/mortality in such a class of short-living patients. Secondary surgery of liver metastasis is gaining acceptance since, under new generation CHT regimens, an increasing amount of patients with distant metastasis initially considered non resectable become resectable, with a significant increase in long term survival. The management of CRC emergency patients still represents a major issue in Western countries, and is associated to high morbidity/mortality. Obstruction is traditionally approached surgically by colonic resection, stoma or internal by-pass, although nowadays CRC stenting is a feasible option. Nevertheless, CRC stent has peculiar contraindications and complications, and its long-term cost-effectiveness is questionable, especially in the light of recently increased survival. Perforation is associated with the highest mortality and remains mostly matter for surgeons, by abdominal lavage/drainage, colonic resection and/or stoma. Bleeding and other CRC-related symptoms (pain, tenesmus, etc.) may be managed by several mini-invasive approaches, including radiotherapy, laser therapy and other transanal procedures.

Forward-viewing radial-array echoendoscope for staging of colon cancer beyond the rectum

AIM: To evaluate feasibility of the novel forward-viewing radial-array echoendoscope for staging of colon cancer beyond rectum as the first series.

METHODS: A retrospective study with prospectively entered database. From March 2012 to February 2013, a total of 21 patients (11 men) (mean age 64.2 years) with colon cancer beyond the rectum were recruited. The novel forward-viewing radial-array echoendoscope was used for ultrasonographic staging of colon cancer beyond rectum. Ultrasonographic T and N staging were recorded when surgical pathology was used as a gold standard.

RESULTS: The mean time to reach the lesion and the mean time to complete the procedure were 3.5 and 7.1 min, respectively. The echoendoscope passed through the lesions in 13 patients (61.9%) and reached the cecum in 10 of 13 patients (76.9%). No adverse events were found. The lesions were located in the cecum (n = 2), ascending colon (n = 1), transverse colon (n = 2), descending colon (n = 2), and sigmoid colon (n = 14). The accuracy rate for T1 (n = 3), T2 (n = 4), T3 (n = 13) and T4 (n = 1) were 100%, 60.0%, 84.6% and 100%, respectively. The overall accuracy rates for the T and N staging of colon cancer were 81.0% and 52.4%, respectively. The accuracy rates among traversable lesions (n = 13) and obstructive lesions (n = 8) were 61.5% and 100%, respectively. Endoscopic ultrasound and computed tomography had overall accuracy rates of 81.0% and 68.4%, respectively.

CONCLUSION: The echoendoscope is a feasible staging tool for colon cancer beyond rectum. However, accuracy of the echoendoscope needs to be verified by larger systematic studies.

Selection of colon cancer patients for neoadjuvant chemotherapy by preoperative CT scan

OBJECTIVE

Preoperative staging is essential to plan correct treatment of colon cancer and calls for objective, accurate methods for the introduction of neoadjuvant chemotherapy, which represents a new treatment option.

PURPOSE

To evaluate the diagnostic accuracy of multislice computed tomography (CT) in local staging of colon cancer correlated with histopathological parameters, including criteria for adjuvant chemotherapy.

MATERIAL AND METHODS

A total of 74 included patients had preoperative CT scans and surgical resection of their colon tumors. Tumor stage (T-stage), extramural tumor invasion (ETI), nodal stage (N-stage), extramural venous invasion (EVI) and the distance from tumor to nearest retroperitoneal fascia (DRF) were retrospectively assessed on the CT scan and compared blindly with the results of the pathological examination, including evaluation of the criteria for adjuvant chemotherapy. Advanced tumors were defined as T3 with ETI ≥5 mm or T4.

RESULTS

Sixty-nine percent of the tumors were correctly T-staged by CT, 7% were overstaged and 24% were understaged. As to correct recognition of ETI on the CT scan, the observer was 73% accurate compared with histology (70% sensitivity (95% CI: 53-82%), 78% specificity (95% CI: 60-90%), 81% positive predictive value (PPV) (95% CI: 63-91%) and 66% negative predictive value (NPV) (95% CI: 49-80%). N-stage, EVI and DRF had poor accuracy: 53%, 53% and 64%. All patients with advanced tumors on CT fulfilled the criteria for adjuvant chemotherapy. Positive predictive value: 100% (95% CI: 88-100%).

CONCLUSION

CT has a potential in the preoperative selection of advanced tumors suitable for neoadjuvant chemotherapy without overtreatment of low-risk patients.

Ultrasound elastography in patients with rectal cancer treated with chemoradiation

OBJECTIVE

The current literature has described several predictive markers in rectal cancer patients treated with chemoradiation, but so far none of them have been validated for clinical use. The purpose of the present study was to compare quantitative elastography based on ultrasound measurements in the course of chemoradiation with tumor response based on T stage classification and the Mandard tumor regression grading (TRG).

MATERIALS AND METHODS

We prospectively examined 31 patients with rectal cancer planned for high dose radiochemotherapy. The tumor and the mesorectal fat elasticity were measured using the Acoustic Radiation Force Impulse to generate information on the mechanical properties of the tissue. The objective quantitative elastography shear wave velocity was compared to the T stage classification and TRG.

RESULTS

The baseline mean tumor elasticity was 3.13 m/s. Two and six weeks after the start of chemoradiation the velocities were 2.17 m/s and 2.11 m/s, respectively. The difference between baseline velocity and velocities during the treatment course was statistically significant, (p<0.0001). Patients with tumor confined to the rectal wall at histopathology (ypT1-2) had a mean elasticity measurement after two weeks of treatment of 1.95 m/s, whereas tumors invading the mesorectal fat (ypT3-4) had a velocity of 2.47 m/s, (p<0.05). The mean elasticity tended to be lower (1.99m/s) after two weeks in patients with TRG 1-2 responses in contrast to 2.24 m/s in those with TRG 3-4.

CONCLUSION

Ultrasound elastography after two weeks of chemoradiation seems to hold early predictive information to the pathological T stage.