Accuracy of transrectal ultrasound after preoperative radiochemotherapy compared to computed tomography and magnetic resonance in locally advanced rectal cancer

Restaging rectal cancer following neoadjuvant chemoradiotherapy

Correct tumour restaging is pivotal for identifying the most personalised surgical treatment for patients with locally advanced rectal cancer undergoing neoadjuvant therapy, and works to avoid both poor oncological outcome and overtreatment. Digital rectal examination, endoscopy, and pelvic magnetic resonance imaging are the recommended modalities for local tumour restaging, while chest and abdominal computed tomography are utilised for the assessment of distant disease. The optimal length of time between neoadjuvant treatment and restaging, in terms of both oncological safety and clinical effectiveness of treatment, remains unclear, especially for patients receiving prolonged total neoadjuvant therapy. The timely identification of patients who are radioresistant and at risk of disease progression remains challenging.

Preoperative T and N Restaging of Rectal Cancer After Neoadjuvant Chemoradiotherapy: An Accuracy Comparison Between MSCT and MRI

Background

It is well established that magnetic resonance imaging (MRI) is better than multi-slice computed tomography (MSCT) for the accurate diagnosis of pretreatment tumor (T) and node (N) staging of rectal cancer. However, the diagnostic value of MRI and MSCT in local restaging of rectal cancer after neoadjuvant chemoradiotherapy (NCRT) is controversial. The aim of this study is to investigate the performance of the two imaging exams in restaging of patients with rectal cancer.

Methods

Patients with rectal cancer from April 2015 to April 2021 were analyzed retrospectively. The inclusion criteria are as follows: 1) diagnosis of rectal cancer through pathology; 2) NCRT had been performed; 3) all patients had undergone both MSCT and MRI examination before the surgery. Exclusion criteria are as follows: 1) incomplete clinical and imaging data; 2) previous history of pelvic surgery. Two radiologists performed T and N staging of patient images. Diagnostic accuracy, consistency analysis, and error restaging distribution of the two imaging exams for T and N restaging of rectal cancer were assessed using postoperative pathological staging as the gold standard.

Results

A total of 62 patients (49 men; mean age: 59 years; age range 29–83 years) were included in the study. The diagnostic accuracy of MSCT and MRI for T restaging was 51.6% (95% CI 39.3%–63.9%) and 41.9% (95% CI 29.6%–54.2%), respectively, and no statistical difference was found between them (p > 0.05). The diagnostic accuracy of MSCT and MRI for N restaging was 56.5% (95% CI 44.2%–68.8%) and 53.2% (95% CI 40.8%–65.6%), respectively, and no statistical difference was found between them (p > 0.05). The consistency analysis showed that T restaging (κ = 0.583, p < 0.001) and N restaging (κ = 0.644, p < 0.001) were similar between MSCT and MRI. There was no significant difference in the distribution of over, accurate, or low staging in T restaging (p > 0.05) and N restaging (p > 0.05) between MSCT and MRI.

Conclusions

MSCT and MRI have similarly poor performance in the diagnosis of preoperative T and N restaging of rectal cancer after NCRT. Neither of them cannot effectively stage the ypT0-1 of rectal cancer. These findings may be of clinical relevance for planning less imaging exam.

The Optimal Application of Transrectal Ultrasound in Staging of Rectal Cancer Following Neoadjuvant Therapy: A Pragmatic Study for Accuracy Investigation

Background: Transrectal ultrasound (TRUS) is a cost-effective test for preoperative assessment of rectal cancer. However, whether the accuracy of TRUS staging is correlated with tumor location remains obscured. This study is designed to explore their relationship and confirm an optimal application of TRUS in rectal cancer restaging.

Methods: From 2005 to 2011, rectal cancer patients with TRUS data were retrospectively reviewed. Patients were divided into five groups according to tumor-involved rectal segment (SEG) above the anal verge: SEG I 1-3cm, II 3-6cm, III 6-9cm, IV 9-12cm, and V 12-16cm. The accuracy and long-term outcomes of tumor staging were compared between ultrasonographic and pathological stages.

Results: 219 patients were included, with 55 (25.1%) in SEG I, 123 (56.2%) in SEG II, 32 (14.6%) in SEG III, 4 (1.8%) in SEG IV and 5 (2.3%) in SEG V. The overall accuracy of TRUS staging was remarkably superior to clinical staging by CT (64.8% vs. 34.7%, P<0.001), with 70.3% and 82.2% for ultrasonographic T and N stages respectively. The accuracy of TRUS reached its peak value when tumors were located in SEG II. The 5-year overall survival had no significant difference between TRUS and pathology staging for all stages. A cox regression analysis indicated that high levels of CEA and tumor location were risk factors of inaccurate staging.

Conclusions: TRUS is still a valuable examination for restaging of rectal cancer after neoadjuvant therapy. The application of TRUS would be optimal for rectal cancer located 3-6cm above the anal verge.

Tumor Volume Reduction Assessed by Planning Computed Tomography in Patients with Rectal Cancer during Preoperative Chemoradiation: Impact of Residual Tumor Volume on the Prediction of Pathologic Tumor Regression

Aims and Background

To determine whether the residual tumor volume measured using the Eclipse treatment planning system correlates with pathologic tumor regression grade after preoperative chemoradiotherpy for rectal cancer.

Materials and Methods

The study included 30 patients with rectal cancer who had undergone preoperative chemoradiotherpy followed by surgery from June 2008 to April 2011 at the Korea University Guro Hospital. The tumor volume was measured using the Eclipse treatment planning system in the initial simulation computed tomography and boost planning computed tomography. The correlation between the residual tumor volume in boost planning computed tomography and the pathologic tumor regression grade was analyzed. Tumor regression grade defined in the American Joint Committee on Cancer 7th edition was used.

Results

The mean and median residual tumor volume was 57.34% ± 20.37% and 52.35% (range, 18.42%-95.79%), respectively. After surgery, pathologic complete response (tumor regression grade 0) occurred in 4 patients (13.33%), moderate response (tumor regression grade 1) in 18 patients (60%), minimal response (tumor regression grade 2) in 4 patients (13.33%), and poor response (tumor regression grade 3) in 4 patients (13.33%). When residual tumor volume was categorized into two groups (<50% and ≥50%), complete or moderate regression (tumor regression grade 0 or 1) was significantly greater for patients with a residual tumor volume <50% (P <0.05). The mean residual tumor volume of tumor regression grade 0 or 1 was 49.07% ± 18.39% and that of tumor regression grade 2 or 3 was 76.31% ± 16.94% (P <0.05).

Conclusions

Residual tumor volume measured using routine boost planning computed tomography during preoperative chemoradiotherpy correlated significantly with pathologic tumor regression grade after surgery.

Advances for achieving a pathological complete response for rectal cancer after neoadjuvant therapy

Neoadjuvant therapy has become the standard of care for locally advanced mid-low rectal cancer. Pathological complete response (pCR) can be achieved in 12%–38% of patients. Patients with pCR have the most favorable long-term outcomes. Intensifying neoadjuvant therapy and extending the interval between termination of neoadjuvant treatment and surgery may increase the pCR rate. Growing evidence has raised the issue of whether local excision or observation rather than radical surgery is an alternative for patients who achieve a clinical complete response after neoadjuvant therapy. Herein, we highlight many of the advances and resultant controversies that are likely to dominate the research agenda for pCR of rectal cancer in the modern era.

Rectal cancer with complete clinical response after neoadjuvant chemoradiotherapy, surgery, or "watch and wait"

PURPOSE

The purpose of this study was to compare the outcomes of patients treated with chemoradiotherapy with a complete clinical response followed by either a "watch and wait" strategy or a total mesorectal excision.

METHODS

This was an observational retrospective study from a single institute. Patients with locally advanced rectal cancer following chemoradiotherapy with a complete clinical response from January 1, 2007 to December 31, 2014 were included.

RESULTS

The study population consisted of 18 patients who opted for a "watch and wait" policy and 26 patients who underwent radical surgery after achieving a complete clinical response. Patients had no documented treatment complications under the watch and wait policy, while 13 patients who underwent radical surgery experienced significant morbidity. There were two local recurrences in the watch and wait group; both were treated with salvage resection and had no associated mortality. In the radical surgery group, 1 patient showed an incomplete pathologic response (ypT0N1), and the remaining 25 patients showed complete pathologic responses; 1 had a distant recurrence, which was managed non-operatively, and 2 patients died of unrelated causes. The 5-year overall survival rate and median disease-free survival time were 100% and 69.78 months in the watch and wait group and 92.30% and 89.04 months in the radical surgery group.

CONCLUSIONS

A watch and wait policy avoids the morbidity associated with radical surgery and preserves oncologic outcomes in our retrospective study from a single institute. It could be considered a therapeutic option in patients with locally advanced rectal cancer following chemoradiotherapy with a complete clinical response.

The accuracy of MRI, endorectal ultrasonography, and computed tomography in predicting the response of locally advanced rectal cancer after preoperative therapy: A metaanalysis

BACKGROUND

To perform a metaanalysis to determine and compare the diagnostic performance of MRI, endorectal ultrasonography (ERUS), and computed tomography (CT) in predicting the response of locally advanced rectal cancer after preoperative therapy.

METHODS

All previously published articles on the role of MRI, CT, and/or ERUS in predicting the response of rectal cancer to preoperative therapy were collected. We divided the objective in 3 parts: the accuracy to assess (i) complete response, (ii) to detect T4 tumors with invasion to the circumferential resection margin (CRM), and (iii) to predict the presence of lymph node metastasis. The pooled estimates of, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated using a bivariate mixed effect analysis.

RESULTS

Forty-six studies comprising 2,224 patients were included. (i) The pooled accuracy to assess complete tumor response were (a) 75% for MRI, (b) 82% for ERUS, (c) and 83% for CT. (ii) Pooled accuracy to detect T4 tumors with invasion to the CRM were (a) 88% and (b) 94% for ERUS. (iii) Pooled accuracy to predict the presence of lymph node metastasis was (a) 72% for MRI, (b) 72% for ERUS, (c) and 65% for CT.

CONCLUSION

MRI, CT, and ERUS cannot be used to predict complete response of locally advanced rectal cancer after CRT. In addition, the positive predictive value for these imaging techniques is low for the assessment of tumor invasion in the CRM. The accuracy of the modalities to predict the presence of metastatic lymph node disease is also low.

Nonoperative management of rectal cancer: identifying the ideal patients

Neoadjuvant chemoradiation (CRT) is considered one of the preferred treatment strategies for patients with locally advanced rectal cancer. This strategy may lead to significant tumor regression, ultimately leading to a complete pathologic response in up to 42% of patients. Assessment of tumor response following CRT and before radical surgery may identify patients with a complete clinical response who could possibly be managed nonoperatively with strict follow-up (watch-and-wait strategy). The present article deals with critical issues regarding appropriate selection of patients for this approach.

Reduced luminal circumference of tumors plays a key role in anorectal function during the early period after neoadjuvant chemoradiation therapy in rectal cancer patients

PURPOSE

The deterioration of anorectal function after neoadjuvant chemoradiation therapy (nCRT) combined with surgery for rectal cancer has not been well defined. The aim of this study was to evaluate the relationship between the tumor response to nCRT and changes in anorectal function during a short-term period after nCRT.

METHODS

We analyzed 100 consecutive patients with available preoperative anorectal manometry data, both before and after nCRT, from 2010 to 2013.

RESULTS

Comparing the manometric data before and after nCRT, the values reflecting rectal sensory function after nCRT was significantly lower than those before nCRT. However, in patients who experienced changed tumor morphology and a reduction in luminal circumferential ratio (LCIR) of tumor after nCRT, the values reflecting rectal sensory function were significantly less decreased after nCRT. On multivariate analysis, the reduction of LCIR after nCRT was a very important factor preventing the impairment of anorectal function during the short-term period in terms of the first rectal sensory threshold (RST) (P = 0.002), the RST of "desire to defecate" (P = 0.006), and rectal compliance (P = 0.003). Additionally, in linear regression analysis, the RST for the desire to defecate was positively affected by tumor morphology (P = 0.015) and the reduced LCIR (P = 0.025), and rectal compliance was positively affected by the reduced LCIR (P = 0.001).

CONCLUSION

The nCRT impaired significantly rectal sensory function during the short-term period after nCRT and before a radical operation. However, this reduced LCIR of tumors after nCRT may prevent or minimize impediments to anorectal function during the short-term period after nCRT.

Role of KRAS mutation as predictor of pathologic response after neoadjuvant chemoradiation therapy for rectal cancer

Individual patient response to neoadjuvant treatment is variable and reproducible biomarkers of response are needed. The role of the V-Ki-ras2 Kirsten rat sarcoma viral oncogene (KRAS) in rectal cancer remains equivocal. The aim of the current study was to evaluate the effect of KRAS mutation on outcomes following neoadjuvant chemoradiation therapy (CRT) for rectal cancer. A total of 76 stage II-III rectal cancer patients underwent preoperative CRT followed by surgery. In every patient tumor-related features and outcome results were considered for analysis and correlation with KRAS mutations. Forty-four patients (58%) obtained a downstaging after CRT, and in 7 patients (9%) a complete pathological response was found. Twenty-six (33%) mutations of KRAS were found in 26 patients. Nineteen mutations (73%) were located in codon 12, 6 in codon 13(23%) and 1 in codon 61. T-level downsizing and tumor downstaging showed no significant association with KRAS mutation status, except for mutation of codon 13(G13D). No correlation between cancer-associated mortality following CRT and surgery and KRAS mutation was observed. No correlation between pelvic recurrence and KRAS mutation was observed. KRAS mutation also failed to correlate with disease-free survival. No patients with a pCR had a local or distant failure. There appears to be no significant difference in pCR, tumor down-staging, T-downsizing or effects on cancer-associated mortality, overall survival and disease-free survival in patients with KRAS mutations except for patients with KRAS codon 13 mutations that seem to be resistant to neoadjuvant CRT and less likely to achieve a pCR.

Surgical strategy for low rectal cancers

The two goals of surgery for lower rectal cancer surgery are to obtain clear "curative" margins and to limit post-surgical functional disorders. The question of whether or not to preserve the anal sphincter lies at the center of the therapeutic choice. Histologically, tumor-free distal and circumferential margins of>1mm allow a favorable oncologic outcome. Whether such margins can be obtained depends of TNM staging, tumor location, response to chemoradiotherapy and type of surgical procedure. The technique of intersphincteric resection relies on these narrow margins to spare the sphincter. This procedure provides satisfactory oncologic outcome with a rate of circumferential margin involvement ranging from 5% to 11%, while good continence is maintained in half of the patients. The extralevator abdominoperineal resection provides good oncologic results, however this procedure requires a permanent colostomy. A permanent colostomy alters several domains of quality of life when located at the classical abdominal site but not when brought out at the perineal site as a perineal colostomy.

Multidisciplinary treatment of rectal cancer in 2014: where are we going?

In the present review we discuss the recent developments and future directions in the multimodal treatment of locally advanced rectal cancer, with respect to staging and re-staging modalities, to the current role of neoadjuvant chemo-radiation and to the conservative and more limited surgical approaches based on tumour response after neoadjuvant combined therapy. When initial tumor staging is considered a high accuracy has been reported for T pre-treatment staging, while preoperative lymph node mapping is still suboptimal. With respect to tumour re-staging, all the current available modalities still present a limited accuracy, in particular in defining a complete response. The role of short vs long-course radiotherapy regimens as well as the optimal time of surgery are still unclear and under investigation by means of ongoing randomized trials. Observational management or local excision following tumour complete response are promising alternatives to total mesorectal excision, but need further evaluation, and their use outside of a clinical trial is not recommended. The preoperative selection of patients who will benefit from neoadjuvant radiotherapy or not, as well as the proper identification of a clinical complete tumour response after combined treatment modalities,will influence the future directions in the treatment of locally advanced rectal cancer.

Magnetic resonance imaging in rectal cancer: a surgeon's perspective

Magnetic resonance imaging (MRI) in rectal cancer was first investigated in 1999 and has become almost mandatory in planning rectal cancer treatment. MRI has a high accuracy in predicting circumferential resection margin involvement and is used to plan neoadjuvant therapy. The accuracy of MRI in assessing mesorectal lymph nodes remains moderate, as there are no reliable criteria to assess nodal involvement. MRI seems to be good in assessing peritoneal involvement in upper rectal cancer; this however has been assessed in only a few studies and needs further research. For low rectal cancers, mesorectum is thin at the level of levator ani especially in relation to prostate; so predicting circumferential resection margin involvement is not easy. However high spatial resolution coronal imaging shows levator muscles, sphincter complex and intersphincteric plane accurately. This is used to stage low rectal tumors and plan plane of surgery (standard surgery, intersphincteric resection, Extralevator abdominoperineal resection). While most centres perform MRI post chemoradiotherapy, its role in accurate staging post neoadjuvant therapy remains debatable. THe role of Diffusion weighted MRI post neoadjuvant therapy is being evaluated in research settings.

The value of TRUS in the staging of rectal carcinoma before and after radiotherapy and comparison with the staging postoperative pathology

AIM

To compare the effectiveness of transrectal ultrasonography (TRUS) with that of postoperative pathological examination in staging rectal carcinoma before surgery and before and after radiotherapy.

MATERIALS AND METHODS

A prospective study was undertaken comprising 62 patients with stage T3 or T4 rectal carcinoma confirmed by endoscopic biopsy.

RESULTS

TRUS showed significant differences (p < 0.01) in tumour echogenicity and volume, border delineation, local invasion, and draining lymph node involvement before and after radiotherapy, and significant reduction in blood flow resistance index after radiotherapy but no difference (p > 0.05) in the classification of tumour blood flow. In ultrasonographic assessments, 53 of the 62 cases (85.5%) showed lower T stages after radiotherapy. TRUS showed an accuracy of 94.1% for T2 cases, 77.3% for T3 cases, and 83.3% for T4 cases, and an overall accuracy of 87.1% in comparison with the results of postoperative pathological examination.

CONCLUSION

TRUS is expected to play a vital role in the accurate preoperative staging of rectal carcinoma with the increasing utilization of adjuvant radiotherapy in rectal carcinoma and to contribute to the assessment of treatment.

Value of transrectal ultrasonography for tumor node metastasis restaging in patients with locally advanced rectal cancer after neoadjuvant chemoradiotherapy

OBJECTIVE

To explore the value of transrectal ultrasonography (TRUS) for tumor node metastasis (TNM) restaging for patients with locally advanced rectal cancer after neoadjuvant chemoradiotherapy (neo-CRT).

METHODS

One hundred and forty-nine patients with locally advanced rectal cancer (cT3-4 or cN+) who underwent TRUS after neo-CRT were retrospectively reviewed. TRUS restaging was compared with the results of post-operative pathological TNM findings.

RESULTS

After neo-CRT, the accuracy of TRUS for diagnosing T-staging was 30.9%, with 60.4% (90/149) of cases overestimated. The sensitivity of TRUS for T-staging (T0 vs T1 vs T2 vs T3 vs T4) were 16.3%, 0%, 12.5%, 42.6% and 75.0%, respectively. The accuracy of TRUS for diagnosing N-staging after neo-CRT was 81.2%, with the sensitivities of N0 and N+ were 93.3% and 31.0%, respectively. After neo-CRT, 27.5% (41/149) of patients achieved pathologically complete response (pCR). The sensitivity, specificity, positive predictive value and negative predictive values of TRUS for pCR were 17.1%, 99.1%, 87.5% and 75.9%, respectively.

CONCLUSIONS

TRUS can be applied for restaging T4 and N0, and has potential for screening out patients with pCR in those with locally advanced rectal cancer after neo-CRT, although some stages are overestimated for T-staging and its sensitivity for predicting pCR is low.

How reliable is current imaging in restaging rectal cancer after neoadjuvant therapy?

In patients with advanced rectal cancer, neoadjuvant chemo radiotherapy provides tumor downstaging and downsizing and complete pathological response in up to 30% of cases. After proctectomy complete pathological response is associated with low rates of local recurrence and excellent long term survival. Several authors claim a less invasive surgery or a non operative policy in patients with partial or clinical complete response respectively, however to identify patients with true complete pathological response before surgical resection remains a challenge. Current imaging techniques have been reported to be highly accurate in the primary staging of rectal cancer, however neoadjuvant therapy course produces deep modifications on cancer tissue and on surrounding structures such as overgrowth fibrosis, deep stroma alteration, wall thickness, muscle disarrangement, tumor necrosis, calcification, and inflammatory infiltration. As a result, the same imaging techniques, when used for restaging, are far less accurate. Local tumor extent may be overestimated or underestimated. The diagnostic accuracy of clinical examination, rectal ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography using 18F-fluoro-2'-deoxy-D-glucose ranges between 25% and 75% being less than 60% in most studies, both for rectal wall invasion and for lymph nodes involvement. In particular the ability to predict complete pathological response, in order to tailor the surgical approach, remains low. Due to the radio-induced tissue modifications, combined with imaging technical aspects, low rate accuracy is achieved, making modern imaging techniques still unreliable in restaging rectal cancer after chemo-radiotherapy.

Patients who undergo preoperative chemoradiotherapy for locally advanced rectal cancer restaged by using diagnostic MR imaging: a systematic review and meta-analysis

PURPOSE

To obtain performance values of magnetic resonance (MR) imaging for restaging locally advanced rectal cancer after neoadjuvant treatment regarding tumor staging, nodal staging, and tumor-free circumferential resection margins (CRMs).

MATERIALS AND METHODS

MEDLINE, EMBASE, and Cochrane databases were searched for studies regarding restaging compared with a reference standard by using the terms rectal neoplasms, MR imaging, and chemotherapy. The Quality Assessment of Diagnostic Accuracy Studies tool was used, and data on imaging criteria, histopathologic criteria, and restaging were extracted. Responders were defined as positives and nonresponders, as negatives. Mean sensitivity, mean specificity, and positive and negative likelihood ratios (LRs) were determined by using a bivariate random-effects model. A positive LR greater than 5 implied moderate results for responders.

RESULTS

Thirty-three studies evaluated 1556 patients. For tumor stage, mean sensitivity was 50.4%, mean specificity was 91.2%, positive LR was 5.76, and negative LR was 0.54. Diffusion-weighted (DW) imaging showed comparable positive LR with significantly improved sensitivity (P = .01) and negative LR (P = .04). Experienced observers showed higher sensitivity (P = .01) and lower negative LR (P = .03) compared with less experienced observers. For CRM, mean sensitivity, mean specificity, positive LR, and negative LR were 76.3%, 85.9%, 5.40, and 0.28, respectively. For nodal stage per patient, mean sensitivity, mean specificity, positive LR, and negative LR were 76.5%, 59.8%, 1.90, and 0.39, respectively; and for nodal stage on a lesion basis, these values were 90.7%, 73.0%, 3.37, and 0.13, respectively.

CONCLUSION

MR imaging showed heterogeneous results of diagnostic performances for restaging rectal cancer after neoadjuvant treatment, but significantly better results were demonstrated when DW imaging was used or with experienced observers. MR imaging can also be used for evaluation of CRM staging, but nodal staging remains challenging.

Management of distal rectal cancer: results from a national survey

Owing to the complexity of distal rectal cancer its management requires a multidisciplinary approach. The diagnosis and the response after neoadjuvant chemoradiotherapy are not easy to assess and therefore the surgical approach is heterogeneous. The purpose of this survey is to evaluate the experiences of members of the Italian Society of Surgery in diagnosis and treatment strategies for rectal cancer and compare it with international practice. A questionnaire was devised comprising 18 questions with 11 sub-items making a total of 29 questions and submitted online to all the 2,500 members of the SIC starting from July 2010. The survey was completed in June 2011. The overall response rate was 17.8 % (444). The majority of the Italian surgeons' responses were in line with the international consensus reflecting the complex management of distal rectal cancer. Other opinions, especially those on staging, diverge from the common view of MRI being the gold standard in the assessment of loco-regional diffusion of the disease and on the superiority of FDG PET-CT versus CT for systemic staging. The timing for the re-staging and for surgery following neoadjuvant chemoradiotherapy does not reflect the international opinion. Italian surgeons are also exposed to the common difficulties encountered internationally in the management of distal rectal cancer. Probably, the implementation of an Italian rectal cancer registry and of many national and international multicentre studies may improve the management of rectal cancer in Italy.