Prediction of rectal lymph node metastasis by pelvic computed tomography measurement

Impact of DNA mismatch repair proteins deficiency on number and ratio of lymph nodal metastases in colorectal adenocarcinoma

BACKGROUND

Approximately 15 % of colorectal adenocarcinomas (CRCs) are characterized by an altered expression of DNA mismatch repair (MMR) proteins (i.e. MMR deficiency [MMRd]). Lymph node ratio (LNR) represents one of the most important prognostic markers in non-advanced CRCs. No significant data are available regarding LNR distribution depending on MMR status.

PURPOSE OF THE STUDY

The aim of the present work was to compare pathological and clinical characteristics of MMRd tumors versus MMR proficient (MMRp) cases. Particular attention was paid to how these molecular sub-groups relate to the LNR.

MATERIALS AND METHODS

A mono-Institutional series of 1037 consecutive surgically treated stage I-IV CRCs were retrospectively selected and data were obtained from pathological reports. Cases were characterized for MMR/MSI status by means of immunohistochemistry or for microsatellite instability (MSI) analysis.

RESULTS

MMRd/MSI tumors (n = 194; 18.7 %) showed significant differences in comparison to MMRp lesions for sex (female prevalence 50.5 % vs 40.7 %; p = 0.013), age (74.2 vs 69.2; p < 0.001), location (right side; p < 0.001), diameter (larger than MMRp; p < 0.001), growth pattern (expansive pattern of growth; p < 0.001), peri- (p = 0.0002) and intra-neoplastic (p = 0.0018) inflammatory infiltrate, presence of perineural invasion (p < 0.001), stage (lower stage at presentation; p < 0.001), grade (higher prevalence of high-grade tumors; p < 0.001), and LNR (lower; p < 0.001).

CONCLUSIONS

MMRd/MSI tumors are a distinct molecular CRC subtype characterized by a significantly lower LNR in comparison to MMRp lesions. These data further support the prognostic impact of MMRd/MSI status in early-stage CRCs.

Imaging Strategies for Rectal Cancer Initial Staging: Does Pelvic Computed Tomography Provide Significantly Additional Findings when High-resolution Magnetic Resonance Imaging has Been Performed?

BACKGROUND

Initial staging of rectal cancer is done by high-resolution magnetic resonance imaging (MRI), however, pelvic computed tomography (CT) is also frequently used. The aim of this study was to evaluate the added clinical benefit of pelvic CT or whether it can alter the initial staging or not.

METHODS

The study was composed of 187 patients with rectal cancer. Firstly, imaging except pelvic CT was evaluated. Secondly, the pelvic CT was evaluated and the staging was adjusted according to the new findings. Subsequently, the two staging results were compared to investigate the added clinical benefit of pelvic CT.

RESULTS

Compared with the imaging data except pelvic CT, new findings revealed by the pelvic CT included metastases of the pelvic bone (n = 1) and pelvic peritoneum (n = 3). However, the new findings did not change the primary staging. Of the three patients with pelvic peritoneal metastasis, two were already determined with peritoneal involvement and ascites by abdominal CT, and the third patient was observed with liver and distant lymph node metastasis. Thus, none of their initial stagings needed to be changed.

CONCLUSION

The addition of pelvic CT to the pre-treatment imaging strategy cannot provide added clinical benefit for the primary evaluation of rectal cancer.

Predictors of Sensitivity to Preoperative Chemoradiotherapy of Rectal Adenocarcinoma

Objectives

The purpose of the study was to identify predictive factors of tumor response to preoperative chemoradiotherapy for rectal adenocarcinoma.

Methods

Ninety-eight patients with nonmetastatic rectal adenocarcinoma received preoperative concurrent chemoradiotherapy and underwent mesorectal excision. After treatment, tumor response according to tumor regression grade were evaluated. The correlation of clinicopathologic factors to tumor response was analyzed.

Results

The results from a univariate analysis indicated that pretreatment carcinoembryonic antigen level ≤3.0 ng/ml (P = 0.002), non-fixed tumor (P = 0.001), and tumor circumferential extent ≤50% (P = 0.001) were associated significantly with a good tumor response. They also indicated that pretreatment positive lymph nodes (P = 0.032) were associated significantly with a poor tumor response. In multivariate analysis, the results indicated that pretreatment carcinoembryonic antigen level (hazard ratio, 2.930; P = 0.003), tumor mobility (hazard ratio, 2.651; P = 0.002) and circumferential extent of tumor (hazard ratio, 2.394; P = 0.019) independently predicted a good pathologic response rate. Pretreatment positive lymph nodes were not significantly associated with a good response (hazard ratio, 0.361; P = 0.191).

Conclusions

Pretreatment carcinoembryonic antigen level, tumor mobility and circumferential extent of tumor may be helpful in predicting responsiveness in rectal adenocarcinoma to preoperative chemoradiotherapy, although the results should be confirmed in larger, more homogeneous studies.

Pelvic Lymph Node Staging by Combined 18F-FDG-PET/CT Imaging in Bladder Cancer Prior to Radical Cystectomy

BACKGROUND

Accurate lymph node (LN) staging in bladder cancer before radical cystectomy is essential as LN metastases have an independent prognostic value. Most studies used a cutoff of > 10 mm in detecting pelvic LN spread. The aim of this study was to evaluate the diagnostic accuracy of contrast-enhanced computed tomography (CT) and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) alone, or combined for preoperative pelvic LN staging.

PATIENTS AND METHODS

We retrospectively analyzed the data of 70 bladder cancer patients that were staged with ¹⁸F-FDG-PET/CT before radical cystectomy between 2012 and 2015. ¹⁸F-FDG-PET images were analyzed visually and semi-quantitatively by calculating the maximum standardized uptake value. CT scans were reviewed using different cutoffs of pelvic LNs, with the best cutoff at 8 mm (area under the curve = 0.684).

RESULTS

Metastatic LNs were confirmed in 53 (2.8%) of 1906 resected LNs in 11 (15.7%) patients. Sensitivity, specificity, and accuracy were 54.5%, 89.8%, and 84.3% for ¹⁸F-FDG-PET alone; 45.5%, 91.5%, and 84.3% for CT (LNs > 8 mm) alone; and 27.3%, 96.6%, and 85.7% for CT (LNs > 10 mm) alone, respectively. Combined ¹⁸F-FDG-PET/CT resulted in a nonsignificant increase of diagnostic accuracy using a cutoff > 8 mm for LN evaluation (63.6%, 86.4%, and 82.9%, respectively). A significant improvement of sensitivity to 63.6% was achieved only when LNs > 10 mm were considered suspicious (P = .046), but this reduced specificity to 88.1% (P = .025).

CONCLUSIONS

Combined ¹⁸F-FDG-PET/CT does not seem to be justified in preoperative staging if the threshold of pelvic LNs is set > 8 mm.

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 Prognostic Role of Para-Aortic Lymph Nodes in Patients with Colorectal Cancer: Is It Regional or Distant Disease?

Introduction

Visible para-aortic lymph nodes of ≥2 mm in size are common metastatic patterns of colorectal cancer (CRC) seen on imaging. Their prognostic value, however, remains inconclusive. We aimed to assess the prognostic role of visible para-aortic lymph nodes (PALNs).

Methods

Patients with confirmed pathologic diagnosis of CRC were enrolled. Correlations among clinicopathologic variables were analyzed using the χ² test. The Cox proportional hazards model was applied for univariate and multivariate analyses. Survival was estimated using the Kaplan-Meier method and log-rank test. A prognostic model for visible PALNs in CRC patients was established.

Results

In total, 4527 newly diagnosed CRC patients were enrolled. Patients with visible PALNs had inferior overall survival compared to those without visible PALNs (5-year overall survival, 67% vs. 76%, P = 0.015). Lymphovascular invasion (LVI) (hazard ratio = 1.865, P = 0.015); nodal disease (pN+) status (hazard ratio = 2.099, P = 0.006); elevated preoperative serum carcinoembryonic antigen (CEA) levels (hazard ratio = 2.263, P < 0.001); and visible PALNs ≥10 mm (hazard ratio = 1.638, P = 0.031) were independent prognostic factors for patients with visible PALNs. If each prognostic factor scored one point, 5-year overall survival of lower- (prognostic score 0–1), intermediate- (prognostic score 2), and high- (prognostic score 3–4) risk groups were, 78%. 54%, and 25% respectively (P < 0.001).

Conclusions

The prognostic model, which included LVI, pN+ status, preoperative serum CEA level, and the size of visible PALNs, could effectively distinguish the outcome of patients with visible PALNs.

The impact of lymph node size to predict nodal metastasis in patients with rectal cancer after preoperative chemoradiotherapy

PURPOSE

During restaging after preoperative chemoradiotherapy (CRT), the assessment of lymph node (LN) metastasis is vital for selecting further treatment strategies. This study aimed to evaluate the impact of LN size to predict LN metastasis in rectal cancer patients after preoperative CRT.

METHODS

A total of 30 consecutive patients who underwent preoperative CRT followed by curative resection of primary rectal cancer were selected as a study group (CRT group). As a control group (non-CRT group), 30 patients who underwent primary tumor resection were selected using a 1:1 case-match design. Matching criteria were gender, age, and clinical T stage. The size of each LN was measured from the surgical specimen. To clarify optimal cutoff values for node size according to the risk of detecting metastasis, receiving-operator characteristic (ROC) curves were generated.

RESULTS

In the non-CRT group, 39/474 LNs were confirmed to have metastasis. In the CRT group, 29/422 LNs showed metastasis. The median size of metastatic LNs was 6.0 mm in CRT group, which was significantly larger than 4.0 mm in the non-CRT group (p = 0.006). The optimal cutoff value for determining metastasis in the CRT group was 4.5 mm, compared to 3.5 mm in the non-CRT group. The accuracy of the cutoff value was much higher in the CRT group (CRT vs. non-CRT, 77.9 vs. 59.9%).

CONCLUSIONS

LN size is a strong indicator for prediction of regional LN metastasis in rectal cancer patients after preoperative CRT, compared to those without CRT.

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.

Diagnostic value of FDG-PET/CT for lymph node metastasis of colorectal cancer

BACKGROUND

Lymph node metastasis is an important prognostic factor in patients with colorectal cancer. We assessed the ability of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) to diagnose lymph node metastases in colorectal cancer patients.

METHODS

We retrospectively analyzed the records of 473 patients who underwent preoperative FDG-PET/CT, followed by curative surgery for colorectal cancer. Lymph node metastases were assessed as proximal or distal, depending on their anatomical location. We analyzed the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of FDG-PET/CT and CT for detecting lymph node metastases.

RESULTS

In detecting proximal lymph nodes, FDG-PET/CT had a sensitivity of 66 %, a specificity of 60 %, a PPV of 63 %, an NPV of 62 %, and an accuracy of 63 %; whereas CT had a sensitivity of 87 %, a specificity of 29 %, a PPV of 57 %, an NPV of 68 %, and an accuracy of 59 % (P = 0.245). FDG-PET/CT and CT also showed similar accuracy in detecting distal lymph nodes (87 vs. 88 %, P = 0.620).

CONCLUSION

Preoperative FDG-PET/CT and CT have comparable accuracy in detecting lymph node metastases of colorectal cancer.

EUS-FNA assessment of extramesenteric lymph node status in primary rectal cancer

BACKGROUND

Preoperative staging is an essential factor in the multidisciplinary management of rectal cancer. The accuracy of imaging alone with CT, magnetic resonance imaging, or rigid endorectal US is poor. The addition of EUS-FNA may enhance extramesenteric lymph node metastases detection (M1 disease) and overall staging accuracy.

OBJECTIVE

To evaluate the frequency of extramesenteric lymph node visualization by EUS and the rate of extramesenteric lymph node metastases by FNA. Secondary goals were to evaluate the clinical, endoscopic, and sonographic features associated with extramesenteric lymph node metastases, disease progression, and overall mortality.

DESIGN

Retrospective cohort study.

SETTINGS

Tertiary referral center.

RESULTS

Forty-one of 316 patients (13%) with primary rectal cancer over a 6-year period had M1 disease by EUS-FNA. Significant clinical, endoscopic, and sonographic features associated with extramesenteric lymph node metastases included the serum carcinoembryonic antigen level, tumor length 4 cm and longer, annularity 50% or more, sessile morphology, and lymph node size. The sensitivity and specificity of CT for extramesenteric lymph node metastases were 44% and 89%, respectively. Twenty-three of 316 rectal cancer endosonographic procedures (7.3%) were up-staged by FNA, which established extramesenteric lymph node metastases. Over a 4-year follow-up, disease progression and overall mortality of patients with extramesenteric lymph node metastases was observed in 6 patients (14.6%) and 14 patients (34%), respectively.

CONCLUSIONS

Preoperative EUS-FNA identification of extramesenteric lymph node metastases outside of standard radiation fields or total mesorectal excision resection margins could affect medical and surgical planning.

Rectal cancer radiotherapy: towards European consensus

BACKGROUND AND PURPOSE

During the first decade of the 21st century several important European randomized studies in rectal cancer have been published. In order to help shape clinical practice based on best scientific evidence, the International Conference on 'Multidisciplinary Rectal Cancer Treatment: Looking for an European Consensus' (EURECA-CC2) was organized. This article summarizes the consensus about imaging and radiotherapy of rectal cancer and gives an update until May 2010.

METHODS

Consensus was achieved using the Delphi method. Eight chapters were identified: epidemiology, diagnostics, pathology, surgery, radiotherapy and chemotherapy, treatment toxicity and quality of life, follow-up, and research questions. Each chapter was subdivided by topic, and a series of statements were developed. Each committee member commented and voted, sentence by sentence three times. Sentences which did not reach agreement after voting round # 2 were openly debated during the Conference in Perugia (Italy) December 2008. The Executive Committee scored percentage consensus based on three categories: "large consensus", "moderate consensus", "minimum consensus".

RESULTS

The total number of the voted sentences was 207. Of the 207, 86% achieved large consensus, 13% achieved moderate consensus, and only three (1%) resulted in minimum consensus. No statement was disagreed by more than 50% of members. All chapters were voted on by at least 75% of the members, and the majority was voted on by >85%. Considerable progress has been made in staging and treatment, including radiation treatment of rectal cancer.

CONCLUSIONS

This Consensus Conference represents an expertise opinion process that may help shape future programs, investigational protocols, and guidelines for staging and treatment of rectal cancer throughout Europe. In spite of substantial progress, many research challenges remain.

Prospective assessment of imaging after preoperative chemoradiotherapy for rectal cancer

BACKGROUND

The aim of the study was to assess the accuracy of imaging techniques in predicting pathologic tumor (ypT), node (ypN) stages and the circumferential resection margin (ypCRM) status of rectal cancers after preoperative chemoradiotherapy (CRT).

METHODS

Using pelvic computed tomography (CT), magnetic resonance imaging (MRI), and endorectal ultrasound (ERUS), 90 consecutive patients with locally advanced mid-to-low rectal cancer were prospectively assessed. Postirradiation T and N stages and infiltration of the CRM, as assessed by CT, MRI and ERUS, were compared with histopathologic findings.

RESULTS

The accuracy of ypT staging was low, whatever the imaging technique used (37% by CT, 34% by MRI, and 27% by ERUS), the most frequent inaccuracy being overstaging. Imaging showed a good specificity and good negative predictive values (NPV) when mural staging was grouped into ypT ≤ 3 and ypT4 categories; in particular, ERUS achieved a 92% specificity and 95% NPV. CRM involvement was correctly predicted in 71% of patients by CT (74% specificity; 93% NPV) and in 85% by MRI (88% specificity; 95% NPV). The accuracy for nodal staging was 62%, 68%, and 65% by CT, MRI and ERUS, respectively; the corresponding NPV were 88%, 78%, and 76%.

CONCLUSION

Current imaging techniques are inaccurate in restaging rectal cancer after CRT but are useful in predicting T ≤ 3 tumors, cases with negative nodes and tumor-free CRM. These findings may be of clinical relevance for planning less invasive surgery.

Multidisciplinary Rectal Cancer Management: 2nd European Rectal Cancer Consensus Conference (EURECA-CC2)

BACKGROUND AND PURPOSE

During the first decade of the 21st century a number of important European randomized studies were published. In order to help shape clinical practice based on best scientific evidence from the literature, the International Conference on 'Multidisciplinary Rectal Cancer Treatment: Looking for an European Consensus' (EURECA-CC2) was organized in Italy under the endorsement of European Society of Medical Oncology (ESMO), European Society of Surgical Oncology (ESSO), and European Society of Therapeutic Radiation Oncology (ESTRO).

METHODS

Consensus was achieved using the Delphi method. The document was available to all Committee members as a web-based document customized for the consensus process. Eight chapters were identified: epidemiology, diagnostics, pathology, surgery, radiotherapy and chemotherapy, treatment toxicity and quality of life, follow-up, and research questions. Each chapter was subdivided by a topic, and a series of statements were developed. Each member commented and voted, sentence by sentence thrice. Sentences upon which an agreement was not reached after voting round # 2 were openly debated during a Consensus Conference in Perugia (Italy) from 11 December to 13 December 2008. A hand-held televoting system collected the opinions of both the Committee members and the audience after each debate. The Executive Committee scored percentage consensus based on three categories: "large consensus", "moderate consensus", and "minimum consensus".

RESULTS

The total number of the voted sentences was 207. Of the 207, 86% achieved large consensus, 13% achieved moderate consensus, and only 3 (1%) resulted in minimum consensus. No statement was disagreed by more than 50% of the members. All chapters were voted on by at least 75% of the members, and the majority was voted on by >85%.

CONCLUSIONS

This Consensus Conference represents an expertise opinion process that may help shape future programs, investigational protocols, and guidelines for staging and treatment of rectal cancer throughout Europe.

Lymph node size in rectal cancer following neoadjuvant chemoradiation--can we rely on radiologic nodal staging after chemoradiation?

OBJECTIVES

Local excision is currently being considered as an alternative strategy for ypT0-2 rectal cancer. However, patient selection is crucial to rule out nodal disease and is performed by radiologic studies that consider size as a surrogate marker for positive nodes. The purpose of this study was to determine the difference in size between metastatic and nonmetastatic nodes and the critical lymph node size after neoadjuvant chemoradiation therapy.

METHODS

The 201 lymph nodes available from 31 patients with ypT0-2 rectal cancer were reviewed and measured. Lymph nodes were compared according to the presence of metastases and size.

RESULTS

There was a mean of 6.5 lymph nodes per patient and 12 positive nodes of the 201 recovered (6%). Ninety-five percent of all lymph nodes were <5 mm, whereas 50% of positive lymph nodes were <3 mm. Metastatic lymph nodes were significantly greater in size (5.0 vs. 2.5mm; P = 0.02). Lymph nodes >4.5 mm had a greater risk of harboring metastases (P = 0.009).

CONCLUSIONS

Patients with ypT0-2 rectal cancer following neoadjuvant chemoradiation have very small perirectal nodes. Individual metastatic lymph nodes are significantly larger. However, a significant number of lymph nodes after neoadjuvant chemoradiation (negative and positive) are <3 mm. Individual lymph node size is not a good predictor of nodal metastases and may lead to inaccurate radiologic staging.

Evaluation of a rabbit rectal VX2 carcinoma model using computed tomography and magnetic resonance imaging

AIM

To establish a rabbit rectal VX2 carcinoma model for the study of rectal carcinoma.

METHODS

A suspension of VX2 cells was injected into the rectum wall under the guidance of X-ray fluoroscopy. Computed tomography (CT) and magnetic resonance imaging (MRI) were used to observe tumor growth and metastasis at different phases. Pathological changes and spontaneous survival time of the rabbits were recorded.

RESULTS

Two weeks after VX2 cell implantation, the tumor diameter ranged 4.1-5.8 mm and the success implantation rate was 81.8%. CT scanning showed low-density foci of the tumor in the rectum wall, while enhanced CT scanning demonstrated asymmetrical intensification in tumor foci. MRI scanning showed a low signal of the tumor on T(1)-weighted imaging and a high signal of the tumor on T(2)-weighted imaging. Both types of signals were intensified with enhanced MRI. Metastases to the liver and lung could be observed 6 wk after VX2 cell implantation, and a large area of necrosis appeared in the primary tumor. The spontaneous survival time of rabbits with cachexia and multiple organ failure was about 7 wk after VX2 cell implantation.

CONCLUSION

The rabbit rectal VX2 carcinoma model we established has a high stability, and can be used in the study of rectal carcinoma.