Relevance of magnetic resonance imaging-detected pelvic sidewall lymph node involvement in rectal cancer

Management of lateral pelvic lymph nodes in rectal cancer: Is it time to reach an Agreement?

In this editorial, we proceed to comment on the article by Chua et al, addressing the management of metastatic lateral pelvic lymph nodes (mLLN) in stage II/III rectal cancer patients below the peritoneal reflection. The treatment of this nodal area sparks significant controversy due to the strategic differences followed by Eastern and Western physicians, albeit with a higher degree of convergence in recent years. The dissection of lateral pelvic lymph nodes without neoadjuvant therapy is a standard practice in Eastern countries. In contrast, in the West, preference leans towards opting for neoadjuvant therapy with chemoradiotherapy or radiotherapy, that would cover the treatment of this area without the need to add the dissection of these nodes to the total mesorectal excision. In the presence of high-risk nodal characteristics for mLLN related to radiological imaging and lack of response to neoadjuvant therapy, the risk of lateral local recurrence increases, suggesting the appropriate selection of strategies to reduce the risk of recurrence in each patient profile. Despite the heterogeneous and retrospective nature of studies addressing this area, an international consensus is necessary to approach this clinical scenario uniformly.

Current perspectives on the management of lateral pelvic lymph nodes in rectal cancer

Significant controversies exist with regards to the optimal management of lateral pelvic lymph nodes metastases (mLLN) in patients with low rectal cancer. The differing views held by Japanese and Western clinicians on the management of mLLN have been well documented. However, the adequacy of pelvic lymph node dissection (PLND) or neoadjuvant chemoradiation (NACRT) alone in addition to total mesorectal excision (TME) have recently come into question, due to the relatively high incidence of lateral local recurrences following PLND and TME, or NACRT and TME alone. Recently, a more selective approach to PLND has been suggested, involving a combination of neoadjuvant therapy, followed by PLND only to patients in whom the oncological benefit is likely to outweigh the risk of potential adverse events. A number of studies have attempted to retrospectively identify certain nodal characteristics on preoperative imaging, such as nodal size, appearance, and size reduction following neoadjuvant therapy. However, no consensus has been reached regarding the optimal criteria for a selective approach to PLND, partly due to the heterogeneity and retrospective nature of most of these studies. This review aims to provide an overview of recent evidence with regards to the diagnostic challenges, considerations for, and outcomes of the current management strategies for mLLN in rectal cancer patients.

MRI-based Radiomics Model for Preoperative Prediction of Lateral Pelvic Lymph Node Metastasis in Locally Advanced Rectal Cancer

RATIONALE AND OBJECTIVES

To develop a magnetic resonance imaging (MRI)-based radiomics model for preoperative prediction of lateral pelvic lymph node (LPLN) metastasis (LPLNM) in patients with locally advanced rectal cancer MATERIALS AND METHODS: We retrospectively enrolled 263 patients with rectal cancer who underwent total mesorectal excision and LPLN dissection. Radiomics features from the primary lesion and LPLNs on baseline MRI images were utilized to construct a radiomics model, and their radiomics scores were combined to develop a radiomics scoring system. A clinical prediction model was developed using logistic regression. A hybrid predicting model was created through multivariable logistic regression analysis, integrating the radiomics score with significant clinical risk factors (baseline Carcinoembryonic Antigen (CEA), clinical circumferential resection margin status, and the short axis diameter of LPLN). This hybrid model was presented with a hybrid clinical-radiomics nomogram, and its calibration, discrimination, and clinical usefulness were assessed.

RESULTS

A total of 148 patients were included in the analysis and randomly divided into a training cohort (n = 104) and an independent internal testing cohort (n = 44). The hybrid clinical-radiomics model exhibited the highest discrimination, with an area under the receiver operating characteristic (AUC) of 0.843 [95% confidence interval (CI), 0.706-0.968] in the testing cohort compared to the clinical model [AUC (95% CI) = 0.772 (0.589-0.856)] and radiomics model [AUC (95% CI) = 0.731 (0.613-0.849)]. The hybrid prediction model also demonstrated good calibration, and decision curve analysis confirmed its clinical usefulness.

CONCLUSION

This study developed a hybrid MRI-based radiomics model that incorporates a combination of radiomics score and significant clinical risk factors. The proposed model holds promise for individualized preoperative prediction of LPLNM in patients with locally advanced rectal cancer.

DATA AVAILABILITY STATEMENT

The data presented in this study are available on request from the corresponding author.

Lateral Pelvic Sidewall Nodes

CASE SUMMARY

A 68-year-old woman presented with rectal bleeding, urgency, and tenesmus. A digital rectal examination confirmed a craggy mass infiltrating into the sphincter complex. Follow-up colonoscopy noted a low-rectal tumor (3 cm from the dentate), and histopathology confirmed a moderately differentiated adenocarcinoma. Subsequent staging with MRI confirmed a 5-cm circumferential low-rectal neoplasm with extramural vascular invasion and threatened circumferential resection margin. The neoplasm abutted the posterior vaginal wall and was invading the internal sphincter complex. Four enlarged mesorectal nodes (>7 mm) and several enlarged right pelvic sidewall nodes (largest at 17 mm) were also observed. There was no evidence of distant disease. The patient underwent long-course neoadjuvant chemoradiotherapy. Restaging showed a good treatment response with some regression and no involvement/encroachment of the vagina. All the mesorectal nodes had reduced in size (~4 mm), and all but one of the right pelvic sidewall nodes had also decreased in size. However, 1 pelvic sidewall node (obturator fossa) still remained at 10 mm. After the tumor board discussion, a decision to proceed to abdominoperineal resection with right sidewall clearance was made. Final histopathology confirmed a moderately differentiated adenocarcinoma with no mesorectal nodal involvement (19 nodes sampled), and 1 of 7 sidewall nodes had evidence of metastatic adenocarcinoma.

Targeted lateral pelvic lymph node excision in the setting of total neoadjuvant therapy for rectal cancer

Targeted lateral pelvic node dissection in the era of total neoadjuvant therapy.

Effect of lateral lymph nodes without malignant characteristics on the prognosis of patients with rectal cancer

Background: Lateral lymph node (LLN) metastasis is a poor prognostic factor for rectal cancer patients. However, the effect of LLNs without malignant characteristics on the prognosis of rectal cancer patients has been uncertain. Methods: Consecutive patients who underwent laparoscopic-assisted low anterior resection were included. Patients with MRI-detected LLNs, but without malignant characteristics, were compared with patients with no MRI-detected LLNs. Results: The local recurrence rate was higher in the LLN-present group than in the LLN-absent group (9.8% vs 2.5%; p = 0.056). The overall survival of patients with no MRI-detected LLNs was significantly better than that of patients with MRI-detected LLNs (p = 0.021). Conclusion: The presence of LLNs, even without malignant features, may lead to worse local control and overall survival.

Systematic review and meta-analysis of long-term oncological outcomes of lateral lymph node dissection for metastatic nodes after neoadjuvant chemoradiotherapy in rectal cancer

BACKGROUND

Standard Western management of rectal cancers with pre-treatment metastatic lateral lymph nodes (LLNs) is neoadjuvant (chemo)radiotherapy (nCRT) followed by total mesorectal excision (TME). In recent years, there is growing interest in performing an additional lateral lymph node dissection (LLND). The aim of this systematic review and meta-analysis was to investigate long-term oncological outcomes of nCRT followed by TME with or without LLND in patients with pre-treatment metastatic LLNs.

METHODS

PubMed, Ovid MEDLINE, Embase, Cochrane Library and Clinicaltrials.gov were searched to identify comparative studies reporting long-term oncological outcomes in pre-treatment metastatic LLNs of nCRT followed by TME and LLND (LLND+) vs. nCRT followed by TME only (LLND-). Newcastle-Ottawa risk-of-bias scale was used. Outcomes of interest included local recurrence (LR), disease-free survival (DFS), and overall survival (OS). Summary meta-analysis of aggregate outcomes was performed.

RESULTS

Seven studies, including 946 patients, were analysed. One (1/7) study was of good-quality after risk-of-bias analysis. Five-year LR rates after LLND+ were reduced (range 3-15%) compared to LLND- (11-27%; RR = 0.40, 95%CI [0.25-0.62], p < 0.0001). Five-year DFS was not significantly different after LLND+ (range 61-78% vs. 46-79% for LLND-; RR = 0.72, 95%CI [0.51-1.02], p = 0.143), and neither was five-year OS (range 69-91% vs. 72-80%; RR = 0.72, 95%CI [0.45-1.14], p = 0.163).

CONCLUSION

In rectal cancers with pre-treatment metastatic LLNs, nCRT followed by an additional LLND during TME reduces local recurrence risk, but does not impact disease-free or overall survival. Due to the low quality of current data, large prospective studies will be required to further determine the value of LLND.

Prognostic significance of MR identified EMVI, tumour deposits, mesorectal nodes and pelvic side wall disease in locally advanced rectal cancer

AIM

To study the prognostic significance of MRI identified tumour deposits (TD), extramural vascular invasion (EMVI), lymph node metastases (LNM) and pelvic sidewall (PSW) disease in rectal cancer.

METHODS

This IRB approved study was conducted on patients with stage IIA-IIIC rectal adenocarcinoma treated with neoadjuvant long course chemoradiotherapy (LCCRT) and total mesorectal excision (TME) type of surgery between 2012-2018. A radiologist blinded to outcome reviewed staging and restaging magnetic resonance imaging (MRI) for TD, EMVI, LNM and PSW. The agreement between four radiologists was studied and we obtained outcome data from a prospectively maintained database. The prognostic significance of imaging findings was assessed.

RESULTS

A total of 297 (186 males) patients with a mean age of 47.3 (SD14.4) years were included in the study. The majority had T3 (n = 206) or T4 (n = 59) stage disease. The mean duration of follow-up was 49.3 ± 25 months (6.6-101 months). 5-year overall (OS) and disease-free survival (DFS) was 84% and 74%, respectively. Staging and restaging MRI had EMVI in 49.5% and 31.3%; TD in 47.5% and 31.6%; LNM in 61.1% and 38.1% and PSW in 11.4% and 6.1%. OS was adversely affected by EMVI, TD and PSW with the adjusted HR (aHR) of 3.32, 3.31, 3.27 for staging MRI and 2.99, 3.1, 2.81 for restaging MRI, respectively, p < 0.05. DFS was affected by EMVI (aHR = 1.85, 2.33) and TD (aHR = 1.83, 2.19), p < 0.05. Persistence of these findings after LCCRT led to worst outcome. Intra- and interobserver agreement for EMVI, TD and LN was 0.789, 0.734, 0.406 and 0.449, 0.354, 0.376, respectively, p < 0.001.

CONCLUSIONS

MRI identified that TD, EMVI and PSW disease are independent poor prognostic indicators in rectal cancer patients. Interobserver agreement for these findings was moderate to fair.

Transabdominal Ultrasonography for Preoperative Diagnosis of Lymph Node Metastasis in Colon Cancer: A Retrospective Cohort Study

Background/Aim

Although computed tomography (CT) is the standard modality for diagnosing lymph node metastasis (LNM), transabdominal ultrasonography (US) can be useful due to its high spatial resolution and use of Doppler signals to precisely analyse lymph nodes. This study aimed to evaluate the accuracy of US for lymph node assessment, establish US-based diagnostic criteria for LNM, and compare the capability of US with that of CT for the diagnosis of LNM.

Patients and Methods

This retrospective, single-institution, cohort study included patients who underwent radical surgery for clinical stage 0-III colon cancer, between March 2012 and February 2019.

Results

Overall, 34.9% (66/189) of patients had pathological LNM. The optimal US diagnostic criteria were 1) short axis ≥7 mm and short/long ratio ≥0.75 and 2) at least two of the following: the absence of hilar echoes, expansive appearance, or peripheral/mixed vascularity by the colour Doppler and/or contrast-enhanced method. Compared to CT, US showed a higher diagnostic sensitivity (54.5% vs. 43.9%; p=0.296), higher concordance with the number of pathological LNM (correlation coefficient: US, 0.42; CT, 0.27) and pathological N diagnosis (weighted ĸ: US, 0.35; CT, 0.18), and higher sensitivity for advanced LNM, including multiple LNMs (47.4% vs. 18.4%; p=0.014) and N2 stage (27.8% vs. 5.6%; p=0.177).

Conclusion

US has higher sensitivity than CT for diagnosing LNM in colon cancer, along with a more accurate preoperative diagnosis of the N stage. Additionally, US may be more helpful than CT alone for preoperatively deciding the appropriateness of neoadjuvant treatment in colon cancer with advanced LNM.

Oncological results in rectal cancer patients with a subcentimetre distal margin after laparoscopic-assisted sphincter-preserving surgery

Background

Distal resection margin (DRM) is closely associated with sphincter‐preserving surgery and oncological safety for patients with mid‐low rectal cancers. However, the optimal DRM has not been determined.

Methods

Data of 378 rectal cancer patients who underwent laparoscopic‐assisted sphincter‐preserving surgery from 2009 to 2015 were retrospectively analysed. Patients were divided into two groups based on DRM: ≤1 cm (n = 74) and >1 cm (n = 304). To minimize the differences between the two groups, propensity‐score matching on baseline features was performed.

Results

Before propensity‐score matching, no significant differences in 5‐year disease‐free survival (DFS) (92.8% versus 81.3%, P = 0.128) and 5‐year overall survival (OS) (83.7% versus 82.2%, P = 0.892) were observed in patients with DRMs of ≤1 cm (n = 74) and >1 cm (n = 304), respectively. After propensity‐score matching (1:1), there were also no significant differences in DFS (88.1% versus 78.2%, P = 0.162) and OS (84.5% versus 84.9%, P = 0.420) between the DRM of ≤1 cm group (n = 65) and >1 cm group (n = 65), respectively. A total of 44 patients received preoperative chemoradiotherapy (CRT). In this cohort, the 5‐year local recurrence (LR) rates (P = 0.118) and the 5‐year DFS rates (P = 0.298) were not significantly different between the two groups. A total of 334 patients received surgery without neoadjuvant CRT. There were also no significant differences in the 5‐year LR rates (P = 0.150) and 5‐year DFS rates (P = 0.172) between the two groups.

Conclusions

When aiming to achieve at least a 1–2 cm distal clinical resection margin, a histological resection margin of <1 cm on the DRM gave equivalent clinical outcomes to a DRM of >1 cm.

Combination of extramural venous invasion and lateral lymph node size detected with magnetic resonance imaging is a reliable biomarker for lateral lymph node metastasis in patients with rectal cancer

PURPOSE

Pathological extramural venous invasion (EMVI) is defined as the active invasion of malignant cells into veins beyond the muscularis propria in colorectal cancer. It is associated with poor prognosis and increases the risk of disease recurrence. Specific findings on MRI (termed MRI-EMVI) are reportedly associated with pathological EMVI. In this study, we aimed to identify risk factors for lateral lymph node (LLN) metastasis related to rectal cancer and to evaluate whether MRI-EMVI could be a new and useful imaging biomarker to help LLN metastasis diagnosis besides LLN size.

METHODS

We investigated 67 patients who underwent rectal resection and LLN dissection for rectal cancer. We evaluated MRI-EMVI grading score and examined the relationship between MRI-EMVI and LLN metastasis.

RESULTS

Pathological LLN metastasis was detected in 18 cases (26.9%), and MRI-EMVI was observed in 32 cases (47.8%). Patients were divided into two cohorts, according to LLN metastasis. Multivariate analyses demonstrated that higher risk of LLN metastasis was significantly associated with MRI-EMVI (P = 0.0112) and a short lateral lymph node axis (≥ 5 mm) (P = 0.0002). The positive likelihood ratios of MRI-EMVI alone, LLN size alone, and the combination of both factors were 2.12, 4.84, and 16.33, respectively. Patients negative for both showed better 2-year relapse-free survival compared to other patients (84.4% vs. 62.1%, P = 0.0374).

CONCLUSIONS

MRI-EMVI was a useful imaging biomarker for identifying LLN metastasis in patients with rectal cancer. The combination of MRI-EMVI and LLN size can improve diagnostic accuracy.

A novel classification method of lymph node metastasis in colorectal cancer

Colorectal cancer lymph node metastasis, which is highly associated with the patient's cancer recurrence and survival rate, has been the focus of many therapeutic strategies that are highly associated with the patient's cancer recurrence and survival rate. The popular methods for classification of lymph node metastasis by neural networks, however, show limitations as the available low-level features are inadequate for classification, and the radiologists are unable to quickly review the images. Identifying lymph node metastasis in colorectal cancer is a key factor in the treatment of patients with colorectal cancer. In the present work, an automatic classification method based on deep transfer learning was proposed. Specifically, the method resolved the problem of repetition of low-level features and combined these features with high-level features into a new feature map for classification; and a merged layer which merges all transmitted features from previous layers into a map of the first full connection layer. With a dataset collected from Harbin Medical University Cancer Hospital, the experiment involved a sample of 3,364 patients. Among these samples, 1,646 were positive, and 1,718 were negative. The experiment results showed the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 0.8732, 0.8746, 0.8746 and 0.8728, respectively, and the accuracy and AUC were 0.8358 and 0.8569, respectively. These demonstrated that our method significantly outperformed the previous classification methods for colorectal cancer lymph node metastasis without increasing the depth and width of the model.

Preoperative assessment and optimisation for pelvic exenteration in locally advanced and recurrent rectal cancer: A review

The pre-operative phase in planning a pelvic exenteration or extended resections is critical to optimising patient outcomes. This review summarises the key components of preoperative assessment and planning in patients with locally advanced rectal cancer (LARC) and locally recurrent rectal cancer (LLRC) being considered for potential curative resection. The preoperative period can be considered in 5 key phases: 1) Multidisciplinary meeting (MDT) review and recommendation for neoadjuvant therapy and surgery, 2) Anaesthetic preoperative assessment of fitness for surgery and quantification of risk, 3) Shared decision making with the patient and the process of informed consent, 4) Prehabilitation and physiological optimisation 5) Technical aspects of surgical planning. This review will focus on patients who have been recommended for surgery by the MDT and have completed neoadjuvant therapy. Other important considerations beyond the scope of this review are the various neoadjuvant strategies employed which in this patient group include Total Neo-adjuvant Therapy and reirradiation. Critical to improving perioperative outcomes is the dual aim of achieving a negative resection margin in a patient fit enough for extended surgery. Advanced, realistic communication is required pre-operatively and should be maintained throughout recovery. Optimising patient's physiological and psychological reserve with a preoperative prehabilitation programme is important, with physiotherapy, psychological and nutritional input. From a surgical perspective, image based technical preoperative planning is important to identify risk points and ensure correct surgical strategy. Careful attention to the entire patient journey through these 5 preoperative phases can optimise outcomes with the accumulation of marginal gains at multiple timepoints.

Prognostic Importance of MRI-Detected Extramural Venous Invasion in Rectal Cancer: A Literature Review and Systematic Meta-Analysis

PURPOSE

Extramural venous invasion (EMVI) is recognized as a poor prognostic factor in rectal cancer. There are well-documented limitations associated with pathology detection of EMVI, including variable reporting and the inability to use it preoperatively to guide neoadjuvant treatment. Magnetic resonance imaging (MRI)-detected EMVI (mrEMVI) has been proposed as an imaging biomarker. This review assesses the prognostic significance of mrEMVI on survival outcomes and whether regression of mrEMVI after neoadjuvant therapy is associated with improvements in survival.

METHODS AND MATERIALS

An electronic search was carried out using MEDLINE and EMBASE databases using the search terms "rectum," "cancer,", "MRI," and "outcomes." A systematic review and meta-analysis were carried out in accordance with Preferred Reporting for Systematic Reviews and Meta-Analyses guidelines using Review Manager software. A qualitative review was performed.

RESULTS

A total of 7399 articles were identified, of which 33 were relevant to the review question. After a qualitative assessment, 20 articles were included in the meta-analysis. Baseline mrEMVI positivity is associated with significantly worsened overall survival (hazard ratio [HR] 1.84; 95% confidence interval [CI], 1.33-2.54; P = .0001) and significantly worsened disease-free survival (HR 2.41; 95% CI, 2.02-2.89; P < .00001). After neoadjuvant treatment, a positive mrEMVI status is associated with a significantly worsened overall and disease-free survival. Only 3 papers specifically looked at mrEMVI regression, but the results show that persistent mrEMVI-positive status after treatment is associated with significantly worsened disease-free survival compared with a change in mrEMVI from positive to negative (HR 1.93; 95% CI, 1.39-2.68; P < .0001). A subgroup analysis of MRI-detected lymph node metastases showed no significant association with survival, with a hazard ratio of 1.33 (95% CI, 0.98-1.80; P = .06).

CONCLUSION

mrEMVI is significantly associated with worsened survival outcomes, both at baseline and after neoadjuvant treatment. Additionally, there is evidence that regression of mrEMVI after neoadjuvant treatment is associated with improved survival compared with mrEMVI persistence. The findings of this review emphasize the need for accurate and consistent reporting of mrEMVI status before and after neoadjuvant treatment and support the inclusion of mrEMVI into staging systems preferentially over lymph node metastases.

Deep transfer learning based on magnetic resonance imaging can improve the diagnosis of lymph node metastasis in patients with rectal cancer

Background

Lymph node (LN) metastasis is the main prognostic factor for local recurrence and overall survival of patients with rectal cancer. The accurate evaluation of LN status in rectal cancer patients is associated with improved treatment and prognosis. This study aimed to apply deep transfer learning to classify LN status in patients with rectal cancer to improve N staging accuracy.

Methods

The study included 129 patients with 325 rectal cancer screenshots of LN T2-weighted (T2W) images from April 2018 to March 2019. Deep learning was applied through a pre-trained model, Inception-v3, for recognition and detection of LN status. The results were compared to manual identification by experienced radiologists. Two radiologists reviewed images and independently identified their status using various criteria with or without short axial (SA) diameter measurements. The accuracy, positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity, and the area under the receiver operating characteristic (ROC) curve (AUC) were calculated.

Results

When the same radiologist performed the analysis, the AUC was not significantly different in the presence or absence of LN diameter measurements (P>0.05). In the deep transfer learning method, the PPV, NPV, sensitivity, and specificity were 95.2%, 95.3%, 95.3%, and 95.2%, respectively, and the AUC and accuracy were 0.994 and 95.7%, respectively. These results were all higher than that achieved with manual diagnosis by the radiologists.

Conclusions

The internal details of LNs should be used as the main criteria for positive diagnosis when using MRI. Deep transfer learning can improve the MRI diagnosis of positive LN metastasis in patients with rectal cancer.

Positive lateral pelvic lymph nodes in low rectal cancer: should we change our practice now?

BACKGROUND

The role of lateral lymph node dissection (LLND) in the treatment of patients with low rectal cancer with enlarged lateral lymph nodes (LLN+) is under investigation. Enthusiasm for LLND stems from a perceived reduction in local recurrence (LR). We aimed to compare the LR rate for LLN+ patients with LLN- patients, treated with neoadjuvant chemoradiotherapy (nCRT) and surgery, in a hospital that does not perform LLND.

METHODS

A retrospective study of all patients with clinical stage 3 low rectal cancer who completed nCRT and surgery between 2008 and 2017 at Western Health was performed. Outcomes for LLN+ patients were compared with LLN- patients. The primary outcome was LR. Secondary outcomes included distant metastases, disease-free survival and overall survival.

RESULTS

There were 110 patients treated for stage 3 low rectal cancer over 10 years. There was no significant difference in the LR rate, with one LR from 28 LLN+ patients and one LR from 82 LLN- patients (4% versus 1.2%, P = 0.44). There were no significant differences in median disease-free survival (41 versus 52 months, P = 0.19) or mean overall survival (62 versus 60 months, P = 0.80). Of all patients studied, 21% developed distant metastases.

CONCLUSION

LR after nCRT and surgery in patients with stage 3 rectal cancer is rare, irrespective of lateral pelvic node status. These data, along with the uncertain benefit and known risks of LLND, supports the continued use of standard therapy in these patients. Strategies to address distant failure in these patients should be explored.

Risk of nodal disease in patients with MRI-detected extramural vascular invasion in rectal cancer: a systematic review and meta-analysis

BACKGROUND

The impact of magnetic resonance imaging-detected extramural vascular invasion (mrEMVI) in distant metastasis is well known but its correlation with prevalence of lymph node metastasis is less studied. The aim of this systematic review and meta-analysis was to assess the prevalence of nodal disease in mrEMVI-positive and negative cases in rectal cancer.

METHODS

Following guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses, a systematic literature search in PubMed, Web of Science, Cochrane Library, and EMBase was carried out to identify relevant studies published up to May 2019.

RESULTS

Our literature search generated 10 studies (863 and 1212 mrEMVI-positive and negative patients, respectively). The two groups (mrEMVI-positive and negative) were significantly different in terms of nodal disease status (odds ratio [OR] 3.15; 95% confidence interval [CI] 2.12-4.67; p < 0.001). The prevalence of nodal disease was 75.90% vs 52.56% in the positive mrEMVI vs negative mrEMVI group, respectively (p < 0.001). The prevalence of positive lymph node in positive mrEMVI patients treated with neoadjuvant/adjuvant chemoradiotherapy (nCRT/CRT) (OR 2.47; 95% CI 1.65-3.69; p < 0.001) was less compared with the patients who underwent surgery alone (OR 6.25; 95% CI 3.74-10.44; p < 0.001).

CONCLUSION

The probability of positive lymph nodes in cases of positive mrEMVI is distinctly greater compared with negative cases in rectal cancer. Positive mrEMVI indicates risk of nodal disease prevalence increased by threefold in rectal cancer.

Lateral lymph node dissection reduces local recurrence of locally advanced lower rectal cancer in the absence of preoperative neoadjuvant chemoradiotherapy: a systematic review and meta-analysis

Background

The impact of lateral lymph node dissection (LLND) in locally advanced lower rectal cancer remains controversial. This study is to compare total mesorectal excision (TME) with or without LLND in lower rectal cancer cases of stage II/III.

Methods

The electronic databases were systematically searched that compared TME with or without LLND among patients with lower rectal cancer in clinical stage II/III. Subgroup analysis was performed considering neoadjuvant chemoradiotherapy (nCRT). The hazard ratios (HR), relative risk (RR), and weighted mean difference (WMD) were pooled.

Results

Twelve studies of 4458 patients of this meta-analysis demonstrate, LLND alone significantly reduced the local recurrence rate of patients who did not receive nCRT (RR 0.71, P = 0.004), while the difference was not significant when combined with nCRT (RR 0.70, P = 0.36). The analysis shows TME with LLND was associated with significantly longer operation time (WMD 90.73 min, P < 0.001), more intraoperative blood loss (WMD 303.20 mL, P < 0.001), and postoperative complications (RR = 1.35, P =0.02). Whereas urinary dysfunction (RR 1.44, P = 0.38), sexual dysfunction (RR 1.41, P = 0.17), and postoperative mortality (RR = 1.52, P = 0.70), were similar between these two groups. Statistically, no significant differences were observed in OS (HR 0.93, P = 0.62), DFS (HR 0.99, P = 0.96), total recurrence (RR 0.98, P = 0.83), lateral recurrence (RR 0.49, P = 0.14), or distal recurrence (RR 0.95, P = 0.78) between these two groups regardless of whether nCRT was performed or not.

Conclusions

The study shows LLND alone decreases the local recurrence without using nCRT irrespective of the survival advantage in locally advanced lower rectal cancer. The benefit of controlling local recurrence by LLND alone makes us reconsider the usage of nCRT with LLND.

Trial registration

The protocol for this meta-analysis was registered prospectively with PROSPERO (CRD42020135575) on 16 May 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-020-02078-1.

Incidence and treatment of positive pelvic sidewall lymph nodes in patients with rectal cancer

AIM

The involvement of pelvic sidewall (PSW) lymph nodes in rectal cancer is a marker of locally advanced disease and poor prognosis. Eastern countries generally advocate lateral lymph node dissection (LLND) over the Western approach of neoadjuvant chemoradiotherapy and more limited surgery. The aim of this study was to evaluate how these advanced cancers were treated in three UK Health Boards.

METHODOLOGY

This was a retrospective review of three colorectal multidisciplinary team meetings from 2008 to 2016. All patients with rectal cancer and suspicious PSW lymph nodes on pretreatment MRI were included.

RESULTS

There were 153 (6.2%) patients who met the inclusion criteria from a total of 2461 diagnosed rectal cancers. There was significant variability between the three centres with surgical intervention ranging from 59.2% to 84.4%, P = 0.015. There were 81 patients who had neoadjuvant chemoradiotherapy prior to surgery; of these 67 (82.7%) still had positive PSW nodes on the restaging MRI, but only 13 (19.4%) had LLND. There was no difference in local recurrence (15.3% vs 11.8%, P = 0.66), 5-year overall survival (69.2% vs 80.1%, P = 0.16) or 5-year disease-free survival (69.2% vs 79.4%, P = 0.72) between patients having LLND and those receiving standard neoadjuvant treatment followed by total mesorectal excision surgery.

CONCLUSIONS

This study has demonstrated that rectal cancer patients with PSW positive nodal disease have advanced disease, mostly of the lower rectum, and receive a highly heterogeneous spectrum of therapies, even within a relatively small geographical area. Greater accuracy in our preoperative staging is needed to select those patients who will benefit from LLND surgery.

Lateral pelvic lymph node dissection in the management of locally advanced low rectal cancer: Summary of the current evidence

Lateral pelvic lymph nodes (LPLN) are a major site for local recurrence following curative resection for low locally advanced rectal cancer. Ongoing advances in imaging techniques have improved predicting LPLN metastasis (LPLNM) during pre-operative staging. However, there is ongoing debate on optimal management of this subgroup of patients with variation between guidance of different societies. In Japan, LPLNM is considered as local disease and addressed by lateral pelvic node dissection (LPLND) in addition to total mesorectal excision (TME). However, in the west, LPLNM is considered as metastatic disease and those patients are offered neoadjuvant chemoradiotherapy (nCRT) followed by TME surgery. The potential surgical risks and morbidity associated with LPLND as well as the uncertainty of the oncological outcome have raised the concern that patients with locally advanced low rectal cancer with LPLNM could be over or under-treated. A comprehensive review of literature was performed, summarizing the current evidence on available modalities for predicting LPLNM, the role of LPLND in the management of advanced low rectal cancer and the available surgical approaches with their impact on surgical and oncological outcomes. LPLND is associated with increased operative time, blood loss and post-operative morbidity. The potential benefits for local disease control and survival still awaits high quality studies. There has been increasing number of reports of the use minimally invasive approaches in LPLND in an attempt to reduce post-operative complications. There is need for high quality evidence to define the role of LPLND in management of patients with advanced low rectal cancer.

Radiological staging of rectal cancer in a resource limited setting

Objective

Current guidelines on rectal cancer (RC) management recommend pre-operative MRI for loco-regional staging and CT for staging of metastases. This allows appropriate selection of patients for chemo-radiotherapy (CRT). However, MRI is not freely available in many low-income countries. We assessed the status of pre-operative imaging for RC in Sri Lanka and evaluated the performance of CT in RC staging.

Results

A pre-tested interview-administered questionnaire was used to assess the pre-operative use of MRI and CT in RC. CT findings from 37 RC patients were then compared with histopathology findings. Of the 64 surgeons interviewed, 57 (89.1%) did not request an MRI for their RC patients. Reasons cited included limited availability and long waiting times due to competing health needs. A CT was requested by all. In RC, the overall accuracy of CT for T staging was 43.2% and 29.7% of T1–T2 tumours were over-staged as T3. The overall accuracy of CT for regional lymph node staging was 70.3%. In summary, CT alone is not suitable for RC staging in any setting. It leads to over-staging and patients may thus receive unnecessary CRT. Steps must be taken to improve access to pre-operative MRI among Sri Lankan RC patients.

Magnetic resonance imaging performed before and after preoperative chemoradiotherapy in rectal cancer: predictive factors of recurrence and prognostic significance of MR-detected extramural venous invasion

PURPOSE

To evaluate the role of magnetic resonance imaging (MRI) performed before and after neoadjuvant chemoradiotherapy (nCRT) in predicting risk of recurrence in rectal cancer and to investigate the prognostic significance of MR-detected extramural venous invasion (mr-EMVI) and of its regression after nCRT.

METHODS

During 2005-2016, 87 patients with rectal cancer underwent pre- and post-nCRT MRI before surgery. Two radiologists independently reviewed MR examinations retrospectively, assessing T stage, nodal involvement, circumferential resection margin (CRM) status, and mr-EMVI. All four parameters assessed in pre- and post-nCRT MRI were correlated with the risk of recurrence. Correlation with disease-free survival (DFS) was investigated for significant predictive factors in pre-nCRT MRI and for mr-EMVI and its possible regression in post-nCRT MRI.

RESULTS

15 of 87 patients developed recurrence, with a relapse-rate of 17.2%. Statistical analysis showed a significant correlation between CRM involvement and mr-EMVI assessed in pre-nCRT MRI and the risk of recurrence; 3 years-DFS in patients positive for these two parameters was significantly shorter compared with negatives. In post-nCRT MRI, all four parameters correlated significantly with recurrence: mr-EMVI affected significantly 3 years-DFS and its regression after nCRT correlated with a trend toward improvement of survival outcomes, although not statistically significant.

CONCLUSIONS

CRM involvement and mr-EMVI assessed in pre-nCRT MRI should be considered early predictive factors of recurrence in rectal cancer. MRI performed after nCRT has a significant value in predicting risk of recurrence: mr-EMVI confirmed to be a poor prognosis predictor and its regression or persistence after nCRT could have influences on treatment and follow-up strategies.

Staging of Locally Advanced Rectal Cancer Beyond TME

The management of rectal cancer is complex and continually evolving. With advancements in technology and the use of multidisciplinary teams to guide the treatment decision making, staging, oncologic, and functional outcomes are improving, and the management is moving toward personalized treatment strategies to optimize each individual patient's outcomes. Key in this evolution is imaging. Magnetic resonance imaging (MRI) has emerged as the dominant method of pelvic imaging in rectal cancer, and use of MRI for staging is best practice in multiple international guidelines. MRI allows a noninvasive assessment of the tumor site, relationship to surrounding structures, and provides highly accurate rectal cancer staging, which is necessary for determining the appropriate treatment strategy. However, the applications of MRI extend far beyond pretreatment staging. MRI can be used to predict outcomes in locally advanced rectal cancer and guide the surgical or nonsurgical plan, serving as a predictive and prognostic biomarker. With continued MRI hardware improvement and new sequence development, MRI may offer new perspectives in the assessment of treatment response and new innovations that could provide better insight into the staging, restaging, and outcomes with rectal cancer.

Postoperative morbidity and mortality after mesorectal excision with laparoscopic versus conventional open lateral lymph node dissection for advanced rectal cancer: A meta-analysis

Lateral lymph node dissection (LLND) is a challenging procedure due to its technical difficulty and higher incidence of surgical morbidity, thus the purpose of this study is to compare the postoperative morbidity and mortality between laparoscopic and conventional open LLND after mesorectal excision (ME) for advanced rectal cancer. A comprehensive search was conducted in August 2019 based on data from PubMed, Embase, Cochrane Library, CNKI and Wanfang Data to identify relevant studies, and studies comparing laparoscopic with conventional open LLND were included. Seven studies with 335 cases in the laparoscopic LLND group and 841 cases in the conventional open LLND group were finally included. Compared with the conventional open LLND group, the laparoscopic LLND group enjoys a lower postoperative morbidity (OR = 0.47,95% CI [0.23, 0.97], P = 0.04), same postoperative mortality (Postoperative mortality in both groups was zero), shorter length of postoperative hospitalization (WMD = -5.30, 95% CI [-8.42, -2.18], P = 0.0009), less wound infection (OR = 0.40,95% CI [0.21, 0.77], P = 0.006), less intestinal obstruction (OR = 0.50,95% CI [0.29, 0.84], P = 0.009), and less urinary retention (OR = 0.61,95% CI [0.38, 0.97], P = 0.04). There were no significant differences in the incidence of anastomotic leakage, abdominal pelvic abscess and urinary tract infection between the two groups (P > 0.05). But in the sensitivity analysis, there was a significant change of urinary tract infection (OR = 0.22, 95%CI [0.06, 0.89], P = 0.03), and the degree of between-study heterogeneity decreased greatly. In conclusion, laparoscopic LLND may be a better alternative to conventional open LLND for advanced rectal cancer with lower postoperative morbidity and shorter postoperative hospital stay.

Rectal cancer lateral pelvic sidewall lymph nodes: a review of controversies and management

BACKGROUND

The management of lateral pelvic lymphadenopathy in low rectal cancer poses an oncological and technical challenge. Interpretation of the literature is confounded by different approaches to management in the East and West, and a lack of randomized data from which to draw accurate conclusions regarding the optimal approach. Recent collaboration between Eastern and Western centres has increased the standardization of care. Despite this, significant differences in international guidelines remain. The aim of this review was to appraise the available literature and propose a management algorithm.

METHODS

A literature review of all relevant studies was performed to summarize the historical evidence, as well as establish the significance of clinically positive lateral pelvic sidewall nodes, and the role of neoadjuvant chemoradiotherapy and lateral pelvic node dissection. A management algorithm was developed based on this review of the literature.

RESULTS

The management of pelvic sidewall lymphadenopathy in rectal cancer is non-standardized, with geographical differences. The mechanism of lateral lymphatic spread is well defined; the risk increases with lower tumour height and advanced T category. Existing data indicate that acceptable disease-free and overall survival can be achieved by neoadjuvant chemoradiotherapy with selective lateral pelvic node dissection.

CONCLUSION

Suspicious lateral pelvic sidewall nodes, particularly in the internal iliac chain, should be considered as resectable locoregional disease, and surgery offered for enlarged nodes that do not respond to neoadjuvant chemoradiotherapy.

Does adding lateral pelvic lymph node dissection to neoadjuvant chemotherapy improve outcomes in low rectal cancer?

PURPOSE

Lateral pelvic lymph node metastasis occurs in 15 to 20% of patients with locally advanced low rectal cancer which increases risk of local recurrence and reduced survival following neoadjuvant chemoradiotherapy (nCRT) and total mesorectal excision (TME). Adding lateral pelvic lymph node dissection (LPLND) could improve outcomes in those patients. This review aims to determine if the addition of LPLND to the conventional management of advanced rectal cancer would yield improved outcomes.

METHODS

OVID Medline, Cochrane, Clinicaltrials.gov , EMBASE, Clinicaltrialsregister.eu, Web of Knowledge and CABAbstracts were searched using the following keywords: 'lateral pelvic lymph node dissection', 'pelvis lymphadenectomy', 'chemoradi*', 'rectal cancer', 'rectal neoplasm', 'rectal carcinoma' and 'rectal tumour'. Studies were included if they were in English and included rectal cancer patients that had nCRT, rectal resection ± LPLND. Primary outcome was 3-year and 5-year local recurrence. Secondary outcome was 3-year and 5-year overall survival.

RESULTS

Six studies were identified with 1210 patients who had nCRT and TME, and 268 patients who had nCRT and rectal resection plus LPLND. Patients who had LPLND had non-significant lower 3-year and 5-year local recurrence rate compared with those who did not (p = 0.10 and p = 0.12, respectively). They demonstrated a lower 3-year overall survival but higher 5-year overall survival and both were not significant (p = 0.81 and p = 0.57, respectively).

CONCLUSION

Available evidence suggests that there is no significant reduction in local recurrence rates or improved survival from LPLND to the current treatment modalities. Further studies are required to define the role of lateral pelvic lymph node dissection in low rectal cancer.

Selective lateral lymph node dissection after neoadjuvant chemoradiotherapy in rectal cancer

BACKGROUND

Lateral lymph node metastasis is one of the leading causes of local recurrence in patients with advanced mid or low rectal cancer. Neoadjuvant chemoradiotherapy (NCRT) can effectively reduce the postoperative recurrence rate; thus, NCRT with total mesorectal excision (TME) is the most widely accepted standard of care for rectal cancer. The addition of lateral lymph node dissection (LLND) after NCRT remains a controversial topic.

AIM

To investigate the surgical outcomes of TME plus LLND, and the possible risk factors for lateral lymph node metastasis after NCRT.

METHODS

This retrospective study reviewed 89 consecutive patients with clinical stage II-III mid or low rectal cancer who underwent TME and LLND from June 2016 to October 2018. In the NCRT group, TME plus LLND was performed in patients with short axis (SA) of the lateral lymph node greater than 5 mm. In the non-NCRT group, TME plus LLND was performed in patients with SA of the lateral lymph node greater than 10 mm. Data regarding patient demographics, clinical workup, surgical procedure, complications, and outcomes were collected. Multivariate logistic regression analysis was performed to evaluate the possible risk factors for lateral lymph node metastasis in NCRT patients.

RESULTS

LLN metastasis was pathologically confirmed in 35 patients (39.3%): 26 (41.3%) in the NCRT group and 9 (34.6%) in the non-NCRT group. The most common site of metastasis was around the obturator nerve (21/35) followed by the internal iliac artery region (12/35). In the NCRT patients, 46% of patients with SA of LLN greater than 7 mm were positive. The postoperative 30-d mortality rate was 0%. Two (2.2%) patients suffered from lateral local recurrence in the 2-year follow up. Multivariate analysis showed that cT4 stage (odds ratio [OR] = 5.124, 95% confidence interval [CI]: 1.419-18.508; P = 0.013), poor differentiation type (OR = 4.014, 95%CI: 1.038-15.520; P = 0.044), and SA ≥ 7 mm (OR = 7.539, 95%CI: 1.487-38.214; P = 0.015) were statistically significant risk factors associated with LLN metastasis.

CONCLUSION

NCRT is not sufficient as a stand-alone therapy to eradicate LLN metastasis in lower rectal cancer patients and surgeons should consider performing selective LLND in patients with greater LLN SA diameter, poorer histological differentiation, or advanced T stage. Selective LLND for NCRT patients can have a favorable oncological outcome.

Management of synchronous lateral pelvic nodal metastasis in rectal cancer in the era of neoadjuvant chemoradiation: A systemic review

BACKGROUND

Lateral pelvic lymph node (LLN) metastasis (LLNM) occur in up to 28% of patients with low rectal tumours. While prophylactic lateral pelvic lymph node dissection (LLND) has been abandoned by most western institutions in the era of neoadjuvant chemoradiation therapy (CRT), the role of selective LLND in patients with enlarged LLN on pre-CRT imaging remains unclear. Some studies have shown improved survival and recurrence outcomes when LLNs show “response” to CRT. However, no management algorithm exists to differentiate treatment for “responders” vs “non-responders”.

AIM

To determine if selective LLND in patients with enlarged LLNs results in improved survival and recurrence outcomes.

METHODS

A systemic search of PubMed and Embase databases for studies reporting on patients with synchronous radiologically suspicious LLNM (s-LLNM) in rectal cancer receiving preoperative-CRT was performed.

RESULTS

Fifteen retrospective, single-centre studies were included. 793 patients with s-LLNM were evaluated: 456 underwent TME while 337 underwent TME with LLND post-CRT. In the TME group, local recurrence (LR) rates range from 12.5% to 36%. Five-year disease free survival (DFS) was 42% to 75%. In the TME with LLND group, LR rates were 0% to 6%. Five years DFS was 41.2% to 100%. Radiological response was seen in 58%. Pathologically positive LLN was found in up to 94% of non-responders vs 0% to 20% in responders. Young age, low tumour location and radiological non-response were associated with final positive LLNM and lowered DFS.

CONCLUSION

LLND is associated with local control in patients with s-LLNM. It can be performed in radiological non-responders given a large majority represent true LLNM. Its role in radiological responders should be considered in selected high risk patients.

Risk factors and therapeutic significance of inguinal lymph node metastasis in advanced lower rectal cancer

PURPOSE

This study aimed to clarify predictors and therapeutic significance of inguinal lymph node metastasis (ILNM) in patients with rectal cancer.

METHODS

Patients with rectal adenocarcinoma invading the anal canal who underwent curative surgery between 2003 and 2019 were retrospectively reviewed. Synchronous and metachronous lymph node (LN) metastasis were collectively defined as final nodal metastasis (f-LNM). Factors associated with f-LNM were analyzed. Moreover, the "modified therapeutic value index," defined by multiplication of the frequency of f-LNM by the 5-year overall survival rate for patients who received treatment for f-LNM, was calculated for each LN area.

RESULTS

A total of 145 patients were enrolled (16 patients with f-ILNM). To predict f-ILNM, the cutoff of the inguinal lymph node (ILN) diameter of 8.5 mm gave an area under the curve of 0.889. Dentate line involvement (odds ratio 33.4) and ILN larger than the cutoff of 8 mm (odds ratio 11.9) were independently associated with f-ILNM. The modified therapeutic value indices of the inguinal, lateral pelvic, and mesorectal LNs in the entire population were 6.1, 8.2, and 20.3 points, respectively. In patients with dentate line invasion by cancer, the index of the ILN increased to 11.7 points. In patients with an ILN > 8 mm, the index further increased to 21.1 points.

CONCLUSION

Dentate line involvement and ILN > 8 mm predicted the development of ILNM in patients with rectal cancer invading the anal canal. Treatment of the ILN should be considered for patients with the above predictors given the significant therapeutic outcomes.

Laparoscopic and robotic lateral lymph node dissection for rectal cancer

In the era of neoadjuvant chemoradiotherapy/radiotherapy and total mesorectal excision, overall oncological outcomes after curative resection of rectal cancer are excellent, with local recurrence rates as low as 5–10%. However, lateral nodal disease is a major cause of local recurrence after neoadjuvant chemoradiotherapy/radiotherapy and total mesorectal excision. Patients with lateral nodal disease have a local recurrence rate of up to 30%. The oncological benefits of lateral pelvic lymph node dissection (LPLND) in reducing local recurrence, particularly in the lateral compartment, have been demonstrated. Although LPLND is not standard in Western countries, technical improvements in minimally invasive surgery have resulted in rapid technical standardization of this complicated procedure. The feasibility and short- and long-term outcomes of laparoscopic and robotic LPLND have been reported widely. A minimally invasive approach has the advantages of less bleeding and providing a better surgical view of the deep pelvic anatomy than an open approach. With precise autonomic nerve preservation, postoperative genitourinary dysfunction has been reported to be minimal. We review recent evidence on the management of lateral nodal disease in rectal cancer and technical improvements of LPLND, focusing on laparoscopic and robotic LPLND.

Lateral Lymph Node Metastases in Locally Advanced Low Rectal Cancers May Not Be Treated Effectively With Neoadjuvant (Chemo)Radiotherapy Only

Background: In the West, pre-treatment abnormal lateral lymph nodes (LLN+) in patients with a low locally advanced rectal cancer (AJCC Stage III), are treated with neoadjuvant (chemo)radiotherapy (nCRT), without a lateral lymph node dissection (LLND). It has been suggested, however, that LLN+ patients have higher local recurrence (LR) rates than similarly staged patients with abnormal mesorectal lymph nodes only (LLN−), but no comparative data exist. Therefore, we conducted this international multi-center study in the Netherlands and Australia of Stage III rectal cancer patients with either LLN+ or LLN− to compare oncological outcomes from both groups.

Materials and Methods: Patients with Stage III low rectal cancer with (LLN+ group) or without (LLN− group) abnormal lateral lymph nodes on pre-treatment MRI were included. Patients underwent nCRT followed by rectal resection surgery with curative intent between 2009 and 2016 with a minimum follow-up of 2-years. No patient had a LLND. Propensity score matching corrected differences in baseline characteristics.

Results: Two hundred twenty-three patients could be included: 125 in the LLN+ group and 98 in the LLN− group. Between groups, there were significant differences in cT-stage and in the rate of adjuvant chemotherapy administered. Propensity score matching resulted in 54 patients in each group, with equal baseline characteristics. The 5-year LR rate in the LLN+ group was 11 vs. 2% in the LLN− group (P = 0.06) and disease-free survival (DFS) was 64 vs. 76%, respectively (P = 0.09). Five-year overall survival was similar between groups (73 vs. 80%, respectively; P = 0.90).

Conclusions: In Western patients with Stage III low rectal cancer, there is a trend toward worse LR rate and DFS rates in LLN+ patients compared to similarly staged LLN− patients. These results suggest that LLN+ patients may currently not be treated optimally with nCRT alone, and the addition of LLND requires further consideration.

The Prognostic Significance of Isolated Tumor Cells Detected Within Lateral Lymph Nodes in Rectal Cancer Patients After Laparoscopic Lateral Lymph Node Dissection

Background: To clarify the definite incidence of isolated tumor cells (ITCs) in lateral lymph nodes (LLNs) and its prognostic significance in rectal cancer patients after laparoscopic lateral lymph node dissection (lap-LLND). Methods: Consecutive rectal cancer patients who underwent standard total mesorectal excision (TME) and lap-LLND were included. All the LLNs were re-examined by hematoxylin and eosin (H&E) stain and immunohistochemistry (IHC) with a monoclonal antibody against cytokeratin 20 to confirm the status of ITCs, micrometastasis, and overt metastasis. Clinicopathological characteristics and oncological outcomes were analyzed. Results: Forty-six patients with TME and lap-LLND were included. Twelve (26.1%) patients with overt metastasis were identified. A total of 705 LLNs from 46 patients were re-examined by H&E with IHC, and ITCs were detected in 27 (3.8%) lymph nodes from 11 (23.9%) patients. No LLNs micrometastasis was found. Patients with overt metastasis had more advanced N stage and more perirectal lymph nodes metastasis. Three patients with LLNs recurrence were identified and lung metastasis was the most common metastatic site. Compared with patients with ITCs and without any metastasis, patients with overt metastasis had worse 3-year cumulative overall survival (85.7%, 83.9%, and 53.3%, respectively) and 3-year cumulative disease-free survival (85.7%, 85.2%, and 43.8%, respectively). Patients with ITCs had higher overall recurrence than patients without any metastasis (42.9% versus 11.5%, P = .035). Multivariate analysis showed that ITC status in LLNs was a significant prognostic factor (hazard ratio 2.689, 95% confidence interval 1.072-6.747; P = .035). Conclusion: ITCs in LLNs detected by the IHC method like overt metastasis detected by H&E staining contributed to higher overall recurrence.

Oncological Outcomes of Patients with Locally Advanced Rectal Cancer and Lateral Pelvic Lymph Node Involvement

INTRODUCTION

The optimal management of patients with radiologically positive lateral pelvic lymph nodes in locally advanced rectal cancer remains unclear. We compared local recurrence rates and oncological outcomes of patients with locally advanced cancer with and without lateral pelvic lymph nodes.

METHODS

Patients who underwent curative surgery for stage III rectal adenocarcinoma between 2009 and 2014 and had a preoperative MRI at our institution as well as preoperative neoadjuvant treatment were included. Patients with positive lateral pelvic lymph nodes (iliac or obturator nodes) on preoperative MRI (LPND +) were compared to patients with no lateral pelvic nodal disease (LPND -). Data were collected from a prospectively maintained institutional database. Differences between the groups were compared in univariate analysis. Log-rank test was used to evaluate overall and disease-free survival between the groups.

RESULTS

A total of 125 patients met inclusion criteria with a mean age of 56.3 ± 12.2 and 75% were male. Median follow-up was 44 months (IQR 32, 106). Positive LPND was present on preoperative MRI in 43/125 (34.4%) patients who were in the LPND (+) group. Seventeen out of 43 patients had a post-neoadjuvant treatment MRI and 15 patients had a decrease in size of nodes or disappearance of LPND. On univariate analysis, LPND (+) and LPND (-) groups were comparable. Local recurrence rates were higher in the LPND (+) group, although this was not statistically significant (16.3% vs. 6%, p = 0.06). Overall and disease-free survival rates were comparable between the LPND (+) and LPND (-) groups (p = 0.97, p = 0.51).

CONCLUSIONS

Management of patients with advanced rectal cancer and radiologically positive lateral pelvic lymph nodes is challenging due to high local recurrence rates. Further studies are needed to develop care pathways for the optimal treatment processes.

Radiation Therapy Dose Escalation to Clinically Involved Pelvic Sidewall Lymph Nodes in Locally Advanced Rectal Cancer

Purpose

Lateral pelvic sidewall lymph nodes (PSW LN) may be involved in up to 24% of locoregionally advanced rectal cancers. PSW LN are not resected in total mesorectal excision (TME), and no standard of care regarding the management of PSW LN exists in the United States. We assessed our institutional experience of preoperative radiation therapy (RT) boost to clinically involved PSW LN that were not planned for resection.

Methods and materials

Data from all patients with rectal adenocarcinoma treated between 2006 and 2018 were reviewed to identify those who received a cumulative dose of >50.4 Gy to suspicious PSW LN during neoadjuvant chemoradiation therapy (nCRT). Demographic, cancer characteristic, treatment, and toxicity data were derived from the chart.

Results

Of a total of 261 patients, 12 patients met the inclusion criteria. The median age was 47.5 years, and 83% of patients were men. All patients had T3/4 disease, 17% of patients had N1b disease and the remainder had N2 disease, and 33% had M1 disease (all ≤2 metastases). Seventy-five percent of patients had moderately or poorly differentiated histology. The mean distance from the anal verge was 4.85 cm (range, 2-8.9 cm), and 58% had ≥2 PSW LN with an average short axis diameter of 1.11 cm (range, 0.4-3.2 cm). Boost doses ranged from 53.48 Gy to 60.2 Gy in 27 to 30 fractions (1.8-2.15 Gy/fraction). The median follow-up time was 18 months. One patient who received concurrent capecitabine and irinotecan had grade 3 perineal dermatitis and anemia during nCRT. The median hospitalization time for TME was 6.5 days. Within 90 days of TME, 1 patient required surgical exploration for perineal wound breakdown, and another required a blood transfusion for anemia. At the time of the last follow up, 75% of patients were alive. Local control at 12 months was 90%.

Conclusions

RT dose escalation to nonresected PSW LN during nCRT was well tolerated with a low risk of acute toxicity and perioperative complications and has a high rate of local control at 12 months. RT boost warrants further study in patients with clinically involved nonresected PSW LN.

Dual energy CT is useful for the prediction of mesenteric and lateral pelvic lymph node metastasis in rectal cancer

The aim of the present retrospective study was to investigate the predictability of dual-energy computed tomography (DECT) for pararectal lymph node (PRLN) metastasis and lateral pelvic lymph node (LPLN) metastasis in rectal cancer (RC). The present study involved 44 patients with RC who were examined by DECT and then underwent surgery between May 2015 and September 2017. LPLN dissection was performed in 24 patients. The normalized iodine concentration (nIC), the ratio of iodine concentration in the lymph node (LN) to that in the common iliac artery on DECT, of the largest PRLN and LPLN was calculated, and the association between LN metastasis and nIC was analyzed. The median nIC value for PRLNs was significantly lower in PRLN metastasis-positive cases compared with PRLN metastasis-negative cases in the arterial phase [0.18 vs. 0.25; P=0.01; cut-off, 0.24; area under the curve (AUC), 0.733] and portal phase (0.47 vs. 0.61; P=0.03; cut-off, 0.59; AUC, 0.701). A significant difference was not identified between the median maximum short axis diameter of PRLNs in PRLN metastasis-positive and metastasis-negative cases (7.6 vs. 6.4 mm; P=0.33). The nIC for LPLNs was not significantly different between LPLN metastasis-positive and metastasis-negative cases in the arterial phase (0.15 vs. 0.21; P=0.19); but was significantly lower in LPLN metastasis-positive cases compared with LPLN metastasis-negative cases in the portal phase (0.29 vs. 0.56; P=0.04; cut-off, 0.29; AUC, 0.877). The maximum short axis diameter of LPLNs was significantly larger in metastasis-positive cases compared with LPLN metastasis-negative cases (9.1 vs. 4.8 mm; P=0.03; cut-off, 7.0 mm; AUC, 0.912). In conclusion, the nIC was identified to be significantly lower in metastasis-positive cases, which may be useful for the prediction of PRLN and LPLN metastases. A combination of size-based diagnosis and DECT may increase the accuracy of preoperative diagnosis.

Optimal diagnostic method using multidetector-row computed tomography for predicting lymph node metastasis in colorectal cancer

Background

Prediction of nodal involvement in colorectal cancer is an important aspect of preoperative workup to determine the necessity of preoperative treatment and the adequate extent of lymphadenectomy during surgery. This study aimed to investigate newer multidetector-row computed tomography (MDCT) findings for better predicting lymph node (LN) metastasis in colorectal cancer.

Methods

Seventy patients were enrolled in this study; all underwent MDCT prior to surgery and upfront curative resection for colorectal cancer. LNs with a short-axis diameter (SAD) ≥ 4 mm were identified on MDCT images, and the following measures were recorded by two radiologists independently: two-dimensional (2D) SAD, 2D long-axis diameter (LAD), 2D ratio of SAD to LAD, 2D CT attenuation value, three-dimensional (3D) SAD, 3D LAD, 3D SAD to LAD ratio, 3D CT attenuation value, LN volume, and presence of extranodal neoplastic spread (ENS), as defined by indistinct nodal margin, irregular capsular enhancement, or infiltration into adjacent structures.

Results

Forty-six patients presented 173 LNs with a SAD ≥ 4 mm, while 24 patients exhibited pathologically confirmed LN metastases. Receiver operating characteristic analysis revealed that 2D LAD was the most sensitive measure for LN metastases with an area under the curve of 0.752 (cut-off value, 7.05 mm). When combined with CT findings indicating ENS, 2D LAD (> or ≤ 7 mm) showed enhanced predictive power for LN metastases (area under the curve, 0.846; p < 0.001).

Conclusions

LAD in axial MDCT imaging is the most sensitive measure for predicting colorectal LN metastases, especially when MDCT findings of ENS are observed.

Predictive factors of pathological lateral pelvic lymph node metastasis in patients without clinical lateral pelvic lymph node metastasis (clinical stage II/III): The analysis of data from the clinical trial (JCOG0212)

BACKGROUND

Mesorectal excision (ME) is the standard surgical procedure for lower rectal cancer. However, in Japan, total or tumor-specific ME with lateral pelvic lymph node dissection (LLND) is the standard surgical procedure for patients with clinical stages II or III lower rectal cancer, because lateral pelvic lymph node metastasis occasionally occurs in these patients. The aim of study was to elucidate the predictive factors of pathological lateral pelvic lymph node metastasis in patients without clinical lateral pelvic lymph node metastasis.

METHODS

Data form the clinical trial (JCOG0212) was analyzed. The JCOG0212 was a randomized controlled trial to confirm the non-inferiority of mesorectal excision alone to mesorectal excision with lateral lymph node dissection for clinical stage II/III patients who don't have clinical lateral pelvic lymph node metastasis in terms of relapse free survival. This study was conducted at a multitude of institution33 major hospitals in Japan. Among the 351 patients who underwent lateral lymph node dissection in the JCOG0212 study, 328 patients were included in this study. Associations between pathological lateral pelvic lymph node metastasis and preoperative and postoperative factors were investigated. The preoperative factors were age, sex, clinical stage, tumor location, distance from anal verge, tumor size, and short-axis diameter of lateral pelvic lymph node on computed tomography and the postoperative factors were pathological T, pathological N, and histological grade.

RESULTS

Among the 328 patients, 24 (7.3%) had pathological lateral pelvic lymph node metastasis. In multivariable analysis of the preoperative factors, patient age (p = 0.067), tumor location (p = 0.025), and short-axis diameter of lateral pelvic lymph node (p = 0.002) were significantly associated with pathological lateral pelvic lymph node metastasis.

CONCLUSIONS

Patient age, tumor location, and short-axis diameter of lateral pelvic lymph node were predictive factors of pathological lateral pelvic lymph node metastasis.

The short-term outcomes of robotic sphincter-preserving surgery for rectal cancer: comparison with open and laparoscopic surgery using a propensity score analysis

PURPOSE

The aim of this study is to clarify the short-term outcomes of robotic sphincter-preserving surgery for rectal cancer in a retrospective study.

METHODS

The short-term outcomes of robotic sphincter-preserving surgery (n = 130) were retrospectively compared to open (n = 234) and laparoscopic surgery (n = 318) by a propensity score analysis.

RESULTS

Robotic surgery was performed more frequently for patients with lower rectal cancer (55%) than open (30%, p < 0.0001) or laparoscopic surgery (36%, p < 0.0001). None of the robotic surgery cases were converted to open surgery. After propensity score matching, robotic surgery was found to be associated with a longer operation time (342 vs. 230 min, p < 0.0001) and less blood loss (7 vs. 420 mL, p < 0.0001) than open surgery. The overall complication rate of robotic surgery was lower than that of open surgery (13 vs. 28%, p = 0.032). Robotic surgery was associated with a lower incidence of surgical site infections (SSIs) than laparoscopic surgery (0 vs. 7%, p = 0.028). There were no cases of anastomotic leakage after robotic surgery. The circumferential resection margin was involved in 0.8% of the patients who underwent robotic surgery; the incidence did not differ among the treatment groups.

CONCLUSIONS

Although robotic surgery for rectal cancer was associated with a longer operation time, it was associated with a very low incidence of SSIs. The degree of safety was comparable to both open and laparoscopic surgery.

Correlations between the sizes of lateral pelvic lymph nodes and metastases in rectal cancer patients treated with preoperative chemoradiotherapy

BACKGROUND

Lateral pelvic lymph node (LLN) dissection is suggested to improve the prognosis of rectal cancer patients; however, accurate diagnosis of LLN metastasis is challenging, especially after preoperative chemoradiotherapy (CRT). The aim of this study was to clarify the diagnostic value of LLN size in rectal cancer patients treated with CRT in terms of metastasis.

METHODS

A total of 204 LLNs dissected from 29 rectal cancer patients treated with CRT were examined. The correlation between the resected LLN size (long and short axes) and patients' metastasis status was examined.

RESULTS

The long axes of metastatic LLNs were significantly longer than those of non-metastatic LLNs (11.0 ± 5.3 versus 4.4 ± 2.8 mm, respectively; P < 0.0001) as were the short axes (8.1 ± 4.5 versus 2.3 ± 1.2 mm, respectively; P < 0.0001). Receiver operating characteristic analyses of the long and short axes indicated optimal cut-off values of 7 and 4 mm for the prediction of pathological LLN metastasis; the area under the curve values were 0.89 and 0.96, respectively. The accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the long axis for the prediction of pathological metastasis were 82.4, 88.2, 82.2, 48.4 and 97.2%, respectively; those of the short axis were 91.7, 94.1, 87.1, 59.3 and 98.7%, respectively.

CONCLUSIONS

The sizes of LLNs significantly correlated with patients' pathological statuses, and their accuracies for the prediction of pathological metastases were high. However, in contrast to the very high NPVs, the PPVs were low (approximately 50%).

Session 4: Shaping radiotherapy for rectal cancer: should this be personalized?

Preoperative radiotherapy continues to be widely used in patients with operable rectal cancer. However, the indications and goals for such treatment are evolving. Professor Marijnen reviews the historic and current evidence base for the use of preoperative neoadjuvant radiotherapy and the future challenges in tailoring the therapy according to the patients' needs and tumour stage.

Prediction of lateral pelvic lymph node metastasis in patients with locally advanced rectal cancer with preoperative chemoradiotherapy: Focus on MR imaging findings

PURPOSE

To investigate the predictive factors for lateral pelvic lymph node (LPLN) metastasis in patients with locally advanced rectal cancer treated with preoperative chemoradiotherapy (CRT).

MATERIALS AND METHODS

Fifty-seven patients with locally advanced rectal cancer and LPLNs larger than 5 mm underwent LPLN dissection (LPLD) after preoperative CRT. The MRI findings, including the apparent diffusion coefficient value and LPLN size reduction rate before/after CRT; clinical factors; and pathologic results were evaluated to identify the predictive factors associated with LPLN metastasis.

RESULTS

LPLN metastasis was confirmed in 23 patients (40.4%). Metastasis was significantly higher in LPLNs with multiplicity, short-axis diameter ≥8 mm before CRT, short-axis diameter >5 mm after CRT, size reduction rate ≤33.3%, heterogeneous signal intensity, and irregular margin (P<0.05) on MR. Multivariable analysis showed that pre-CRT short-axis diameter of LPLNs ≥8 mm, size reduction rate ≤33.3%, and heterogeneous signal intensity were independently associated with LPLN metastasis.

CONCLUSIONS

The size and signal intensity of LPLN before and after CRT are useful MRI findings to predict LPLN metastasis and are helpful to determine the indications for LPLD.

The Perfect Total Mesorectal Excision Obviates the Need for Anything Else in the Management of Most Rectal Cancers

This article discusses the local control of primary rectal cancer and its locoregional spread in the light of modern advances. In recent years, the use of neoadjuvant chemoradiation has spread widely. However, its true benefit is not always balanced with its morbidities. Often total mesorectal excision (TME) is the best option. We will discuss the indications for immediate surgery for chemoradiation in advance and the importance of a delay in the management plan. To understand this selection, it is mandatory to know the true extent of tissue at risk for tumor dissemination and spread. Considering that TME may be enough for many patients and that most local recurrences are failures of surgical technique we introduce a new concept of total mesorectal irradiation. This exploits the new reality that precise, focused neoadjuvant therapy can offer a better response with fewer complications. Together these important changes in cancer board (multidisciplinary team) planning can also offer selected patients complete control of their cancer with no need for surgery.

Current issues of preoperative radio(chemo)therapy and its future evolution in locally advanced rectal cancer

Neoadjuvant therapies are effective for local control and tumor downstaging. Up to date, preoperative long-course chemoradiotherapy and short-course radiotherapy are the two primary guideline-recommended neoadjuvant therapies for locally advanced rectal cancer patients. However, clinicians throughout the world are trying their best to further optimize the regimens and concepts of neoadjuvants. Hence, there is an urgent need to summarize evidence regarding indications of neaoadjuvant therapies and relative merits of current standard regimens. In addition, we also reviewed the optimized regimens mainly based on short-course radiotherapy with delayed surgery, consolidation chemotherapy, induction chemotherapy, chemotherapy alone without radiation and concepts in terms of organ preservation and personalized treatments to further explore the future evolution of neoadjuvant therapies in rectal cancer.