Inferior mesenteric artery lymph node metastasis in rectal cancer treated with neoadjuvant chemoradiotherapy: Incidence, prediction and prognostic impact

Development and validation of artificial intelligence models for preoperative prediction of inferior mesenteric artery lymph nodes metastasis in left colon and rectal cancer

BACKGROUND

Dissection of lymph nodes at the roots of the inferior mesenteric artery (IMAN) should be offered only to selected patients at a major risk of developing IMAN involvement. The aim of this study is to present the first artificial intelligence (AI) models to predict IMAN metastasis risk in the left colon and rectal cancer patients.

METHODS

A total of 2891 patients with descending colon including splenic flexure, sigmoid colon and rectal cancer undergoing major primary surgery and IMAN dissection were included as a study cohort, which was then split into a training set (67%) and a testing set (33%). Feature selection was conducted using the least absolute shrinkage and selection operator (LASSO) regression model. Seven AI algorithms, namely Support Vector Machine (SVM), Logistic Regression (LR), Extreme Gradient Boosting (XGB), Light Gradient Boosting (LGB), Decision Tree Classifier (DTC), Random Forest (RF) classifier, and Multilayer Perceptron (MLP), as well as traditional multivariate LR model were employed to construct predictive models. The optimal hyperparameters were determined with 5 fold cross-validation. The predictive performance of models and the expert surgeon was assessed and compared in the testing set independently.

RESULTS

The IMAN involvement incidence was 4.6%. The optimal set of features selected by LASSO included 10 characteristics: neoadjuvant treatment, age, synchronous liver metastasis, synchronous lung metastasis, signet ring adenocarcinoma, neural invasion, lymphovascular invasion, CA199, endoscopic obstruction, T stage evaluated by MRI. The most accurate model derived from MLP showed excellent prediction power with area under the receiver operating characteristic curve (AUROC) of 0.873 and produced 81.0% recognition sensitivity and 82.5% specificity in the testing set independently. In contrast, the judgment of IMAN metastasis by expert surgeon yield rather imprecise and unreliable results with a significantly lower AUROC of 0.509. Additionally, the proposed MLP had the highest net benefits and the largest reduction of unnecessary IMAN dissection without the cost of additional involved IMAN missed.

CONCLUSION

MLP model was able to maintain its prediction accuracy in the testing set better than other models and expert surgeons. Our MLP model could be used to help identify IMA nodal metastasis and to select candidates for individual IMAN dissection.

Significance of Nerve Plane for Inferior Mesenteric Plexus Preservation in Laparoscopic Rectal Cancer Surgery

Background

Station 253 node dissection with high ligation of the inferior mesenteric artery (IMA) is difficult to perform without damage to the surrounding autonomic nerve plexuses. This study aimed to investigate the significance of the nerve plane for inferior mesenteric plexus (IMP) preservation in laparoscopic rectal cancer surgery.

Methods

A total of 56 consecutive rectal patients underwent laparoscopic en bloc station 253 node dissection with high ligation of the IMA. Station 253 nodes were divided into the extra- and intra-nerve plane station 253 nodes for further H&E staining and immunohistochemical analysis. Based on IMP nerve plane-based evidence and histopathological results, a novel nerve-sparing technique, IMP nerve plane orientation, was proposed and performed on 68 rectal cancer patients. Urinary and sexual functions in all patients were evaluated at 6 months postoperatively.

Results

Lymph node metastasis was not found, but abundant nerve bundles containing gangliocytes were observed in extra-nerve plane station 253 nodes. The nerve plane was identified intraoperatively and then confirmed by both postoperative gross specimen evaluation and histopathological analysis. The novel nerve-sparing technique (IMP nerve plane orientation) was successfully performed with no postoperative complications, and the operated patients had improved postoperative urinary and sexual functions.

Conclusion

The nerve plane is helpful for IMP preservation and station 253 node dissection. This novel nerve-sparing technique of nerve plane orientation is technically feasible and safe, which could result in faster recovery of urinary and sexual functions.

Prognostic Value of the Distribution of Lymph Node Metastasis in Locally Advanced Rectal Cancer After Neoadjuvant Chemoradiotherapy

Background: The objective of this study is to assess the prognostic value of lymph node metastasis distribution (LND) in locally advanced rectal cancer (LARC) after neoadjuvant chemoradiotherapy (nCRT). Methods: This study included 179 patients with pathological stage III LARC who underwent nCRT followed by radical surgery. LND was classified into three groups: LND1, lymph node metastasis at the mesorectum (140/179, 78.2%); LND2, lymph node metastasis along the inferior mesenteric artery trunk nodes (26/179, 14.5%); LND3, lymph node metastasis at the origin of the IMA (13/179, 7.3%). Clinicopathologic characteristics were analyzed to identify independent prognostic factors. Result: LND showed better stratification for 3-year DFS (LND1 66.8, LND2 50, and LND3 15.4%, P < 0.01) compared to the ypN (3-year DFS: N1 59.9 and N2 60.3%, P = 0.34) and ypTNM (3-year DFS: IIIA 68.6%, IIIB 57.5%, and IIIC 53.5, P = 0.19) staging systems. Similar results were found for 3-year LRFS and DMFS. According to multivariate survival analysis, LND was shown to be an independent prognostic factor for DFS, LRFS, and DMFS in patients with positive lymph nodes (P < 0.01, in all cases). Conclusion: LND is an independent prognostic factor in stage III rectal cancer after nCRT. LND can be used as a supplementary indicator for the ypTNM staging system in patients with LARC after nCRT.

Preoperative carbon nanoparticle injection improves inferior mesenteric artery lymph node retrieval in patients with rectal cancer

BACKGROUND

Inferior mesenteric artery lymph node (station 253 node) metastasis occurs in approximately 0.3% to 13.9% of rectal cancer patients. This study examined whether carbon nanoparticles could aid in harvesting more station 253 nodes and evaluated the relationship between the number of station 253 nodes retrieved and station 253 node metastasis.

METHOD

A total of 480 consecutive rectal cancer patients were enrolled in this prospective cohort study between August 2014 and October 2018. Ninety-one patients (18.96%) received a preoperative submucosal injection of carbon nanoparticles (CN+ group), and 389 patients did not receive an injection (CN- group). The number of lymph node retrievals was analyzed, and the relevant risk factors for station 253 node metastasis were identified using univariate and multivariate analyses.

RESULTS

The mean number of station 251, 252, and 253 lymph nodes and total lymph nodes retrieved in the CN+ group were higher than that retrieved in the CN- group. The percentage of patients with ≥4 station 253 nodes retrieved (54.0% vs 28.3%, P = .004) were higher in the CN+ group than in the CN- group. Retrieval of ≥4 station 253 nodes was an independent risk factor for station 253 node metastasis (OR: 2.40, 95% CI: 1.22-4.74, P = .012).

CONCLUSION

The preoperative submucosal injection of carbon nanoparticles was helpful for increasing the number of station 253 nodes harvested, and a minimum of 4 examined station 253 nodes was necessary for standard D3 lymph node dissection in rectal cancer.

Analysis of risk factors and prognosis of 253 lymph node metastasis in colorectal cancer patients

Background

This study aimed to explore potential risk factors for 253 lymph node metastasis, and to identify the prognostic impact of 253 lymph node metastasis in colorectal cancer patients.

Methods

A retrospective study was conducted of 391 colorectal cancer patients who underwent surgical treatments that included 253 lymph node dissection. Clinicopathological features, molecular indexes and 1-year overall survival rates were analyzed.

Results

Univariate analyses revealed the following risk factors for 253 lymph node metastasis: high preoperative levels of CEA, large tumour max diameters, and numbers of harvested lymph nodes, presence of vessel carcinoma emboli, low level of MSH6 and MLH1 immunohistochemical staining intensity. Multivariate analysis showed that elevated MLH1 immunohistochemical staining intensity was an independent protective factor for 253 lymph node metastasis (OR: 0.969, 95% CI 0.945, 0.994, P = 0.015). A significant difference was found in 1-year overall survival rate between 253 lymph node-positive and lymph node-negative colorectal cancer patients (88.9% vs.75.0%, P < 0.001).

Conclusions

253 lymph node-positive colorectal cancer patients had a worse prognosis than the 253 lymph node-negative patients. 253 lymph node dissection may improve the prognosis of colorectal cancer patients with high risk factors for 253 lymph node metastasis.

Pathological features of lymph nodes around inferior mesenteric artery in rectal cancer: a retrospective study

Objective

This study aimed to explore the pathological characteristics of lymph nodes around inferior mesenteric artery in rectal cancer and its risk factors and its impact on tumor staging.

Methods

485 rectal cancer patients underwent proctectomy surgery were collected in this study. Clinical features of patients, including gender, age, BMI, tumor size, pathological type, differentiation, nerve invasion, lymph nodes, tumor marker, and pathological examinations, were analyzed.

Results

A total of 485 cases were included in this study. There were 29 cases with IMA-LN metastasis; the metastasis rate was 5.98% (29/485). Positive IMA-LNs were associated with distance from anal verge, CEA, pathological type, differentiation, nerve invasion, T stage, and N stage. Multivariate analysis showed that distance from anal verge, CEA level, differentiation, and T stage were independent risk factors for positive IMA-LNs.

Conclusion

Distance from anal verge, CEA level, differentiation, and T stage were independent risk factors for positive IMA-LNs. No skip metastasis occurred in IMA-LNs. We should choose the appropriate surgical methods to achieve better oncological results and reduce the incidence of postoperative complications.

Lymph Node Regression to Neoadjuvant Chemoradiotherapy in Patients with Locally Advanced Rectal Cancer: Prognostic Implication and a Predictive Model

AIM

Currently, few studies have focused on the prognostic impact of lymph node regression to neoadjuvant chemoradiotherapy (NCRT) in rectal cancer. This study aimed to explore the prognostic impact of lymph node regression grade (LRG) in patients with locally advanced rectal cancer (LARC) following NCRT and radical surgery and develop a predictive nomogram for disease-free survival (DFS).

METHODS

LARC patients undergoing NCRT and radical surgery between 2013 and 2014 were enrolled and divided into LRG low (≤ 2), middle (3-9), and high (≥ 10) groups. Clinicopathological characteristics and survival outcomes were compared. Predictors for DFS were identified by Cox regression analysis, and a nomogram was constructed.

RESULTS

A total of 257 LARC patients were eligible, including LRG low (n = 149), middle (n = 59), and high (n = 49) groups. Higher LRG score was associated with higher TRG, more advanced ypT and ypN stages, and poorer OS and DFS (all P < 0.001). Cox regression analysis demonstrated that tumor differentiation (poor and anaplastic, HR = 2.048, P = 0.048), ypTNM stage (HR = 2.389, P = 0.015), and LRG-sum (HR = 1.020, P = 0.029) were independent prognostic determinants for DFS after NCRT. A nomogram for DFS was developed with a C-index of 0.68 (95%CI 0.64-0.72).

CONCLUSION

LRG is an important prognostic indicator for DFS in LARC patients after NCRT. A predictive nomogram based on LRG was developed to guide more tailored adjuvant treatment and surveillance.

Prognostic value of apical lymph node metastasis at the inferior mesenteric artery in sigmoid and rectal cancer patients who undergo laparoscopic surgery

BACKGROUND AND OBJECTIVES

Evidence supporting the importance of apical lymph nodes (LNs) and the potential long-term impact of LN metastases at the inferior mesenteric artery (IMA) lymphectomy remains limited. This study aimed to evaluate the prognostic value of LNs at the IMA (IMA-LN) in sigmoid and rectal cancer patients undergoing laparoscopic surgery.

METHODS

We retrospectively evaluated 265 consecutive patients who underwent laparoscopic sigmoid or rectal cancer surgery between August 2016 and May 2020. They were divided into two groups according to the pathological results of the IMA LNs: IMA-LN negative (n = 248) and IMA-LN positive (n = 17).

RESULTS

The IMA-LN negative group had significantly better overall survival (OS) (p = .020) and disease-free survival (DFS) (p = .000) than did the IMA-LN positive group. IMA-LN metastasis was associated with worse OS and DFS regardless of the pN stage. Patients with IMA-LN metastasis had a higher risk of postoperative recurrence, especially liver (p = .000) and lung (p = .025) metastasis, than did those without metastasis. However, there was no significant difference in the local recurrence rate between the two groups.

CONCLUSIONS

IMA-LN metastasis is an independent risk factor for poor prognosis in sigmoid and rectal cancer. Dissecting and evaluating IMA-LN separately is a more accurate and practical method for predicting prognosis.

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.

A nationwide study on the incidence of mesenteric ischaemia after surgery for rectal cancer demonstrates an association with high arterial ligation

AIM

The incidence of mesenteric ischaemia after resection for rectal cancer has not been investigated in a population-based setting. The use of high ligation of the inferior mesenteric artery might cause such ischaemia, as the bowel left in situ depends on collateral blood supply after a high tie.

METHOD

The Swedish Colorectal Cancer Registry was used to identify all patients subjected to an abdominal resection for rectal cancer during the years 2007-2017 inclusive. Mesenteric ischaemia within the first 30 postoperative days was recorded, classified as either stoma necrosis or colonic necrosis. Multivariable logistic regression was used to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for mesenteric ischaemia in relation to high tie, with adjustment for confounding.

RESULTS

Some 14 657 patients were included, of whom 59 (0.40%) had a reoperation for any type of mesenteric ischaemia, divided into 34 and 25 cases of stoma necrosis and colonic necrosis, respectively. Compared with patients who did not require reoperation for mesenteric ischaemia following rectal cancer surgery, the proportion having high tie was greater (54.2% vs 38.5%; P = 0.032). The adjusted OR for reoperation due to any mesenteric ischaemia with high tie was 2.26 (95% CI 1.34-3.79), while the corresponding estimates for stoma and colonic necrosis, respectively, were 1.60 (95% CI 0.81-3.17) and 3.69 (95% CI 1.57-8.66).

CONCLUSION

The incidence of reoperation for mesenteric ischaemia after abdominal resection for rectal cancer is low, but the use of a high tie might increase the risk of colonic necrosis demanding surgery.

Prognostic Implication of Negative Lymph Node Count in ypN+ Rectal Cancer after Neoadjuvant Chemoradiotherapy and Construction of a Prediction Nomogram

PURPOSE

This study aimed to investigate the prognostic significance of negative lymph nodes (NLNs) for ypN+ rectal cancer after neoadjuvant chemoradiotherapy (nCRT) and radical surgery and to construct a nomogram predicting disease-free survival (DFS).

METHOD

One hundred fifty-eight eligible patients were included. X-tile analysis was performed to determine cutoff values of NLNs. Clinicopathological and survival outcomes were compared. A Cox regression analysis was performed to identify prognostic factors of DFS. A nomogram was constructed and validated internally.

RESULTS

X-tile analysis identified cutoff values of 4 and 16 in terms of DFS (χ² = 8.129, p = 0.017). The 3-year DFS rates for low (≤ 4), middle (5-16), and high (≥ 17) NLNs group was 15.2, 55.5, and 73.1%, respectively (P = 0.017). NLN count (NLNs ≥ 17, HR = 0.400, P = 0.022), IMA nodal metastasis (HR = 1.944, P = 0.025), tumor differentiation (poor/anaplastic, HR = 1.805, P = 0.021), and ypT4 stage (HR = 7.787, P = 0.047) were independent prognostic factors of DFS. A predicting nomogram incorporating the four significant predictors was developed with a C-index of 0.64.

CONCLUSION

NLN count was an independent prognostic factor of DFS in patients with ypN+ rectal cancer following nCRT. A nomogram incorporating NLN count, IMA nodal metastasis, tumor differentiation, and ypT stage could stratify rectal cancer patients with different DFS and might be helpful during clinical decision-making.

Prognostic significance of neoadjuvant rectal score in locally advanced rectal cancer after neoadjuvant chemoradiotherapy and construction of a prediction model

AIM

To evaluate the prognostic significance of neoadjuvant rectal (NAR) score after neoadjuvant chemoradiotherapy (nCRT) for locally advanced rectal cancer (LARC), and to develop a nomogram predicting disease-free survival (DFS).

METHOD

A total of 522 LARC patients undergoing nCRT and surgery were included. NAR scores were calculated using the equation [5pN-3(cT-pT) + 12]^2/9.61, and classified as low (<8), intermediate (8-16), and high (>16). Clinicopathological and survival outcomes were compared. Cox regression analysis was performed to identify risk factors of DFS. A predicting nomogram was developed and validated internally.

RESULTS

For NAR score classification, 193 (37.0%) were low, 183 (35.0%) were intermediate, and 146 (28.0%) were high. Higher NAR score was associated with fewer pCR, lower tumor regression grade (TRG), and higher ypTNM stage. A total of 5-year DFS for low, intermediate, and high NAR groups was 85.6%, 71.9%, and 47.2%, respectively (P < 0.001). NAR score (HR = 2.488, P = 0.002), TRG (HR = 2.811, P = 0.047), CRM involvement (HR = 2.703, P = 0.002), and IMA nodal metastasis (HR = 2.441, P = 0.001) were independent prognostic factors of DFS. A predicting nomogram was developed with C-index of 0.701.

CONCLUSION

NAR score could help in predicting DFS after nCRT. A nomogram was developed to identify subpopulations with aggressive tumors during clinical decision-making.

Survival analysis in rectal carcinoma after neoadjuvant chemoradiation: various methods with different results

PURPOSE

Survival is an important indicator of outcome quality in rectal carcinoma. The 5-year survival rate is the typical outcome measurement. In patients with neoadjuvant chemoradiation followed by curative surgery, 7 years of follow-up is recommended. Different methods of survival analysis lead to different results. Here, we compared four different methods.

METHODS

The data of 439 patients with rectal carcinoma treated with neoadjuvant chemoradiation followed by curative total mesorectal excision (TME) surgery between 1995 and 2010 were analysed. After stratifying by stage, relative survival (RS), cancer-related survival (CRS), overall survival (OS) and disease-free survival (DFS) were compared. In particular, the 3-year disease-free survival rate was compared to the 5- and 7-year overall survival rates.

RESULTS

In the total cohort, the 5-year survival rates ranged from 90% (RS), over 84% (CRS) and 83% (OS) to 72% (DFS). Depending on the stage of disease, the differences between the 5-year survival rates varied between 10 and 32 percentage points. The differences were lowest in UICC stage y0 and highest in UICC stage yIV. The 3-year DFS-rate was always lower (worse) than the 5-year OS rate and higher (better) than the 7-year OS rate, with the exception of stage yIV.

CONCLUSIONS

Comparisons of survival are only meaningful if the same methods are applied. The 3-year rate of DFS was always worse than the rate of 5-year OS. Therefore, the 3-year rate of DFS appears to be a useful surrogate indicator in rectal carcinoma treatment studies.