Prognostic Impact of the Number of Examined Lymph Nodes in Stage II Colorectal Adenocarcinoma: A Retrospective Study

Personalized prediction of survival rate with combination of penalized Cox models in patients with colorectal cancer

The investigation into individual survival rates within the patient population was typically conducted using the Cox proportional hazards model. This study was aimed to evaluate the performance of machine learning algorithm in predicting survival rates more than 5 years for individual patients with colorectal cancer. A total of 475 patients with colorectal cancer (CRC) and complete data who had underwent surgery for CRC were analyze to measure individual's survival rate more than 5 years using a machine learning based on penalized Cox regression. We conducted thorough calculations to measure the individual's survival rate more than 5 years for performance evaluation. The receiver operating characteristic curves for the LASSO penalized model, the SCAD penalized model, the unpenalized model, and the RSF model were analyzed. The least absolute shrinkage and selection operator penalized model displayed a mean AUC of 0.67 ± 0.06, the smoothly clipped absolute deviation penalized model exhibited a mean AUC of 0.65 ± 0.07, the unpenalized model showed a mean AUC of 0.64 ± 0.09. Notably, the random survival forests model outperformed the others, demonstrating the most favorable performance evaluation with a mean AUC of 0.71 ± 0.05. Compared to the conventional unpenalized Cox model, recent machine learning techniques (LASSO, SCAD, RSF) showed advantages for data interpretation.

Construction and validation of a nomogram model for predicting the overall survival of colorectal cancer patients

BACKGROUND

Colorectal cancer (CRC) is a frequent cancer worldwide with varied survival outcomes.

OBJECTIVE

We aimed to develop a nomogram model to predict the overall survival (OS) of CRC patients after surgery.

DESIGN

This is a retrospective study.

SETTING

This study was conducted from 2015 to 2016 in a single tertiary center for CRC.

PATIENTS

CRC patients who underwent surgery between 2015 and 2016 were enrolled and randomly assigned into the training (n = 480) and validation (n = 206) groups. The risk score of each subject was calculated based on the nomogram. All participants were categorized into two subgroups according to the median value of the score.

MAIN OUTCOME MEASURES

The clinical characteristics of all patients were collected, significant prognostic variables were determined by univariate analysis. Least absolute shrinkage and selection operator (LASSO) regression was applied for variable selection. The tuning parameter (λ) for LASSO regression was determined by cross-validation. Independent prognostic variables determined by multivariable analysis were used to establish the nomogram. The predictive capacity of the model was assessed by risk group stratification.

RESULTS

Infiltration depth, macroscopic classification, BRAF, carbohydrate antigen 19 - 9 (CA-199) levels, N stage, M stage, TNM stage, carcinoembryonic antigen levels, number of positive lymph nodes, vascular tumor thrombus, and lymph node metastasis were independent prognostic factors. The nomogram established based on these factors exhibited good discriminatory capacity. The concordance indices for the training and validation groups were 0.796 and 0.786, respectively. The calibration curve suggested favorable agreement between predictions and observations. Moreover, the OS of different risk subgroups was significantly different.

LIMITATIONS

The limitations of this work included small sample size and single-center design. Also, some prognostic factors could not be included due to the retrospective design.

CONCLUSIONS

A prognostic nomogram for predicting the OS of CRC patients after surgery was developed, which might be helpful for evaluating the prognosis of CRC patients.

A systematic review and meta-analysis of the use of methylene blue to improve the lymph node harvest in rectal cancer surgery

BACKGROUND

Methylene blue staining of the resected specimen has been described as an alternative to the conventional palpation and visual inspection method to improve lymph node harvest. This meta-analysis evaluates the usefulness of this technique in surgery for rectal cancer, particularly after neoadjuvant therapy.

METHODS

Randomized controlled trials (RCTs) comparing lymph node harvest in methylene blue-stained rectal specimens to those of unstained specimens were identified from the Medline, Embase, and Cochrane databases. Non-randomized studies and those with only colonic resections were excluded. The quality of RCTs was assessed using Cochrane's risk of bias tool. A weighted mean difference (WMD) was calculated for overall harvest, harvest after neoadjuvant therapy, and metastatic nodal yield. In contrast, the risk difference (RD) was calculated to compare yields of less than 12 lymph nodes between the stained and unstained specimens.

RESULTS

Study selection comprised seven RCTs with 343 patients in the unstained group and 337 in the stained group. Overall lymph node harvest and harvest after neoadjuvant therapy were significantly higher in stained specimens with a WMD of 13.4 and 10.6 and a 95% confidence interval (CI) of 9.5-17.2 and 4.8-16.3, respectively. Harvest of metastatic lymph nodes was significantly higher in the stained group (WMD 1.0, 95% CI 0.6-1.4). The yield of less than 12 lymph nodes was significantly higher in the unstained group with RD of 0.292 and 95% CI of 0.182-0.403.

CONCLUSION

Despite a small number of patients, this meta-analysis confirms improved lymph node harvest in surgical specimens stained with methylene blue compared with unstained specimens.

New Personal Model for Forecasting the Outcome of Patients with Histological Grade III-IV Colorectal Cancer Based on Regional Lymph Nodes

Background

Metastases at regional lymph nodes could easily occur in patients with high-histological-grade colorectal cancer (CRC). However, few models were built on the basis of lymph nodes to predict the outcome of patients with histological grades III-IV CRC.

Methods

Data in the Surveillance, Epidemiology, and End Results databases were used. Univariate and multivariate analyses were performed. A personalized prediction model was built in accordance with the results of the analyses. A nomogram was tested in two datasets and assessed using a calibration curve, a consistency index (C-index), and an area under the curve (AUC).

Results

A total of 14,039 cases were obtained from the database. They were separated into two groups (9828 cases for constructing the model and 4211 cases for validation). Logistic and Cox regression analyses were then conducted. Factors such as log odds of positive lymph nodes (LODDS) were utilized. Then, a personalized prediction model was established. The C-index in the construction and validation groups was 0.770. The 1-, 3-, and 5-year AUCs were 0793, 0.828, and 0.830 in the construction group, respectively, and 0.796, 0.833, and 0.832 in the validation group, respectively. The calibration curves showed well consistency in the 1-, 3- and 5-year OS between prediction and reality in both groups.

Conclusion

The nomogram built based on LODDS exhibited considerable reliability and accuracy.

Improved Accuracy of Lymph Node Staging and Long-Term Survival Benefit in Colorectal Cancer With Ex Vivo Arterial Methylene Blue Infiltration

Introduction:Ex vivo methylene blue (MB) injection into the main supplying arteries of the colorectal specimen after surgical removal is an uncomplicated technique to support lymph node harvest during pathological evaluation. The primary aim of this randomized, interventional, bicentric trial was to evaluate the impact of MB injection on lymph node yield, with secondary aims assessing the accuracy of lymph node staging and the effect on 5-year overall survival for patients undergoing resection of colorectal cancer.

Methods: In the study period between December 2013 and August 2015, 200 colorectal resections were performed at two independent onco-surgery centers of Hungary. Following surgical resection, each specimen was randomly assigned either to the control (standard pathological work-up) or to the MB staining group before formaldehyde fixation. Patient-level surgical and clinical data were retrieved from routinely collected clinical datasets. Survival status data were obtained from the National Health Insurance Fund of Hungary.

Results: A total of 162 specimens, 82 in the control and 80 in the MB groups, were included for analysis. Baseline characteristics were equally distributed among study groups, except for specimen length. Both the median of total number of lymph nodes retrieved (control 11 ± 8 [0–33] nodes vs. MB 14 ± 6 [0–42] nodes; p < 0.01), and the ratio of cases with at least 12 removed lymph nodes (36/82, 43.9% vs. 53/80, 66.3%; p < 0.01) were higher in the MB group. The rate of accurate lymph node staging was non-significantly improved. As for rectal cancer, nodal staging accuracy (16/31, 51.6% vs. 23/30, 76.7%; p = 0.04) and the proportion with minimum 12 lymph node retrieval (7/31, 22.6%, vs. 18/30, 60%; p < 0.01) was improved by MB injection. In Mantel–Cox regression, a statistically significant survival benefit with methylene blue injection at 5 years post-surgery was proven (51.2% vs. 68.8%; p = 0.04).

Conclusion: In our experience, postoperative ex vivo arterial methylene blue injection appears to be an uncomplicated technique, improving lymph node yield and decreasing the chance of insufficient nodal staging. The technique might also associate with a 5-year overall survival benefit.

Critical prognostic value of the log odds of negative lymph nodes/tumor size in rectal cancer patients

BACKGROUND

The number of negative lymph nodes (NLNs) and tumor size are associated with prognosis in rectal cancer patients undergoing surgical resection. However, little is known about the prognostic significance of the NLN count after adjusting for tumor size.

AIM

To assess the prognostic impact of the log odds of NLN/tumor size (LONS) in rectal cancer patients.

METHODS

Data of patients with stage I–III rectal cancer were extracted from the Surveillance, Epidemiology, and End Results Program database. These patients were randomly divided into a training cohort and a validation cohort. Univariate and multivariate Cox regression analyses were used to determine the prognostic value of the LONS. The optimal cutoff values of LONS were calculated using the "X-tile" program. Stratified analysis of the effect of LONS on cancer-specific survival (CSS) and overall survival (OS) were performed. The Kaplan-Meier method with the log-rank test was used to plot the survival curve and compare the survival data among the different groups.

RESULTS

In all, 41080 patients who met the inclusion criteria were randomly divided into a training cohort (n = 28775, 70%) and a validation cohort (n = 12325, 30%). Univariate and multivariate analyses identified the continuous variable LONS as an independent prognostic factor for CSS [training cohort: Hazard ratio (HR) = 0.47, 95% confidence interval (CI): 0.44–0.51, P < 0.001; validation cohort: HR = 0.46, 95%CI: 0.41-0.52, P < 0.001] and OS (training cohort: HR = 0.53, 95%CI: 0.49-0.56, P < 0.001; validation cohort: HR = 0.52, 95%CI: 0.42-0.52, P < 0.001). The X-tile program indicated that the difference in CSS was the most significant for LONS of -0.8, and the cutoff value of -0.4 can further distinguish patients with a better prognosis in the high LONS group. Stratified analysis of the effect of the categorical variable LONS on CSS and OS revealed that LONS was also an independent predictor, independent of pN stage, pT stage, tumor-node-metastasis stage, site, age, sex, the number of examined lymph nodes, race, preoperative radiotherapy and carcinoembryonic antigen level.

CONCLUSION

LONS is associated with improved survival of rectal cancer patients independent of other clinicopathological factors.