Development and evaluation of a Japanese prediction model for low anterior resection syndrome after rectal cancer surgery

The effect of robotic surgery on low anterior resection syndrome in patients with lower rectal cancer: a propensity score-matched analysis

BACKGROUND

Many patients experience anorectal dysfunction after rectal surgery, which is known as low anterior resection syndrome (LARS). Robotic systems have many technical advantages that may be suitable for functional preservation after low rectal resection. Thus, the study aimed to explore whether robotic surgery can reduce the incidence and severity of LARS.

METHODS

Patients undergoing minimally invasive sphincter-sparing surgery for low rectal cancer were enrolled between January 2015 and December 2020. The patients were divided into robotic or laparoscopic groups. The LARS survey was conducted at 6, 12 and 18 months postoperatively. Major LARS scores were analysed as the primary endpoint. In order to reduce confounding factors, one-to-two propensity score matches were used.

RESULTS

In total, 342 patients were enrolled in the study. At 18 months postoperatively, the incidence of LARS was 68.7% (235/342); minor LARS was identified in 112/342 patients (32.7%), and major LARS in 123/342 (36.0%). After matching, the robotic group included 74 patients, and the laparoscopic group included 148 patients. The incidence of major LARS in the robotic group was significantly lower than that in the laparoscopic group at 6, 12, and 18 months after surgery. In multivariate logistic regression analysis, tumour location, laparoscopic surgery, intersphincteric resection, neoadjuvant therapy, and anastomotic leakage were independent risk factors for major LARS after minimally invasive sphincter-sparing surgery for low rectal cancer. Furthermore, a major LARS prediction model was constructed. Results of model evaluation showed that the nomogram had good prediction accuracy and efficiency.

CONCLUSIONS

Patients with low rectal cancer may benefit from robotic surgery to reduce the incidence and severity of LARS. Our nomogram could aid surgeons in setting an individualized treatment program for low rectal cancer patients.

Validity assessment of the POLARS score tool in the prediction of post rectal cancer surgery LARS score in a population-based Swedish cohort

OBJECTIVE

Low anterior resection syndrome (LARS) is one of the most common functional impairments after rectal cancer surgery with a high impact on quality of life. The Pre-Operative LARS score (POLARS) nomogram and its online tool has been developed to predict the degree of postoperative LARS. The aim of this study was to analyse how accurately the POLARS score could predict LARS scores when compared with actual patient-reported LARS (PR-LARS) scores in a population-based Swedish cohort.

DESIGN

This retrospective cohort study included patients who underwent curative rectal cancer surgery between 2007 and 2013 in Stockholm County and were identified using the Swedish Colorectal Cancer Registry (SCRCR). Information regarding preoperative risk factors, patient and treatment characteristics, and presence of LARS postoperatively were collected from patient charts, SCRCR and patient questionnaires. The POLARS model formula was used to predict LARS scores, which then were compared with the actual PR-LARS scores. Individual LARS score differences between the two estimates were shown with a modified Bland-Altman plot of difference.

RESULTS

The cohort included 477 patients, of whom 359 (75%) of patients were categorised as having no/minor LARS based on the POLARS score. The correctly identified patients by the POLARS score were 80/255 (31%) in the major LARS group and 184/222 (83%) no/minor LARS group. The sensitivity was 31% for major LARS and the positive predictive value was 68%.

CONCLUSION

The POLARS score has a low sensitivity for major LARS in this Swedish cohort. Other methods to predict the risk of LARS need to be developed.

A novel nomogram to predict low anterior resection syndrome (LARS) after ileostomy reversal for rectal cancer patients

BACKGROUND AND AIM

Low anterior resection syndrome (LARS) in patients undergoing low or ultra-low anterior resection (LAR) is a common problem and significantly impacts the quality of life. Patients with an ileostomy after LAR are more likely to develop LARS. However, there hasn't been a model predicting LARS occurrence in these patients. This study aims to construct a nomogram to predict the probability of LARS occurrence in patients with temporary ileostomy and guide preventive strategies before reversal.

METHODS

168 patients undergoing LAR with ileostomy from one center were enrolled as the training cohort, and 134 patients of the same inclusion criteria from another center were enrolled as the validation cohort. The training cohort was screened for risk factors for major LARS using univariate and multivariate logistic regression. The nomogram was constructed using the filtered variables, the ROC curve was used to describe the model's discrimination, and the calibration was used to describe the accuracy.

RESULTS

The optimal cut-off value for stoma closure time was 128 days. Three risk factors were identified using logistic regression analysis: preoperative radiotherapy (OR = 3.038, [95%CI 1.75-5.015], P = 0.005), stoma closure time (OR = 2.298, [95%CI 1.088-4.858], P = 0.029) and pN stage (OR = 1.739, [95%CI 1.235-3.980], P = 0.001). A nomogram was constructed based on these three variables and showed good performance predicting major LARS after stoma reversal. The area under the curve (AUC) was 0.827 in the training group and 0.821 in the validation group; The calibration curve suggested good precision in both groups.

CONCLUSIONS

This novel nomogram can accurately predict the probability of major LARS occurrence after ileostomy reversal for rectal cancer patients. This model can help screen ileostomy patients with high risks and guide individualized preventive strategies before stoma reversal.

A predictive nomogram model for low anterior resection syndrome after rectal cancer resection

BACKGROUND

The aim of this study was to identify risk factors associated with the low anterior resection syndrome (LARS) and to construct a nomogram capable of predicting the risk of LARS in patients who undergo rectal cancer resection.

METHODS

About 538 patients who had undergone anterior resection were recruited as a development set. In addition, 114 patients with rectal cancer were analysed as a validation set to test the new nomogram. Patients in the development set were grouped into two separate cohorts: those with major LARS and those with minor or no LARS. Multiple logistic regression was conducted to detect risk factors for major LARS.

RESULTS

The prevalence of major LARS was 40.7%, of minor LARS was 28.6% and the proportion with no LARS was 30.7% in the development set. In multivariate analysis, female gender, preoperative chemoradiation, low tumour height, diverting ileostomy, postoperative anastomotic leakage were shown to be independently associated with major LARS occurring in patients after rectal cancer resection. The area under the curve (AUC) values of the nomogram were 0.726 (95% CI: 0.682-0.769) and 0.750 (95% CI: 0.655-0.845) in the development and validation sets, respectively. The calibration curves and Hosmer-Lemeshow goodness of fit tests showed that the model was acceptably accurate.

CONCLUSION

A nomogram model based on risk factors could be valuable as a predictor of the probability of major LARS after rectal cancer surgery, and provides a guide that clinical staff can use to take preventive measures for high-risk patients.