Development and Validation of The Post-RT LARS Prediction Model (PORTLARS)

Study Overview
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Brief Summary
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Bowel dysfunction is common after a restorative rectal cancer resection. Neoadjuvant radiotherapy is an influential factor that impairs bowel function and quality of life. However, almost half patients who have received primary surgery with preoperative radiotherapy are able to restore a good or moderate bowel function in the long term. This multicenter observational study aims to identify the risk factors of severe bowel dysfunction after rectal cancer resection and neoadjuvant radiotherapy, in accordance with the LARS score, and to build a model that predicts long-term major LARS in the early stage of follow-up. Development and validation cohorts are enrolled from tertiary hospitals in China.

Official Title
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Development and Validation of a Nomogram to Predict Severe Bowel Dysfunction After Rectal Cancer Resection and Neoadjuvant Radiotherapy: A Multicenter, Observational Clinical Study

Conditions
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Low Anterior Resection Syndrome, Radiotherapy, Rectal Cancer

Intervention / Treatment
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* Other: Questionnaire


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Curative low anterior resection for nonmetastatic rectal cancer Preoperative radiotherapy Exclusion Criteria: Death Metastasis or recurrence Postoperative radiotherapy Cognitive disorder Intestinal stoma Rectal cancer resection for <12 months Stoma reversal for <6 months
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Development<br>A primary cohort of eligible patients from the Sixth Affiliated Hospital of Sun Yat-sen University is used for model derivation. | Other: Questionnaire<br>* The LARS score is used for assessment of bowel dysfunction after rectal cancer resection.<br>|
| Internal cross-validation<br>A cohort of consecutive patients from the Sixth Affiliated Hospital of Sun Yat-sen University is used for internal cross-validation. | Other: Questionnaire<br>* The LARS score is used for assessment of bowel dysfunction after rectal cancer resection.<br>|
| External validation<br>An independent cohort of eligible patients from other hospitals is used for external validation. | Other: Questionnaire<br>* The LARS score is used for assessment of bowel dysfunction after rectal cancer resection.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Area under the curve (AUC) | The AUC of PORTLARS in predicting major bowel dysfunction after restorative rectal cancer resection with neoadjuvant radiotherapy. The AUC is evaluated by calculating the area under curve of receiver operating characteristics which plots the proportion of true positive cases (sensitivity) against the proportion of false positive cases (1-specificity) based on various predictive probability threshold. | Over one year after restorative rectal cancer resection | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sensitivity | The sensitivity of PORTLARS in predicting major bowel dysfunction after restorative rectal cancer resection with neoadjuvant radiotherapy. Model sensitivity is evaluated by calculating the proportion of the 'predicted major LARS' subjects among the total 'actual major LARS' subjects. | Over one year after restorative rectal cancer resection | 
| Specificity | The specificity of PORTLARS in predicting major bowel dysfunction after restorative rectal cancer resection with neoadjuvant radiotherapy. Model specificity is evaluated by calculating the proportion of the 'predicted no/minor LARS' subjects among the total 'actual no/minor LARS' subjects. | Over one year after restorative rectal cancer resection | 
| Positive prediction value (PPV) | The PPV of PORTLARS in predicting major bowel dysfunction after restorative rectal cancer resection with neoadjuvant radiotherapy. Model PPV is evaluated by calculating the proportion of the 'actual major LARS' subjects among the total 'predicted major LARS' subjects. | Over one year after restorative rectal cancer resection | 
| Negative prediction value (NPV) | The NPV of PORTLARS in predicting major bowel dysfunction after restorative rectal cancer resection with neoadjuvant radiotherapy. Model NPV is evaluated by calculating the proportion of the 'actual no/minor LARS' subjects among the total 'predicted no/minor LARS' subjects. | Over one year after restorative rectal cancer resection | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Bowel Dysfunction, Low Anterior Resection Syndrome, Radiotherapy, Rectal Cancer