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

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

Status

Completed

Phases

Unknown

Study type

Observational

Source

ClinicalTrials.gov

Registry ID

NCT05129215

Acronym

PORTLARS

Enrollment

901

Registered

2021-11-22

Start date

2020-03-06

Completion date

2022-10-31

Last updated

2022-11-30

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Low Anterior Resection Syndrome, Radiotherapy, Rectal Cancer

Keywords

Bowel Dysfunction, Low Anterior Resection Syndrome, Radiotherapy, Rectal Cancer

Brief summary

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.

Interventions

OTHERQuestionnaire

The LARS score is used for assessment of bowel dysfunction after rectal cancer resection.

Study design

Observational model

COHORT

Time perspective

CROSS_SECTIONAL

Eligibility

Sex/Gender

ALL

Healthy volunteers

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

Design outcomes

Primary

Measure	Time frame	Description
Area under the curve (AUC)	Over one year after restorative rectal cancer resection	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.

Secondary

Measure	Time frame	Description
Sensitivity	Over one year after restorative rectal cancer resection	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.
Specificity	Over one year after restorative rectal cancer resection	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.
Positive prediction value (PPV)	Over one year after restorative rectal cancer resection	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.
Negative prediction value (NPV)	Over one year after restorative rectal cancer resection	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.

Other

Measure	Time frame	Description
Net reclassification index (NRI)	Over one year after restorative rectal cancer resection	The additive NRI of PORTLARS compared to other models is evaluated by calculating the percentage of the 'actual major LARS' subjects correctly reclassified to the percentage of the 'actual no/minor LARS' subjects who are correctly reclassified.

Countries

China

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 10, 2026