ProLARS Trial: Prospective Longitudinal Follow-up of Low Anterior Resection Syndrome (LARS) and COREFO Score After Rectum Surgery in Patients Undergoing Upfront Surgery or Different Neo-adjuvant Treatment Regimens (ProLARS)

OBJECTIVE Low anterior resection syndrome (LARS) is a term for functional bowel complaints occurring after low anterior resection. Symptoms can range from faecal incontinence and frequent loose stools to urgency and incomplete emptying with great impact on quality of life. Little is known about the longitudinal evolution of LARS and the impact of different schedules of neoadjuvant chemoradiotherapy combined with surgery.

The investigators aim to investigate the incidence and evolution of functional bowel complaints in function of different neoadjuvant treatment regimens, type of surgery and adjuvant therapy in patients who undergo surgery for rectal cancer. The investigators focus on following objectives: evolution of LARS- and COREFO-scores per treatment regimen and their impact on work incapacity; identification of possible risk factors potentially related to functional outcome; monitoring and treatment of LARS.

METHODS This will be a multicentre prospective interventional study. The study population will consist of adult patients with rectal cancer, regardless of any neo-adjuvant therapy. Patients will be included for 5 years with a 2 year postoperative follow-up. Interim analysis will be made after 2 years of inclusion. Patients with intellectual disability or clinical colon obstruction are excluded. Automated online questionnaires including LARS and COREFO scores, incapacity for work and defecation quality will be sent at different time points (figure 1) using REDCap.

RESULTS and CONCLUSIONS Longitudinal change of LARS- and COREFO-scores will be visually summarized. Patient, disease or procedure specific risk factors will be assessed as well.

LARS is proven to be the principal postoperative problem after rectal surgery. If the investigators can predict the severity of LARS (minor or major LARS), this can be extremely helpful in deciding whether to perform a sphincter-sparing resection or a rectal amputation instead. Furthermore, the investigators want to offer perspective to patients who are susceptible to a disturbed postoperative bowel function.

Study Overview

• Status: Recruiting
• Conditions: Rectal Adenocarcinoma; Total Mesorectal Excision; LARS - Low Anterior Resection Syndrome; Low Anterior Resection; Rectal Resection
• Intervention / Treatment: Other: Questionnaire

• Study Type: Interventional
• Enrollment (Estimated): 100
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Niels Komen, MD PhD; Phone Number: +32 3 821 30 00; Email: niels.komen@uza.be
• Study Contact Backup: Name: Juul Meurs, MD; Phone Number: +32476617623; Email: juul.meurs@gmail.com

Study Locations

• Belgium
  • Antwerp
    • Edegem, Antwerp, Belgium, 2650
      • Recruiting
      • University Hospital Antwerp
      • Contact: Lieselotte Iket; Phone Number: +32 3 821 30 00; Email: studies.abdominaleheelkunde@uza.be

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 18 years or older.
• Diagnosis of rectal cancer, discussed at the multidisciplinary consultation, with the intention to perform a sphincter preserving total mesorectal excision (TME) or partial mesorectal excision (PME), regardless of the need of neoadjuvant treatment.

Exclusion Criteria:

• History of inflammatory bowel disease (Crohn's disease, ulcerative colitis) due to often persistent bowel complaints and therefore distorted baseline and follow-up data.
• Dementia or intellectual disability.
• Patients who are obstructive and in need a decompressive stoma or rectal stenting due to the lack of baseline data as they are often admitted to the hospital in an urgent setting

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Non-Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Upfront surgery; Patients who undergo rectal resection without neo-adjuvant therapy	Other: Questionnaire; Online questionnaire regarding LARS- and COREFO-scores, quality of defecation process, incapacity for work and initiation of treatment for potential LARS at different moments in time
Other: Neo-adjuvant therapy; Patients who receive neo-adjuvant therapy before undergoing rectal surgery	Other: Questionnaire; Online questionnaire regarding LARS- and COREFO-scores, quality of defecation process, incapacity for work and initiation of treatment for potential LARS at different moments in time

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The evolution of the COREFO-score (Colorectal Functional Outcome questionnaire) at 2 years after rectal surgery compared to baseline (absolute difference) will be examined	27 questions on 5-point Likert scale Higher score = worse bowel function	2 years from when rectal resection or stoma reversal was performed

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Evolution of LARS-score (low anterior resection syndrome) at 2 years after rectal surgery compared to baseline (absolute difference)	0-20 = no LARS 21-29 = minor LARS 30-42 = major LARS	2 years from when rectal resection or stoma reversal was performed
The evolution of the LARS-score (low anterior resection syndrome) at 2 years after rectal surgery compared to baseline (relative difference) will be examined.	0-20 = no LARS 21-29 = minor LARS 30-42 = major LARS	2 years from when rectal resection or stoma reversal was performed
The evolution of the COREFO-score (Colorectal Functional Outcome questionnaire) at 2 years after rectal surgery compared to baseline (relative difference) will be examined	27 questions on 5-point Likert scale Higher score = worse bowel function (min 0 - max 100)	2 years from when rectal resection or stoma reversal was performed
The evolution of the LARS-score (low anterior resection syndrome) in the absence of baseline data will be examined as well (absolute difference), comparing 2-year outcome to earliest results.	0-20 no LARS 21-29 minor LARS 30-42 major LARS (min 0 - max 42)	2 years from when rectal resection or stoma reversal was performed
The evolution of the LARS-score (low anterior resection syndrome) in the absence of baseline data will be examined as well (relative difference), comparing 2-year outcome to earliest results.	0-20 no LARS 21-29 minor LARS 30-42 major LARS (min 0 - max 42)	2 years from when rectal resection or stoma reversal was performed
The evolution of the COREFO-score (Colorectal Functional Outcome questionnaire) in the absence of baseline data will be examined as well (absolute difference), comparing 2-year outcome to earliest results.	27 questions on 5-point Likert scale Higher score = worse bowel function (min 0 - max 100)	2 years from when rectal resection or stoma reversal was performed
The evolution of the COREFO-score (Colorectal Functional Outcome questionnaire) in the absence of baseline data will be examined as well (relative difference), comparing 2-year outcome to earliest results.	27 questions on 5-point Likert scale Higher score = worse bowel function (min 0 - max 100)	2 years from when rectal resection or stoma reversal was performed
LARS-score (low anterior resection syndrome) score at diagnosis	0-20 no LARS 21-29 minor LARS 30-42 major LARS (min 0 - max 42) LARS = low anterior resection syndrome Using a questionnaire Unit = mean score (0-42)	At diagnosis = baseline
COREFO-score at diagnosis (Colorectal Functional Outcome questionnaire)	27 questions on 5-point Likert scale Higher score = worse bowel function (min 0 - max 100) COREFO = Colorectal Functional Outcome questionnaire Using a questionnaire Unit = mean score (0-100)	At diagnosis = baseline
LARS-score (low anterior resection syndrome) after neo-adjuvant therapy	0-20 no LARS 21-29 minor LARS 30-42 major LARS (min 0 - max 42) LARS = low anterior resection syndrome Using a questionnaire Unit = mean score (0-42)	After neo-adjuvant therapy (up to 6 months from baseline)
COREFO-score after neo-adjuvant therapy (Colorectal Functional Outcome questionnaire)	27 questions on 5-point Likert scale Higher score = worse bowel function (min 0 - max 100) COREFO = Colorectal Functional Outcome questionnaire Using a questionnaire Unit = mean score (0-100)	After neo-adjuvant therapy (up to 6 months from baseline)
LARS-score (low anterior resection syndrome) shortly prior to surgery when there is a delay of 4 or more weeks after finishing neoadjuvant therapy	0-20 no LARS 21-29 minor LARS 30-42 major LARS (min 0 - max 42) LARS = low anterior resection syndrome Using a questionnaire Unit = mean score (0-42)	2 days prior to surgery
COREFO-score (Colorectal Functional Outcome questionnaire) shortly prior to surgery when there is a delay of 4 or more weeks after finishing neoadjuvant therapy	27 questions on 5-point Likert scale Higher score = worse bowel function (min 0 - max 100) COREFO = Colorectal Functional Outcome questionnaire Using a questionnaire Unit = mean score (0-100)	2 days prior to surgery
LARS-scores (low anterior resection syndrome) postoperatively after 1 month, 3 months, 6 months, 1 year and 2 years	0-20 no LARS 21-29 minor LARS 30-42 major LARS (min 0 - max 42) LARS = low anterior resection syndrome Using a questionnaire Unit = mean score (0-42)	Postoperatively after 1 month, 3 months, 6 months, 1 year and 2 years
COREFO-scores (Colorectal Functional Outcome questionnaire) postoperatively after 1 month, 3 months, 6 months, 1 year and 2 years	27 questions on 5-point Likert scale Higher score = worse bowel function (min 0 - max 100) COREFO = Colorectal Functional Outcome questionnaire Using a questionnaire Unit = mean score (0-100)	Postoperatively after 1 month, 3 months, 6 months, 1 year and 2 years
Evolution of quality of defecation process	Visual analogue scale 0-10 0 = worst defecation ever 10 = best defecation ever	2 years after rectal resection or stoma reversal
Incapacity for work	Time (days) between date of start work incapacity and date back to work (if not yet retired)	At diagnose (baseline), 2 days after radiotherapy, 1 week after chemotherapy and 1 month after rectal resection
Initiation of treatment for potential LARS (low anterior resection syndrome) during follow-up	Yes/no: Dietary measures; Medication (probiotics, antidiarrheals, ...); Pelvic floor physiotherapy; Transanal irrigation, rectal irrigation, enema; Neuromodulation (neurostimulator); Other Calculating proportion of patients who received treatment for LARS	Up to 2 years after rectal resection

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gender	Male, female, other	Baseline
Year of birth	Year of birth	Baseline
Age	Age at diagnosis and at surgery	Baseline to date of surgery
Hospital admission data	Length of stay in days (date of admission for rectal resection until date of dismission)	After rectal resection
Medical history	Smoking, diabetes mellitus, abdominal, cardiac, pulmonary (yes/no)	Baseline
Anthropometry	Body mass index (kg/m²)	Baseline
Tumor location	Distance in cm from recto-anal angle, based on MRI	After restaging prior to surgery
Presence of lateral lymph nodes	Presence of lateral lymph nodes (yes/no)	After restaging prior to surgery
cTNM	Clinical TNM classification of tumor: T: tumor size; N: nodal involvement; M: metastasis	After restaging prior to surgery
Percentage of rectal circumference involved	Percentage of rectal circumference involved: on imaging (CT/MRI), coloscopy or ultrasound-endoscopy	After restaging prior to surgery
Circumferential resection margin	Circumferential resection margin (CRM; on MRI; measured from gland; in mm)	After restaging prior to surgery
Neoadjuvant therapy	The eventual use of neoadjuvant therapy: radiotherapy (RT), chemotherapy (CT) (yes/no)	From baseline to surgery
Radiotherapy dose	Radiotherapy dose (Gy)	From baseline to surgery
Chemotherapy type and frequency	Certain type of chemotherapy, used for certain amount of cycles	From baseline to surgery
Surgical approach	Surgical approach: Open; Laparoscopy; Robot; Transanal (TaTME)	At surgery
Configuration of anastomosis	Configuration of colorectal/coloanal anastomosis: End-to-End; Side-to-End; End-to-Side; Side-to-Side	At surgery
Manual or stapled anastomosis	Manual or stapled anastomosis	At surgery
Conversion	Conversion during surgery: Robot to laparoscopy (yes/no); Laparoscopy to open (yes/no)	At surgery
Diverting ileostomy	Use of a diverting ileostomy (yes/no)	At surgery
Baseline CEA	Baseline CEA: Carcinoembryonic antigen (µg/L)	At baseline
Histology type	Histology type of tumor (adenocarcinoma, squamous cell carcinoma, neuro-endocrine tumor etc.)	After surgery
Tumor differentiation	Well differentiated Moderately differentiated poorly differentiated	After surgery
Tumor perforation	Tumor perforation on histology (yes/no)	After surgery
Radical resection	Radical resection: R0, R1, R2	After surgery
pTNM	Pathological TNM classification of tumor; T: tumor size; N: nodal involvement; M: metastasis	After surgery
Disease free interval	Disease free interval: the period of time between the primary treatment of a malignancy and the first sign of tumor recurrence (in months)	Up to 2 years after rectal resection
Type of complication	Type of complication: Urinary tract infection; Pulmonary complications; Surgical site infection; Intra-abdominal collections/abscess; Eventration/evisceration; Ileus; Small bowel obstruction; Anastomotic leakage; Deep venous thrombosis; Postoperative bleeding; Acute renal failure; High output ileostomy; Other stoma related complications; Other (yes/no)	After rectal resection during admission
Early complications	Early complications: before 30 days after surgery	Between surgery and 30 days after surgery
Late complications	Late complications: more than 30 days after surgery	From 30 days after surgery up to 2 years after surgery
Anastomotic leakage	Definition of anastomotic leakage: Clinically manifest insufficiency of the anastomosis leading to a clinical state requiring treatment, diagnosed in accordance with surgical practice guidelines by a senior surgeon (no additional or systematic routine iconography nor colonoscopy); Radiological evidence of anastomotic leakage if the patient is clinically symptomatic. Fistulas communicating with the anastomosis on CT scan are classified as AL together with presacral abscesses if extravasation of the colonic contrast is visible on radiological imaging (ref. SAFE 2019 Clinical Investigation Plan) (yes/no)	Up to 3 months after surgery
Clavien-Dindo classification	Clavien-Dindo classification (grade 0, I, II, IIIa, IIIb, IVa, IVb, V): Grade I: Minor deviation from normal course; no drugs or interventions needed (only supportive care). Grade II: Requires pharmacological treatment (e.g. antibiotics, blood transfusion, TPN). Grade III: Requires surgical, endoscopic, or radiological intervention IIIa: without general anesthesia IIIb: with general anesthesia Grade IV: Life-threatening complication requiring ICU care IVa: single-organ dysfunction IVb: multi-organ dysfunction Grade V: Death	After admission for rectal resection
CCI-score	CCI-score: comprehensive complication index (score from 0-100 calculated with online calculator: https://www.cci-calculator.com/cci-calculator)	After admission for rectal resection

Collaborators and Investigators

• Sponsor: University Hospital, Antwerp
• Investigators: Principal Investigator: Niels Komen, MD PhD, University Hospital, Antwerp

Study record dates

Study Major Dates

• Study Start (Actual): August 26, 2024
• Primary Completion (Estimated): August 1, 2029
• Study Completion (Estimated): August 1, 2029

Study Registration Dates

• First Submitted: April 12, 2025
• First Submitted That Met QC Criteria: January 5, 2026
• First Posted (Actual): January 14, 2026

Study Record Updates

• Last Update Posted (Actual): January 14, 2026
• Last Update Submitted That Met QC Criteria: January 5, 2026
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Total mesorectal excision; Rectal resection; Low anterior resection; LARS; Rectal carcinoma
• Additional Relevant MeSH Terms: Postoperative Complications; Pathologic Processes; Neoplasms by Site; Neoplasms; Intestinal Diseases; Gastrointestinal Neoplasms; Digestive System Neoplasms; Digestive System Diseases; Gastrointestinal Diseases; Colorectal Neoplasms; Intestinal Neoplasms; Rectal Diseases; Colonic Diseases; Pathological Conditions, Signs and Symptoms; Low Anterior Resection Syndrome; Rectal Neoplasms; Health Care Quality, Access, and Evaluation; Investigative Techniques; Epidemiologic Methods; Data Collection; Health Care Evaluation Mechanisms; Quality of Health Care; Public Health; Environment and Public Health; Surveys and Questionnaires
• Other Study ID Numbers: 6510

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No