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Understanding and Tailored Treatment of Low Anterior Resection Syndrome (PATO-LARS)

1 de mayo de 2026 actualizado por: Esben Bolvig Mark, Aalborg University Hospital

The goal of this observational study is to learn why some patients develop low anterior resection syndrome (LARS) after colorectal cancer treatment. The study also aims to identify different subtypes of LARS and understand which patients may respond to specific treatments.

The main questions it aims to answer are:

  • What physiological and imaging changes are associated with LARS?
  • How do patients with LARS differ from patients without LARS after colorectal cancer surgery?
  • Are there measurable differences between LARS, patients treated with organ-preserving chemoradiotherapy, and patients with fecal incontinence?

Participants will:

  • Complete advanced physiological and imaging assessments related to bowel function

  • Be compared with four control groups:

    • patients without LARS after colorectal cancer surgery
    • patients treated with organ-preserving chemoradiotherapy
    • patients with fecal incontinence and urge fecal incontinence
  • Take part in a single study visit where all measurements are performed

Descripción general del estudio

Estado

Reclutamiento

Condiciones

Descripción detallada

Low anterior resection syndrome (LARS) is a common long-term complication after colorectal cancer surgery. Up to 80% of patients experience symptoms such as urgency, frequent bowel movements, clustering, and fecal incontinence. These symptoms can severely affect quality of life, and the underlying causes are not fully understood. LARS appears to result from several interacting mechanisms, including sensory changes, altered motility, reduced reservoir function, sphincter dysfunction, and effects of chemotherapy or radiotherapy. Because different patients may have different dominant mechanisms, treatment responses vary widely.

This observational study aims to investigate the physiological and imaging characteristics of LARS using advanced assessment methods. The goal is to better understand the mechanisms behind LARS, identify distinct patient subtypes, and support development of more targeted treatment strategies.

The study will include 50 patients with minor or major LARS after rectal cancer surgery. Their results will be compared with four control groups:

  • patients who had rectal cancer surgery but did not develop LARS,
  • patients with fecal incontinence (before/after sacral nerve stimulation),
  • patients with urge fecal incontinence (before/after dorsal genital nerve stimulation), and
  • patients treated with organ-preserving chemoradiotherapy ("watch-and-wait"), whose rectum has not been surgically removed.

All participants will attend a single study visit that includes advanced physiological measurements, Magnetic Resonance Imaging (MRI)-based assessments, and standardized questionnaires. These methods are not part of routine clinical care but are used to explore mechanisms such as motility, sensory function, sphincter activity, and rectal reservoir function.

Patients with LARS will also be followed during their standard stepwise treatment pathway. They will complete questionnaires before and during each treatment step, which may include dietary advice, medication, pelvic floor training (biofeedback), and rectal emptying techniques such as mini-enemas or transanal irrigation. This follow-up will help determine how different physiological patterns relate to treatment response.

The study is conducted in collaboration between Aarhus University Hospital and Aalborg University Hospital, with expert input from The Royal London Hospital (UK) and Motilis SA (Switzerland).

Tipo de estudio

De observación

Inscripción (Estimado)

145

Contactos y Ubicaciones

Esta sección proporciona los datos de contacto de quienes realizan el estudio e información sobre dónde se lleva a cabo este estudio.

Estudio Contacto

  • Nombre: Esben B Mark, PhD
  • Número de teléfono: +45 97663523
  • Correo electrónico: e.mark@rn.dk

Ubicaciones de estudio

  • Dinamarca
      • Aalborg, Dinamarca, 9220
        • Activo, no reclutando
        • Aalborg University Hospital
      • Aarhus, Dinamarca, 8200
        • Reclutamiento
        • Aarhus University Hospital
        • Contacto:
          • Gitte K Sørensen, Research Nurse
          • Número de teléfono: +45 2499 5223
          • Correo electrónico: gittesoe@rm.dk
        • Investigador principal:
          • Peter Christensen, MD, Professor
      • Vejle, Dinamarca, 7100
        • Reclutamiento
        • Vejle Hospital
        • Contacto:

Criterios de participación

Los investigadores buscan personas que se ajusten a una determinada descripción, denominada criterio de elegibilidad. Algunos ejemplos de estos criterios son el estado de salud general de una persona o tratamientos previos.

Criterio de elegibilidad

Edades elegibles para estudiar

  • Adulto
  • Adulto Mayor

Acepta Voluntarios Saludables

No

Método de muestreo

Muestra no probabilística

Población de estudio

During outpatient visits, the treatment responsible doctor will identify eligible patients. Patients will be recruited at the following departments:

  1. LARS patients - patient operated for rectal cancer at Department of Surgery, Aarhus University Hospital, with rectal resection with sphincter preservation and primary anastomosis.
  2. Watch and wait patients - patient treated for rectal cancer with organ preservation at Aalborg University Hospital or Vejle Hospital.
  3. Patients with Faecal Incontinence planned for neuromodulation at Pelvic Floor Unit, Department of Surgery, AUH.

Descripción

Inclusion Criteria:

General:

  • Must be able to read and understand Danish.
  • All participants must be adults and >18 years and have full legal capacity.
  • Assessed by study personnel to have understood the research protocol, being able to comply with investigation procedures as well as ability to come to the hospital at the agreed timepoints, and to complete the trial.

Specific inclusion criteria for LARS patients:

  • Patients operated for rectal cancer with a rectal resection and sphincter preserving surgery at a minimum of three months postop.
  • If patients have received a temporary protective ileostomy, this should have been reversed for a minimum of three months postop.

Specific inclusion criteria for fecal incontinence patients and urge fecal incontinence patients

  • Patients planned for neuromodulation.
  • Satisfactory interoperative test results leading to permanent implantation of a pacemaker for sacral nerve modulation.

Specific inclusion criteria for "watch and wait" patients:

• Rectum/colon cancer patients treated with organ-preserving treatment, i.e., chemotherapy and radiotherapy with a complete clinical and radiological response at a minimum of 12 months posttreatment.

Exclusion Criteria:

General exclusion criteria

  • Persons that are not able to understand information
  • Connective tissue disorders
  • Parkinson's disease
  • Non-MRI compatible pacemaker, clips or other metal objects in the body. Patients implanted with a pacemaker for sacral nerve modulation will not undergo MRI postoperatively.
  • Piercings that cannot be removed before MRI
  • Claustrophobia
  • Allergic to latex
  • Abdominal diameter equal or more than 140 cm
  • Have other individual factors, in the opinion of the physician/healthcare professional, in which participating is contraindicated
  • Participation in concomitant clinical trial
  • Known intestinal obstruction, significant intestinal strictures or perforation. If in doubt about intestinal stricture, the patient will be examined with MRI of the small intestine, colonoscopy or other supplementing examination
  • Disorders of swallowing
  • Pregnant women

Specific exclusion criterias for LARS patients

  • History of anastomotic leakage following rectal resection and sphincter preserving therapy
  • Evidens of local recurrence or dessimination of the cancer

Plan de estudios

Esta sección proporciona detalles del plan de estudio, incluido cómo está diseñado el estudio y qué mide el estudio.

¿Cómo está diseñado el estudio?

Detalles de diseño

Cohortes e Intervenciones

Grupo / Cohorte
LARS, minor or major symptoms

LARS score ≥ 20; Patients operated for rectal cancer with a rectal resection and sphincter preserving surgery at a minimum of three months postoperative.

If patients have received a temporary protective ileostomy, this should have been reversed for a minimum of three months postoperative.
LARS, no symptoms

LARS score < 20; Patients operated for rectal cancer with a rectal resection and sphincter preserving surgery at a minimum of three months postoperative.

If patients have received a temporary protective ileostomy, this should have been reversed for a minimum of three months postoperative.
Faecal Incontinence
  • Patients planned for neuromodulation
  • Satisfactory interoperative test results leading to permanent implantation of a pacemaker for sacral nerve modulation
Faecal Incontinence, urge
  • Patients planned for neuromodulation
  • Satisfactory interoperative test results leading to permanent implantation of a pacemaker for sacral nerve modulation
  • Faecal urgency occurring ≥3 episodes per week, with or without associated Faecal incontinence (≥1 episode per week), and a St. Mark's Incontinence Score of ≥9
Watch and wait
Rectum/colon cancer patients treated with organ-preserving treatment, i.e., chemotherapy and radiotherapy with a complete clinical and radiological response at a minimum of 12 months posttreatment

¿Qué mide el estudio?

Medidas de resultado primarias

Medida de resultado
Medida Descripción
Periodo de tiempo
EuroQol 5-Dimension, 5-Level quality-of-life questionnaire
Periodo de tiempo: From baseline visit to the end of each standardized treatments at 4 weeks

The EuroQol 5-Dimension, 5-Level questionnaire assesses generic health-related quality of life across five domains: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each domain has five response levels ranging from "no problems" to "extreme problems."

Score range and direction:

Higher scores indicate better health-related quality of life. Includes a visual analogue scale (0-100) where higher scores indicate better self-rated health.
From baseline visit to the end of each standardized treatments at 4 weeks
Low Anterior Resection Syndrome Score
Periodo de tiempo: From baseline visit to the end of each standardized treatments at 4 weeks

The Low Anterior Resection Syndrome (LARS) Score is a disease-specific symptom questionnaire assessing bowel dysfunction after low anterior resection. It includes five items covering incontinence, frequency, clustering, urgency, and impact on daily life.

Score range and direction:

Total score ranges from 0 to 42. Higher scores indicate more severe bowel dysfunction.

Severity categories:

0-20: No LARS 21-29: Minor LARS 30-42: Major LARS
From baseline visit to the end of each standardized treatments at 4 weeks

Medidas de resultado secundarias

Medida de resultado
Medida Descripción
Periodo de tiempo
St Mark's Incontinence score
Periodo de tiempo: • Applied at baseline and four weeks into all treatment periods

Description:

The St. Mark's Incontinence Score assesses the severity of fecal incontinence across multiple domains, including incontinence to gas, liquid, and solid stool, urgency, use of pads, and lifestyle impact.

Score range and direction:

Total score ranges from 0 to 24. Higher scores indicate more severe fecal incontinence.
• Applied at baseline and four weeks into all treatment periods
Colostomy Impact Score
Periodo de tiempo: From baseline visit to the end of each standardized treatments at 4 weeks

The Colostomy Impact Score is a disease-specific questionnaire evaluating the impact of living with a colostomy on daily functioning, social participation, body image, and emotional well-being.

Score range and direction:

Total score ranges from 0 to 100. Higher scores indicate greater negative impact of the colostomy on quality of life.
From baseline visit to the end of each standardized treatments at 4 weeks
Bristol Stool Form Scale
Periodo de tiempo: From baseline visit to the end of each standardized treatments at 4 weeks

The Bristol Stool Form Scale classifies stool consistency into seven categories ranging from hard, lumpy stools to entirely liquid stools. It is used as an indicator of bowel transit and stool form.

Score range and direction:

Scale ranges from Type 1 to Type 7. Lower types (1-2) indicate harder stools and slower transit. Middle types (3-4) indicate normal stool form. Higher types (6-7) indicate loose or watery stools and faster transit.
From baseline visit to the end of each standardized treatments at 4 weeks
Patient Assessment of Constipation Symptoms (PAC-SYM)
Periodo de tiempo: From baseline visit to the end of each standardized treatments at 4 weeks

The Patient Assessment of Constipation Symptoms questionnaire measures symptom severity in constipation across three domains: abdominal symptoms, stool symptoms, and rectal symptoms.

Score range and direction:

Each item is scored 0-4; total score ranges from 0 to 48. Higher scores indicate more severe constipation symptoms.
From baseline visit to the end of each standardized treatments at 4 weeks
Wexner Incontinence Score
Periodo de tiempo: From baseline visit to the end of each standardized treatments at 4 weeks

The Wexner Incontinence Score evaluates the severity of fecal incontinence based on frequency of incontinence to gas, liquid, and solid stool, need for pads, and lifestyle alteration.

Score range and direction:

Total score ranges from 0 to 20. Higher scores indicate more severe fecal incontinence.
From baseline visit to the end of each standardized treatments at 4 weeks
Hospital Anxiety and Depression Scale (HADS)
Periodo de tiempo: From baseline visit to the end of each standardized treatments at 4 weeks

The Hospital Anxiety and Depression Scale assesses symptoms of anxiety and depression in medical populations. It consists of two subscales: HADS-Anxiety and HADS-Depression.

Score range and direction:

Each subscale ranges from 0 to 21. Higher scores indicate more severe symptoms of anxiety or depression. Total score (0-42) may be reported but is less commonly used.
From baseline visit to the end of each standardized treatments at 4 weeks
Whole gut and segmental transit times as measured with 3D-Transit
Periodo de tiempo: At baseline

Whole-gut and segmental gastrointestinal transit times are measured using the Motilis 3D-Transit system. The system tracks the movement of an electromagnetic capsule through the gastrointestinal tract, allowing calculation of segmental transit times (stomach, small intestine, colon) and total whole-gut transit time. This measure evaluates gastrointestinal motility patterns at baseline.

Score range and direction:

Transit times are continuous measures reported in minutes or hours.

There is no fixed upper or lower limit, as transit times vary physiologically between individuals.

Longer transit times indicate slower gastrointestinal motility.

Shorter transit times indicate faster gastrointestinal motility.
At baseline
Colonic and segmental colonic volumes
Periodo de tiempo: At baseline

Magnetic resonance imaging is used at baseline to quantify total colonic volume and segmental colonic volumes (ascending, transverse, descending, sigmoid/rectum colon). Volumes are derived from semi-automated segmentation of the colon on T2-weighted images. This measure evaluates baseline colonic morphology and storage capacity.

Score range and direction:

Colonic volumes are continuous measures reported in milliliters (mL).

There is no fixed upper or lower limit, as volumes vary physiologically between individuals.

Higher values indicate larger colonic or segmental volume.

Lower values indicate smaller colonic or segmental volume.
At baseline
Resting Anal Pressure Measured by High-Resolution Anorectal Manometry
Periodo de tiempo: At baseline
Resting anal pressure will be measured using high-resolution anorectal manometry according to standard manometric protocols. Resting anal pressure reflects basal anal sphincter tone, primarily related to internal anal sphincter function. The outcome will be reported as a continuous physiological measure in millimeters of mercury (mmHg). There are no fixed minimum or maximum values because pressures vary physiologically between individuals. Higher values indicate higher resting anal sphincter tone, while lower values indicate reduced resting sphincter tone.
At baseline
Maximal Voluntary Anal Squeeze Pressure Measured by High-Resolution Anorectal Manometry
Periodo de tiempo: At baseline
Maximal voluntary anal squeeze pressure will be measured using high-resolution anorectal manometry according to standard manometric protocols. Squeeze pressure reflects voluntary external anal sphincter contractile strength. The outcome will be reported as a continuous physiological measure in millimeters of mercury (mmHg). There are no fixed minimum or maximum values because pressures vary physiologically between individuals. Higher values indicate stronger voluntary anal sphincter contraction, while lower values indicate reduced voluntary sphincter contractile function.
At baseline
Rear-Front Pressure Gradient Measured by the Fecobionics Device
Periodo de tiempo: At baseline
The rear-front pressure gradient will be measured using the Fecobionics device during simulated stool evacuation. The Fecobionics device records axial pressure patterns during defecation. The rear-front pressure gradient reflects the pressure difference between the rear and front sensors of the device during evacuation and provides a measure of propulsive force relative to outlet resistance. The outcome will be reported as a continuous physiological measure in millimeters of mercury (mmHg). There are no fixed minimum or maximum values because values vary physiologically between individuals. Higher values indicate stronger propulsive pressure relative to outlet resistance, whereas lower values may indicate impaired propulsion or increased outlet resistance.
At baseline
Compare the physiological findings in LARS patients with controls
Periodo de tiempo: At baseline
Compare the physioligal findings in LARS patients with a) no-LARS patients, b) organ-preservation patients and c) patient with fecal incontinence
At baseline
Investigate the physiological changes in anorectal function associated with neuromodulation in patients with urge fecal incontinence
Periodo de tiempo: From baseline to after 30 minutes of active neuromodulation
Changes in anorectal function measured by the Fecobionics Device
From baseline to after 30 minutes of active neuromodulation
Investigate the physiological changes in anorectal function associated with neuromodulation in patients with urge fecal incontinence
Periodo de tiempo: From baseline to after 30 minutes of active neuromodulation
Changes in anorectal function measured by high-resolution anorectal manometry
From baseline to after 30 minutes of active neuromodulation
Investigate the physiological changes in anorectal function associated with neuromodulation in patients with fecal incontinence
Periodo de tiempo: From baseline to after active neuromodulation at Visit 2
Changes in anorectal function measured by the Fecobionics Device
From baseline to after active neuromodulation at Visit 2
Investigate the physiological changes in anorectal function associated with neuromodulation in patients with fecal incontinence
Periodo de tiempo: From baseline to after active neuromodulation at Visit 2
Changes in anorectal function measured by high-resolution anorectal manometry
From baseline to after active neuromodulation at Visit 2
Change in VAS Urgency Score From Before to During Stimulation at the Baseline Visit
Periodo de tiempo: Baseline visit: immediately before stimulation and during active stimulation
The participant's perceived urgency to defecate during the examination will be assessed using a visual analogue scale. Participants with fecal incontinence will rate their urgency to defecate on a numeric scale from 0 to 10, where 0 indicates no desire to defecate and 10 indicates maximal urgency. The outcome will be reported as the change in VAS urgency score from the pre-stimulation assessment to the stimulation assessment at the baseline visit. Higher scores indicate stronger urgency to defecate.
Baseline visit: immediately before stimulation and during active stimulation
Resting-State Electroencephalography
Periodo de tiempo: At baseline

Resting-state electroencephalography is recorded with the participant at rest to assess baseline cortical activity patterns. Measures include spectral power across standard frequency bands (theta, alpha, beta).

Score range and direction:

Spectral power values are continuous and do not have fixed upper limits.

Higher or lower values reflect differences in cortical activity depending on frequency band.
At baseline
Evoked Potential Amplitude During Rectal Balloon Distension
Periodo de tiempo: At baseline

Electroencephalography is recorded during rapid rectal balloon distension to elicit cortical evoked potentials. The primary measure is the amplitude of the evoked response to visceral stimulation.

Score range and direction:

Amplitude is measured in microvolts (µV).

Higher amplitudes indicate stronger cortical responses to visceral stimulation.
At baseline
Evoked Potential Latency During Rectal Balloon Distension
Periodo de tiempo: At baseline

Electroencephalography is recorded during rectal balloon distension to measure the latency of cortical evoked potentials, reflecting the timing of sensory pathway activation.

Score range and direction:

Latency is measured in milliseconds (ms).

Longer latencies indicate slower or delayed cortical processing.

Shorter latencies indicate faster neural conduction.
At baseline
Defecation Index Measured by the Fecobionics Device
Periodo de tiempo: Baseline
The defecation index will be derived from Fecobionics measurements obtained during simulated stool evacuation. The index summarizes expulsion performance and anorectal function based on prespecified Fecobionics-derived variables. The outcome will be reported as a continuous index value. There are no fixed minimum or maximum values. Higher values indicate more efficient expulsion and better defecatory performance, whereas lower values indicate reduced defecatory performance.
Baseline

Colaboradores e Investigadores

Aquí es donde encontrará personas y organizaciones involucradas en este estudio.

Patrocinador

Aalborg University Hospital

Colaboradores

Aarhus University Hospital
Danish Cancer Society
Vejle Hospital

Investigadores

  • Investigador principal: Peter Christensen, MD, Professor, Pelvic Floor Unit, Department of Surgery, Aarhus University Hospital

Fechas de registro del estudio

Estas fechas rastrean el progreso del registro del estudio y los envíos de resultados resumidos a ClinicalTrials.gov. Los registros del estudio y los resultados informados son revisados ​​por la Biblioteca Nacional de Medicina (NLM) para asegurarse de que cumplan con los estándares de control de calidad específicos antes de publicarlos en el sitio web público.

Fechas importantes del estudio

Inicio del estudio (Actual)

17 de septiembre de 2024

Finalización primaria (Estimado)

31 de diciembre de 2026

Finalización del estudio (Estimado)

31 de diciembre de 2026

Fechas de registro del estudio

Enviado por primera vez

20 de abril de 2026

Primero enviado que cumplió con los criterios de control de calidad

1 de mayo de 2026

Publicado por primera vez (Actual)

7 de mayo de 2026

Actualizaciones de registros de estudio

Última actualización publicada (Actual)

7 de mayo de 2026

Última actualización enviada que cumplió con los criterios de control de calidad

1 de mayo de 2026

Última verificación

1 de mayo de 2026

Más información

Términos relacionados con este estudio

Palabras clave

Términos MeSH relevantes adicionales

Otros números de identificación del estudio

  • R325-A19027

Plan de datos de participantes individuales (IPD)

¿Planea compartir datos de participantes individuales (IPD)?

NO

Descripción del plan IPD

Individual participant data will not be shared because the study involves sensitive health information and data protection regulations (GDPR) prevent public sharing of identifiable or de-identified participant-level data.

Información sobre medicamentos y dispositivos, documentos del estudio

Estudia un producto farmacéutico regulado por la FDA de EE. UU.

No

Estudia un producto de dispositivo regulado por la FDA de EE. UU.

No

Esta información se obtuvo directamente del sitio web clinicaltrials.gov sin cambios. Si tiene alguna solicitud para cambiar, eliminar o actualizar los detalles de su estudio, comuníquese con register@clinicaltrials.gov. Tan pronto como se implemente un cambio en clinicaltrials.gov, también se actualizará automáticamente en nuestro sitio web. .

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