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NCT Number: NCT07146334

Low Powered Colorectal Anastomosis After Rectal Excision (OASIS)

The objectiive of this prospective, international cohort is to compare two anastomotic techniques (DS vs TTSS) by collecting data during the surgery, and postoperatively (morbidity and functional outcomes).

The choice of technique is left to the discretion of the surgeon based on her/his practices.

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Key information

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Hôpital Universitaire de Belgique, Leuven, Belgium

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About this study

There are a variety of available anastomotic techniques to facilitate restorative surgery following total mesorectal excision (TME) for rectal cancer. However, there is no good quality evidence demonstrating the superiority of any single technique with regards to the potential sequalae of restorative surgery including anastomotic leakage and functional impact. Double-stapled anastomotic technique (DST) for colorectal anastomosis is the most widely used technique worldwide. An alternative to DST is the hand-sewn coloanal anastomotic (CAA) technique, which is traditionally reserved for patients with ultralow rectal tumours requesting restorative surgery or in cases of technical difficulties whereby a low colorectal anastomosis is converted to a coloanal anastomosis. More recently, the Transanal Transection and Single Staple anastomosis (TTSS) technique has been described. The TTSS technique has the potential to mitigate the difficulties encountered with DST and the potential complications and long-term functional sequalae encountered with handsewn anastomosis. Moreover, powered mechanical circumferential staplers represent a significant advancement in colorectal surgery, particularly in performing anastomosis following rectal excision. These devices are designed to provide consistent staple formation and controlled tissue compression, reducing the variability associated with manual stapling.

AL has a significant impact on clinical, patient-reported, and oncological outcomes. To mitigate the impact of AL a diverting stoma is routinely used to protect the distal anastomosis and facilitate anastomotic healing, with these stomas reversed once the integrity and patency of the distal anastomosis is confirmed. However, there is a significant complication profile associated with the routine use of diverting stomas. Through the incorporation of appropriate pre-operative risk stratification and careful post-operative surveillance a selective stoma strategy is associated with good clinical and functional outcomes.

The use of Double-stapled anastomotic technique (DST) or Transanal Transection Single-Stappled (TTSS) by laparoscopic or robotic approach, using or not a defunctionning stoma could not be separately tested in randomized trial.

In this exploratory, observational, prospective, IDEAL stage 2b International cohort study, we aim to include 400 patients with resection rectal and low powered colorectal anastomosis.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age ≥ 18
  • Patients with rectal cancer lower than 12 cm from the anal verge requiring either a stapling anastomosis below 7 cm from the anal verge,
  • Patients with powered mechanical anastomosis (INTOCARE devices)
  • Patients with no metastasis
  • Patients operated on by mini-invasive rectal excision (laparoscopic, robotic or TaTME);
  • Patients with or without defunctioning ileostomy;
  • Patients with or without neoadjuvant treatment;
  • Patient who benefits by medicare system;
  • Signed and dated informed consent

Exclusion criteria

  • Patients with handsewn anastomosis
  • Patients with perforated rectal cancer or preoperative pelvic sepsis ;
  • Patients with inflammatory bowel disease;
  • Patients operated on in emergency ;
  • Patients with extended-TME or pelvic exenteration;
  • Pregnancy or breast feeding period
  • Legal incapacity or physical, psychological social or geographical status interfering with the patient's ability to agree to participate in the study
  • Persons deprived of liberty or under guardianship

Treatment and study plan

Primary outcomes

  1. To assess and compare the rate of anastomotic leakage at 1 month after rectal excision between double and single-stapling low colorectal anastomosis using advanced powered stapler

    Time frame: From the surgery to one month

    Proportion of anastomotic leakage (clinical and radiological) at 1 month after rectal surgery between double- and single-stapling low colorectal anastomosis using advanced powered stapler.

Secondary outcomes

  1. Overall morbidity and mortality rates at 1 month

    Time frame: At 1 month after the end of the surgery

    Postoperative morbidity and mortality according Clavien-Dindo classification at 1 month

  2. The rate of anastomotic leakage at 6 and 12 months after rectal surgery;

    Time frame: At 12 month after the end of the surgery

    Rate of defunctioning stoma at 1, 6 and 12 months after surgery;

  3. Quality of life with QLQ C30 questionnaire

    Time frame: At 1, 6 and 12 months after rectal surgery

    The EORTC QLQ-C30 is a questionnaire developed to assess the quality of life of cancer patients.

    This is a patients self-rating questionnaire that measures five functional scales (physical, role, social, emotional, and cognitive) three symptom scales (fatigue, pain, nausea and vomiting) A global health status / QoL scale, and a number of single items assessing additional symptoms commonly reported by cancer patients (dyspnea, loss of appetite, insomnia, constipation and diarrhea) and perceived financial impact of the disease. Scores can be linearly transformed to provide a score from 0 to 100 REF. Higher scores represent better functioning on the functional scales and a higher level of symptoms of the symptom scales.

    9 dimensions will be assessed with: PF : Physical Functioning RF : Role Functioning CF : Cognitive Functioning EF : Emotional Functioning SF: Social Functioning FA : Fatigue PA : Pain NV : Nausea and Vomiting QL : Global health status

  4. Quality of life with QLQ CR29 questionnaire

    Time frame: At 1,6 and 12 months after rectal surgery

    The QLQ-CR29 (Quality of life of rectal cancer patients with 29 questions) has five functional and 18 symptom scales. Scores can be linearly transformed to provide a score from 0 to 100. Higher scores represent better functioning on the functional scales and a higher level of symptoms of the symptom scales.

  5. Qualiy of life with EQ5D-5L

    Time frame: At 1, 6 and 12 months after rectal surgery

    Mean Score of the EQ-5D-5L Quality of Life The EQ-5D-5L essentially consists of 2 pages: the EQ-5D descriptive system and the EQ visual analogue scale (EQ VAS).The questionnaire is a self-report survey that measures quality of life across 5 domains: : mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each dimension has 5 levels: no problems, slight problems, moderate problems, severe problems and extreme problems. The patient is asked to indicate his/her health state by ticking the box next to the most appropriate statement in each of the five dimensions. This decision results in a 1-digit number that expresses the level selected for that dimension. The digits for the five dimensions can be combined into a 5-digit number that describes the patient's health state

    • The EQ VAS records the patient's self-rated health on a vertical visual analogue scale, numbered from 0 to 100.

    ( 100 means "the best health you can imagine" and 0 means "the worst health you

  6. Digestive function with LARS score

    Time frame: At 1, 6 and 12 months after rectal surgery

    The LARS questionnaire (low anterior resection score) evaluates bowel function. Five questions regarding incontinence for flatus and liquid stools, frequency, clustering and urgency for defecation are taken into account. The score ranges from 0 to 42 is divides into no LARS (0 to 20 points), minor LARS (21 to 29 points), and major LARS (30 to 42 points).

  7. Anal Incontinence with Wexner score ( or Vaizey score)

    Time frame: At 1,6 and 12 months after rectal surgery

    The WEXNER score assesses the importance of anal incontinence, it varies from 0 to 20, where 20 corresponding to total anal incontinence

    The Vaizey score assesses the importance of anal incontinence score from 0-28 where 0 means better outcomes

  8. Female Sexual Function Index (FSFI) scale scores

    Time frame: At 1, 6 and 12 months after rectal surgery

    Measured in female patients. The Female Sexual Function Index (FSFI) is a 19-item self-report inventory designed to assess female sexual function. It comprises six domains: desire, arousal ,lubrication orgasm, satisfaction, pain. The maximum score for each domain is 6.0, obtained by summing item responses and multiplying by a correction factor. The total composite sexual function score is a sum of domain scores and ranges from 2.0 (not sexually active and no desire) to 36.0.

  9. International Index of Erectile Function (IIEF)-5

    Time frame: At 1,6 and 12 months after rectal surgery

    Measured in male patients

    IIEF assessment assesses to a limit the psychosexual background and the partner relationship, both considered important factors in the presentation of male sexual dysfunction.

    Scores of 0 to 5 are awarded to each of the 15 questions, then the scores are interpreted in the view of the5 domains from the original study.

    Domain A Erectile Function Domain B Orgasmic Function Domain C Sexual Desire Domain D Intercourse Satisfaction Domain E Overall Satisfaction

  10. International Prostate Symptom Score (IPSS)

    Time frame: At 1, 6 and 12 months after surgery

    The International Prostate Symptom Score (I-PSS) is based on the answers to seven questions concerning urinary symptoms and one question concerning quality of life.

    Each question concerning urinary symptoms allows the patient to choose one out of six answers indicating increasing severity of the particular symptom.

    The answers are assigned points from 0 to 5. The total score can therefore range from 0 to 35 (asymptomatic to very symptomatic).

  11. Predictive factors for anastomotic fistula

    Time frame: From the surgery to 12 months

    To identify predictive factors of anastomotic fistula from the surgery to 12 months

    Comparison of the clinical and perioperative data . The differences in proportions will be compared.

Study contacts

Contact information is provided by the study sponsor or research team.

Hélène HMM MAILLOU-MARTINAUD, CRA

CONTACT

[email protected]

+33 6 68 68 68 05

Quentin QD DENOST, Prof

CONTACT

[email protected]

+ 33 (0)5 47 50 15 75

Sponsors and collaborators

Lead sponsor

Bordeaux Colorectal Institute

Other

Registry information

Official study title

Low Powered Colorectal Anastomosis After Rectal Excision : An Exploratory, Observational, Prospective, IDEAL Stage 2b International Cohort Study (OASIS)

Acronym: OASIS

Important dates

Study start
2025
Primary completion
2029
Study completion
2029
First posted
Aug 28, 2025
Registry last updated
Aug 28, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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