The effect on incisional hernia of absorbable barbed suture for midline fascial closure in minimally invasive surgery for colorectal and gastric cancers: study protocol for a randomized controlled trial

Laparoscopic and robotic surgery has become a preferred treatment option for colorectal and gastric cancers rather than open surgery because of its minimally invasive nature and short-term operative outcomes [1‐5]. During minimally invasive gastrointestinal surgery, mini-laparotomy is used for extracorporeal anastomosis, specimen extraction, or single-port surgery. Midline incision is widely used for mini-laparotomy [6], because it is easy to perform, results in minimal blood loss, provides a better surgical view, and is more convenient for closure than other types of incision [7]. However, a midline incision carries a high incidence of incisional hernia [8].

Incisional hernia is a commonly encountered complication after abdominal surgery, with a reported incidence of 10–32% [9, 10]. Incisional hernia diminishes a patient’s quality of life due to pain and discomfort [11]. Although minimally invasive surgery with a smaller incision and limited abdominal wall trauma is expected to reduce incisional hernia, the incidence of incisional hernia of this approach did not differ from that of open surgery [12, 13]. Several methods of abdominal closure have been reported to prevent incisional hernia after abdominal surgery. A running technique with long-lasting monofilament suture material is recommended to prevent incisional hernia [14]. However, monofilament suture has the disadvantage of being easily loosening and requiring a surgical knot, resulting in a potential risk of incisional hernia [15].

Barbed suture is a new type of suture material, first patented in 1964. It consists of standard monofilament suture with tiny barbs along its length that are designed to anchor the suture without the need for knots [16]. These new materials have become popular for skin and uterine closures during cesarean section, orthopedic surgery, and gastrointestinal surgery due to reduced tissue trauma and convenience [17‐20]. In animal experiments, barbed sutures for fascia closure showed adequate tensile strength [21]. However, they are yet to be clinically adopted owing to insufficient evidence of their safety and efficacy as compared to those of conventional suture materials. Therefore, we propose a randomized controlled clinical trial (Barbed trial) to compare the outcomes of absorbable barbed sutures and conventional absorbable monofilament sutures for midline fascia closure in minimally invasive surgery for colorectal and gastric cancers.

This study aimed to evaluate the safety and efficacy of absorbable barbed sutures for midline fascia closure in minimally invasive surgery for colorectal and gastric cancers in comparison with conventional absorbable monofilament sutures.

The Barbed trial is a prospective, superiority, single-center, randomized trial comparing the clinical outcomes of absorbable barbed sutures and monofilament sutures. A total of 312 patients will be enrolled and randomly allocated to use absorbable barbed or monofilament sutures for midline fascia closure in a 1:1 ratio. The surgical procedure used to close the midline fascia was standardized for both types of suture material. The investigator will examine the patients until discharge and at 6, 12, 18, 24, and 36 months postoperatively (Fig. 1). This study is ongoing at Jeonbuk National University Hospital and will last 3 years for each patient. This trial was registered with the Clinical Research Information Service of Korea.

This study will enroll participants who are scheduled to undergo minimally invasive gastric or colorectal cancer surgery at Jeonbuk National University Hospital. This study was approved and supported by the Institutional Review Board of Jeonbuk National University Hospital (CUH 2021-09-040).

The trial details will be explained in full to potential participants by investigators, and an informed consent form will be provided. Adequate time will be given to participants to consider their decision regarding trial participation. Subsequently, participants can sign the informed consent and they can withdraw at any time during the trial.

Not applicable as no participant data and biological specimens were collected in this study.

The participant timeline is shown in Fig. 2.

We mainly have used absorbable monofilament sutures for fascia closure, and the overall incidence of incisional hernia was about 15%. Barbed suture began to be used for fascial closure in August 2020 during colorectal surgery. Before this randomized controlled trial, we conducted a pilot study of barbed suture for fascia closure. A total of 60 patients underwent fascia closure with barbed suture during laparoscopic colorectal surgery, and incisional hernia occurred in 2 patients (3.3%) within 1 year after surgery. Assuming additional patients with an incisional hernia during follow-up period, we determined possible incisional hernia rate to 5% in the barbed suture group for 3 years after surgery. Therefore, we hypothesized that the incidence of incisional hernia at 3 years after surgery will be lower in the barbed suture group than in the monofilament suture group. The sample size was calculated on the basis of this analysis plan, assuming that the incisional hernia rate of the barbed suture and monofilament groups at 3 years after surgery will be 5% and 15%, respectively. We calculated that 141 patients per group needed to achieve a two-sided α of 0.05 and statistical power of 80% using a chi-squared test. Assuming a 10% dropout rate, it is necessary to recruit 312 patients. Finally, 156 patients were assigned to the barbed suture and monofilament groups. The calculations were performed using G*Power 3.1.

Patients who are scheduled to undergo minimally invasive gastric or colorectal cancer surgery will be considered as candidates for trial enrolment in concordance with the inclusion and exclusion criteria. Informed consent will be obtained from all participants by investigators. We are confident that we can enroll a sufficient number of eligible patients, as our institution conducts over 150 surgeries for gastric cancer and 300 surgeries for colorectal cancer annually.

Eligible patients will be randomly allocated to use absorbable barbed or monofilament sutures for midline fascia closure in a 1:1 ratio. Stratified randomization was performed by medical statisticians who do not participate in this study. This randomization is based on an independent, computer-based sequence generated from the implementation of the dynamic algorithm with the cancer types as the stratifying variables.

To achieve randomization, a computer-generated sequence methodology will be used, which will ensure that both the randomization methodology and the allocation sequence are concealed from both the investigator and the participants.

An independent medical statistician will generate a stratified randomization list for allocation sequence. Investigators will enroll and assign participants to interventions.

After the interventions are assigned, participants will be blinded. The results will be kept confidential from the participants throughout the entire trial. Surgeons will not be blinded because the intervention involves a surgical procedure.

As investigators are aware of the participant allocation, unblinding would not be required.

Participants are patients with gastric or colorectal cancer who require regular follow-up to evaluate cancer recurrence. We expect that participants will be available for follow-up due to concerns of cancer recurrence.

The study data will be collected and recorded electronically, and stored securely on computers and hard drives. Only the investigators will have access to the participants’ files, and they will be the only ones authorized to make changes to the information. This will ensure that the data remains accurate and validated throughout the study.

Datasets will be anonymized, and only summary data, which cannot identify individual participants, will be presented in the manuscript.

Not applicable as no biological specimens were collected in this study.

A planned analysis will be performed after all patients have completed their 3-year follow-up. Categorical variables will be presented as numbers with percentages, and continuous variables will be presented as means with standard deviations or medians with interquartile ranges. The analysis will be performed using the intention-to-treat approach. The primary outcome will be analyzed using chi-squared and Kaplan-Meier tests. Risk factors for incisional hernia will be analyzed using the Cox regression analysis. Secondary outcomes will be tested using the chi-squared test for categorical variables and the t-test or Mann-Whitney test for continuous variables, as appropriate. The level of statistical significance will be set at p < 0.05.

We have no plans to conduct any interim analyses, since both interventions have low risk.

Loss to follow-up will be minimized due to the characteristics of cancer patients. If missing data is exceed 5% of any variable, multiple imputations will be used to handle missing values.

The full protocol and final datasets will be available from the corresponding author on reasonable request.

The authors will coordinate and steer this study.

We do not have composition of the data monitoring committee.

Any adverse events that required additional pharmacological, interventional, or surgical management within 30 days after surgery will be collected and monitored. We regarded adverse events as postoperative complications and graded according to the Clavien-Dindo classification [23]. Adverse events will be treated according to the standards of care.

The study data will be maintained in accordance with Good Clinical Practice requirements by the investigators. The original study data and information will be securely stored for a minimum of 5 years following the completion of the study. Data monitoring reports will be submitted to the ethics committee every 3 months.

If the protocol needs to be modified, it will be reviewed again by the ethics committee, and, upon approval, the trial registry and protocol will be updated.

The findings will be published in peer-reviewed journals and disseminated through scientific and academic conferences.