Safety and Efficacy Evaluation of Single-Port Versus Multi-Port Robotic-Assisted Radical Distal Gastrectomy for Gastric Cancer

Technical success is defined as completion of the protocol-specified gastrectomy, lymph node dissection, and gastrointestinal reconstruction using the robotic surgical approach assigned at randomization. In the single-port group, technical success requires completion using the single-port robotic system without conversion to multi-port robotic surgery, conventional laparoscopic surgery, or open surgery, and without any unplanned additional port beyond those permitted by the protocol. In the multi-port group, technical success requires completion using the multi-port robotic system without conversion to conventional laparoscopic surgery or open surgery. Failure to complete the assigned robotic procedure because of participant-related, operative, or device-related reasons will be classified as technical failure. The prespecified noninferiority margin is -10 percentage points.

Total duration of the surgical procedure, recorded in minutes according to the protocol-defined timing criteria.

Duration required for robotic docking, recorded in minutes according to the protocol-defined timing criteria.

Duration of robotic console operation, recorded in minutes according to the protocol-defined timing criteria.

Estimated volume of blood loss during surgery, recorded in milliliters.

Intraoperative complications will be recorded and graded according to the Satava classification system.

R0 resection is defined as complete tumor resection with no microscopic residual tumor at the resection margins, as determined by postoperative pathological examination.

Total number of lymph nodes retrieved and identified during postoperative pathological examination.

Total number of pathologically confirmed metastatic lymph nodes identified during postoperative pathological examination.

Any postoperative complication occurring from the end of surgery through postoperative Day 30 will be recorded according to the predefined study protocol and graded using the Clavien-Dindo classification.

Severe postoperative complications are defined as postoperative complications classified as Clavien-Dindo Grade III or higher.

Prespecified surgery-related complications include anastomotic leakage, anastomotic bleeding or stenosis, duodenal stump leakage, pancreatic fistula or postoperative pancreatitis, intra-abdominal bleeding, intra-abdominal infection or abscess, bile leakage, chylous or lymphatic leakage, delayed gastric emptying, postoperative ileus or bowel obstruction, internal hernia, bowel perforation or ischemic necrosis, and wound complications requiring clinical intervention.

Percentage of participants requiring an unplanned surgical reoperation for any postoperative reason within 30 days after the index surgery.

Percentage of participants requiring an unplanned hospital readmission within 30 days after the index surgery.

All-cause mortality occurring within 30 days after the index surgery.

This is the prespecified primary outcome of the embedded postoperative pain and early recovery substudy, which is planned to include 140 participants from the parent randomized trial. Resting postoperative pain will be assessed using the Visual Analog Scale (VAS) on postoperative Days 1, 2, and 3 according to a standardized assessment procedure. For the primary analysis, a linear mixed-effects model for repeated measures will be applied, adjusting for pre-specified confounding factors including study site. It will estimate the overall mean resting VAS score across postoperative Days 1-3 for each group, together with the between-group difference and its 95% confidence interval. Higher VAS scores indicate greater pain intensity. The prespecified superiority hypothesis evaluates whether the overall resting VAS pain level across postoperative Days 1-3 is lower in the single-port group than in the multi-port group.

This is a prespecified supportive outcome of the embedded postoperative pain and early recovery substudy. Resting postoperative pain will be assessed using the Visual Analog Scale (VAS) at 6 hours after surgery according to the standardized assessment procedure. Higher VAS scores indicate greater pain intensity.

This is a prespecified time-point-specific supportive outcome of the embedded postoperative pain and early recovery substudy. Resting postoperative pain will be assessed using the Visual Analog Scale (VAS) on postoperative Day 1 according to the standardized assessment procedure. VAS scores on postoperative Day 1 will be analyzed separately to compare pain intensity between the single-port and multi-port groups. Where appropriate, estimated marginal means and the between-group difference at postoperative Day 1 will be derived from the prespecified linear mixed-effects model. Multiplicity adjustment will be applied according to the prespecified statistical analysis plan. Higher VAS scores indicate greater pain intensity. This analysis is supportive of the primary longitudinal analysis and does not constitute a separate confirmatory superiority hypothesis.

This is a prespecified time-point-specific supportive outcome of the embedded postoperative pain and early recovery substudy. Resting postoperative pain will be assessed using the Visual Analog Scale (VAS) on postoperative Day 2 according to the standardized assessment procedure. VAS scores on postoperative Day 2 will be analyzed separately to compare pain intensity between the single-port and multi-port groups. Where appropriate, estimated marginal means and the between-group difference at postoperative Day 2 will be derived from the prespecified linear mixed-effects model. Multiplicity adjustment will be applied according to the prespecified statistical analysis plan. Higher VAS scores indicate greater pain intensity. This analysis is supportive of the primary longitudinal analysis and does not constitute a separate confirmatory superiority hypothesis.

This is a prespecified time-point-specific supportive outcome of the embedded postoperative pain and early recovery substudy. Resting postoperative pain will be assessed using the Visual Analog Scale (VAS) on postoperative Day 3 according to the standardized assessment procedure. VAS scores on postoperative Day 3 will be analyzed separately to compare pain intensity between the single-port and multi-port groups. Where appropriate, estimated marginal means and the between-group difference at postoperative Day 3 will be derived from the prespecified linear mixed-effects model. Multiplicity adjustment will be applied according to the prespecified statistical analysis plan. Higher VAS scores indicate greater pain intensity. This analysis is supportive of the primary longitudinal analysis and does not constitute a separate confirmatory superiority hypothesis.

This is a prespecified secondary or supportive outcome of the embedded postoperative pain and early recovery substudy. Rescue analgesia is defined as additional analgesic treatment administered because of inadequate pain control beyond the protocol-specified routine postoperative analgesic regimen. The proportion of participants requiring at least one rescue analgesic intervention during the prespecified postoperative observation period will be recorded and compared between the single-port and multi-port groups. This outcome does not have a separate confirmatory superiority hypothesis.

This is a prespecified secondary or supportive outcome of the embedded postoperative pain and early recovery substudy. All postoperative opioid analgesics administered during the prespecified observation period will be recorded. Individual opioid doses will be converted to morphine milligram equivalents (MME) using a prespecified standardized conversion method, and cumulative MME will be calculated for each participant to allow quantitative comparison of postoperative opioid requirements between the single-port and multi-port groups. This outcome does not have a separate confirmatory superiority hypothesis.

Total abdominal wall incision length will be calculated as the sum of the lengths of all abdominal surgical incisions and recorded in centimeters according to the standardized study assessment procedure. This outcome will be assessed in randomized participants to compare abdominal wall trauma between the single-port and multi-port robotic surgical groups. It is also included as a prespecified supportive outcome of the embedded postoperative pain and early recovery substudy.

The length of the longest individual abdominal wall surgical incision will be measured in centimeters according to the standardized study assessment procedure. This outcome will be assessed in randomized participants to compare the extent of abdominal wall trauma between the single-port and multi-port robotic surgical groups. It is also included as a prespecified supportive outcome of the embedded postoperative pain and early recovery substudy.

Time to first postoperative flatus is defined as the time from the end of surgery to the first passage of flatus and will be recorded in hours. This outcome will be assessed in randomized participants to compare early postoperative gastrointestinal recovery between the single-port and multi-port robotic surgical groups.

Time to first postoperative defecation is defined as the time from the end of surgery to the first postoperative bowel movement and will be recorded in hours. This outcome will be assessed in randomized participants to compare early postoperative gastrointestinal recovery between the single-port and multi-port robotic surgical groups.

Time to first postoperative walking lasting more than 5 minutes is defined as the time from the end of surgery to the first postoperative walking episode lasting more than 5 minutes and will be recorded in hours. Brief standing or walking episodes lasting 5 minutes or less will not be considered as meeting this outcome. This outcome will be assessed in randomized participants to compare early postoperative functional recovery between the single-port and multi-port robotic surgical groups. It is also included as a prespecified supportive outcome of the embedded postoperative pain and early recovery substudy.

Time to first postoperative oral intake is defined as the time from the end of surgery to the first postoperative oral intake of liquid, soft food, or regular food and will be recorded in days. This outcome will be assessed in randomized participants to compare early postoperative recovery between the single-port and multi-port robotic surgical groups.

Time to meeting discharge criteria is defined as the time from the end of surgery until the participant meets all prespecified discharge criteria. These criteria include stable vital signs without fever; recovery of gastrointestinal function with adequate oral intake and no requirement for intravenous nutritional support; ability to ambulate independently without significant discomfort; and satisfactory wound and drainage status with laboratory findings considered clinically acceptable according to the study protocol. This outcome will be assessed in randomized participants to compare early postoperative recovery between the single-port and multi-port robotic surgical groups.