Safety and Short-term Outcomes of Modular Robotic System for Siewert II/III Gastroesophageal Junction Cancer

A Prospective Single-arm Study Evaluating the Safety and Short-term Outcomes of Modular Robotic System for Siewert II/III Gastroesophageal Junction Cancer

Siewert type II/III gastroesophageal junction (GEJ) adenocarcinoma is a challenging malignancy located at the anatomical transition between the esophagus and stomach. Due to its complex anatomical location and mixed biological characteristics of esophageal and gastric cancers, the optimal surgical strategy remains controversial. Current surgical approaches vary in terms of operative access, extent of resection, and lymph node dissection. Although minimally invasive laparoscopic and integrated robotic surgery have demonstrated potential advantages in improving perioperative outcomes, limitations remain when managing complex procedures involving both abdominal and mediastinal fields.

Split-type robotic surgical systems, characterized by independently movable robotic carts, provide greater flexibility in robotic arm positioning and may overcome some limitations associated with conventional integrated robotic platforms, particularly in extensive multi-quadrant procedures requiring simultaneous abdominal and mediastinal lymph node dissection. However, clinical evidence regarding the safety and effectiveness of split-type robotic surgery for Siewert type II/III GEJ cancer remains limited.

This prospective single-arm clinical study aims to evaluate the feasibility, safety, and short-term surgical outcomes of split-type robotic radical surgery for patients with Siewert type II/III GEJ adenocarcinoma. The study will assess perioperative outcomes, including operative characteristics, postoperative complications, lymph node dissection quality, and short-term recovery parameters. The findings of this study are expected to provide preliminary clinical evidence regarding the application of split-type robotic technology in complex GEJ cancer surgery and support future large-scale clinical investigations.

Siewert type II/III gastroesophageal junction (GEJ) adenocarcinoma represents a unique clinical entity located at the junction between the distal esophagus and proximal stomach. According to the Siewert classification, type II tumors are defined as tumors with their epicenter located from 1 cm above to 2 cm below the esophagogastric junction, whereas type III tumors extend from 2 cm to 5 cm below the junction. Due to their distinct anatomical characteristics and lymphatic drainage patterns, these tumors present unique challenges in surgical management.

Siewert type II tumors have a relatively increased risk of mediastinal lymph node metastasis, while Siewert type III tumors primarily involve abdominal lymphatic pathways. Consequently, significant controversy remains regarding the optimal surgical approach, including the choice between transthoracic and transabdominal approaches, esophagectomy versus gastrectomy, and the appropriate extent of lymphadenectomy. In particular, the management of Siewert type II tumors remains debated because of their overlapping features between esophageal and gastric cancers. Currently, Siewert type III tumors are generally treated according to gastric cancer principles, with total gastrectomy and D2 lymphadenectomy being widely accepted surgical strategies.

Minimally invasive surgery has increasingly been applied in GEJ cancer treatment. Previous studies have demonstrated that laparoscopic surgery may provide advantages in reducing surgical trauma and improving short-term postoperative recovery compared with open surgery. However, existing evidence is primarily derived from retrospective studies, with considerable heterogeneity and limited long-term oncological outcome data.

Robotic-assisted surgery has emerged as an advanced minimally invasive approach, offering three-dimensional visualization, enhanced instrument dexterity, motion scaling, and improved ergonomics. Small retrospective series using the da Vinci integrated robotic platform for Siewert type II/III GEJ cancer surgery have demonstrated acceptable perioperative safety and feasibility. However, conventional integrated robotic systems have limitations in complex procedures requiring extensive operative fields. Due to restricted robotic arm mobility and fixed configuration, procedures involving both thoracic and abdominal regions may require intraoperative redocking, which may interrupt surgical workflow, prolong operative time, and reduce procedural efficiency.

The split-type robotic surgical system provides an alternative robotic platform design consisting of multiple independently movable robotic carts. This configuration allows more flexible arrangement of robotic arms according to surgical requirements and may be particularly advantageous for Siewert type II/III GEJ cancer surgery, where both mediastinal and abdominal lymph node dissection may be required. Compared with integrated robotic systems, split-type robotic platforms may reduce the need for intraoperative redocking, maintain procedural continuity, decrease mechanical interference, and improve surgical efficiency during complex multi-quadrant operations.

The Carina™ Split-type Surgical Robotic System and compatible surgical instruments developed by Ruilong Nuofu (Shanghai) Medical Technology Co., Ltd. have obtained approval from the National Medical Products Administration (NMPA) of China. The system has fulfilled regulatory requirements for investigator-initiated clinical studies according to relevant medical device regulations and clinical trial quality management principles. Previous clinical applications of the Carina™ system in multiple surgical specialties, including gastrointestinal surgery, have demonstrated acceptable safety profiles and perioperative outcomes.

Nevertheless, despite these theoretical advantages, clinical evidence regarding the application of split-type robotic systems in radical surgery for Siewert type II/III GEJ cancer remains lacking. In particular, whether split-type robotic surgery can improve operative efficiency, facilitate lymph node dissection, reduce surgical interruptions, and maintain acceptable perioperative safety has not been prospectively evaluated.

Therefore, this prospective single-arm clinical study is designed to investigate the feasibility, safety, and short-term outcomes of split-type robotic radical surgery for patients with Siewert type II/III GEJ adenocarcinoma. The study will evaluate perioperative parameters, including operative time, intraoperative blood loss, conversion rate, postoperative complications, recovery indicators, pathological outcomes, and lymph node dissection results.

The results of this study will provide preliminary clinical evidence regarding the role of split-type robotic technology in complex GEJ cancer surgery. These findings may serve as a foundation for future multicenter clinical trials, optimization of robotic surgical strategies, establishment of standardized surgical protocols, and improvement of clinical outcomes for patients with Siewert type II/III GEJ adenocarcinoma.

Inclusion Criteria:

1. Age between 18 and 80 years, inclusive, regardless of sex.
2. Histologically and/or cytologically confirmed Siewert type II or type III gastroesophageal junction tumor, with clinical staging according to AJCC 8th edition TNM classification indicating suitability for curative surgical resection.
3. Adequate organ function as assessed by the investigator before surgery.
4. Provision of written informed consent and willingness to participate in the study.
5. Ability and willingness to comply with study procedures and follow-up requirements.
6. ECOG performance status of 0-1.
7. Absence of distant metastasis confirmed by preoperative thoracoabdominal and pelvic CT or PET-CT.

Exclusion Criteria:

1. Patients with body mass index (BMI) <18.5 kg/m² or BMI ≥35 kg/m².
2. Patients with severe cardiac, pulmonary, neurological, hepatic, or renal diseases that may prevent tolerance of surgery or anesthesia.
3. Patients unable to tolerate pneumoperitoneum or considered by the investigator to have extensive intra-abdominal adhesions or other conditions preventing safe establishment of pneumoperitoneum.
4. Patients with severe coagulation disorders that contraindicate minimally invasive surgery.
5. Patients with active pulmonary tuberculosis.
6. Patients with severe uncontrolled diseases, acute infections, severe physical deterioration, massive ascites, active intra-abdominal bleeding, or shock.
7. Patients with metastatic lymph nodes fused together or encasing major blood vessels, making curative resection infeasible.
8. Patients with previous abdominal/pelvic surgery, radiotherapy, or chemotherapy that may affect the feasibility of laparoscopic or robotic surgery.
9. Pregnant or breastfeeding women.
10. Patients currently participating in other clinical trials involving investigational drugs or medical devices.
11. Patients considered unsuitable for this study by the investigator.