Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract (20/1000000). They occur mainly in the stomach (50-60% of cases), followed by the small intestine(20-30%), rectum (about 10%), and are usually asymptomatic. They are often discovered after prophylactic imaging or endoscopic examinations, or during surgery on another occasion. In symptomatic cases, they commonly present with bleeding from the gastrointestinal tract, abdominal discomfort, pain, or signs for intestinal obstruction.^[1]

The mainstay of treatment is radical surgical resection with clean resection margins and avoidance of disease dissemination, especially for tumors ≥2 cm.^[2,3] This condition can be fulfilled using different surgical techniques and extent of surgery–local excision, wedge resection for small masses, proximal and distal resections, and even total gastrectomies, depending on the size and location of the formation.

In the early development of minimally invasive surgery, the limiting factors for its application in these tumors include limitations caused by their size, and the risk of injury with subsequent peritoneal dissemination. The first consensus decision^[4] by the 2004 Consensus Conference limited the laparoscopic approach for tumors >2 cm in size (National Comprehensive Cancer Network – NCCN). With time and further development of surgical techniques, the contraindications caused by the size of the tumor disappeared, while retaining the recommendations based on oncological principles.(ESMO Gastrointestinal stromal tumors: ESMO EURACAN GENTURIS Clinical Practice Guidelines for diagnosis, treatment and follow-up).^[5]

In the last decade, robotic surgery began to occupy a significant portion of surgical interventions in abdominal surgery, thanks to the advantages it has over open and laparoscopic techniques, offering equivalent oncological results in the treatment of malignant neoplasms.^[6,7]

The aim of this study was to evaluate the safety and feasibility of robotic surgery of gastro intestinal stromal tumors.

From November 2021 to April 2022, four patients with proven gastric GIST passed through the Department of Surgery at University Hospital Kaspela, Plovdiv, Bulgaria. All of them were confirmed preoperatively using immunohistochemical examination of biopsy material taken by esophagogastroduodenoscopy, staged by computed tomography and surgically treated using the da Vinci robotic system (Intuitive Surgical, Inc., Sunnyvale, CA). The definitive staging and postoperative diagnosis confirmation of GIST was once again performed using the immunohistochemical examination of CD117 (KIT) positive cells.

The position of the patients on the operating table was supine, with arms tucked by the side of the body. A Veress needle was inserted through a small supraumbilical incision and an initial CO2 insufflation was performed, at a pressure of 12 mmHg. Next, the first robotic 8 mm trocar was inserted through the incision. The remaining three robotic trocars were placed under direct vision, in line with the first, two to the right of the umbilicus and one to the left, at a distance of about 7-8 cm from each other. An infraumbilical assistant port, near the lateral edge of the rectus abdominis muscle on the left, was additionally placed, representing the air seal cannula. After positioning all of the trocars, the patient was placed in the reverse Trendelenburg position.

A laparoscopic exploration of the peritoneal cavity to rule out the presence of peritoneal or liver metastases was then performed. This was followed by the docking of the robotic system and beginning of surgery (Fig. 1).

The characteristics of the patients are presented in Table 1. The compared indicators include tumor location, tumor growth type and size, Fletcher’s score, postsurgical morbidity and length of hospital stay.

These initial results include four patients – three women and one man, diagnosed with GIST and undergoing robotic gastric resection of varying extents. The average age of the patients was 64.3 years (53-72 years). In three of the cases, the disease was asymptomatic, and was detected during routine GIT examinations, and in the fourth, complaints of abdominal discomfort and dyspepsia were presented. In all patients, an intraoperative ultrasound was performed, with biopsy of the tumor formations, proving the latter preoperatively by immunohistochemical examination. The lesions were located in the region of the corpus, along the anterior wall in two patients, in the antrum in one, and in the cardia, in the area near the esophagogastric junction in one patient. All of the tumors had an endophytic growth and its average size was 5 cm (4-7 cm). According to their extent the surgical procedures included two distal resections, in cases with location in the corpus, one proximal resection, due to GIST in the cardia, and one antrumectomy. No conversion was required in any of the cases. We did not register intraoperative complications, tumor rupture or dissemination. The average blood loss in this initial group of patients was about 70 ml (80-120 ml), and for this reason the patients did not need hemotransfusions in the postoperative period. Histopathological examination according to the Fletcher criteria classified one of the tumors as low risk and the other three as intermediate. The average operative time in all of the cases was 255 minutes (220-320 minutes).

As a complication, we observed a low-flow fistula in the patient with the proximal resection, which closed spontaneously and was classified as grade I according to the Clavien-Dondo classification. The average hospital stay in our group was 8.2 days (4-11 days). The follow-up period of the patients was 9.75 months (8-11 months), and no recurrence was recorded during this short interval.

The most common location of gastrointestinal stromal tumors is the stomach. They are characterized by exo- and endophytic growth patterns, and their biological behavior and tendency to metastasize varies.^[8] Lymph node involvement by metastatic disease is very rare, and for this reason lymph node dissection is not recommended. Recurrences are usually due to translocation of cells at the contact of the tumor formation with adjacent abdominal structures, most often the peritoneum, and in a very small percentage of cases due to unclean resection margins. The pseudocapsule covering tumors growing towards the peritoneal cavity protects them from dissemination, but it is thin and easily ruptures spontaneously in case of rapid growth, trauma or rough handling intraoperatively.^[9–13]

A resection margin of 1-2 cm in healthy tissue is considered oncological safety, with low local recurrence rate. Therefore, with an appropriate location, wedge resection is the method of choice for most of the GISTs. However, the possibility of different gastric resections and even gastrectomies for certain tumor sizes and locations remains.^[14] A series of studies and meta-analyses have proven the safety of minimally invasive surgery in the treatment of these tumors. The main limiting factor was tumor size above 2 cm, considering the risk of tumor rupture during the surgery, with its subsequent dissemination, resulting in recurrence and deterioration of survival.^[15]

Liao et al. found out that laparoscopic surgery (LS) for intestinal GISTs led to oncological outcomes that were comparable to those of laparotomy after a long-term follow-up and that LS was associated with favorable perioperative outcomes and a shorter hospital stay compared to laparotomy. With strict oncological precautions and protection, laparoscopic treatment may be a safe and effective procedure for small- and medium-sized intestinal GISTs.^[16]

Recently, minimally invasive surgery is increasingly being utilized for resection of gastric and small bowel GIST, with improved postoperative outcomes, where overall survival after minimally invasive or open surgery was comparable, even in challenging scenarios of neoadjuvant treatment or large tumors (≥10 cm).^[17]

Gevorkian et al. consider that the utilization of robotic-assisted resections of GI cancers is rapidly increasing with more frequent use in younger and healthier patients, where with the utilization of robotic-assisted resections, perioperative outcomes and oncologic safety have not been compromised.^[18]

In our initial group, the average size of the tumors was 5 cm, and we recorded no cases of injury and dissemination, due to the experience of the surgical team in laparoscopic surgery and correct instrument selection. These results coincide with modern minimally invasive and robotic approaches in the treatment of GIST, relying on the safety and reliability of surgical techniques, proven by a number of multicenter studies.^[19–21] In our patients, the main factors were location and the determination of macroscopically clean resection margins.

Based on the short-term results of our first few cases with gastrointestinal stromal tumors operated robotically, we can conclude that this type of surgery is safe and oncologically equivalent to conventional procedures. The benefits of robotic over laparoscopic surgery are well-known, but there are also disadvantages related mainly to the extended operative time and increased cost of the procedure..