Large Japanese study finds robotic surgery reduces blood loss, conversions and hospital stays, with fewer major complications after distal gastrectomy

Robotic gastrectomy was associated with lower blood loss, fewer conversions to open surgery and shorter hospital stays than laparoscopic surgery in a large Japanese study of gastric cancer patients, while robotic distal gastrectomy also reduced major postoperative complications.

Surgery remains the primary curative treatment for gastric cancer, with laparoscopic gastrectomy established as a standard minimally invasive approach. While laparoscopic surgery can support faster recovery than open surgery, it remains technically demanding because surgeons operate within a confined space using rigid instruments.

Robotic gastrectomy was developed to address some of these limitations by providing greater instrument dexterity, precision and three-dimensional visualisation. Although its use has expanded, whether robotic surgery provides meaningful clinical advantages over conventional laparoscopy in routine practice has remained uncertain.

In Japan, robotic gastrectomy became eligible for national health insurance coverage in 2018, increasing access to the procedure and expanding opportunities for surgeons to gain experience with robotic techniques.

Researchers from Fujita Health University, the University of Tokyo, Gunma University and other institutions analysed contemporary nationwide data to assess whether robotic surgery was associated with improved outcomes. Their findings were published in Gastric Cancer on May 29, 2026.

The researchers used Japan’s National Clinical Database to identify patients who underwent minimally invasive distal gastrectomy or total gastrectomy between January 2023 and December 2024. Propensity score matching was used to account for differences between patients before comparing robotic and laparoscopic procedures.

The analysis included 9,743 matched pairs of robotic and laparoscopic distal gastrectomy cases and 1,617 matched pairs of total gastrectomy cases.

“RG has become broadly integrated into routine clinical practice across Japan. Under these contemporary conditions, it remains essential to clarify whether RG offers tangible clinical advantages over LG,” said Susumu Shibasaki, professor in the Department of Surgery at Fujita Health University–Okazaki Medical Center.

Robotic surgery took longer than laparoscopic surgery for both types of gastrectomy. Robotic distal gastrectomy took approximately 50 minutes longer on average, while robotic total gastrectomy required almost 70 additional minutes.

Despite the longer operating times, robotic surgery was associated with several favourable short-term outcomes.

For both distal and total gastrectomy, robotic surgery resulted in 33–40% lower blood loss, a 50–65% lower likelihood of conversion to open surgery and shorter postoperative hospital stays than laparoscopic surgery.

The benefits were particularly evident in distal gastrectomy. Robotic distal gastrectomy was associated with a lower rate of major postoperative complications than laparoscopic surgery, as well as fewer intra-abdominal infections.

The rate of major postoperative morbidity after robotic distal gastrectomy was 4.3%, compared with 4.9% after laparoscopic surgery. However, robotic total gastrectomy did not produce a significant difference in the primary morbidity outcome, with rates of 8.7% and 8.3%, respectively.

“Although the absolute magnitudes of these differences were small, the consistent benefits across multiple perioperative outcomes indicate that RG may achieve a level of minimal invasiveness beyond LG, which itself is a highly refined minimally invasive approach,” said Shibasaki.

The researchers also compared the findings with an earlier nationwide analysis conducted before robotic gastrectomy became covered by Japan’s national health insurance system. They found that outcomes following robotic surgery had improved, which they attributed to advances in robotic technology, increasing surgical experience and expanded training opportunities.

The researchers noted that the difference between distal and total gastrectomy could reflect the greater technical demands of total gastrectomy. Surgeons also perform total gastrectomy less frequently, potentially limiting opportunities to build experience with robotic techniques.

The findings suggest that robotic gastrectomy can provide several short-term perioperative benefits over laparoscopic surgery in routine clinical practice, particularly for distal gastrectomy. However, the study was observational and focused on short-term outcomes, meaning further research will be needed to determine whether the differences translate into longer-term benefits for patients with gastric cancer.

“Over the next 5–10 years, these findings are expected to accelerate the widespread adoption of robotic surgery. As a result, more patients will have access to safer, higher quality surgical care, leading to better recovery, fewer complications, and improved overall outcomes,” said Shibasaki.