花井 恒一

BACKGROUND: Robotic surgery for rectal cancer has grown popular in recent years and has primarily used the da Vinci Surgical System (Intuitive Surgical, CA, USA; da Vinci). In 2020, Japan introduced the hinotori™ Surgical Robot System (Medicaroid, Kobe, Japan; hinotori). We report our initial surgical experiences with robotic surgery using hinotori for rectal cancer and its feasibility and safety comparing with da Vinci. METHODS: A single-institution retrospective study was conducted. Between November 2022 and November 2023, 38 and 96 patients with rectal cancer underwent robotic surgery using hinotori and da Vinci, respectively. The primary endpoint was the incidence of postoperative complications of the Clavien-Dindo classification (CD) grade ≥ II within postoperative 30 days. Secondary endpoints included surgical and console time, blood loss, conversion to other approaches, number of dissected lymph nodes, and postoperative hospital stay. A propensity score matching (PSM) analysis was used to adjust for imbalance in baseline characteristics. RESULTS: After PSM, a total of 76 patients (hinotori: 38, da Vinci: 38) were included. Compared to the da Vinci group, the hinotori group showed a similar postoperative complication rate of CD ≥ II (15.8% vs. 18.4%), comparable operative time (280.5 vs. 258 min), comparable console time (166 vs. 156 min), and less blood loss (9 vs. 17.5 mL, p = 0.025). There was no conversion in either group. The number of dissected nodes and postoperative stay were similar between the two groups. CONCLUSION: Our findings support that robotic surgery for rectal cancer using hinotori is as safe as surgery performed using the da Vinci system.

BACKGROUND: The da Vinci™ Surgical System, recognized as the leading surgical robotic platform globally, now faces competition from a growing number of new robotic surgical systems. With the expiration of key patents, innovative entrants have emerged, each offering unique features to address limitations and challenges in minimally invasive surgery. The hinotori™ Surgical Robot System (hinotori), developed in Japan and approved for clinical use in November 2022, represents one such entrant. This study demonstrates initial insights into the application of the hinotori in robot-assisted surgeries for patients with rectal neoplasms. METHODS: The present study, conducted at a single institution, retrospectively reviewed 28 patients with rectal neoplasms treated with the hinotori from November 2022 to March 2024. The surgical technique involved placing five ports, including one for an assistant, and performing either total or tumor-specific mesorectal excision using the double bipolar method (DBM). The DBM uses two bipolar instruments depending on the situation, typically Maryland bipolar forceps on the right and Fenestrated bipolar forceps on the left, to allow precise dissection, hemostasis, and lymph node dissection. RESULTS: The study group comprised 28 patients, half of whom were male. The median age was 62 years and the body mass index stood at 22.1 kg/m2. Distribution of clinical stages included eight at stage I, five at stage II, twelve at stage III, and three at stage IV. The majority, 26 patients (92.9%), underwent anterior resection using a double stapling technique. There were no intraoperative complications or conversions to other surgical approaches. The median operative time and cockpit time were 257 and 148 min, respectively. Blood loss was 15 mL. Postoperative complications were infrequent, with only one patient experiencing transient ileus. A median of 18 lymph nodes was retrieved, and no positive surgical margins were identified. CONCLUSIONS: The introduction of the hinotori for rectal neoplasms appears to be safe and feasible, particularly when performed by experienced robotic surgeons. The double bipolar method enabled precise dissection and hemostasis, contributing to minimal blood loss and effective lymph node dissection.

BACKGROUND: The potential benefits of robotic-assisted compared with laparoscopic surgery for locally advanced cancer have not been sufficiently proven by prospective studies. One factor is speculated to be the lack of strict surgeon criteria. The aim of this study was to assess outcomes for robotic surgery in patients with locally advanced rectal cancer with strict surgeon experience criteria. METHODS: A criterion was set requiring surgeons to have performed more than 40 robotically assisted operations for rectal cancer. Between March 2020 and May 2022, patients with rectal cancer (distance from the anal verge of 12 cm or less, cT2-T4a, cN0-N3, cM0, or cT1-T4a, cN1-N3, cM0) were registered. The primary endpoint was the rate positive circumferential resection margin (CRM) from the pathological specimen. Secondary endpoints were surgical outcomes, pathological results, postoperative complications, and longterm outcomes. RESULTS: Of the 321 registered patients, 303 were analysed, excluding 18 that were ineligible. At diagnosis: stage I (n = 68), stage II (n = 84) and stage III (n = 151). Neoadjuvant therapy was used in 56 patients. There were no conversions to open surgery. The median console time to rectal resection was 170 min, and the median blood loss was 5 ml. Fourteen patients had a positive CRM (4.6%). Grade III-IV postoperative complications were observed in 13 patients (4.3%). CONCLUSION: Robotic-assisted surgery is feasible for locally advanced rectal cancer when strict surgeon criteria are used.

BACKGROUND AND AIM: Colitis-associated intestinal cancer (CAC) can develop in patients with inflammatory bowel disease; however, the malignant grade of CAC may differ from that of sporadic colorectal cancer (CRC). Therefore, we compared histological findings distinct from cancer stage between CAC and sporadic CRC to evaluate the features of CAC. METHODS: We reviewed the clinical and histological data collected from a nationwide database in Japan between 1983 and 2020. Patient characteristics were compared to distinguish ulcerative colitis (UC), Crohn's disease (CD), and sporadic CRC. Comparisons were performed by using all collected data and propensity score-matched data. RESULTS: A total of 1077 patients with UC-CAC, 297 with CD-CAC, and 136 927 with sporadic CRC were included. Although the prevalence of well or moderately differentiated adenocarcinoma (Tub1 and Tub2) decreased according to tumor progression for all diseases (P < 0.01), the prevalence of other histological findings, including signet ring cell carcinoma, mucinous carcinoma, poorly differentiated adenocarcinoma, or squamous cell carcinoma, was significantly higher in CAC than in sporadic CRC. Based on propensity score-matched data for 982 patients with UC and 268 with CD, the prevalence of histological findings other than Tub1 and Tub2 was also significantly higher in those with CAC. At pT4, mucinous carcinoma occurred at a significantly higher rate in patients with CD (45/86 [52.3%]) than in those with sporadic CRC (13/88 [14.8%]) (P < 0.01). CONCLUSION: CAC, including early-stage CAC, has a higher malignant grade than sporadic CRC, and this difference increases in significance with tumor progression.