Yosuke Kobayashi

PURPOSE: To develop an educational program that enables young surgeons to safely perform laparoscopic transabdominal preperitoneal repair (TAPP). METHODS: This retrospective study comprised 365 patients who underwent elective TAPP performed by surgical residents (SRs; n = 145 patients) and board-certified surgeons (BCSs; n = 220 patients) from January 2018 to December 2023. An educational program for SRs has been underway since April 2021 to facilitate efficient learning and ensure the safe performance of TAPP. This program comprises four steps and highlights the two points mentioned, including understanding technical principles and acquiring fundamental skills. The surgical outcomes of laparoscopic TAPP performed by SRs and BCSs were compared retrospectively. RESULTS: A total of 43 operators (16 SRs and 27 BCSs) performed the laparoscopic TAPP. The SRs demonstrated longer operative times (median 126 vs. 98 min; p < 0.01). No significant differences in the rates of seroma (7.6% vs. 5.5%), grade IIIa or higher Clavien-Dindo complications (early: 0.7 vs. 0.9%; late: 0.7% vs. 0%), and recurrence at 1 year after surgery (1.4% vs. 0.5%) were observed between the SR and BCSs groups. Following the implementation of the educational program in April 2021, laparoscopic TAPP procedures performed by SRs were associated with significantly shorter operation times compared to those conducted before the program was introduced. CONCLUSIONS: SRs who received presurgical education improved the operative time in laparoscopic TAPP, although with intraoperative guidance from Endoscopic Surgical Skill Qualification System-qualified surgeons.

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 AND PURPOSE: Accurate recurrence risk evaluation in patients with stage II and III colorectal cancer (CRC) remains difficult. Traditional histopathological methods frequently fall short in predicting outcomes after adjuvant chemotherapy. This study aims to evaluate the use of comprehensive genomic profiling combined with machine learning for prognostic risk stratification in patients with CRC. METHODS: A machine learning model was developed using a training cohort of 52 patients with stage II/III CRC who underwent curative surgery at Fujita Health University Hospital. Genomic DNA was isolated from formalin-fixed, paraffin-embedded tissue sections and analyzed with a 160 cancer-related gene panel. The random forest algorithm was used to determine key genes affecting recurrence-free survival. The model was validated by developing a risk score with internal and external cohorts, including 44 patients from Keio University Hospital. RESULTS: Six key genes (KRAS, KIT, SMAD4, ARID2, NF1, and FBXW7) were determined as significant prognostic risk predictors. A risk score system integrating these genes with clinicopathological factors effectively stratified patients in both internal (p < 0.001) and external cohorts (p = 0.017). CONCLUSIONS: This study reveals that machine learning, combined with comprehensive genomic profiling, significantly improves prognostic risk stratification in patients with stage II/III CRC after adjuvant chemotherapy. This approach provides a promising tool for individualized treatment strategies, warranting further validation with larger cohorts.

Colorectal cancer (CRC) is well characterized in terms of genetic mutations and the mechanisms by which they contribute to carcinogenesis. Mutations in APC, TP53, and KRAS are common in CRC, indicating key roles for these genes in tumor development and progression. However, for certain tumors with low frequencies of these mutations that are defined by tumor location and molecular phenotypes, a carcinogenic mechanism dependent on BRAF mutations has been proposed. We here analyzed targeted sequence data linked to clinical information for CRC, focusing on tumors with a high tumor mutation burden (TMB) in order to identify the characteristics of associated mutations, their relations to clinical features, and the mechanisms of carcinogenesis in tumors lacking the major driver oncogenes. Analysis of overall mutation frequencies confirmed that APC, TP53, and KRAS mutations were the most prevalent in our cohort. Compared with other tumors, TMB-high tumors were more frequent on the right side of the colon, had lower KRAS and higher BRAF mutation frequencies as well as a higher microsatellite instability (MSI) score, and showed a greater contribution of a mutational signature associated with MSI. Ranking of variant allele frequencies to identify genes that play a role early in carcinogenesis suggested that mutations in genes related to the DNA damage response (such as ATM and POLE) and to MSI (such as MSH2 and MSH6) may precede BRAF mutations associated with activation of the serrated pathway in TMB-high tumors. Our results thus indicate that TMB-high tumors suggest that mutations of genes related to mismatch repair and the DNA damage response may contribute to activation of the serrated pathway in CRC.

BACKGROUND: In the field of abdominal surgery, including colorectal cancer surgery, robotic surgery has become widespread, and the introduction of new robotic platforms is increasing. As a result, the incidence of subcutaneous emphysema (SE) as a postoperative complication has increased; however, the causes, grade, and perioperative course of SE have not been definitively examined. Therefore, we aimed to evaluate potential risk factors of SE after robotic colorectal cancer surgery. METHODS: Between November 2022 and March 2024, 244 consecutive patients who underwent robotic colorectal cancer surgery using the da Vinci Xi (n = 190) or the hinotori™ platform (n = 54) were retrospectively analyzed. Risk factors associated with postoperative SE were assessed by multivariate analysis using logistic regression models. Moreover, the grade of SE and its perioperative course were investigated based on the two robotic platforms. RESULTS: Postoperative SE was observed in 95 patients (38.9%). Nine patients (3.7%) had severe SE. The risk factors for SE were female sex, older age (≥ 80 years), and maximum intraabdominal pressure (max IAP) with CO2 insufflation > 10 mmHg (odds ratio [95% confidence interval]: 1.981 [1.105-3.552], p = 0.022; 2.765 [1.310-5.835], p = 0.008; and 13.249 [1.227-143.020], p = 0.033, respectively). Additionally, the incidence of SE when using the hinotori™ platform was significantly lower than when using the da Vinci Xi platform (0.302 [0.135-0.667], p = 0.004). CONCLUSIONS: Max IAP with CO2 > 10 mmHg was associated with SE during robotic colorectal cancer surgery. Compared with the use of da Vinci Xi, the use of hinotori™ was associated with fewer incidences of postoperative SE, especially in females and older patients (≥ 80 years).