The KRAS G12D mutation increases the risk of unresectable recurrence of resectable colorectal liver-only metastasis.

PURPOSE: Unresectable recurrence is a critical predictor of outcomes for colorectal cancer patients. We attempted to identify the prognostic factors, especially for unresectable recurrence-free survival (URFS) as a new endpoint, in patients with resectable colorectal liver-only metastasis (CRLOM). METHODS: We investigated patients with resectable CRLOM, who underwent an R0 resection for both CRC and CRLOM between January, 2014 and March, 2019 at a single institution. The exclusion criteria were patients who received neoadjuvant treatment, the absence of data for genetic analyses, and the presence of multiple cancers, synchronous CRC, or familial adenomatous polyposis. The prognostic factors were examined retrospectively using data on pre-hepatectomy factors, including primary tumor molecular profiling results. RESULTS: We analyzed the data of 101 patients who underwent curative-intent surgery for CRLOM. Multivariate analysis revealed that KRAS G12D mutation-positivity (hazard ratio [HR]: 7.69; p < 0.01), RYR2 mutation-positivity (HR: 4.03; p < 0.01), and KRAS G12S mutation-positivity (HR: 3.96; p = 0.03), CA19-9 > 37 U/ml before hepatectomy (HR: 3.62; p < 0.01), and primary tumor pN2 stage (HR: 3.22; p = 0.03) were significant predictors of the URFS. CONCLUSIONS: This is the first study to show that specific KRAS and RYR2 mutations were associated with the URFS.

Short-term and long-term outcomes after robotic radical surgery for rectal gastrointestinal stromal tumor.

BACKGROUND: The optimal approach for ensuring both complete resection and preservation of anal function in rectal gastrointestinal stromal tumor (GIST) remains unknown. The aim of this study was to clarify short-term and long-term outcomes after robotic radical surgery for rectal GIST. METHODS: A total of 13 patients who underwent robotic radical surgery for rectal GIST between December 2011 and April 2022 were included. All robotic procedures were performed using a systematic approach. A supplemental video of robotic radical surgery for rectal GIST is attached. The short-term outcome was the incidence of postoperative complications during the first 30 days after surgery. Surgical outcomes were retrieved from a prospective database. Long-term outcomes, including overall survival and recurrence-free survival, were determined in all patients. RESULTS: Median distance from the tumor to the anal verge was 4.0 cm. Surgical margins were negative in all patients. Two patients underwent neoadjuvant imatinib therapy. All patients underwent sphincter-preserving surgery. None underwent conversion to open or laparoscopic surgery. The incidence of postoperative Clavien-Dindo grade II and grade ≥ III complications was 7.7% and 0%, respectively. The median postoperative hospital stay was 7 days. Twelve patients (92.3%) underwent stoma closure within 5 months of the initial surgery. Median follow-up time was 76 months. The 5-year overall survival and recurrence-free survival rates were both 100%. None of the patients had recurrence. CONCLUSION: Short-term and long-term outcomes after radical robotic surgery for rectal GIST were favorable. Robotic surgery might be a useful surgical approach for rectal GIST.

Risk factors for stoma prolapse after laparoscopic loop colostomy.

BACKGROUND: Stoma prolapse (SP) is a common stoma-related complication, particularly in loop colostomies. This study aimed to investigate potential risk factors for SP development after laparoscopic loop colostomy. METHODS: In total, data from 140 patients who underwent laparoscopic loop colostomy were analyzed between September 2016 and March 2022. Risk factors for SP were investigated retrospectively. RESULTS: The median follow-up duration after colostomy was 12.5 months, and SP occurred in 33 (23.6%) patients. Multivariate analysis showed that being overweight (body mass index ≥ 25; odds ratio [OR], 8.69; 95% confidential interval [CI], 1.61-46.72; p = 0.012) and having a thin rectus abdominis penetration of the stoma (< 8.9 mm; OR, 8.22; 95% CI, 2.50-27.05; p < 0.001) were independent risk factors for SP. Other patient characteristics and surgical factors associated with stoma construction were unrelated to SP development. CONCLUSIONS: Being overweight and the route penetrating the thinner rectus abdominis during stoma construction was associated with a significantly higher incidence of SP after laparoscopic loop colostomy. Selecting a construction site that penetrates the thicker rectus abdominis muscle may be crucial for preventing SP.

Prediction model of the risk for lateral local recurrence in locally advanced rectal cancer without enlarged lateral lymph nodes: Lessons from a Japanese multicenter pooled analysis of 812 patients.

Aim: Although the oncological impact of lateral lymph node dissection on enlarged lateral lymph nodes has been gradually accepted over the last decade, that on lateral lymph nodes without swelling remains doubtful. This study aimed to develop a prediction model for the future risk of lateral local recurrence and to clarify the value of adding lateral lymph node dissection in locally advanced rectal cancer without enlarged lateral lymph nodes. Methods: This retrospective, multi-institutional study recruited 812 patients with cStage II/III low rectal cancer without enlarged lateral lymph nodes <7 mm. Total lateral local recurrence was a hypothetical value of future risk of lateral local recurrence when lateral lymph node dissection was never performed. Results: Overall, total lateral local recurrences were observed in 67 patients (8.3%). In the multivariate analyses, the strongest risk factor for total local recurrences was no preoperative chemoradiotherapy (odds ratio [OR][95%Cl]: 33.2 [4.56-241.7], P < 0.001), followed by tumor distance ≤40 mm (OR [95%Cl]: 2.71 [1.51-4.86], P < 0.001) and lateral lymph node 5-7 mm (OR[95%Cl]: 2.38 [1.26-4.48], P = 0.007). In patients with lateral lymph nodes of 5-7 mm, the total lateral recurrence rate was 4.8% after preoperative chemoradiotherapy. Lateral lymph node dissection could reduce from a total lateral local recurrence of 21.6% to an actual lateral local recurrence of 8.0% in patients without preoperative treatment. Conclusion: We introduce a novel prediction model of future risk of lateral local recurrences, which has the potential to enable us to indicate lateral lymph node dissection selectively according to the patients' risks.