Financial support: The VOLTAGE study is an investigator-initiated investigational new drug (IND) clinical trial. A research grant and nivolumab were provided by Ono Pharmaceutical Co., Ltd.

The anatomy of the rectourethralis muscle is essential for performing radical prostatectomy and proctectomy. The rectourethralis muscle is known to continue to the rectal wall posteriorly and to the membranous urethra anteriorly. However, the lateral extent of the rectourethralis muscle remains unclear. This study aimed to verify the hypothesis that the rectourethralis muscle laterally extends and directly adheres to the levator ani. Eight male cadavers were used for macroscopic dissection, and three male cadavers were used for immunohistological analysis using anti-smooth muscle and anti-skeletal muscle antibodies. The rectourethralis muscle laterally extended smooth muscle fibers both superoposteriorly and inferoanteriorly toward the levator ani. The smooth muscle fibers sandwiched the levator ani superoanteriorly and inferoanteriorly. A few smooth muscle fibers of the rectourethralis muscle inserted into the levator ani. This study clarified the spatial distribution of the rectourethralis muscle and its detailed positional relationship with the levator ani. The findings are valuable especially to urologists and anorectal surgeons for dissecting an optimal layer around the urethra and the rectum, and for avoiding rectal or urethral injuries during surgery. Clin. Anat., 2018. © 2018 Wiley Periodicals, Inc.

The levator ani muscle attaches directly to the longitudinal muscle of the rectum. The spatial relationship between the smooth and skeletal muscles differed in different portions of the anal canal. For intersphincteric resection, dissection must be performed between the longitudinal muscle of the rectum and the levator ani muscle/external anal sphincter, and the appropriate surgical lines must be selected based on the specific structural characteristics of each portion.

AimThe anatomy of the region between the vagina and anal canal plays an essential role when performing a proctectomy for low‐lying tumours. However, the anatomical characteristics of this area remain unclear. The purpose of the present study was to clarify the configuration, and both lateral and inferior extensions, of the muscle bundles in the anorectal anterior wall in females.MethodsUsing cadaveric specimens, macroscopic anatomical and histological evaluations were conducted at the anatomy department of our institute. Macroscopic anatomical specimens were obtained from six female cadavers. Histological specimens were obtained from eight female cadavers.ResultsThe smooth muscle fibres of the internal anal sphincter and longitudinal muscle extended anteriorly in the anorectal anterior wall of females and the muscle bundles showed a convergent structure. The anterior extending smooth muscle fibres merged into the vaginal smooth muscle layer, distributed subcutaneously in the vaginal vestibule and perineum and spread to cover the anterior surface of the external anal sphincter and the levator ani muscle. Relatively sparse space was observed in the region anterolateral to the rectum on histological analysis.ConclusionSmooth muscle fibres of the rectum and vagina are intermingled in the median plane, and there is relatively sparse space in the region anterolateral to the rectum. Therefore, when detaching the anorectal canal from the vagina during proctectomy, an approach from both the lateral sides should be used.

4100 Background: Chemoradiotherapy (CRT) followed by radical surgery (S) is standard therapy for patients (pts) with locally advanced rectal cancer (LARC). Sequential use of an anti-PD-1 antibody after radiation demonstrates synergistic effects in in vivo models, and an anti-PD-1 antibody is effective in pts with microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC). We studied nivolumab (nivo) and radical S following CRT (50.4 Gy with capecitabine 1,650 mg/m2) in T3–4 NanyM0 LARC. Methods: After the quality-assured CRT, 240 mg q2 weeks x 5 cycles of nivo and radical S were investigated. In cohort A-1, for pts with microsatellite stable (MSS) LARC, the primary endpoint was a centrally confirmed pathological complete response (pCR) rate using AJCC tumor regression grading. The estimated required sample size assuming null and alternative hypotheses pCR = 10% and 30% was 37 pts, with a 1-sided alpha of 5% and power of 90%. In Cohort A-2, 5 pts with MSI-H LARC were included in an exploratory manner. Results: From Jan/2017 to Oct/2019, a targeted number of pts was included and assessed. In cohort A-1, 30% (11/37; 90% CI 18-44%) of pCR (AJCC grade (gr) 0) rate and 38% (14/37) of major pathological response (MPR) (AJCC gr 0+1) rate were observed. Clinical CR was observed in one additional pt (3%) refusing S after nivo. In cohort A-2, 60% (3/5) of pCR rate and 60% (3/5) of MPR rate were observed. As of Jan/2020, only 2 pts (1 local and 1 metastatic) in cohort A-1 and none in cohort A-2 recurred. Immune-related severe adverse events were observed in 3 pts (gr 3 myasthenia, gr 3 interstitial nephritis, and gr 2 peripheral motor neuropathy); all fully recovered and received radical S. During the follow-up period, one additional pt with gr 2 colitis was observed. No treatment-related deaths were observed. Conclusions: Promising pCR rates of 30% and 60%, with mild toxicities, were shown in MSS and MSI-H LARC pts treated with nivo plus radical S after CRT, suggesting the candidate therapy for the future non-surgical approach. Clinical trial information: NCT02948348 .

Whether indocyanine green fluorescence angiography (ICG-FA) during rectal surgery is effective in reducing anastomotic leakage remains unclear. This study aimed to investigate the effect of intraoperative ICG-FA on anastomotic leakage after sphincter-sparing surgery for malignant rectal tumors. MethodsThis was a retrospective, single-center cohort study conducted on 852 consecutive patients who underwent laparoscopic sphincter-sparing surgery from January 2007 to June 2017 at our institution. The incidence of anastomotic leakage was compared between patients who underwent ICG-FA to determine the proximal resection margin and those in whom this technique was not performed, using logistic regression analysis, including propensity score. ResultsA total of eight patients were excluded (one patient with previous low anterior resection and seven patients who underwent simultaneous resection for other primary cancers), resulting in 844 patients being analyzed. Before propensity score matching, 141 patients (16.7%) who underwent ICG-FA were compared with 703 patients (83.3%) in whom ICG-FA was not performed. The incidence of anastomotic leakage was 2.8% (4/141) in the ICG-FA group and 12.4% (87/703) in the control group (p = 0.001).After propensity score matching (n = 420), the patient characteristics between the two groups were well 4 balanced, and the incidence of anastomotic leakage was 2.8% (4/141) in the ICG-FA group and 13.6% (38/279) in the control group (p = 0.001). Logistic regression analyses using propensity score showed that patients who underwent ICG-FA had significantly lower odds of anastomotic leakage. ConclusionIntraoperative ICG-FA is a promising method to reduce anastomotic leakage after laparoscopic rectal surgery.

Introduction Recent studies have revealed the extended nature of smooth muscle structures in the pelvic floor, revising the conventional understanding of the “perineal body.” Our aim was to clarify the three‐dimensional configuration and detailed histological properties of the smooth muscle structures in the region anterior to the rectum and anal canal in men. Materials and methods Four male cadavers were subjected to macroscopic and immunohistological examinations. The pelvis was dissected from the perineal side, as in the viewing angle during transperineal surgeries. Serial transverse sections of the region anterior to the rectum and anal canal were stained with Masson's trichrome and immunohistological stains to identify connective tissue, smooth muscle, and skeletal muscle. Results There was a series of smooth muscle structures continuous with the longitudinal muscle of the rectum in the central region of the pelvic floor, and three representative elements were identified: the anterior bundle of the longitudinal muscle located between the external anal sphincter and bulbospongiosus; bilateral plate‐like structures with transversely‐oriented and dense smooth muscle fibers; and the rectourethral muscle located between the rectum and urethra. In addition, hypertrophic tissue with smooth muscle fibers extended from the longitudinal muscle in the anterolateral portion of the rectum and contacted the levator ani. Conclusions The series of smooth muscle structures had fiber orientations and densities that differed among locations. The widespread arrangement of the smooth muscle in the pelvic floor suggests a mechanism of dynamic coordination between the smooth and skeletal muscles.

Aim In patients with a previous history of rectal anastomotic leakage (AL), the surgical indications and timing for closure of a diverting stoma have to be carefully judged. Even if AL has apparently healed before stoma closure, re‐leakage may occur after closure. The aim of this study was to determine the incidence and risk factors for recurrent AL following stoma closure. We also examined the treatment strategies aiming to minimize the risk of recurrent AL. Methods From January 2009 to December 2016, 1008 patients underwent sphincter‐saving surgery [low anterior resection, all‐sphincter‐preserving rectal resection with hand‐sewn coloanal anastomosis (CAA) and intersphincteric resection (ISR)] for primary rectal cancer with curative intent at our hospital. A total of 69 patients with AL with a Clavien–Dindo Grade III or more who subsequently underwent closure of a diverting stoma were retrospectively reviewed for this study. Results The incidence of recurrent leakage after stoma closure in this series was 13% overall with an incidence of 25% in the CAA/ISR group and 5% in the low anterior resection group. Significant risk factors included hand‐sewn anastomosis (P = 0.0257) compared to stapled anastomosis, ischaemia at the anastomotic site as the cause of initial AL (P < 0.001) and a shorter interval between confirmation of healing and stoma closure (P = 0.00952). Conclusion Ischaemia at the anastomotic site was the main risk factor for recurrent leakage, particularly after CAA/ISR. Additional treatment options before stoma closure should be considered to avoid re‐leakage in such cases.