Soichiro Ishihara

The University of Tokyo | Todai · Department of Surgical Oncology

Background: We carried out robot-assisted lateral pelvic lymph node dissection (LPLND) for rectal cancer with a stereotactic navigation system. The purpose of this study was to evaluate the accuracy and feasibility of the system. Methods: We constructed a navigation system based on the Polaris Spectra optical tracking device (Northern Digital In...

Purpose: Data regarding risk factors for recurrence in stage I colorectal cancer patients are limited. The aim of this study was to clarify the existence of a high-recurrence-risk population among stage I colorectal cancer patients. Methods: This analysis included 7,539 stage I colorectal cancer patients treated between 1997 and 2012 at 24 leadi...

Objective The accuracy of identifying a CRT-response by a pre-operative radiological examination is limited, and another approach is necessary. We constructed endoscopic image-based radiomics classifiers to predict the response of locally advanced rectal cancers (LARCs) to neoadjuvant chemotherapy (NA-CRT). Design: We enrolled 90 patients who had u...

Purpose : The second Houston valve is used as a surrogate for estimating the position of the peritoneal reflection; however, the concordance between the positions of the valve and peritoneal reflection has not yet been investigated. This study aimed to clarify this positional relationship. Methods : The positions of the second Houston valve and per...

Background Several studies have demonstrated that right-sided tumors have poorer prognosis than left-sided tumors in patients with unresectable colorectal cancer (CRC). The predictive ability of the tumor sidedness in CRC treated with chemotherapy in each sex is unclear. Methods Subjects were 964 unresectable recurrent patients treated with chemot...

Background: In recent years, it has become clear that, in addition to normal cytokines, phospholipid mediators play an important role in the development, growth, infiltration, and metastasis of cancer and in the cancer microenvironment. A phospholipid analysis method using tandem mass spectrometry (LC-MS/MS) with high detection sensitivity has ena...

Background : The oncologic outcomes are generally considered equivalent for both laparoscopic and open surgery. However, our previous single-center study found a greater risk of postoperative peritoneal metastasis (PM) after laparoscopic colectomy (LC) than after open colectomy (OC) in patients with pathological T4a (pT4a) colon cancer. This multic...

Purpose Temporary ileostomy is sometimes created after colorectal surgery and may cause renal impairment. However, the impact of ileostomy on renal function during adjuvant chemotherapy for colorectal cancer (CRC) remains unknown. The aim of the present study was to examine the effects of ileostomy on renal function during adjuvant chemotherapy. Me...

Background/aim: CD133 and hypoxia-inducible factor 1α (HIF-1α) have been reported to be affected by chemoradiotherapy (CRT), but the combinatorial assessment of these markers for prognosis after CRT has not been fully investigated. Therefore, we aimed to predict recurrence and prognosis in patients with rectal cancer by assessing changes in the ex...

Background: Persistent descending mesocolon (PDM) is a fetal abnormality in which the left-sided colon is not fused to the retroperitoneum, and it is often accompanied by the adhesion between the mesocolon and small bowel mesentery. Due to its rarity, whether PDM exhibits anatomical characteristics of the inferior mesenteric artery (IMA) and left...

Background and objective: Laparoscopic resection for obstructive colon cancer (CC) after insertion of self-expanding metallic stents (SEMSs) is reportedly difficult. However, this has not yet been thoroughly investigated. Therefore, we investigated the influence of SEMS insertion on laparoscopic resection. Methods: This retrospective comparative...

Background: Complex interactions among endogenous and exogenous factors influence the incidence of colorectal cancer (CRC). Germline mutations in mismatch repair (MMR) genes causing Lynch syndrome (LS) are major endogenous factors. The exogenous factor, alcohol consumption, is potentially associated with CRC incidence among patients with LS. Howev...

Purpose Randomized controlled trials (RCTs) demonstrated that a laparoscopic approach provides short-term benefits, such as reduced blood loss and a shorter hospital stay, in patients who undergo rectal surgery. On the other hand, a few RCTs investigating proctocolectomy with ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC) or famili...

Background The diagnosis of colitis-associated cancer or dysplasia is important in the treatment of ulcerative colitis. Immunohistochemistry of p53 along with hematoxylin and eosin (H&E) staining is conventionally used to accurately diagnose the pathological conditions. However, evaluation of p53 immunohistochemistry in all biopsied specimens is ex...

Background: The American Joint Committee on Cancer tumor-node-metastasis staging system for rectal cancer defines lateral pelvic lymph nodes (LPLNs) only in the internal iliac region as regional. However, the Japanese Society for Cancer of the Colon and Rectum (JSCCR) staging system, also considers obturator lymph nodes (LNs) as regional. This ret...

The histological growth pattern of liver metastases (desmoplastic, pushing, and replacement patterns) at the tumor–liver parenchymal interface is a prognostic factor in patients with colorectal cancer. However, data regarding its association with the primary tumor characteristics and molecular alterations are limited. This study evaluated the histo...

Purpose Obstructive colitis (OC) is a risk factor of anastomotic leakage in colorectal cancer resection. We aimed to clarify the relationship between the severity of OC and clinicopathological findings and to detect predictive factors of OC. Methods We retrospectively reviewed 43 cases of colectomy after self-expandable metallic stent placement fo...

Anal canal cancer (ACC) has been reported to be an uncommon cancer in Japan, as in the USA, Europe, and Australia. This retrospective multi‐institutional study was conducted to clarify the characteristics of ACC in Japan. First, the histological ACC type cases treated between 1991 and 2015 were collected. A detailed analysis of the characteristics...

Postoperative recurrence of colorectal cancer (CRC) eventually leads to therapeutic failure; therefore, treatment strategies based on accurate prediction of recurrence are urgently required. To identify biomarkers that can predict treatment outcomes, we compared the mutational profiles of surgically resected specimens from patients with recurrent c...

Purpose Preoperative chemoradiotherapy (CRT) followed by total mesorectal excision (TME) without lateral lymph node (LLN) dissection is widely performed for lower advanced rectal cancer. However, it is unclear whether residual cancer cells in the LLNs undergo apoptosis, disappear, or regrow if unresected. Methods Overall, 293 consecutive patients...

87 Background: In primary analysis from the TRUSTY study, trifluridine/tipiracil (FTD/TPI) plus bevacizumab (BEV) failed to show non-inferiority to irinotecan and fluoropyrimidine plus BEV in overall survival (OS) as second-line treatment in patients (pts) with metastatic colorectal cancer (mCRC) (median OS, 14.8 vs. 18.1 months: HR, 1.38: 95% CI;...

Background The spread of coronavirus disease 2019 (COVID-19) had a major impact on the health of people worldwide. The clinical background and clinical course of inflammatory bowel disease (IBD) among Japanese patients with COVID-19 remains unclear. Methods This study is an observational cohort of Japanese IBD patients diagnosed with COVID-19. Dat...

Background Preoperative chemoradiotherapy (CRT) is the standard therapy for locally advanced rectal cancer (LARC). However, the changes that the patient’s physical status during CRT, such as host systemic inflammatory response, nutritional status, and muscle depletion, are still unclear. We evaluated the clinical significance of malnutrition and sa...

Background/aim: This study aimed to determine the effectiveness of surgical site infection (SSI) prevention approaches in rectal cancer surgery. Patients and methods: A total of 1,408 patients who underwent elective rectal cancer surgery between 1995 and 2017 were reviewed. Patients were divided into three groups: control group (group A, n=245),...

Background Para-aortic lymph node (PALN) metastasis is an ominous manifestation indicating a poor prognosis in colorectal cancer (CRC) patients; however, some treatments prolong survival. In this study, we investigated predictors of prolonged survival in CRC patients after PALN metastasis.Methods We examined 141 patients with CRC that metastasized...

Introduction: Preoperative chemoradiotherapy (CRT) is the standard therapy for downstaging in locally advanced lower rectal cancer. However, it remains unclear whether rectal cancers downstaged by preoperative therapy show similar prognoses to those of the same stage without preoperative therapy. We previously demonstrated that preoperative CRT di...

PurposeWe investigated whether or not computed tomographic colonography (CTC) is a viable alternative to double-contrast barium enema (BE) for a preoperative rectal cancer evaluation.Methods The size and distance from the anal canal to the lower or upper tumor borders were laterally measured in 147 patients who underwent CTC and BE. Measurements we...

Background This study aimed to investigate the effect of sarcopenia on the prognosis of advanced lower rectal cancer patients receiving neoadjuvant chemoradiotherapy (CRT). Sarcopenia has been recognized as an adverse factor for surgical outcomes in several malignancies. However, the impact of preoperative sarcopenia on rectal cancer patients recei...

Background: Lateral pelvic lymph node dissection for rectal cancer is challenging due to the complexity of the pelvic wall anatomy, and incomplete lateral pelvic lymph node dissection may result in local recurrence in the lateral pelvis. Although three-dimensional printed organ models are useful for understanding spatial anatomy, it currently rema...

Background: Some studies have reported that adhesion prevention barriers (APBs) reduce adhesion after abdominal surgery; however, evidence showing that APBs reduce the incidence of postoperative small bowel obstruction (SBO), one of the most serious complications after abdominal surgery, is little. One concern is that APBs are usually applied only...

Background and aims: A detailed understanding of antitumor immunity is essential for optimal cancer immune therapy. Although defective mutations in the B2M and HLA-ABC genes, which encode molecules essential for antigen presentation, have been reported in several studies, the effects of these defects on tumor immunity have not been quantitatively...

Background/aim: The inferior mesenteric arteries (IMA) are occluded in some colorectal cancer patients. This study evaluated the impact of IMA occlusion on the calibre of collateral arteries. Patients and methods: As an IMA obstruction model, 20 patients who underwent abdominal aortic aneurysm surgery, with ligated, excluded, or embolised IMA, w...

Background Staphylococcus schleiferi is a gram-positive pathogenic coccus which causes canine skin and ear infections. Only four cases of human infection caused by Staphylococcus schleiferi subspecies coagulans have been reported. Herein, we present the first case of catheter-related bloodstream infection caused by S. schleiferi subspecies coagulan...

Aim Oxaliplatin-based adjuvant chemotherapy was demonstrated to be beneficial for stage III or high-risk stage II colorectal cancer (CRC). Moreover, a recent international collaborative trial suggested 3-month CAPOX as an alternative regimen for low-risk stage III colorectal cancer (CRC) patients. Thus, it is important to clarify the frequency and...

Background and aim Although past history of colorectal cancer (CRC) is a known risk factor for developing second CRC, the optimal surveillance protocol has not been established. Using hazard function analysis to evaluate changes in the hazard rate for the development of second primary CRCs or high-grade adenomas (HGA), we aimed to clarify when and...

Background: Enoxaparin, a low molecular weight heparin, has been used to prevent thrombotic events during major surgery without increasing the rate of hemorrhage. On the other hand, it was reported to cause liver injury, but the details of liver injury induced by prophylactic enoxaparin after abdominal surgery remain unclear. Aims: This study ai...

Surgical treatment of the transverse colon is difficult because of the many variations of blood vessels. We reviewed the patterns of vascular anatomy and the definition of the vessels around the splenic flexure. We searched the PubMed database for studies on the vascular anatomy of the splenic flexure that were published from January 1990 to Octobe...

Introduction: Multiple primary malignancies (MPMs) are likely to develop in patients with colorectal cancer (CRC); however, their prognoses are unclear. This study aims to investigate the prognostic impacts and clinicopathological features of multiple CRCs and extracolorectal malignancies (EMs) with CRC. Methods: We retrospectively evaluated a t...

Purpose The descending branch of the left colic artery (dLCA) is under-recognized and has not been clearly defined. The dLCA is often confused with the sigmoid artery (SA) originating from the left colic artery (LCA). We clarified the anatomical characteristics of the dLCA and searched for surrogate measures to identify it. Methods Arterial phase,...

PurposeThis study aimed to elucidate the benefits and limitations of preoperative chemoradiotherapy (CRT) in rectal cancer treatment, specifically in T4b rectal cancer.Methods This retrospective cohort study reviewed 1014 consecutive patients with clinical T3/4a/T4b adenocarcinomas of the lower rectum, who underwent total mesorectal excision at the...

Background Analysis of long-term clinical outcomes of patients with familial adenomatous polyposis is critical in reducing or preventing the incidence of extracolonic malignancies after initial surgery. The aim of the present study was to clarify the long-term outcomes, and establish a surveillance strategy for surgically treated familial adenomato...

Background: Although methods to overcome difficulties associated with mirror-image conditions have been investigated, the ideal spatial relationship among the operator line of sight, monitor location, and camera location remains unclear. Moreover, the best training method for improving laparoscopic surgical skills under varying operator line of si...

Background: We conducted this study to review the patient characteristics associated with long-term survival in patients with peritoneal metastases from colorectal cancer who underwent cytoreductive surgery (CRS). Methods: We retrospectively investigated patients with peritoneal metastases from CRC treated with curative intent surgery with or wi...

Background Preoperative chemoradiotherapy is used preferably for locally advanced rectal cancer, followed by a watch-and-wait strategy for cases showing clinical complete response. However, there is a discordance between pathological and clinical complete response rates. We aimed to propose a tumor regression grade (TRG) that truly reflects the the...

PurposeD3 dissection is the standard treatment modality for locally advanced low rectal cancer in Japan. The benefit of lateral pelvic lymph node (LPLN) dissection (LPLND) and lymph nodes along the root of inferior mesenteric artery (253 LN) dissection (253 LND) for low rectal cancer has often been studied separately, and few studies have investiga...

The presence of extramural tumor deposits without lymph node structure (EX) is an important prognostic factor in patients with colorectal carcinoma. However, there is no English literature on neuroendocrine tumor (NET) with EX. We report a patient with rectal NET with extracapsular metastasis of a regional lymph node that was considered to be EX. A...

3507 Background: The efficacy of trifluridine/tipiracil (FTD/TPI) plus bevacizumab (BEV) as a later-line treatment for metastatic colorectal cancer (mCRC) has been demonstrated in clinical trials. Therefore, we conducted a randomized phase 2/3 study to determine whether FTD/TPI plus BEV is non-inferior to either FOLFIRI or S-1 and irinotecan plus B...

BackgroundFOLFOX therapy, a standard treatment for colorectal cancer (CRC), causes a rare, but serious adverse event, hyperammonemia. However, the risk factors of hyperammonemia remain unknown.Methods We examined 74 patients who received mFOLFOX6 therapy with or without biologics for CRC between April 2013 and March 2018 in Yaizu City Hospital. Cli...

Background/aim: Lysophosphatidylinositol (LPI) is a subspecies of the lysophospholipid mediators produced when phospholipase hydrolyzes membrane phosphatidylinositol. Previously, we used mass spectrometry-based lipidomics to demonstrate that LPI is selectively elevated in colorectal cancer (CRC) tissues. Here, we hypothesized that the expression l...

Background Ectopic decidua is the presence of decidual tissue outside the uterus. Ectopic decidua of the appendix is a rare entity that can present with abdominal symptoms mimicking appendicitis. We report a case of a 39-year-old female patient at 27 weeks gestational age with a 2-day history of right lower quadrant abdominal pain. Case presentati...

Background: Although liver resection is the only potentially curative treatment for colorectal liver metastases, recurrence is frequent. We previously published the early results of a randomized controlled phase 3 trial showing that adjuvant therapy with uracil-tegafur and leucovorin significantly prolongs recurrence-free survival. This study soug...

The Deloyers procedure is performed after extended left colectomy, enabling the reach of the proximal colon to the rectum for anastomosis while preserving sufficient blood supply. We report a case of the Deloyers procedure performed safely under indocyanine green (ICG) fluorescence guidance. A 50-year-old man with obesity (body mass index, 35.7 kg/...

Background and Objectives Most guidelines of colorectal cancers (CRCs) recommend evaluating the serum carcinoembryonic antigen (CEA) level during postoperative surveillance to detect tumor recurrence, which originates from postsurgery residual tumor cells. We hypothesized that the postadjuvant chemotherapy CEA level may be the most accurate biomark...

Background Evaluating anorectal function using real‐time tissue elastography (RTE) has not been reported. A previous study reported that in the internal anal sphincter (IAS) of surgical specimens of patients with rectal cancer who underwent abdominoperineal resection, there was an increased fibrosis trend in those who underwent pre‐operative chemor...

One-stage resections of primary colorectal cancer and liver metastases have been reported to be feasible and safe. Minimally invasive approaches have become more common for both colorectal and hepatic surgeries. This study aimed to investigate outcomes of these combined surgical procedures among different approaches.We retrospectively analyzed pati...

Background/aims: Restorative proctocolectomy (RPC) with ileal pouch-anal anastomosis and handsewn anastomosis for ulcerative colitis requires pulling down of the ileal pouch into the pelvis, which can be technically challenging. We examined risk factors for the pouch not reaching the anus. Methods: Clinical records of 62 consecutive patients who...

The definitive risk factors for parastomal hernia (PSH), a complication of stoma construction that can lead to severe morbidity, remain unclear. Therefore, this study aimed to determine risk factors for PSH after rectal surgery in Japanese patients. We retrospectively included 134 patients who underwent rectal tumor surgery and covering stoma const...

Preoperative chemoradiotherapy (CRT) for rectal cancer contributes to tumor down-staging and decreases locoregional recurrence. However, each patient shows a significantly different response to CRT. Therefore, the identification of predictive factors to CRT response would be beneficial to avoid unnecessary treatment. Cancer immunity in patients has...

A 37-year-old woman presented with crampy lower abdominal pain during menstruation. A laparoscopy was performed, and a diagnosis of omental endometriosis was made.

Purpose A diverting stoma is created to prevent anastomotic leakage and related complications impairing sphincteric function in rectal surgery. However, diverting stoma may be left unclosed. This study is aimed to analyze preoperative factors including anorectal manometric data associated with diverting stoma non-reversal before rectal surgery. We...

Background Applications of three‐dimensional (3‐D) printed solid organ models for navigation and simulation were previously reported for abdominal surgeries, and their usefulness was shown by subjective evaluation. However, thus far, no study has examined the effect of intraoperative movements for tissue handling. Novel, deformable 3‐D printed mode...

Introduction and importance Colorectal surveillance via colonoscopy in patients with Lynch syndrome reduces the mortality of colorectal cancer. On the other hand, it is unclear whether surveillance for other malignancies, including small bowel cancer, is beneficial. We report a patient with Lynch syndrome who developed ileal cancer after surgery fo...

56 Background: Systemic chemotherapy can cause loss of skeletal muscle mass in colorectal cancer (CRC) patients in the neoadjuvant and palliative settings. However, it is largely unknown how the body composition is changed by chemotherapy rendering unresectable CRC to resectable disease or how it affects the prognosis. This study aimed at elucidati...

Background and Objectives An optimal postoperative surveillance protocol for colorectal cancer (CRC) is dependent on understanding the time line of recurrence. By hazard function analysis, this study aimed at evaluating the time of occurrence of metastasis. Methods A total of 21,671 Stage I–III colon cancer patients were retrospectively included f...

Background Mobilization of the splenic flexure can be a challenging surgical step in colorectal surgery. This study aimed to classify the splenic flexure based on the three-dimensional (3D) coordinates of the splenic hilum and left renal hilum. This classification was used to compare splenic flexure mobilization during colorectal resection. Method...