Impact of the Diverting Stoma on Renal Function.

BACKGROUND: Although loop ileostomy as a diverting stoma has been considered to affect renal dysfunction, few reports have compared loop colostomy with loop ileostomy regarding renal function. This is an important issue in the current setting of increased opportunities to perform surgery on patients with poor renal function. OBJECTIVE: This study aims to reveal the effect of ileostomy on renal dysfunction compared to colostomy following sphincter-preserving rectal surgery. DESIGN: This study was a retrospective analysis. We compared preoperative and postoperative blood urea nitrogen, serum creatinine and estimated glomerular filtration rate values. SETTINGS: The study was conducted at a single academic institution in Osaka, Japan. PATIENTS: From October 2013 to November 2021, 135 consecutive patients underwent rectal surgery with diverting stoma are included. MAIN OUTCOME MEASURES: Differences in pre- and postoperative renal function values by stoma creation site in patients with preoperative chronic kidney disease. Risk factors for patients with newly kidney disease after stoma creation. RESULTS: In the preoperative chronic kidney disease (+) patients, the differences between the pre- and post-values in the blood urea nitrogen (p = 0.047) and the serum creatinine (P = 0.028) values were higher than in the preoperative chronic kidney disease (-) patients. In the preoperative chronic kidney disease (+) patients, ileostomy was significantly associated with an elevation of the serum creatinine value (p = 0.025) and a decrease in estimated glomerular filtration rate value (p = 0.041) from the pre-operative one compared with that of colostomy. In multivariate analysis, ileostomy (odds ratio; 7.443, p = 0.011) and hypertension (4.226, p = 0.008) were independent risk factors of newly kidney disease postoperatively. LIMITATIONS: Limitations to our study includes its retrospective nature and bias due to the stoma site being determined by each surgeon. CONCLUSION: We should take care to choose diverting stoma especially in patients with a risk of kidney disfunction. See Video Abstract.

Final analyses of the prospective controlled trial on the efficacy of uracil and tegafur/leucovorin as an adjuvant treatment for stage II colon cancer with risk factors for recurrence using propensity score-based methods (JFMC46-1201).

BACKGROUND: The efficacy of adjuvant chemotherapy for high-risk stage II colon cancer (CC) has not been well established. Using propensity score matching, we previously reported that the 3-year disease-free survival (DFS) rate was significantly higher in patients treated with uracil and tegafur plus leucovorin (UFT/LV) against surgery alone. We report the final results, including updated 5-year overall survival (OS) rates and risk factor analysis outcomes. METHODS: In total, 1902 high-risk stage II CC patients with T4, perforation/penetration, poorly differentiated adenocarcinoma/mucinous carcinoma, and/or < 12 dissected lymph nodes were enrolled in this prospective, non-randomized controlled study based on their self-selected treatment. Oral UFT/LV therapy was administered for six months after surgery. RESULTS: Of the 1880 eligible patients, 402 in Group A (surgery alone) and 804 in Group B (UFT/LV) were propensity score-matched. The 5-year DFS rate was significantly higher in Group B than in Group A (P = 0.0008). The 5-year OS rates were not significantly different between groups. The inverse probability of treatment weighting revealed significantly higher 5-year DFS (P = 0.0006) and 5-year OS (P = 0.0122) rates in group B than in group A. Multivariate analyses revealed that male sex, age ≥ 70 years, T4, < 12 dissected lymph nodes, and no adjuvant chemotherapy were significant risk factors for DFS and/or OS. CONCLUSION: The follow-up data from our prospective non-randomized controlled study revealed a considerable survival advantage in DFS offered by adjuvant chemotherapy with UFT/LV administered for six months over surgery alone in individuals with high-risk stage II CC. TRIAL REGISTRATION: Japan Registry of Clinical Trials: jRCTs031180155 (date of registration: 25/02/2019), UMIN Clinical Trials Registry: UMIN000007783 (date of registration: 18/04/2012).

MRI navigation surgery, including lateral pelvic lymph node dissection following chemoradiotherapy, improves local control and functional preservation of the middle to low rectal cancer.

PURPOSE: The purpose of this study is to examine the appropriateness of MRI navigation surgery following chemoradiotherapy (CRT), including lateral pelvic lymph node dissection (LLND) for middle to low rectal cancer. METHODS: Forty-three consecutive patients with cT2-4b rectal cancer within 10 cm from the anal verge who underwent laparoscopic radical surgery following CRT (45-50.4Gy + S1 80mg/m2) from January 2014 and February 2020 were analyzed. We decided on the operative procedure, including LLND, based on the restaging MRI. We examined the rates of 3-year postoperative local pelvic recurrence, permanent stoma, and recurrent risk factors (Group S). We also compared the results to that of the fourteen patients who enrolled in the previous phase II trial and underwent laparoscopic radical surgery following CRT (40Gy + S-1 (80mg/m2) or UFT (300 mg/m2)) for consecutive cT2-4b rectal cancer below the peritoneal reflection. The operative procedure was decided at the initial MRI diagnosis, and the LLND was not performed (Group P). RESULTS: We had no local pelvic recurrence in Group S, and the three-year local pelvic recurrence-free survival was significantly better in Group S than P (100 % in S 85.1 % in P, p < 0.05). The permanent stoma rate was not different between the Groups, irrespective of the significantly high rate of cCRM(+) in Group S. The Cox proportional hazards model for significant factors of recurrence on the univariate analysis revealed that ycM and ycEMVI scores were independently significant (p < 0.001). CONCLUSION: MRI navigation surgery, including LLND for rectal cancer following chemoradiotherapy, improves local control and functional preservation.

Analysis of the clinicopathological features of tailgut cyst with emphasis on the development of neoplastic lesions.

Tailgut cyst is a rare congenital cyst occurring in the retrorectal space and development of neoplastic lesions in tailgut cyst has been reported. Due to the rarity of the tumor, the histogenesis of neoplastic lesions in tailgut cyst has remained elusive. In the present study, the clinicopathological features of tailgut cyst were analyzed with a particular focus on the development of neoplastic lesions. The clinicopathological features of four patients with tailgut cyst (one female and three males) were retrospectively reviewed. No symptoms were present in two patients. Perineal discomfort, and constipation and urinary retention, were described in the other two patients, respectively. Magnetic resonance imaging showed that the cystic lesions were hypointense on T1- and hyperintense on T2-weigted images in all patients. Histopathological analysis revealed that all lesions were multilocular, and cystic walls were covered by squamous and ciliated epithelia without nuclear atypia. The development of neoplastic lesions was noted in two patients. Dysplastic change composed of piling-up proliferation of glandular cells with mild to moderate nuclear atypia was present in one patient, and invasive adenocarcinoma with a dysplasia component was observed in another patient. Dysplasia of the glandular cells, as seen in two patients in the present series, may be a precursor lesion of invasive adenocarcinoma; therefore, adenocarcinoma arsing in tailgut cyst may show a dysplasia-carcinoma sequence. While the reported incidence of neoplastic lesions in tailgut cysts is ~9% or less, their frequency remains to be accurately determined. Therefore, complete surgical resection is important for the management of patients with tailgut cyst. Additional clinicopathological and molecular studies with large cohorts may be required to clarify the histogenesis of neoplastic lesion in tailgut cyst.

Long-term survival and functional outcomes of laparoscopic surgery for clinical stage I ultra-low rectal cancers located within 5 cm of the anal verge: A prospective phase II trial (Ultimate trial).

OBJECTIVE: To clarify the long-term oncological outcomes and postoperative anal, urinary, and sexual functions after laparoscopic surgery for clinical stage I very low rectal carcinoma located near the anal canal. SUMMARY BACKGROUND DATA: Laparoscopic surgery is widely applied for rectal cancer; however, concerns remain, with some studies showing poorer outcomes compared to open surgery. METHODS: This single-arm, phase II trial included patients registered preoperatively from 47 institutions in Japan. The planned sample size was 300. The primary endpoint was the 3-year local recurrence rate. Anal, urinary, and sexual functions were evaluated using a prospective questionnaire. RESULTS: Three-hundred patients were registered between January 2014 and March 2017. Anus-preserving surgery was performed in 278 (93%), including 172 who underwent intersphincteric resection (58%) and 106 (36%) who underwent low anterior resection. The 3-year cumulative local recurrence rate was 6.3%. At 3 years postoperatively, 87% of patients used their own anus, and the median incontinence score improved from 12 at 3 months to 8 at 3 years. Only 5% of patients had severe incontinence (incontinence score of 16 points). Postoperative urinary function evaluation showed that International Prostate Symptom Score and Overactive Bladder Symptom Score decreased 1 week after surgery, but recovered to preoperative level 1 month after surgery. International Consultation on Incontinence Questionnaire-Sort Form remained almost stable after surgery. Sexual function evaluation using the International Index of Erectile Function-5 and International Index of Erectile Function-15 revealed that the patients had deteriorated 3 months after surgery but had recovered only slightly by 6 months. CONCLUSIONS: Laparoscopic surgery achieves feasible long-term oncological outcomes and a high rate of anus preservation with moderate anal function, and an acceptable incontinence score. While urinary function recovered rapidly, sexual function showed poor recovery.

Clinicopathological features and prognosis of primary small bowel adenocarcinoma: a large multicenter analysis of the JSCCR database in Japan.

BACKGROUND: The clinicopathological features and prognosis of primary small bowel adenocarcinoma (PSBA), excluding duodenal cancer, remain undetermined due to its rarity in Japan. METHODS: We analyzed 354 patients with 358 PSBAs, between January 2008 and December 2017, at 44 institutions affiliated with the Japanese Society for Cancer of the Colon and Rectum. RESULTS: The median age was 67 years (218 males, 61.6%). The average tumor size was 49.9 (7-100) mm. PSBA sites consisted of jejunum (66.2%) and ileum (30.4%). A total of 219 patients (61.9%) underwent diagnostic small bowel endoscopy, including single-balloon endoscopy, double-balloon endoscopy, and capsule endoscopy before treatment. Nineteen patients (5.4%) had Lynch syndrome, and 272 patients (76.8%) had symptoms at the initial diagnosis. The rates for stages 0, I, II, III, and IV were 5.4%, 2.5%, 27.1%, 26.0%, and 35.6%, respectively. The 5-year overall survival rates at each stage were 92.3%, 60.0%, 75.9%, 61.4%, and 25.5%, respectively, and the 5-year disease-specific survival (DSS) rates were 100%, 75.0%, 84.1%, 59.3%, and 25.6%, respectively. Patients with the PSBA located in the jejunum, with symptoms at the initial diagnosis or advanced clinical stage had a worse prognosis. However, multivariate analysis using Cox-hazard model revealed that clinical stage was the only significant predictor of DSS for patients with PSBA. CONCLUSIONS: Of the patients with PSBA, 76.8% had symptoms at the initial diagnosis, which were often detected at an advanced stage. Detection during the early stages of PSBA is important to ensure a good prognosis.

Outcomes of Metastatic and Unresectable Small Bowel Adenocarcinoma in Japan According to the Treatment Strategy: A Nationwide Observational Study.

PURPOSE: Limited information is available regarding the characteristics and outcomes of stage IV small bowel adenocarcinoma (SBA) in Japan. This study examined the clinical and pathological characteristics and outcomes according to the treatment strategies in patients with stage IV SBA. METHODS: This retrospective observational study used the data of patients with jejunal or ileal adenocarcinoma collected by the Small Bowel Malignant Tumor Project of the Japanese Society for Cancer of the Colon and Rectum. Descriptive statistics were expressed as the mean (standard deviation) or median (range). Survival analysis was performed using Kaplan-Meier curves and pairwise log-rank tests. RESULTS: Data from 128 patients were analyzed. The treatment strategies were chemotherapy alone (26 of 128, 20.3%), surgery alone (including palliative surgery; 21 of 128, 16.4%), surgery + chemotherapy (74 of 128, 57.8%), and best supportive care (7 of 128, 5.5%). The median (range) overall survival was 16 (0-125) months overall, and 11 (1-38) months, 8 (0-80) months, 18 (0-125) months, and 0 (0-1) months for the chemotherapy, surgery, surgery + chemotherapy, and best supportive care groups, respectively. Three main categories of chemotherapeutic regimen were used: a combination of fluoropyrimidine and oxaliplatin (F + Ox), fluoropyrimidine and irinotecan (F + Iri), and single-agent fluoropyrimidine. Among patients treated with chemotherapy, the median (range) OS was 16 (1-106) months overall, and 17 (1-87) months, 29 (7-39) months, and 16 (1-106) months in patients treated with fluoropyrimidine, F + Iri, and F + Ox, respectively. CONCLUSION: Patients treated with surgery, chemotherapy, or both had a better prognosis than those who received best supportive care. Among patients who received chemotherapy, survival did not differ according to the chemotherapeutic regimen.

The academic impact and value of an international online surgery lecture series.

Due to the worldwide travel restrictions caused by the 2019 coronavirus disease pandemic, many universities and students lost opportunities to engage in international exchange over the past 2 years. Teleconferencing systems have thus been developed to compensate for severe travel restrictions. Kansai Medical University in Japan and Vilnius University in Lithuania have a collaborative research and academic relationship. The two universities have been conducting an online joint international surgery lecture series for the medical students of both universities. Fifteen lectures were given from October 2021 to May 2022. The lectures focused on gastrointestinal surgery, gastroenterology, radiology, pathology, genetics, laboratory medicine, and organ transplantation. A survey of the attendees indicated that they were generally interested in the content and satisfied with attending this lecture series. Our efforts were successful in providing Japanese and Lithuanian medical students with the opportunity to engage in international exchange through lectures held in each other's countries.

Significance of desmoplastic reactions on tumor deposits in patients with colorectal cancer.

It has been well recognized that the tumor microenvironment serves important roles in the progression and invasion of cancer. The desmoplastic reaction (DR) is a fibrous tissue reaction around tumor cells, and the prognostic significance of DR in colorectal cancer (CRC) has been established. Tumor deposits (TD) are also an important prognostic indicator of CRC. Notably, immature type DR has been linked to poor prognosis. In addition, immature type DR is significantly associated with a higher pT stage, presence of lymphovascular invasion and lymph node metastasis; however, to the best of our knowledge, the association between DR and TD has not yet been examined. The present study aimed to clarify this association. This study included 443 consecutive patients with pT3 or pT4 CRC who underwent surgical resection. The histopathological features, including DR and TD, were evaluated. Statistical analyses of the presence of TD, DR and other clinicopathological parameters were performed. The present cohort included 205 female and 238 male patients; 293 (66.1%) and 150 (33.9%) patients were classified as pT3 and pT4, respectively. Immature, intermediate and mature DR were noted in 282 (63.7%), 91 (20.5%) and 70 patients (15.8%), respectively. TD was observed in 93 (21.0%) patients. Immature type DR was significantly associated with a higher pT stage (P<0.0001), presence of lymph node metastasis (P<0.0001), lymphatic (P=0.0007), venous (P<0.0001) and perineural invasion (P<0.0001), and higher tumor budding (TB) (P<0.0001). Moreover, immature type DR was significantly associated with the presence of TD (P<0.0001). The present study demonstrated a significant association between immature type DR and the presence of TD, and suggested a close relationship between lymphovascular invasion, DR, TB and TD. Additional studies are required to analyze the detailed mechanism underlying the development of immature DR in CRC to define novel treatment strategies.

Optimal diagnostic criteria for lateral lymph node dissection using magnetic resonance imaging: a multicenter prospective study.

BACKGROUND: LLND in cases with suspected lateral lymph node (LLN) metastasis has been focused on as a novel treatment strategy in recent years. However, the optimal indication for LLND in rectal cancer patients has not been determined. This study aimed to establish the optimal indication for lateral lymph node dissection (LLND) in patients with rectal cancer using magnetic resonance imaging (MRI). METHODS: A total of 209 patients with rectal adenocarcinoma who underwent total mesorectal excision and LLND in 13 hospitals were prospectively registered. By matching the sizes of the harvested LNs and those in magnetic resonance imaging (MRI), the pathological outcome of each LN was confirmed one-by-one. Using parameters of the LLNs in MRI, the optimal diagnostic criteria for LLND were established. RESULTS: Of 3241 harvested LLNs, including 83 metastatic nodes, 1010 (31.1%) were visualized on MRI. Although all parameters assessed showed strong correlations with the presence of metastasis, none of these parameters could discriminate metastatic LLNs from non-metastatic nodes with sufficient sensitivity. However, by using the combination of long axis and short/long ratio in pretreatment MRI, we could establish optimal criteria for LLND. The sensitivity and specificity of the criteria for LLN metastasis were 94.3% and 40.2%, respectively. CONCLUSIONS: In conclusion, we established novel criteria for LLND in rectal cancer patients using MRI. Our criteria will be of great clinical use in determining indications for LLND.

Two cases of 18F-FDG-PET/CT positive Schloffer tumor following curative surgery of colon cancer.

We report two cases of Schloffer tumor that required resection after radical colon cancer surgery because of suspected lymph node recurrence on contrast-enhanced (CE) CT and 18F-FDG-PET/CT. Case1 is a 69-year-old man with sigmoid colon cancer pStage IIA, and case2 is a 61-year-old man with descending colon cancer pStage IIIB.

Use of ileal bypass in the surgical management of two rare cases of ileal-neobladder fistula in patients who underwent radical cystectomy.

PURPOSE: An entero-neovesical fistula (ENF) is a rare troublesome complication of an orthotopic ileal bladder substitution. We report on a novel, safe technique to close ileal neovesical fistulas without extensive adhesiolysis using an NK-stapler (ENDOPATH® ENDOCUTTER ETS; Johnson & Johnson, Cincinnati, OH, USA). PATIENTS: We treated two cases of postoperative ENF after orthotopic ileal bladder substitution for radical cystectomy. Case 1 was a 63-year-old male with occasional fecaluria, and Case 2 was a 73-year-old male who experienced continuous fecaluria.Surgical procedureAfter laparotomy, we mobilized the ascending colon to bypass the anastomosis of the primary surgery by an ileo-ileal, ileo-ascending colon anastomosis. The distance between the fistula and bypass was about 10 cm. We made tunnels in the mesentery between the bypass and fistula, without damaging blood vessels, to insert the jaw of the NK-stapler. We closed the afferent and efferent loops using NK-staplers (45 mm ×2), followed by a Lembert anastomosis covering the stapler's suture lines. RESULTS: They were discharged on the ninth and seventh postoperative days, respectively. In Case 1, we experienced recanalization of the fistula after three postoperative months and required second closure with the same procedure was needed. They have not experienced any symptoms of ENF since. CONCLUSIONS: This technique is worth considering for the surgical treatment of ENF because it does not require unnecessary dissection and can ultimately achieve fistula closure.

Characteristics of anal canal cancer in Japan.

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 of anal canal squamous cell carcinoma (SCC) cases was then conducted. The results of the histological types revealed that of the 1781 ACC cases, 435 cases (24.4%) including seven cases of adenosquamous cell carcinomas were SCC and 1260 cases (70.7%) were adenocarcinoma. However, the most common histological type reported in the USA, Europe, and Australia is SCC. Most ACC cases are adenocarcinomas and there is a low incidence of SCC in Japan which is different from the above-mentioned countries. Moreover, we reclassified T4 into the following two groups based on tumor size: T4a (tumor diameter of 5 cm or less) and T4b (tumor diameter of more than 5 cm). The results of the TNM classification of SCC revealed that the hazard ratio (HR) to T1 of T2, T3, T4a, and T4b was 2.45, 2.28, 2.89, and 4.97, respectively. As T4b cases had a worse prognosis than T4a cases, we propose that T4 for anal canal SCC in Japan be subclassified into T4a and T4b.

Prospective observational study of the efficacy of oral uracil and tegafur plus leucovorin for stage II colon cancer with risk factors for recurrence using propensity score matching (JFMC46-1201).

BACKGROUND: The efficacy of adjuvant chemotherapy for high-risk stage II colon cancer (CC) has not been well established. We compared the effects of surgery with and without oral uracil and tegafur plus leucovorin (UFT/LV) in patients with high-risk stage II CC, adjusting for potential risk factors. METHODS: We enrolled patients with histologically confirmed stage II colon adenocarcinoma with at least one of the following conditions: T4 disease, perforation/penetration, poorly differentiated adenocarcinoma/mucinous carcinoma, or < 12 dissected lymph nodes. Patients chose to be non-randomized or randomized to undergo surgery alone (NR-Group S or R-Group S) or surgery followed by 6 months of UFT/LV (NR-Group U or R-Group U). The primary endpoint was disease-free survival (DFS) after adjusting for previously reported risk factors using propensity score matching (1:2) and inverse probability of treatment weighting (IPTW) in the non-randomized arm. RESULTS: Overall, 1,902 (98%) and 36 (2%) patients were enrolled in the non-randomized and randomized arms, respectively. There were too few patients in the randomized arm and these were therefore excluded from the analysis. Of the 1,902 patients, 402 in NR-Group S and 804 in NR-Group U were propensity score-matched. The 3-year DFS rate (95% confidence interval) was significantly higher in NR-Group U (80.9% [77.9%-83.4%]) than in NR-Group S (74.0% [69.3%-78.0%]) (hazard ratio, 0.64 [0.50-0.83]; P = 0.0006). The 3-year overall survival rate was not significantly different between NR-Group S and NR-Group U. Significantly higher 3-year DFS (P = 0.0013) and overall survival (P = 0.0315) rates were observed in NR-Group U compared with NR-Group S using IPTW. CONCLUSIONS: Adjuvant chemotherapy with UFT/LV showed a significant survival benefit over surgery alone in patients with high-risk stage II CC characterized by at least one of the following conditions: T4 disease, perforation/penetration, poorly differentiated adenocarcinoma/mucinous carcinoma, or < 12 dissected lymph nodes. TRIAL REGISTRATION: Japan Registry of Clinical Trials: jRCTs031180155 (date of registration: 25/02/2019) (UMIN Clinical Trials Registry: UMIN000007783 , date of registration: 18/04/2012).

Curative resection of ureteral metastasis of rectal cancer: a case report and review of literature.

The metastasis to the ureter in colorectal cancer had been recognized at the stage of an autopsy. These days, according to the progression of diagnostic modalities, a few cases of long-time survival after curative surgery of metastatic ureteral tumor of colorectal cancer were reported. We present a case of a metastatic ureteral tumor of rectal cancer who had 32 months of recurrence-free survival after extirpation. After preoperative chemoradiotherapy, a 47-year-old man underwent laparoscopic low anterior resection and left unilateral pelvic node dissection for lower rectal cancer. He underwent several metastasectomies for recurrent tumors in the liver and lung. At the 42nd postoperative month, a contrast-enhanced CT scan showed thickening of the ureteral wall and left hydronephrosis. Transureteroscopic biopsy revealed metastatic adenocarcinoma of rectal cancer. At the 52nd postoperative month, partial ureteral resection and vesicoureteral neo-anastomosis were performed after confirming negative resection margin with rapid intraoperative pathology. He has 32 months of recurrence-free survival after metastasectomy of the left ureter. We review the literature presenting surgery of the metastatic ureteral tumor of colorectal cancer. Although it is a rare recurrence pattern, curative resection of ureteral metastasis might provide a possibility of long-time recurrence-free survival in such patients.

Image Navigation Surgery With the Fluorescent Ureteral Catheter of Recurrent Tumors in the Pelvic Cavity.

INTRODUCTION: Ureteral injury during pelvic surgery is a serious complication that requires special attention. The fluorescent ureteral catheter near-infrared ray catheter sets are 6.0F catheters containing fluorescent substances along their length that can be recognized by a laparoscopic indocyanine green camera. We present our experience using a near-infrared ray catheter in 6 consecutive patients who underwent surgery for recurrent pelvic tumors. TECHNIQUE: The near-infrared ray catheters were inserted into the bilateral ureters in all patients, with the exception of patient 5 (left unilateral), by urologists using a cystoscope with the same technique as that commonly used in placing ureteral stents under general anesthesia. A laparoscopic indocyanine green camera was adapted to identify the ureters. From February 2020 to July 2020, 6 consecutive patients with recurrent pelvic tumors underwent surgery using a near-infrared ray catheter. In 3 patients, recurrent tumors were detected in the pelvic cavity after surgery for colon cancer (1 patient each of peritoneal recurrence behind the seminal vesicles, lymph node metastasis on the residual superior rectal artery, and peritoneal recurrence at the peritoneal reflection). Two patients had postoperative local recurrences of rectal cancer. The last patient had a recurrence of cervical carcinoma invading the rectum. RESULTS: All patients underwent surgery under ureteral image navigation using near-infrared ray catheter not only for ureter preservation during the operation (4 patients) but also for the combined resection of the ureter with recurrent tumors (2 patients). One patient experienced postoperative ureteral stenosis on postoperative day 21 that required a ureteral double J-stent placement in the left ureter. CONCLUSION: Near-infrared ray catheter has the potential to reduce inadvertent periureteral dissection because the ureter can be identified before approaching it.

Pathological Complete Response of Clinical T4b Ascending Colon Cancer after Preoperative Chemotherapy Using Pembrolizumab.

Preoperative chemotherapy is efficacious in several cancers. However, it is not an established treatment for locally advanced colon cancer, particularly cases with microsatellite instability-high (MSI-H)/deficient mismatch repair. Herein, we report a case of pathological complete response of MSI-H clinical T4b ascending colon cancer to preoperative treatment with pembrolizumab. A 78-year-old man was diagnosed with ascending colon cancer that invaded into the iliacus muscle and enlarged regional lymph nodes. The tumor was classified as T4bN1bM0 stage IIIC according to the 8th Union for International Cancer Control guidelines, with MSI-H status. Based on our initial diagnosis, this tumor could not be resected completely. Thus, the patient underwent preoperative therapy with CAPOX (capecitabine and oxaliplatin combination) plus bevacizumab. After 4 cycles of preoperative CAPOX/bevacizumab, we observed tumor reduction corresponding to a partial response based on the Response Evaluation Criteria in Solid Tumors criteria. Nevertheless, tumor invasion of the iliacus muscle persisted. Since oxaliplatin-induced peripheral sensory neuropathy was observed, we discontinued treatment with oxaliplatin and changed the regimen to pembrolizumab in anticipation of the therapeutic effect of this immune checkpoint inhibitor against MSI-H tumors. After 2 cycles of therapy with pembrolizumab (200 mg/body on day 1 every 3 weeks), there was drastic tumor regression. In addition, computed tomography indicated that all lymph node metastases had disappeared. Therefore, the patient underwent laparoscopic right hemicolectomy with D3 lymph node dissection. Analysis of the resected specimen showed pathological complete response.