World's first report of sigmoidectomy for sigmoid cancer using the Saroa surgical system with tactile feedback.

Increasing evidence based on the safety and benefits of robot-assisted surgery indicates the disadvantage of the lack of tactile feedback. A lack of tactile feedback increases the risk of intraoperative complications, prolongs operative times, and delays the learning curve. A 40-year-old female patient presented to our hospital with a positive fecal occult blood test. A colonoscopy revealed type 2 advanced cancer of the sigmoid colon, and histological examination showed a well-differentiated adenocarcinoma. Furthermore, abdominal contrast-enhanced computed tomography revealed a tumor in the sigmoid colon and several swollen lymph nodes in the colonic mesentery without distant metastases. The patient was diagnosed with cStage IIIb (cT3N1bM0) sigmoid cancer and underwent sigmoidectomy using the Saroa Surgical System, which was developed by RIVERFIELD, a venture company at the Tokyo Medical and Dental University, and the Tokyo Institute of Technology. Based on adequate simulation, surgery was safely performed with appropriate port placement and arm base-angle adjustment. The operating time was 176 min, with a console time of 116 min and 0 ml blood loss. The patient was discharged 6 days postoperatively without complications. The pathological diagnosis was adenocarcinoma, tub1, tub2, pT2N1bM0, and pStage IIIa. Herein, we report the world's first surgery for sigmoid cancer using the Saroa Surgical System with tactile feedback in which a safe and appropriate oncological surgery was performed.

Sigmoid take-off in rectosigmoid cancer as a landmark identifying benefit from neoadjuvant chemoradiation: A retrospective comparative cohort study.

INTRODUCTION: There is no standard treatment strategy for rectosigmoid cancer because of the diverse definitions of the proximal rectal origin. This study aimed to evaluate sigmoid take-off compared with other landmarks of the rectosigmoid junction in guiding oncological therapy and outcomes. MATERIALS AND METHODS: This retrospective, comparative cohort study included patients diagnosed with rectosigmoid carcinoma at our centre between January 2010 and December 2018. The patients were classified into the neoadjuvant treatment group and upfront surgery group. The oncological outcomes were compared between the two groups in relation to the tumor position. RESULTS: A total of 656 patients (median age 64 years) were included. After propensity score matching, the 3- and 5-year overall survival and disease-free survival in patients in both the groups were comparable. However, when only patients with rectal cancer as defined by the sigmoid take-off point were included, the disease-free survival rate in the upfront surgery group was significantly lower than that in the neoadjuvant treatment group (p = 0.03 in patients who underwent computed tomography, p = 0.03 in patients who underwent magnetic resonance imaging). The turning point of the beneficial hazard ratio of neoadjuvant therapy was compared according to the different definitions of the rectosigmoid junction and the sigmoid take-off was found to be the most effective. CONCLUSION: The sigmoid take-off point is a suitable landmark for identifying the rectosigmoid junction and is an important defining criterion for assessing the benefit of neoadjuvant therapy. The application of this definition in clinical practice and future trials is warranted.

Infantile inflammatory myofibroblastic tumour of the sigmoid colon: a diagnostic dilemma.

An inflammatory myofibroblastic tumour (IMT) is an uncommon neoplasm composed of inflammatory cells and myofibroblasts in a fibrous stroma. They are mostly seen in the lungs and rarely involve the gastrointestinal tract. An 8-month-old infant presented with a history of lower abdominal lump for 2 months. Her CT scan confirmed a large, lobulated mass in the retroperitoneum arising from the pelvis. The mass was found to be arising from the sigmoid colon on laparotomy which was excised. Histopathology showed a cellular tumour composed of spindle cells and inflammatory lymphocytic infiltrate. Immunohistochemistry revealed positive staining for anaplastic lymphoma kinase and smooth muscle actin, confirming the diagnosis of IMT. The patient is doing well at her 6-month follow-up. Ours is the youngest case of sigmoid IMT among the only other series of eight cases reported in the literature indicating its rarity.

Resection of sigmoid cancer with bladder invasion using laparoscopic combined with a cystoscopic holmium laser: an innovative surgical procedure.

The aim of this study was to introduce a new surgical procedure for the resection of sigmoid colon tumours invading the bladder by combining laparoscopy and cystoscopy, and the feasibility and safety of the method were verified. The data of 6 patients with sigmoid colon cancer invading the bladder in a tertiary hospital in Chongqing from January 2020 to October 2022 were collected, sigmoid colon tumour resection was performed by this procedure, and the data related to the surgery were recorded. All six patients successfully underwent sigmoid colon tumour resection, and all sigmoid colon and bladder resections had negative margins. The mean total operative time was 211.66 ± 27.33 min, and the mean resection time of the bladder tumour was 22.16 ± 4.63 min. The median blood loss was 100 ml, and the mean number of retrieved lymph nodes was nineteen. There were no serious intraoperative complications in any of the cases. After operation, the first flatus and defecation were 4 and 4.5 days, respectively. The mean time of drainage tube retention and the time of bladder flushing were 3 and 1.5 days, respectively. The mean time of urinary tube retention was 7.5 days. There were no intestinal obstructions, dysuria, or other complications. For patients with sigmoid colon tumours invading the bladder, this method can effectively resect sigmoid colon tumours and minimize the loss of bladder tissue at the same time, which helps to prolong the survival of these patients. The surgical method is safe, reliable, and feasible.

[Analysis of prognosis and influencing factors of No. 253 lymph node metastasis in descending colon, sigmoid colon, and rectal cancer: a multicenter study].

Objectives: To analyze the influencing factors of No. 253 lymph node metastasis in descending colon cancer, sigmoid colon cancer, and rectal cancer, and to investigate the prognosis of No. 253 lymph node-positive patients by propensity score matching analysis. Methods: A retrospective analysis was performed on clinical data from patients with descending colon cancer, sigmoid colon cancer, rectosigmoid junction cancer, and rectal cancer who underwent surgery between January 2015 and December 2019 from the Cancer Hospital of the Chinese Academy of Medical Sciences, China-Japan Friendship Hospital, Peking Union Medical College Hospital, General Hospital of the Chinese People's Liberation Army, and Peking University Cancer Hospital. A total of 3 016 patients were included according to inclusion and exclusion criteria, comprising 1 848 males and 1 168 females, with 1 675 patients aged≥60 years and 1 341 patients aged<60 years. Clinical and pathological factors from single center data were subjected to univariate analysis to determine influencing factors of No. 253 lymph node metastasis, using a binary Logistic regression model. Based on the results of the multivariate analysis, a nomogram was constructed. External validation was performed using data from other multicenter sources, evaluating the effectiveness through the area under the receiver operating characteristic curve and the calibration curve. Using data from a single center, the No. 253 lymph node-positive group was matched with the negative group in a 1∶2 ratio (caliper value=0.05). Survival analysis was performed using the Kaplan-Meier method and Log-rank test. The Cox proportional hazards model was used to determine independent prognostic factors. Results: (1) The tumor diameter≥5 cm (OR=4.496,95%CI:1.344 to 15.035, P=0.015) T stage (T4 vs. T1: OR=11.284, 95%CI:7.122 to 15.646, P<0.01), N stage (N2 vs. N0: OR=60.554, 95%CI:7.813 to 469.055, P=0.043), tumor differentiation (moderate vs. well differentiated: OR=1.044, 95%CI:1.009 to 1.203, P=0.044; poor vs. well differentiated: OR=1.013, 95%CI:1.002 to 1.081, P=0.013), tumor location (sigmoid colon vs. descending colon: OR=9.307, 95%CI:2.236 to 38.740, P=0.002), pathological type (mucinous adenocarcinoma vs. adenocarcinoma: OR=79.923, 95%CI:15.113 to 422.654, P<0.01; signet ring cell carcinoma vs. adenocarcinoma: OR=27.309, 95%CI:4.191 to 177.944, P<0.01), and positive vascular invasion (OR=3.490, 95%CI:1.033 to 11.793, P=0.044) were independent influencing factors of No. 253 lymph node metastasis. (2) The area under the curve of the nomogram prediction model was 0.912 (95%CI: 0.869 to 0.955) for the training set and 0.921 (95%CI: 0.903 to 0.937) for the external validation set. The calibration curve demonstrated good consistency between the predicted outcomes and the actual observations. (3) After propensity score matching, the No. 253 lymph node-negative group did not reach the median overall survival time, while the positive group had a median overall survival of 20 months. The 1-, 3- and 5-year overall survival rates were 83.9%, 61.3% and 51.6% in the negative group, and 63.2%, 36.8% and 15.8% in the positive group, respectively. Multivariate Cox analysis revealed that the T4 stage (HR=3.067, 95%CI: 2.357 to 3.990, P<0.01), the N2 stage (HR=1.221, 95%CI: 0.979 to 1.523, P=0.043), and No. 253 lymph node positivity (HR=2.902, 95%CI:1.987 to 4.237, P<0.01) were independent adverse prognostic factors. Conclusions: Tumor diameter ≥5 cm, T4 stage, N2 stage, tumor location in the sigmoid colon, adverse pathological type, poor differentiation, and vascular invasion are influencing factors of No. 253 lymph node metastasis. No. 253 lymph node positivity indicates a poorer prognosis. Therefore, strict dissection for No. 253 lymph node should be performed for colorectal cancer patients with these high-risk factors.

A new lymph node ratio-based staging system for rectosigmoid cancer: a retrospective study with external validation.

BACKGROUND: This study evaluated the clinical value of a new American Joint Committee on Cancer (AJCC) tumor node metastasis (TNM) staging prediction model based on lymph node ratio (LNR) in rectosigmoid cancer (RSC). METHODS: The analysis included 1444 patients with nonmetastatic RSC diagnosed pathologically between 2010 and 2016 who were collected from the National Cancer Institute Surveillance, Epidemiology, and Results database. The AJCC N-stage was redefined according to the LNR cutoff point, and the ability of the new staging system to predict prognosis was compared with that of the AJCC TNM staging system. Data from 739 patients from our hospital were used for external validation. RESULTS: According to the number of examined lymph nodes and LNR, the N stage was divided into five groups (LNR0-5). The 5-year OS of patients divided according to the new T lymph node ratio M (TLNRM) staging into stage I (T1LNR1, T1LNR2), IIA (T1LNR3, T2LNR1, T2LNR2, T2LNR3, T1LNR4, T3LNR1), IIB (T2LNR4), IIC (T3LNR2, T4a LNR1, T1LNR5), IIIA (T3LNR3, T2LNR5, T4b LNR1, T4a LNR2, T3LNR4), IIIB (T3LNR5, T4a LNR3, T4a LNR4, T4b LNR2), and IIIC (T4b LNR3, T4a LNR5, T4b LNR4, T4b LNR5) was significantly different ( P <0.05). Decision curve analysis showed that the net income of the new TLNRM staging system for different decision thresholds was higher than the prediction line of the traditional eighth TNM staging system. The smaller Akaike information criterion and Bayesian information suggested that the new staging system had a higher sensitivity for predicting prognosis than the traditional staging system. TLNRM II and III patients benefited from adjuvant chemotherapy, while adjuvant chemotherapy did not improve the prognosis of TNM II patients. These findings were confirmed by the external validation data. CONCLUSION: The new TLNRM staging system was superior to the eighth edition AJCC staging system for staging and predicting the prognosis of patients with RSC and may become an effective tool in clinical practice.

Implications of the new MRI-based rectum definition according to the sigmoid take-off: multicentre cohort study.

BACKGROUND: The introduction of the sigmoid take-off definition might lead to a shift from rectal cancers to sigmoid cancers. The aim of this retrospective cohort study was to determine the clinical impact of the new definition. METHODS: In this multicentre retrospective cohort study, patients were included if they underwent an elective, curative total mesorectal excision for non-metastasized rectal cancer between January 2015 and December 2017, were registered in the Dutch Colorectal Audit as having a rectal cancer according to the previous definition, and if MRI was available. All selected rectal cancer cases were reassessed using the sigmoid take-off definition. The primary outcome was the number of patients reassessed with a sigmoid cancer. Secondary outcomes included differences between the newly defined rectal and sigmoid cancer patients in treatment, perioperative results, and 3-year oncological outcomes (overall and disease-free survivals, and local and systemic recurrences). RESULTS: Out of 1742 eligible patients, 1302 rectal cancer patients were included. Of these, 170 (13.1 per cent) were reclassified as having sigmoid cancer. Among these, 93 patients (54.7 per cent) would have been offered another adjuvant or neoadjuvant treatment according to the Dutch guideline. Patients with a sigmoid tumour after reassessment had a lower 30-day postoperative complication rate (33.5 versus 48.3 per cent, P < 0.001), lower reintervention rate (8.8 versus 17.4 per cent, P < 0.007), and a shorter length of stay (a median of 5 days (i.q.r. 4-7) versus a median of 6 days (i.q.r. 5-9), P < 0.001). Three-year oncological outcomes were comparable. CONCLUSION: Using the anatomical landmark of the sigmoid take-off, 13.1 per cent of the previously classified patients with rectal cancer had sigmoid cancer, and 54.7 per cent of these patients would have been treated differently with regard to neoadjuvant therapy or adjuvant therapy.

[A Case of Liver Metastasis of Colorectal Cancer Successfully Treated with Hepatic Arterial Infusion Chemotherapy after Systemic Chemotherapy Was Difficult to Administer].

The patient underwent partial sigmoid colon resection for sigmoid colon cancer with hyper CEA blood(1,110.6 ng/mL) and concurrent liver metastases mostly in the right lobe of the liver, followed by systemic chemotherapy(SOX plus BEV). Seven courses of chemotherapy resulted in PR on imaging, and CEA was reduced to 5.0 ng/mL, which was within reference values. As he continued chemotherapy, frequent hematologic toxicities and adverse events forced frequent dose reductions and changes in the chemotherapy schedule. About 2 years after surgery(19 courses of SOX plus BEV), the liver metastases became slightly enlarged on imaging, and the CEA was also increasing. The patient did not wish to undergo systemic chemotherapy and requested hepatic arterial infusion chemotherapy(HAIC), which has relatively few side effects and adverse events. HAIC with pyrimidine fluoride alone is ongoing for 22 courses, and tumor markers have decreased again with PR on imaging. Performance status has been good without hematologic toxicity or adverse events for approximately 1 year during the course of HAIC. HAIC is a weakly recommended therapy in the colorectal cancer treatment guidelines, but it is considered one of the most effective therapies with relatively few side effects.

Pelvic CT in addition to MRI to differentiate between rectal and sigmoid cancer on imaging using the sigmoid take-off as a landmark.

BACKGROUND: The sigmoid take-off (STO) is a recently established landmark to discern rectal from sigmoid cancer on imaging. STO-assessment can be challenging on magnetic resonance imaging (MRI) due to varying axial planes. PURPOSE: To establish the benefit of using computed tomography (CT; with consistent axial planes), in addition to MRI, to anatomically classify rectal versus sigmoid cancer using the STO. MATERIAL AND METHODS: A senior and junior radiologist retrospectively classified 40 patients with rectal/rectosigmoid cancers using the STO, first on MRI-only (sagittal and oblique-axial views) and then using a combination of MRI and axial CT. Tumors were classified as rectal/rectosigmoid/sigmoid (according to published STO definitions) and then dichotomized into rectal versus sigmoid. Diagnostic confidence was documented using a 5-point scale. RESULTS: Adding CT resulted in a change in anatomical tumor classification in 4/40 cases (10%) for the junior reader and in 6/40 cases (15%) for the senior reader. Diagnostic confidence increased significantly after adding CT for the junior reader (mean score 3.85 vs. 4.27; P < 0.001); confidence of the senior reader was not affected (4.28 vs. 4.25; P = 0.80). Inter-observer agreement was similarly good for MRI only (κ=0.77) and MRI + CT (κ=0.76). Readers reached consensus on the classification of rectal versus sigmoid cancer in 78%-85% of cases. CONCLUSION: Availability of a consistent axial imaging plane - in the case of this study provided by CT - in addition to a standard MRI protocol with sagittal and oblique-axial imaging views can be helpful to more confidently localize tumors using the STO as a landmark, especially for more junior readers.

Endometrioma Causing Near-Complete Obstruction of the Sigmoid Colon.

Endometriosis is characterized by extra-uterine endometrial gland and stroma implantation. Intestinal endometriosis is believed to affect about one-third of patients with endometriosis4; 72-95% of patients experience recto-sigmoid involvement.2,3 Occasionally, endometriotic lesions precipitate mass effect or infiltrate the bowel wall, mimicking a neoplasm. In the index case, we evaluated a G0P0 41-year-old perimenopausal female with near obstructing sigmoid endometrioma, clinically presented, investigated, and managed in the lines of sigmoid colon carcinoma. Computed Tomography revealed marked distention of the distal descending and proximal sigmoid colon to the level of a [possible] intraluminal mass. CA-125 was 247.4. Transvaginal ultrasound revealed a heterogeneous irregularity adjacent the left adnexa. Flexible sigmoidoscopy to 12-15 cm was unable to pass liquid or visualize the lumen secondary to extrinsic colonic obstruction. She underwent exploratory laparotomy with sigmoidectomy, oversew of rectal stump, and descending colostomy. Left fallopian tube and ovary were adherent to sigmoid mass, therefore, removed en-bloc. Histopathological report revealed extensive endometriosis involving the muscularis propria and serosal surface of colon and ovary, with fibrinous serosal adhesions of the sigmoid colon. While inconsistent clinical presentation, similar radiographic features, and colonoscopy with other inflammatory or malignant lesions of the bowel makes the preoperative diagnosis challenging, colonic endometriosis is to always be considered as one of the differential diagnoses in reproductive age women with patterned, cyclic gastrointestinal symptoms, and intestinal masses of uncertain etiology or diagnosis.

[A Case of the Metastatic Colonic Carcinoma from an Endometrial Carcinoma].

A woman in her 80s, had undergone radical surgery for an endometrial carcinoma 9 years earlier, and her 5-year postoperative follow-up had been completed without recurrence. She consulted an orthopedic surgeon with a chief complaint of a mass in the left inguinal region, and was referred to surgery after MRI scan revealed lymph node metastases in the left inguinal and external iliac region and a sigmoid colon tumor. Due to postoperative adhesion of the uterine cancer, the colonoscope could not be inserted to the tumor, and no tissue diagnosis was made. CT and PET scans revealed a sigmoid colon tumor plus periungual lymph node metastasis, and it was determined that radical surgery was possible, and the patient underwent resection. Surgery was performed by laparoscopic resection of the sigmoid colon and lymphadenectomy, with R0 resection. The sigmoid colon tumor and lymph nodes were of the same histology as the 9-year-old endometrial carcinoma, leading to the diagnosis of colon and lymph node recurrence 9 years after endometrial carcinoma surgery.

[A Case of Resected Diffuse Large B-Cell Lymphoma Diagnosed with Liver Metastasis and Peritoneal Dissemination after Surgery for Sigmoid Colon Cancer].

We experienced a case of diffuse large B-cell lymphoma(DLBCL)that developed around the kidney about 1 year after surgery for sigmoid colon cancer. In this case, imaging findings suggestive of liver metastasis were also observed at the same time of diagnosis, therefore, diagnosis was difficult because the possibility of peritoneal dissemination could not be ruled out. The lesion was excised by surgery and a definitive diagnosis was obtained by tissue diagnosis, leading to appropriate treatment. However, one wrong step could lead to the wrong treatment policy. Therefore, when there is any doubt about the diagnosis, it is considered important to proactively perform tissue diagnosis.

[A Case of Robot-Assisted Laparoscopic Surgery for Stenotic Sigmoid Colon Cancer with Simultaneous Lateral Lymph Node Metastasis].

The patient is a 63-year-old man. He visited his previous physician for abdominal pain. After close examinations, he was diagnosed with stenotic sigmoid colon cancer with left lateral lymph node metastasis. On the same day, colonic stenting was performed to relieve the symptoms of stenosis. After 1 month of stenting, a robot-assisted laparoscopic sigmoid colectomy and left lateral lymph node dissection were performed. Postoperative pathological examination revealed regional lymph node metastasis and left lateral lymph node metastasis(#283); the patient was diagnosed with pT4aN1bM1a(LYM), fStage Ⅳa. The patient was discharged on postoperative day 10, and is stable 5 months after surgery without recurrence. This case suggests that robot-assisted laparoscopic lateral lymph node dissection can be effective even in atypical cases of sigmoid colon cancer with lateral lymph node metastasis.

[A Case of Double Cancer of Squamous Cell Carcinoma of the Rectum and Adenocarcinoma of the Sigmoid Colon].

A 72-year-old male was transported to our hospital with complaints of heart palpitations and dyspnea since a month earlier and was immobile. Blood examination showed severe anemia, and colonoscopy revealed circumferential tumors in the rectum and the sigmoid colon. Histopathologic examination revealed the tumors as squamous cell carcinoma of the rectum and adenocarcinoma of the sigmoid colon. Therefore, they were diagnosed as double colorectal cancers. CT and MRI showed that rectal cancer invaded the seminal vesicles and the prostate; therefore, the patient underwent neoadjuvant chemoradiotherapy(oral capecitabine and concomitant radiation therapy: a total dose of 50.4 Gy/28 Fr)followed by total pelvic exenteration. Subsequent specimen pathology revealed a tumor regression grading of Grade 2 for the rectal and sigmoid colon cancers, and both were staged as ypT3N0M0, ypStage Ⅱa. Herein, we report a rare case of double cancer of adenocarcinoma of the sigmoid colon and squamous cell carcinoma of the rectum with a literature review.

[A Case of Locally Advanced Giant Sigmoid Colon Cancer Successfully Treated with Neoadjuvant Chemotherapy].

A 51-year-old woman presented to our hospital complaining of a lower abdominal mass and dysuria. She was diagnosed with advanced sigmoid colon cancer. The tumor was large, involving the bladder, and occupying the pelvic cavity. She received neoadjuvant chemotherapy with 4 courses of mFOLFOX6, in addition to panitumumab. The treatment resulted in a marked reduction of the tumor. A laparoscopic sigmoid colon resection, total cystectomy, neobladder reconstruction, complete uterine and bilateral adnexa resection and partial ileal resection were performed. The histopathological diagnosis was ypT4b(bladder), ypN0, ypStage Ⅱc, all with negative surgical margins. Adjuvant chemotherapy was not administered owing to the patient's refusal. She remained recurrence-free for 3 years of postoperative follow up.

[A Case of Sigmoid Colon Cancer with Simultaneous Solitary Adrenal Metastasis Refractory to Preoperative Diagnosis].

A 72-year-old man was referred to our urology department due to a giant adrenal tumor detected by computed tomography( CT). Endocrine screening showed that cortisol, renin, aldosterone, adrenaline, and noradrenaline levels were all normal, and there was no evidence of adrenal hyperfunction. The adrenal tumor was so large that we suspected malignancy. Contrast-enhanced CT of the abdomen was performed for qualitative diagnostic purposes, and showed wall thickening of the sigmoid colon extending for approximately 6 cm. Lower gastrointestinal endoscopy was performed and revealed a full circumferential type 2 tumor in the sigmoid colon. Biopsy results showed intermediate differentiated ductal adenocarcinoma. Tumor markers were as follows: CEA 23.1 ng/mL, CA19-9 962 U/mL. The adrenal tumor was suspected of being malignant due to its size, but imaging examinations did not lead to a diagnosis of primary or metastatic disease. There were no tumors other than those in the sigmoid colon and adrenal glands. Since complete resection was deemed possible, sigmoid colon resection and combined left adrenalectomy were performed for both a diagnosis and treatment. A histopathological examination revealed that the histology of the adrenal tumor resembled that of colorectal cancer, leading to a diagnosis of left adrenal metastasis from sigmoid colon cancer.

[Brain Metastasis Following Conversion Surgery for Sigmoid Colon Cancer-A Case Report].

A 64-year-old man was diagnosed with KRAS-mutant type sigmoid colon cancer with metastasis in the lung, liver, left adrenal gland, and para-aortic lymph node(T3N1M1b, Stage ⅣB[Union for International Cancer Control 8th edition]). Laparoscopic transverse colostomy was performed to treat colonic obstruction. Subsequently, a combination regimen of capecitabine plus oxaliplatin plus bevacizumab was administered. After 5 courses of chemotherapy, the S8 liver tumor disappeared completely. Sigmoidectomy, para-aortic lymph node dissection, and left adrenal gland resection were performed. After 3 months, right S3 segmental pneumonectomy and right S8 and S10 partial pneumonectomy were performed. R0 resection for the primary lesion and metastatic lesions of the chest and abdomen was achieved. Following the conversion surgery, he was administered the adjuvant chemotherapy regimen of uracil-tegafur plus Leucovorin. After 2 courses of chemotherapy, he presented to our hospital complaining of vomiting and dizziness. Contrast-enhanced magnetic resonance imaging revealed multiple brain metastases. Thus, we should be mindful of the possibility of brain metastasis in cases of unresectable colon cancer showing satisfactory response to chemotherapy with an indication of conversion surgery.

[A Case of MSI-High Sigmoid Colon Cancer in Which Long-Term Survival Was Achieved by Pembrolizumab for Recurrent Lesions Resistant to Conventional Chemotherapy].

The patient underwent sigmoidectomy with D3 lymph node dissection and partial bladder resection for sigmoid colon cancer(cT4bN1M0, cStage Ⅲa), after preoperative chemotherapy with mFOLFOX plus panitumumab, and FOLFOXIRI plus bevacizumab. Postoperative adjuvant chemotherapy was performed by 8 courses of CAPOX. He relapsed hilar lymph nodes and peritoneal dissemination after 13 months after surgery, he underwent resection of the recurrent lesions. Four months after, he developed recurrence in liver and peritoneum. Although he was treated with FOLFIRI plus ramucirumab or aflibercept, resulted in progression of disease, then he received trifluridine tipiracil hydrochloride plus bevacizumab. At this point, the Japanese health insulance had started to cover pembrolizumab, this therapy was started as the fourth chemotherapy after the diagnosis of high frequency microsatellite instability(MSI), and then tumor markers rapidly declined. He underwent 38 courses of pembrolizumab, the recurrent lesions both liver and peritoneum disappeared. He had stoma closure, peritoneal dissemination disappeared not only intraoperatively but also in histologically from the peritoneal scar. He has received pembrolizumab for 4 years without another recurrence. Here, we report a case of MSI-high sigmoid colon cancer in which long-term survival was achieved by pembrolizumab for recurrent lesions resistant to conventional chemotherapy.