Incidence and molecular characteristics of deficient mismatch repair conditions across nine different tumors and identification of germline variants involved in Lynch-like syndrome.

BACKGROUND: Based on molecular characteristics, deficient DNA mismatch repair (dMMR) solid tumors are largely divided into three categories: somatically MLH1-hypermethylated tumors, Lynch syndrome (LS)-associated tumors, and Lynch-like syndrome (LLS)-associated tumors. The incidence of each of these conditions and the corresponding pathogenic genes related to LLS remain elusive. METHODS: We identified dMMR tumors in 3609 tumors from 9 different solid organs, including colorectal cancer, gastric cancer, small-bowel cancer, endometrial cancer, ovarian cancer, upper urinary tract cancer, urinary bladder cancer, prostate cancer, and sebaceous tumor, and comprehensively summarized the characterization of dMMR tumors. Characterization of dMMR tumors were performed as loss of at least one of MMR proteins (MLH1, MSH2, MSH6, and PMS2), by immunohistochemistry, followed by MLH1 promotor methylation analysis and genetic testing for MMR genes where appropriate. Somatic variant analysis of MMR genes and whole exome sequencing (WES) were performed in patients with LLS. RESULTS: In total, the incidence of dMMR tumors was 5.9% (24/3609). The incidence of dMMR tumors and the proportion of the three categorized dMMR tumors varied considerably with different tumor types. One to three likely pathogenic/pathogenic somatic MMR gene variants were detected in 15 out of the 16 available LLS tumors. One patient each from 12 patients who gave consent to WES demonstrated non-MMR germline variants affect function (POLQ or BRCA1). CONCLUSIONS: Our data regarding the LS to LLS ratio would be useful for genetic counseling in patients who are suspected to have LS, though the genetic backgrounds for the pathogenesis of LLS need further investigation.

[Development of Cancer of the Remnant Colorectal Segment after Ileal-Pouch Anal Anastomosis/Ileorectal Anastomosis in Patients with Familial Adenomatous Polyposis].

PURPOSE: This retrospective study was performed to investigate the recent trend of occurrence of cancer of the remnant colorectal segment(RCRS)after ileal-pouch anal anastomosis(IPAA)/ileorectal anastomosis(IRA)and to consider the optimal surveillance methods in patients with familial adenomatous polyposis(FAP)undergoing(procto)colectomy. PATIENTS AND METHODS: The subject was a total of patients with FAP undergoing IPAA or IRA between 2005 and 2022. Clinicopathological data were extracted from medical charts and analyzed. Cumulative incidence of cancer in the RCRS and overall survival after treatment of such tumors were calculated by the Kaplan-Meier method. RESULTS: There were 45 male and 56 female. IPAA was performed in 49 patients(hand-sewn; n=33, stapled; n=16)and IRA was performed in 52 patients. The median age at initial colorectal surgery was 32 years old(range, 13-66 years old). Median postoperative follow-up was 11 years(range, 1-48 years). Eighty-one patients were confirmed to have pathogenic variant of APC by genetic test. The cumulative incidence of cancer of the RCRS did not differ between patients undergoing IPAA and those undergoing IRA(p= 0.73, 4.1% versus 1.9% at 10 years). The cumulative 5-year overall survival rate after additional surgery for the tumor of RCRS was 82%. CONCLUSION: This study has several limitations due to single institutional retrospective study with small cases and non-standardized postoperative endoscopic surveillance. However, our results seem to show satisfactory oncological outcomes of patients with FAP in terms of the control of cancer of the RCRS under postoperative periodic surveillance, regardless of the type of colorectal resection.

[A Case of Transverse Colon Cancer Associated with Lynch Syndrome with Excellent Response to Pembrolizumab].

A 47-year-old woman diagnosed with transverse colon cancer with liver, peritoneal, and lymph node metastases was admitted. Modified FOLFOX6(mFOLFOX6)regimen was given as a first line chemotherapy and was followed by pembrolizumab after 1 cycle of the mFOLFOX6, because microsatellite instability(MSI)test of the tumor showed high-frequency MSI. Because of the transverse colon obstruction after 2 cycles of pembrolizumab, she underwent right hemicolectomy. Histological examination of the resected specimen revealed no residual tumor cells in the primary tumor and reginal lymph nodes. Immunohistochemistry for mismatch repair proteins(IHC-MMR)showed loss of MSH2 and MSH6 expression. Genetic test identified a MSH2 pathogenic variant leading to the diagnosis of Lynch syndrome. The present case shows the importance of MSI test or IHC-MMR before the treatment of metastatic colorectal cancer.

[Complete Response to Immune Checkpoint Inhibitors in Unresectable Gastric Cancer-A Report of Five Cases].

Immune checkpoint inhibitors(ICIs)are widely used for the treatment of unresectable gastric cancer. We treated approximately 70 patients with ICIs. ICI treatment with pembrolizumab was administered for MSI-high cases and nivolumab for MSS cases in the second- or third-line chemotherapy. We observed 5 cases of complete response. Among these, 2 patients presented with liver metastases, 2 with peritoneal disseminations, and 1 with pulmonary metastasis. In 1 patient, the primary tumor invaded the diaphragm and descending aorta; whereas, in another patient the primary tumor invaded the pancreas and liver. All patients had progressive disease after first-line chemotherapy.

Usefulness of genotyping APC gene for individualizing management of patients with familial adenomatous polyposis.

BACKGROUND: Colorectal polyp burden is crucial for the management of patients with familial adenomatous polyposis (FAP). However, accurate evaluation of polyp burden is difficult to standardize. This study aimed to examine the possible utility of genotype-oriented management of colorectal neoplasms in patients with FAP. METHODS: Clinicopathological data from genetically proven patients with FAP was analyzed using the database of a nationwide retrospective Japanese multicenter study. The cumulative incidence of CRC was evaluated between different genotype groups. Genotype-1 were defined as germline variants on attenuated FAP-associated regions (codons 1-177, alternative splice site of exon 10 (codon 312), 1581-2843) and Genotype-2 as the other variants. Weibull and Joinpoint analyses were performed to determine the annual percentage changes in CRC risk. RESULTS: Overall, 69 men and 102 women were included. Forty-eight patients underwent colorectal resection for the first CRC, and five patients underwent resection for first cancer in the remnant anorectal segment after prophylactic surgery. The 70-year cumulative incidence of CRC in all patients was 59.3%. Patients with Genotype-1 (n = 23) demonstrated a lower risk of CRC stages II-IV than those with Genotype-2 (n = 148, P = 0.04). The risk of stage II-IV CRC was estimated to increase markedly at the age of 49 years in the Genotype-1 patients and 34 years in the Genotype-2 patients, respectively. CONCLUSIONS: Different interventional strategies based on genotypes may be proposed for the clinical management of patients with FAP. This policy needs to be validated in further prospective studies focusing on long-term endoscopic intervention and optimal age at prophylactic (procto)colectomy.

[A Rare Case of Cronkhite-Canada Syndrome Associated with Gastric Cancer and Gastric Outlet Obstruction].

Cronkhite-Canada syndrome(CCS)is a rare non-inherited disease characterized by gastrointestinal polyposis and ectodermal abnormalities. We report a rare case of CCS associated with gastric cancer and gastric outlet obstruction with a review of the literature. A 75-year-old man was admitted because of frequent vomiting and hypoproteinemia. He was diagnosed with CCS due to typical clinical and laboratory findings including alopecia, nail atrophy, hypoproteinemia, and typical gastrointestinal polyposis. Upper endoscopic examination also pointed out a large gastric cancer mainly located in the antrum and the reversible pyloric obstruction caused by the gastric tumor. Biopsy of the tumor revealed tubular adenocarcinoma. Computed tomography demonstrated the dilated duodenum caused by packing of the gastric tumor. 1.5 months after prednisolone therapy, he underwent total gastrectomy with complete resection of the dilated duodenal bulb. Histological examination revealed gastric cancer(pap>tub1)classified into Stage ⅢC. Postoperative course was uneventful and he moved to another hospital. To our knowledge, including the present case, there were 20 reported cases of CCS associated with gastric cancer from Japan(1979-2022). Also, 7 cases of CCS associated with gastric outlet obstruction was reported.

Recent trends in the morbidity and mortality in patients with familial adenomatous polyposis: a retrospective single institutional study in Japan.

BACKGROUND: This study aimed to assess current trends in morbidity and mortality among patients with familial adenomatous polyposis (FAP). These data can be used for optimal surveillance and management of such patients. METHODS: Data (November 2001 and April 2020) of genetically confirmed patients with FAP (n = 87) and their first-degree relatives with FAP phenotype (n = 20) were extracted from the Saitama Medical Center database. Standardized mortality ratio (SMR) and standardized incidence ratio (SIR) were estimated using indirect method. RESULTS: Overall, 46 men and 61 women were included; the median age at FAP diagnosis was 28.0 years for both. The SMR for all causes of death was 47.7 (95% confidence interval [CI] 19.1-98.2) in women and 26.5 (95% CI 9.73-57.8) in men. The SIR for colorectal cancer (CRC) was 860 (95% CI 518-1340) in women and 357 (95% CI 178-639) in men. The SMR for CRC was 455 (95% CI 93.7-1330) in women and 301 (95% CI 62.0-879) in men. Thirteen patients died during the observation period, and CRC was the leading cause of death (46%). Other causes of death included desmoid tumor (n = 2), small intestinal cancer (n = 2), ovarian cancer (n = 1), duodenal cancer (n = 1), and sepsis (n = 1). CONCLUSIONS: The mortality ratio, estimated using SMR, remained high. CRC was the leading cause of death, whereas almost half of the causes of deaths were extra-colonic tumors. Life-long management of extra-colonic diseases may improve the prognosis in these patients.

BRAF V600E mutations in right-side colon cancer: Heterogeneity detected by liquid biopsy.

INTRODUCTION: The prognosis for metastatic colorectal cancer patients (mCRC) with the BRAFV600E mutation is poor. BRAFV600E mutation frequency is reportedly low among Asians; however, the frequency of the BRAFV600E mutation in right-side colon cancer may not be low, even among Asians. In addition, spatial heterogeneity of BRAFV600E mutations also exists, as for RAS mutations. In this prospective observational study, we evaluated BRAFV600E mutations in cancer tissue and plasma of Japanese right-side colon cancer patients. METHOD: 215 patients with right-side colon cancer were included. BRAFV600E mutations of cancer tissue and plasma were detected using droplet digital PCR. Blood plasma of patients with BRAFV600E mutations in cancer tissue or plasma was drawn at intervals throughout chemotherapy, and BRAFV600E mutations were evaluated. RESULTS: BRAFV600E mutations were detected in tissue samples from 35 of 215 patients (16.3%, cecum; 22.4%, ascending colon; 17.8%, and transverse colon; 9.0%). BRAFV600E mutations were detected in plasma of 10 of 215 (4.7%) patients. Eight of the ten patients had BRAFV600E mutations in their primary tumours, but two (both were Stage IV) patients did not. Sensitivity of liquid biopsy to detect BRAFV600E mutations was 10.3% (3/29) in Stage I-III patients and 83.3% (5/6) in Stage IV patients. CONCLUSION: BRAFV600E mutations are observed in right-side colon cancer at high frequency, especially in the cecum. BRAFV600E mutations can be detected in plasma and the detection rate is high in patients with advanced cancer. Spatial heterogeneity was observed using liquid biopsy.

[Report of Multidisciplinary Treatment for Sisters with Li-Fraumeni Syndrome].

Li-Fraumeni syndrome(LFS)is a hereditary cancer disorder caused by germline variant in TP53 and characterized by various malignancies. Multidisciplinary treatment is needed for tumors of LFS, however, radiation therapy is a relative contraindication because of frequent development of secondary malignancy such as sarcoma in the irradiated field. Case 1: A 22- year-old woman who was diagnosed with LFS by genetic test when she developed upper rectal cancer. Her rectal tumor with marked bilateral lateral lymph node dissection was successfully removed by low anterior resection with extensive lateral lymph node dissection. She underwent resection for ovarian metastasis followed by chemotherapy and radiotherapy but subsequently died by the disease 32 months postoperatively. Case 2(elder sister of Case 1): A brain tumor was identified in the left high frontal lobe to the parietal lobe because of consciousness disorder, after the genetic diagnosis of LFS. The brain tumor was successfully resected. Histological examination revealed diffuse astrocytoma(WHO grade Ⅱ). Local recurrence was observed 46 months later, and radiation therapy was performed. Six months have passed since radiation therapy, no exacerbation of local recurrence has been observed.

[A Case of Curative Resection of a Retroperitoneal Liposarcoma].

A 55-year-old woman had been admitted to a hospital with abdominal bloating. Retroperitoneal liposarcoma was suspected and diagnosed as not resectable. She was then referred to our hospital with dyspnea and difficulties with movement due to the huge mass. An abdominal CT revealed a large mass originating in the left retroperitoneum. The tumor occupied most of the abdominal cavity, resulting in the displacement of her organs. However, there was no evidence of infiltration of the tumor into the aorta and inferior vena cava. Under a provisional diagnosis of retroperitoneal liposarcoma, a surgical resection was undertaken. The resected specimen had a maximum diameter of 48 cm and weighed 14 kg. Histopathological examination revealed a differentiated liposarcoma. The patient remains alive 6 months after the operation, without recurrence.

[A Case of Malignant Peripheral Nerve Sheath Tumor of the Anus Resected by Robot Assisted-APR].

An 81-year-old female visited a local hospital with complaints of anal pain. A tumor was found on the right side of her anus, and the histopathological diagnosis was a non-epithelial malignant tumor. Therefore, the patient was referred to our hospital. Result of imaging inspection revealed that the tumor had invaded the lower rectum, but had not distantly metastasized. Based on the findings of another biopsy, the patient was diagnosed with a malignant peripheral nerve sheath tumor (MPNST). Robot-assisted abdominoperineal resection(D1)was performed, and the lesion was resected without any pathological remnants. During the postoperative period, the patient developed perineal wound infection. Subsequently, the patient was discharged from the hospital on postoperative day 10. At the 6-month postoperative follow-up, no recurrence was noted. Most MPNSTs occur in the limbs, trunk, and neck. MPNST in the primary gastrointestinal tract or in the vicinity of the gastrointestinal tract is relatively rare, and in principle, combined resection of the intestinal tract is required for surgical treatment. Here, we report a case of MPNST that occurred near the anus and infiltrated to the lower rectum and was completely resected by robot-assisted abdominoperineal resection.

[A Case Report of Perianal Paget's Disease Treated with Robot-Assisted Surgery for Positive Margins after Local Excision].

The patient is a 73-year-old man who was diagnosed with perianal Paget's disease by skin biopsy. Biopsy from the dentate line did not show any tumor cells. The patient was considered to undergo sphincter-preserving local resection and subsequently underwent the procedure. Histopathological examination of the resected specimen revealed perianal Paget's disease with a positive anorectal margin. The patient was referred to our department due to postoperative anal stenosis. On the 32nd postoperative day, a double barreled sigmoid colostomy was performed. However, considering the inability to adequately check for detect due to anorectal stenosis and the expected unfavorable anorectal function caused by sphincter- preserving re-operation, a robot-assisted abdominoperineal resection(D1)was performed 7 months after the initial surgery. Histopathological examination of the resected specimen revealed no residual tumor cells in the resected specimen. After local excision for perianal Paget's disease, the skin of the buttock becomes scarred due to skin valve formation and skin grafting, making closure of the perineal wound difficult when performing abdominoperineal resection. In robot-assisted surgery, it is relatively easy to remove the anorectal muscles from the abdominal cavity and reach the sciatico-rectal fossa, thus reducing the size of the perineal wound.

Prevalence and molecular characteristics of DNA mismatch repair deficient endometrial cancer in a Japanese hospital-based population.

BACKGROUND: The prevalence and molecular characteristics of defective DNA mismatch repair endometrial cancers in the Japanese population have been underexplored. Data supporting clinical management of patients with Lynch-like syndrome and germline variant of uncertain significance of mismatch repair genes are still lacking. METHODS: Immunohistochemistry of mismatch repair proteins (MLH1, MSH2, MSH6 and PMS2) was performed on formalin-fixed paraffin-embedded sections prepared from resected primary endometrial cancers in 395 women with a median age of 59 years. Genetic and/or epigenetic alterations of the mismatch repair genes were also investigated. RESULTS: Loss of expression of one or more mismatch repair proteins was observed in 68 patients (17.2%). A total of 17 out of 68 patients (25%, 4.3% of all cases) were identified as candidates for genetic testing for Lynch syndrome after excluding 51 patients with MLH1 hypermethylated cancer. Fourteen of these 17 patients subjected to genetic testing were found to have Lynch syndrome (n = 5), germline variant of uncertain significance (n = 2) or Lynch-like syndrome (n = 7). Compared with patients with Lynch syndrome, those with germline variant of uncertain significance and Lynch-like syndrome tended to demonstrate an older age at the time of endometrial cancer diagnosis (P = 0.07), less fulfillment of the revised Bethesda guidelines (P = 0.09) and lower prevalence of Lynch syndrome-associated tumors in their first-degree relatives (P = 0.01). CONCLUSIONS: This study provides useful information for management in patients with DNA mismatch repair endometrial cancer. Specifically, cancer surveillance as recommended in patients with Lynch syndrome might not be necessary in patients with germline variant of uncertain significance and Lynch-like syndrome and their relatives.

[Two Cases of Esophageal Neuroendocrine Carcinoma That Were Successfully Controlled by Multi-Modality Therapy].

Esophageal neuroendocrine carcinoma is extremely rare, and its treatment strategy has not been established. We report 2 cases esophageal neuroendocrine carcinoma. Case 1: A 74-year-old man was diagnosed as having esophageal neuroendocrine carcinoma(clinical T3N4M0, Stage Ⅳa). He received 60 Gy of radiation therapy with etoposide(100 mg/m2)plus cisplatin(80 mg/m2). No recurrence has been detected 1 year after treatment. Case 2: A 78-year-old man was diagnosed as esophageal neuroendocrine carcinoma(clinical T3N0M0, Stage Ⅱ). He underwent esophagectomy with 3 field lymph nodes dissection. Adjuvant chemotherapy was administered with irinotecan(60 mg/m2)plus cisplatin(60 mg/m2). After chemotherapy, he survived 1 year without recurrence.

[Three Cases of Conversion Surgery for Unresectable Gastric Cancer with Multiple Liver Metastases].

We herein report 3 cases of advanced gastric cancer with multiple liver metastases who was successfully treated with systemic chemotherapy and underwent conversion surgery with liver resection. There were 2 males and 1 female patients with a range 68 to 74 years of age. Two patients received S-1 plus oxaliplatin therapy and 1 received S-1 plus cisplatin therapy. All patients survived after 5-49 months postoperatively.

[Changes in Renal Function and Feasibility of Adjuvant Chemotherapy for Colorectal Cancer Patients with Diverting Ileostomy after Ileal Pouch-Anal Anastomosis].

We investigated changes in estimated glomerular filtration rate(eGFR)in 11 colorectal cancer patients(6 familial adenomatous polyposis, 5 ulcerative colitis)who underwent restorative proctocolectomy with ileal pouch-anal anastomosis(IPAA) and diverting ileostomy(DI), the tolerability and adverse events of adjuvant chemotherapy(ACT)in 4 cases. After IPAA, eGFR decreased significantly(p=0.02)and did not return to the preoperative level even after stoma closure(p<0.01). mFOLFOX6 was selected as the regimen in 4 candidates, and no significant changes in eGFR after ACT were observed. The relative dose intensity of oxaliplatin was 91.7%, and no gastrointestinal adverse events of Grade 3 or higher were observed. Although in a small number of cases, mFOLFOX6 as ACT after IPAA and DI may be feasible.

[A Case of Carcinoma of the Ileostomy Site Associated with Familial Adenomatous Polyposis-Report of a Case].

We report a rare carcinoma of the permanent ileostomy site developing 20 years or more after total proctocolectomy (TPC)in a 65-year-old woman with familial adenomatous polyposis(FAP). She underwent TPC for rectal cancer associated with FAP in her 40th at other institution. She also underwent pancreas-sparing total duodenectomy for duodenal mucosal cancer associated with severe duodenal polyposis at 59 years at our institution. She was referred to our hospital again complaining of the mass of the ileostomy site, 10 cm in diameter. Though biopsy revealed no definite malignancy, serum CA19-9 was elevated(98 U/mL), leading to a preoperative diagnosis to be ileal carcinoma. The involved bowel was widely resected. Histological examination demonstrated Stage ⅡA ileal carcinoma. Postoperative course was uneventful and she is well without recurrence 7 months after the ileal resection. This case seems valuable in that long-term surveillance including ileal carcinoma is important in the management of FAP patients whose colorectal cancer and duodenal cancer have been already well controlled.

[Conversion Surgery following Second-Line Chemotherapy for Unresectable Gastric Cancer].

We retrospectively analyzed clinicopathological and survival data of 8 patients with unresectable gastric cancer who underwent conversion surgery(CS)following second-line chemotherapy from April 2013 to December 2020. There were 7 males and 1 female patients with a median age of 69(64-76)years old. Five patients had 1 unresectable factor, 2 had 2 unresectable factors, and 1 had 3 unresectable factors. All patients achieved R0 resection. The median survival time(MST) of patients with CS following second-line chemotherapy was significantly longer than that without CS(73.4 vs 12.3 months, respectively). The MST of patients with CS following first-line chemotherapy was significantly longer than that without CS (22.9 vs 12.3 months, respectively). This study suggested that CS following first- or second-line chemotherapy may improve survival duration for unresectable gastric cancer.

Prevalence and Molecular Characterization of Defective DNA Mismatch Repair in Small-bowel Carcinoma in a Japanese Hospital-based Population.

OBJECTIVES: To investigate the prevalence and molecular characteristics of defective DNA mismatch repair (dMMR) in small-bowel carcinoma (SBC) in a Japanese-hospital population. METHODS: Immunohistochemistry was performed to evaluate the expression of MMR proteins (MLH1, MSH2, MSH6, and PMS2) in formalin-fixed paraffin-embedded sections prepared from surgically resected primary SBCs from 30 patients during March 2002 to March 2017. Genetic testing for Lynch syndrome was performed in patients who demonstrated MMR protein loss. RESULTS: Two of 30 patients (6.7%) demonstrated concomitant loss of MSH2/MSH6 protein expression. Further genetic testing identified a pathogenic MSH2 variant in one of these patients. CONCLUSIONS: The prevalence of dMMR SBCs in a Japanese hospital-based population seems lower than that reported in previous studies. To determine whether dMMR SBCs might be strongly linked to Lynch syndrome, there is a need for further investigation with a larger sample size.

A Model for Predicting DNA Mismatch Repair-deficient Colorectal Cancer.

BACKGROUND/AIM: Identifying patients with DNA mismatch repair-deficient (dMMR) colorectal cancer (CRC) is vital to improve treatment and identify patients with Lynch syndrome (LS). We developed a prediction model for dMMR CRC using clinicopathologic features. PATIENTS AND METHODS: We reviewed the medical records of 1,147 patients who underwent resection of stage I-IV CRC in whom universal screening for LS using immunohistochemistry for MMR proteins had performed. Univariate and multivariate logistic regression analyses were used to build a prediction model of dMMR CRC. RESULTS: The prevalence of dMMR CRC was 5.2%. Age (≥75 years), tumor location (right-sided colon), main histologic features (poor differentiation), maximum tumor size (≥65 mm), and stage (I/II) were independent significant variables related to dMMR. We created a formula for predicting the likelihood of dMMR, and the probability ranged from 0.2% to 83%. CONCLUSION: dMMR CRC can be identified efficiently using clinicopathologic features obtained in daily clinical practice.