Lynch syndrome (LS) is a prevalent genetic condition associated with colorectal cancer (CRC). Accurate identification of LS patients is challenging, and a universal tumor screening approach has been recommended. We present the methodology and results of universal LS screening in our hospital\'s Pathology Department. This retrospective study analyzed CRC tumors from a 5-year period (2017-2021). Immunohistochemistry was used to assess MMR protein expression, followed by BRAF V600E analysis and MLH1 promoter methylation. Statistical analysis examined associations between clinicopathologic variables MMR status and LS-suspected tumors. The study analyzed 939 colorectal carcinomas, with 8.7% exhibiting mismatch repair (MMR) deficiency, significantly lower than previous research. After applying the algorithm, 24 LS-suspected cases were identified, accounting for 2.6% of tested patients and 29.3% of MMR-deficient tumors. Our study establishes the feasibility of universal testing for all new cases of CRC in detecting individuals at risk for LS, even in the absence of clinical information. To gain a comprehensive understanding of the MMR status in our population, further investigations are warranted.

OBJECTIVE: Lynch syndrome (LS) is estimated to affect 1-3.9% of patients with colorectal cancer (CRC). Testing for LS is important in determining management and establishing surveillance for \"Lynch families\". Previous studies have identified poor rates of testing for LS in CRC patients. This study aimed to describe adherence to guidelines for testing of newly diagnosed CRC for LS.
METHODS: A single institution cohort study of patients over 18 years with colorectal adenocarcinoma from 2018-2022 in Te Tai Tokerau, Aotearoa New Zealand was conducted. Rates of baseline immunohistochemistry (IHC) testing for mismatch repair (MMR) deficiency, further testing for MLH1-deficient cases and rates of germline mutational analysis were audited to determine adherence to national guidelines. The rate of LS in newly diagnosed CRC was estimated.
RESULTS: Six hundred and sixty patients were eligible for universal testing for LS, of which 84% (n=553) completed initial IHC testing. MMR deficiency was reported in 20% (n=114) cases. Eighty-nine percent (n=101) was attributable to MLH1 deficiency, of which 99% (n=100) were appropriately tested for BRAF-V600E mutation. Sixty-four percent (4/11) patients indicated for hypermethylation testing were appropriately tested. Seventeen patients had an indication for germline mutational analysis, of which only 29% (n=5) were tested. The estimated incidence of LS in newly diagnosed CRC was 0.7-3.8%.
CONCLUSIONS: Compliance with initial IHC testing was good. However, there is a need to improve rates of confirmation genetic testing. The incidence of confirmed LS in this study is 0.7%, however this may be as high as 3.9%.

BACKGROUND: Lynch syndrome (LS) is a genetic disease with increased risk of colorectal cancer and other malignancies. There are few reported cases of thyroid cancer in LS patients. The aim of this study is to investigate the presence of thyroid nodules in LS patients and to explore their association with the genetic features of the disease.
METHODS: A retrospective and descriptive analysis was conducted to include all LS patients followed at the CEMAD (Centro Malattie Apparato Digerente) of Fondazione Policlinico Universitario A. Gemelli IRCCS. The characteristics of LS disease, gene mutations, and previous history of thyroid disease were evaluated. Majority of patients underwent thyroid ultrasound (US), and nodule cytology was performed when needed.
RESULTS: Of a total of 139 patients with LS, 110 patients were included in the study. A total of 103 patients (74%) underwent thyroid ultrasound examinations, and 7 patients (5%) had a previous history of thyroid disease (cancer or multinodular goiter). The mean age was 51.9 years. Thyroid nodules were found in 62 patients (60%) who underwent US, and 9 of them (14%) had suspicious features of malignancy, inducing a fine-needle aspiration biopsy. A cytologic analysis classified 7 of 9 cases (78%) as TIR2 and 2 (22%) as TIR3a. Between patients with nodular thyroid disease (single nodule, multinodular goiter, and cancer), most of them (25 patients, 36% of total) were carriers of the MSH6 mutation, while 22 (32%), 17 (24%), and 5 (7%) had MSH2, MLH1, and PMS2 mutations, respectively.
CONCLUSIONS: A high prevalence of thyroid nodules was found in patients with LS, especially in MSH6-carrying patients. Performing at least one thyroid ultrasound examination is suggested for the detection of nodular thyroid disease in LS patients. Systematic investigations are needed to estimate their prevalence, features, and risk of malignant transformation.

The incidence of colorectal cancer (CRC) is closely linked to metabolic diseases. Accumulating evidence suggests the regulatory role of AMP-activated protein kinase (AMPK) in cancer metabolic reprogramming. In this study, wild-type and AMPK knockout mice were subjected to azoxymethane-induced and dextran sulfate sodium (AOM/DSS)-promoted colitis-associated CRC induction. A stable AMPK-deficient Caco-2 cell line was also established for the mechanistic studies. The data showed that AMPK deficiency accelerated CRC development, characterized by increased tumor number, tumor size, and hyperplasia in AOM/DSS-treated mice. The aggravated colorectal tumorigenesis resulting from AMPK ablation was associated with reduced α-ketoglutarate production and ten-eleven translocation hydroxylase 2 (TET2) transcription, correlated with the reduced mismatch repair protein mutL homolog 1 (MLH1) protein. Furthermore, in AMPK-deficient Caco-2 cells, the mRNA expression of mismatch repair and tumor suppressor genes, intracellular α-ketoglutarate, and the protein level of TET2 were also downregulated. AMPK deficiency also increased hypermethylation in the CpG islands of Mlh1 in both colonic tissues and Caco-2 cells. In conclusion, AMPK deficiency leads to reduced α-ketoglutarate concentration and elevates the suppressive epigenetic modifications of tumor suppressor genes in gut epithelial cells, thereby increasing the risk of colorectal tumorigenesis. Given the modifiable nature of AMPK activity, it holds promise as a prospective molecular target for the prevention and treatment of CRC.

Objective: To investigate the clinicopathological characteristics and prognostic factors of sporadic mismatch repair deficient (dMMR) colorectal cancer. Methods: A total of 120 cases of sporadic dMMR colorectal cancer from July 2015 to April 2021 were retrospectively collected in Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College. Patients with Lynch syndrome; synchronous multiple colorectal cancers; preoperative anti-tumor treatments such as chemotherapy and radiotherapy; and those with incomplete follow-up information were excluded based on family history and next-generation sequencing (NGS) test results. Immunohistochemical stains were used to detect the expression of mismatch repair proteins, methylation-specific PCR for methylation testing, and fluorescent PCR for BRAF V600E gene mutation detection. The clinical and pathological data, and gene mutation status were analyzed. Follow-up was done to assess survival and prognosis including progression-free survival and overall survival rate. Results: Sporadic dMMR colorectal cancer occurred more frequently in the right side of the colon, in females, and in the elderly. Morphologically, it was mostly moderately-differentiated, and most patients had low-grade tumor budding. In terms of immunohistochemical expression, MLH1 and PMS2 loss were dominant, and there were age and location-specificities in protein expression. MLH1 methylation was commonly detected in elderly female patients and rare in young male patients; while MLH1 and PMS2 deficiency, and BRAF V600E mutation occurred more often on the right side (P<0.05). The 3-year and 5-year progression-free survival rates were 90.7% and 88.7% respectively, and the 3-year and 5-year overall survival rates were 92.8% and 90.7% respectively. Tumor budding status was an independent risk factor affecting patient recurrence (hazard ratio=3.375, 95% confidence interval: 1.060-10.741, P=0.039), patients with low-grade tumor budding had better prognosis, and those with medium or high-grade tumor budding had poor prognosis. Conclusion: For dMMR colorectal cancer patients, tumor budding status is an independent risk factor for recurrence.
目的： 深入探讨散发性错配修复缺陷（dMMR）结直肠癌的临床病理学特征，并分析影响其预后的关键因素。 方法： 回顾性收集2015年7月至2021年4月在中国医学科学院 北京协和医学院 北京协和医院接受治疗的120例散发性dMMR结直肠癌患者的资料。根据家族史及二代测序检测结果排除林奇综合征患者，排除同时性多发结直肠癌术前进行放化疗等抗肿瘤治疗以及随访资料缺失的患者。采用免疫组织化学方法检测错配修复蛋白的表达情况，利用甲基化特异性PCR方法进行甲基化检测，通过荧光PCR方法对BRAF V600E基因突变进行筛查。主要观察指标包括临床病理资料、基因突变状况、随访数据以及生存与预后分析。预后指标主要关注疾病无进展生存期和总体生存期。 结果： 散发性dMMR结直肠癌更常见于右半结肠、女性和老年患者，形态学以中分化居多，存在低级别肿瘤出芽的患者占多数。免疫组织化学表达方面，以MLH1、PMS2缺失为主，且蛋白表达有年龄及部位的特殊性。MLH1甲基化多见于老年女性患者，而在MLH1和PMS2缺失的年轻男性患者中较为少见。BRAF V600E基因突变在右半结肠的肿瘤中检出频率更高（P<0.05）。此类肿瘤患者的3年和5年无进展生存率分别为90.7%和88.7%，3年和5年总体生存率分别为92.8%和90.7%。肿瘤出芽状态是影响肿瘤复发的独立危险因素（风险比=3.375，95%置信区间：1.060~10.741，P=0.039），其中低级别肿瘤出芽的患者预后较好，而中、高级别肿瘤出芽的患者预后较差。 结论： 在散发性dMMR结直肠癌患者中，肿瘤出芽状态是影响肿瘤复发的独立危险因素。.

OBJECTIVE: Although early-detected cervical cancer is associated with good survival, the prognosis for late-stage disease is poor and treatment options are sparse. Mismatch repair deficiency (MMR-D) has surfaced as a predictor of prognosis and response to immune checkpoint inhibitor(s) in several cancer types, but its value in cervical cancer remains unclear. This study aimed to define the prevalence of MMR-D in cervical cancer and assess the prognostic value of MMR protein expression.
METHODS: Expression of the MMR proteins MLH-1, PMS-2, MSH-2, and MSH-6 was investigated by immunohistochemical staining in a prospectively collected cervical cancer cohort (n=508) with corresponding clinicopathological and follow-up data. Sections were scored as either loss or intact expression to define MMR-D, and by a staining index, based on staining intensity and area, evaluating the prognostic potential. RNA and whole exome sequencing data were available for 72 and 75 of the patients and were used for gene set enrichment and mutational analyses, respectively.
RESULTS: Five (1%) tumors were MMR-deficient, three of which were of neuroendocrine histology. MMR status did not predict survival (HR 1.93, p=0.17). MSH-2 low (n=48) was associated with poor survival (HR 1.94, p=0.02), also when adjusting for tumor stage, tumor type, and patient age (HR 2.06, p=0.013). MSH-2 low tumors had higher tumor mutational burden (p=0.003) and higher frequency of (frameshift) mutations in the double-strand break repair gene RAD50 (p<0.01).
CONCLUSIONS: MMR-D is rare in cervical cancer, yet low MSH-2 expression is an independent predictor of poor survival.

MLH1 promoter hypermethylation (MPH) analysis is an essential step in the universal tumor testing algorithm for Lynch syndrome, the most common inherited predisposition to colorectal cancer (CRC). MPH usually indicates sporadic CRC. EPM2AIP1 gene shares the same promoter as MLH1, therefore MPH should also silence EPM2AIP1 transcription leading to loss of protein expression on immunohistochemistry (IHC). It has been previously reported that EPM2AIP1 IHC can be used as a surrogate for MPH in endometrial cancer. Our goal was to evaluate the feasibility of EPM2AIP1 IHC as a surrogate for MPH in CRC. 101 microsatellite instable CRC cases were selected, including 19 cases from whole tumor sections and 82 cases from tissue microarrays. 74 cases were with MPH and 27 without MPH. All 74 cases with MPH showed absent MLH1 by IHC, but only 47 (64%) exhibited loss of expression of EPM2AIP1. Of the 27 cases without MPH, 9 (33%) cases had unexpected loss of EPM2AIP1 expression. Of note, 10 cases were MLH1-mutated Lynch syndrome without MPH, and 2 of these cases showed unexpected loss of EPM2AIP1 staining. Of the 6 cases with double somatic mutations of MLH1 gene (without MPH), only 4 cases demonstrated intact expression of EPM2AIP1 as expected. Taken together, EPM2AIP1 loss was 64% sensitive and 67% specific for MPH, with an accuracy of 64%. We conclude that, unless stain quality improves with different clones or platforms, EPM2AIP1 IHC will likely not be useful as a surrogate test for MPH in CRC.

BACKGROUND: Serrated lesions and polyps (SP) are precursors of up to 30 % of colorectal cancers (CRC) through the serrated pathway. This often entails early BRAF mutations and MLH1 hypermethylation leading to mismatch repair deficient (dMMR) CRC. We investigated predictors of dMMR CRC among patients with co-occurrence of CRC and SP to increase our knowledge on the serrated pathway.
METHODS: We used data from The Danish Pathology Registry and Danish Colorectal Cancer Groups Database from the period 2010-2021 to investigate risk factors for development of dMMR CRC. We used logistic regression models to identify difference in risk factors of developing dMMR CRC in comparison to CRC with proficient MMR (pMMR).
RESULTS: We included 3273 patients with a median age of 70.7 years [64.3,76.4] of which 1850 (56.5 %) were male. dMMR CRC was present in 592 patients (18.1 %), with loss of MLH1/PMS2 being most common. The risk of dMMR CRC was significantly higher in females OR 3.47 [2.87;4.20]. When adjusting for age, SP subtype, conventional adenomas (CA), anatomical location and lifestyle factors, female sex remained the strongest predictor OR 2.84 [2.27;3.56]. The presence of sessile serrated lesions with or without dysplasia was related to higher risk OR 1.60 [1.11;2.31] and OR 1.42 [1.11;1.82] respectively, while conventional adenomas constituted a lower risk OR 0.68 [0.55;0.84].
CONCLUSIONS: In conclusion we found several predictors of whom female sex had the strongest correlation with dMMR CRC in patients with SP.

BACKGROUND: The optimal interval of colonoscopy (CS) surveillance in cases with Lynch syndrome (LS), and stratification according to the causative mismatch repair gene mutation, has received much attention. To verify a feasible and effective CS surveillance strategy, we investigated the colorectal cancer (CRC) incidence at different intervals and the characteristics of precancerous colorectal lesions of LS cases.
METHODS: This retrospective multicenter study was conducted in Japan. CRCs and advanced adenomas (AAs) in 316 LS cases with germline pathogenic variants (path_) were analyzed according to the data of 1,756 registered CS.
RESULTS: The mean time interval for advanced CRCs (ACs) detected via CS surveillance was 28.7 months (95% confidence interval: 13.8-43.5). The rate of AC detection within (2.1%) and beyond 2 years (8.7%) differed significantly (p = 0.0003). AAs accounted for 43%, 46%, and 41% of lesions < 10 mm in size in the MLH1-, MSH2-, and MSH6-groups, respectively. The lifetime incidence of metachronous CRCs requiring intestinal resection for path_MLH1, path_MSH2, and path_MSH6 cases was 34%, 23%, and 14% in these cases, respectively. The cumulative CRC incidence showed a trend towards a 10-year delay for path_MSH6 cases as compared with that for path_MLH1 and path_MSH2 cases.
CONCLUSIONS: In cases with path_MLH1, path_MSH2, and path_MSH6, maintaining an appropriate CS surveillance interval of within 2 years is advisable to detect of the colorectal lesion amenable to endoscopic treatment. path_MSH6 cases could be stratified with path_MLH1 and MSH2 cases in terms of risk of metachronous CRC and age of onset.

BACKGROUND: Breast cancer, particularly triple-negative breast cancer (TNBC), poses a significant global health burden. Chemotherapy was the mainstay treatment for TNBC patients until immunotherapy was introduced. Studies indicate a noteworthy prevalence (0.2% to 18.6%) of mismatch repair protein (MMRP) deficiency in TNBC, with recent research highlighting the potential of immunotherapy for MMRP-deficient metastatic breast cancer. This study aims to identify MMRP deficiency in TNBC patients using immunohistochemistry.
METHODS: A retrospective cohort study design was used and included TNBC patients treated between 2015 and 2021 at King Hussein Cancer Center. Immunohistochemistry was conducted to assess MMRP expression.
RESULTS: Among 152 patients, 14 (9.2%) exhibited deficient MMR (dMMR). Loss of PMS2 expression was observed in 13 patients, 5 of whom showed loss of MLH1 expression. Loss of MSH6 and MSH2 expression was observed in one patient. The median follow-up duration was 44 (3-102) months. Despite the higher survival rate (80.8%, 5 years) of dMMR patients than of proficient MMR patients (62.3%), overall survival did not significantly differ between the two groups.
CONCLUSIONS: Approximately 9% of TNBC patients exhibit dMMR. dMMR could be used to predict outcomes and identify patients with TNBC who may benefit from immunotherapy.