Mismatch repair protein deficiency assessed by immunohistochemistry in sporadic colorectal carcinoma

Context: Globally, colorectal carcinoma (CRC) ranks the third most commonly diagnosed malignant disease, one of the leading causes of cancer deaths. Aims: To study the spectrum of clinicopathological characteristics of sporadic colorectal carcinoma and to assess mismatch repair gene deficiency by the expression pattern of the proteins assessed by immunohistochemistry. Setting and Design: Observational study conducted in a tertiary care hospital in West Bengal. Materials and Methods: Fifty-two surgically resected specimens of CRC received from January 2018 to May 2019 were studied for clinical, morphological, MSI status. Statistical Analysis Used: IBM SPSS 23. Results: A total of 50% of the cases belonged to younger and 50% to the older population, with male predominance being 53.8%. The most common histologic type was adenocarcinoma (88.5%). The majority was found to be well-differentiated carcinoma (50%). The majority cases were of the T3 stage accounting to 38.5%. A total of 24 out of 52 cases (46.15%) had an absent expression of at least one mismatch repair (MMR) protein. A significant correlation was found between the young age group and microsatellite instability (MSI) with a P value of 0.001. A significant association was found between MSI and tumor differentiation with P value of 0.018. A significant association was found between MSH6 and histological type with P value of 0.012. A significant association was found between MSI and tumor stage with P value of 0.032. Conclusions: This study shows a significantly higher number of sporadic colon cancers involving the young age group, and younger cases showed significant association with MSI. This alarming trend needs validation by studies involving larger populations and can be helpful prognostically as well as in formulating chemotherapeutic regimens.

Predictive value of multimodal magnetic resonance imaging based radiomics model for micro-satellite instability of rectal cancer / 中华消化外科杂志

Objective:To investigate the predictive value of multimodal magnetic resonance imaging (MRI) based radiomics model for microsatellite instability (MSI) of rectal cancer.Methods:The retrospective cohort study was conducted. The clinicopathological data of 117 patients with rectal cancer who were admitted to 2 medical centers, including 74 in Ningbo Urology & Nephrology Hospital and 43 in the First Affiliated Hospital of Zhejiang University School of Medicine, from January 2020 to December 2022 were collected. There were 73 males and 44 females, aged (63±5)years. Based on random number table, all 117 patients were divided into the training dataset of 70 cases and the test dataset of 47 cases with a ratio of 7:3. All patients underwent pelvic MRI exami-nation. Observation indicators: (1) construction of radiomics prediction model and analysis of charac-teristics; (2) analysis of factors influencing MSI of rectal cancer in the training dataset; (3) construc-tion and evaluation of the prediction model for MSI of rectal cancer. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was conducted using the t test. Measurement data with skewed distribution were represented as M( Q1, Q3), and compari-son between groups was conducted using the Mann-Whitney U test. Count data were described as absolute numbers, and comparison between groups was conducted using the chi-square test. Univariate analysis was conducted using the one way ANOVA and multivariate analysis was conducted using the Logistic regression model with forward method. The receiver operating characteristic curve was drawn, and the area under the curve (AUC), decision curve, calibration curve and Delong test were used to evaluate the predictive ability of prediction model. Results:(1) Construction of radiomics prediction model and analysis of characteristics. Five thousand five hundred and eighty radiomics features were finally extracted from the 117 patients. Based on the feature selection using the maximum correlation minimum redundancy method, and the least absolute shrinkage and selection operator fitting algorithm, 9 radiomics features were finally selected. The radiomics prediction model was constructed based on calculation of the radiomics score. (2) Analysis of factors influencing MSI of rectal cancer in the training dataset. Results of multivariate analysis showed that platelet count was an independent influencing factor for MSI of rectal cancer [ odds ratio=1.13, 95% confidence interval ( CI) as 1.06-1.21, P<0.05]. (3) Construction and evaluation of the prediction model for MSI of rectal cancer. The clinical prediction model and clinical-radiomics combined prediction model were constructed based on the results of multivariate analysis. The AUC of clinical prediction model, radiomics prediction model, clinical-radiomics combined prediction model in the training dataset was 0.94 (95% CI as 0.86-0.98), 0.96 (95% CI as 0.88-0.99), 0.99 (95% CI as 0.93-1.00), respectively, with the sensitivity and specificity as 90.7%, 91.2%, 96.9% and 85.0%, 88.9%, 94.3%. Results of Delong test showed that there was a significant difference in the predictive performance between the clinical-radiomics combined prediction model and the clinical prediction model ( Z=2.20, P<0.05), and there was no significant difference between the radiomics prediction model and the clinical-radiomics combined prediction model or the clinical prediction model ( Z=1.94, 0.60, P>0.05). The AUC of clinical prediction model, radiomics prediction model, clinical-radiomics combined prediction model in the test dataset was 0.97 (95% CI as 0.88-1.00), 0.86 (95% CI as 0.73-0.95), 0.97(95% CI as 0.87-1.00), respectively, with the sensitivity and specificity as 99.3%, 95.8%, 99.3% and 85.7%, 73.9%, 90.5%. Results of Delong test showed that there was a significant difference in the predictive performance between the clinical-radiomics combined prediction model and the radiomics prediction model ( Z=2.21, P<0.05), and there was no significant difference between the clinical prediction model and the clinical-radiomics combined prediction model or the radiomics prediction model ( Z=0.17, 1.82, P>0.05). Results of calibration curve showed that clinical prediction model, radiomics prediction model, clinical-radiomics combined prediction model had good ability in predicting the MSI status of rectal cancer. Results of decision curve showed that compared to clinical prediction model and radiomics prediction model, clinical-radiomics combined prediction model had greatest net gain in predicting the MSI of rectal cancer. Conclusion:The prediction model based on 9 radiomics features after selecting can effectively predict the MSI status of rectal cancer, and the clinical-radiomics combined prediction model has a better prediction efficiency.

Application and challenge of microsatellite instability detection in colorectal cancer / 中华消化外科杂志

Colorectal cancer (CRC) is one of the most common gastrointestinal cancers. The incidence and mortality of CRC are still rising in China. It is of great importance to explore the molecular mechanisms of the development and progression of CRC. Microsatellites are short tandem repeats that are distributed throughout the genome. Detection of microsatellite instability (MSI) is of great value in the diagnosis and treatment of CRC. MSI detection is an important method for Lynch syndrome screening. For patients with stage Ⅱ CRC, MSI status is an influencing factor for post-operative recurrence and an important reference for adjuvant therapy. For patients with stage Ⅳ CRC, MSI status is an important indicator for screening potential patients suitable for treatment of immune checkpoint inhibitors. However, there are still problems concerning the application of MSI. The detection methods of MSI have not been fully unified. The requirement of MSI detection in CRC patients are universal but not precise. MSI is not a valid predictor for the prognosis of CRC patients, and it could not effectively predict the efficacy of chemotherapy and immunotherapy. Moreover, with the application of other molecular markers, such as programmed death-1, programmed death-ligand 1, tumor mutation burden and immunoscore, the value of MSI in CRC is being challenged and remains to be unveiled with more studies. The authors investigate the problems in MSI detection and application, in order to provide reference for clinical practice.

'Oasis' in 'death desert': attach importance to the diagnosis and treatment for pancreatic cancer with microsatellite instability-high/deficient mismatch repair / 中华消化外科杂志

Pancreatic cancer (PC) is a malignant digestive tract tumor with poor prognosis. Most of patients with PC are insensitive to traditional strategies of chemotherapy, targeted therapy and immunotherapy. PC with microsatellite instability-high/deficient mismatch repair (MSI-H/dMMR) is rare in clinic, which has distinctive clinicopathological characteristics and better prognosis from conventional PC. Reasonable acquisition of pancreatic tumor biopsy and accurate assessment of MSI-H/dMMR status are helpful for accurate diagnosis of such patients. Individualized treatment strategy based on immunotherapy can significantly improve the prognosis of patients with MSI-H/dMMR PC. Based on relevant literatures of domestic and foreign, the authors discuss the current status and research hotspots of diagnosis and treatment for MSI-H/dMMR PC.

Analysis of microsatellite instability in endometrial cancer: The significance of minimal microsatellite shift / 北京大学学报(医学版)

OBJECTIVE@#To analyze the differences and characteristics of microsatellite instability (MSI) in endometrial cancer (EMC), by using colorectal cancer (CRC) as control.@*METHODS@#In the study, 228 cases of EMC were collected. For comparative analysis, 770 cases of CRC were collected. Mismatch repair (MMR) expression was detected by immunohistochemistry (IHC), and microsatellite instability (MSI) was analyzed by PCR and capillary electrophoresis fragment analysis (MSI-PCR). MSI-PCR was detected using five mononucleotide repeat markers: BAT-25, BAT-26, NR-21, NR-24, and MONO-27.@*RESULTS@#In EMC, we found 27.19% (62/228) of deficient mismatch repair (dMMR) using IHC, significantly higher than CRC (7.79%, 60/770). Meanwhile, subclonal expression of MMR protein was found in 4 cases of dMMR-EMC and 2 cases of dMMR-CRC. According to the criteria of major micro-satellite shift, we found 16.23% (37/228) of MSI-high (MSI-H), 2.63% (6/228) of MSI-low (MSI-L), and 81.14% (185/228) of microsatellite stability (MSS) in EMC using MSI-PCR. The discor-dance rate between MMR-IHC and MSI-PCR in EMC was 11.84% (27/228). In CRC, we found 8.05% (62/770) of MSI-H, 0.13% (1/770) of MSI-L, and 91.82% (707/770) of MSS. The discordance rate between MMR-IHC and MSI-PCR in CRC was only 0.52% (4/770). However, according to the criteria of minimal microsatellite shift, 12 cases of EMC showed minimal microsatellite shift including 8 cases of dMMR/MSS and 4 cases of dMMR/MSI-L and these cases were ultimately evaluated as dMMR/MSI-H. Then, 21.49% (49/228) of EMC showed MSI-H and the discordance rate MMR-IHC and MSI-PCR in EMC decreased to 6.58% (15/228). No minimal microsatellite shift was found in CRC. Compared with EMC group with major microsatellite shift, cases with minimal microsatellite shift showed younger age, better tumor differentiation, and earlier International Federation of Gynecology and Obstetrics (FIGO) stage. There were significant differences in histological variant and FIGO stage between the two groups (P < 0.001, P=0.006).@*CONCLUSION@#EMC was more prone to minimal microsatellite shift, which should not be ignored in the interpretation of MSI-PCR results. The combined detection of MMR-IHC and MSI-PCR is the most sensitive and specific method to capture MSI tumors.

Colorectal cancer: histopathological profile and prevalence of dna repair system deficiency in patients submitted to surgical treatment in a university hospital / Câncer colorretal: perfil histopatológico e prevalência da deficiência do sistema de reparação do dna em pacientes submetidos a tratamento cirúrgico em um hospital universitário

ABSTRACT BACKGROUND: Part of colorectal cancer cases occurs due to modifications in the DNA mismatch repair system, which are responsible for microsatellite instability. This alteration results in an unconventional phenotypic pattern of colorectal cancer. AIMS: To describe the epidemiological, histopathological and molecular profiles of patients with colorectal cancer who underwent surgical treatment in a reference hospital. METHODS: This is a cross-sectional, retrospective study with a quantitative approach, that included a review of patients' medical records who underwent oncological surgery for colorectal cancer. RESULTS: A total of 122 colorectal cancer cases were identified, with microsatellite instability detected in 8.2% of the sample. The gender distribution was similar, with 52.46% males, and the weighted average age was 63 years (standard deviation±11.65). However, in the microsatellite instability group, the predominant age was below 60 years. Regarding the histological type, adenocarcinoma not otherwise specified accounted for 80.33% of the cases, being the most prevalent in both groups, with the mucinous type being more frequent among the instability cases. The pT3 pathological staging (46.72%) was the most predominant. The topography was more prevalent on the left (60.66%), but there was a significant difference when compared to the group with microsatellite instability, in which 80% of the neoplasms were located on the right (p=0.006). CONCLUSIONS: Differences in age and neoplastic topography found in microsatellite instability samples highlight the distinctive presentation pattern of the disease. Recognizing these characteristics is essential for developing prevention strategies, in addition to early and accurate diagnosis of colorectal cancer.

RESUMO RACIONAL: Parte dos casos de câncer colorretal ocorre devido a alterações nas enzimas de reparo do DNA, responsáveis pela instabilidade de microssatélites. Esta alteração resulta em um padrão fenotípico não convencional de câncer colorretal. OBJETIVOS: Descrever os aspectos epidemiológicos, histopatológicos e moleculares dos pacientes com câncer colorretal submetidos a tratamento cirúrgico em hospital de referência. MÉTODOS: Trata-se de um estudo transversal, retrospectivo com abordagem quantitativa, com revisão de prontuários médicos de pacientes submetidos a cirurgia oncológica por câncer colorretal. RESULTADOS: Foram registrados 122 casos de câncer colorretal, com instabilidade de microssatélites detectada em 8,2% da amostra. A distribuição por sexo foi semelhante, sendo 52,46% do sexo masculino, e média ponderada de idade de 63 anos (±11,65), contudo no grupo com instabilidade, a faixa etária predominante foi abaixo de 60 anos. Em relação ao tipo histológico, o adenocarcinoma sem outra especificação representou 80,33% dos casos, sendo o mais prevalente em ambos os grupos, mas com maior frequência do tipo mucinoso em caso de instabilidade. O estadiamento patológico pT3 (46,72%) foi predominante. A topografia da neoplasia foi mais prevalente à esquerda (60,66%), mas houve diferença significativa em relação ao grupo com instabilidade de microssatélites, no qual 80% das neoplasias localizavam-se à direita (p=0,006019). CONCLUSÕES: As diferenças de idade e topografia neoplásica encontradas nas amostras com instabilidade de microssatélites destacam o padrão não habitual de apresentação da doença. O conhecimento, portanto, dessas distinções é necessário para o desenvolvimento de estratégias de prevenção, além de diagnóstico precoce e preciso do câncer colorretal.

Microsatellite instability and its relationship with clinicopathological characteristics of patients with endometrial carcinoma / 肿瘤研究与临床

Objective:To explore the status of microsatellite instability (MSI) and its relationship with clinicopathological characteristics of patients with endometrial carcinoma.Methods:The clinical data of 365 patients with endometrial carcinoma who received surgery in Shanxi Province Cancer Hospital between January 2020 and December 2021 were retrospectively analyzed. Immunohistochemistry was used to detect the expressions of 4 DNA mismatch repair (MMR) proteins (MLH1, MSH2, MHS6, and PMS2), estrogen receptor (ER), progesterone receptor (PR), and p53 mutant protein in postoperative cancer tissue samples from 365 patients with endometrial carcinoma. All patients were divided into MSI group (1 or more non-expression of MMR protein) and microsatellite stability (MSS) group (4 proteins were all expressed), and the clinicopathological characteristics of patients in both groups were compared. φ efficient was used to analyze the correlation of MSI with ER, PR, p53 mutant protein expressions. Results:There were 72 cases (19.7%) in MSI group and 293 cases (80.3%) in MSS group; and the age of all patients was (53±19) years (21-83 years). There were statistically significant differences in the proportion of MSI patients in endometrial carcinoma patients with different age [>50 years vs. ≤50 years: 22.1% (61/276) vs. 12.4% (11/89)], tumor diameter [≤2 cm vs. > 2 cm: 25.9% (30/116) vs. 16.8% (42/249)], International Federation of Gynecology and Obstetrics (FIGO) staging [stage Ⅲ-Ⅳ vs. stage Ⅰ-Ⅱ: 31.1% (14/45) vs. 18.1% (58/320)], histological type [type Ⅰ vs. type Ⅱ: 21.7% (71/327) vs. 2.6% (1/38)] (all P < 0.05). There were no statistically significant differences in the proportion of MSI patients with different depth of invasion, degree of differentiation, lymph node metastasis, vascular involvement, and lesion location (all P > 0.05). Among 327 cases of type Ⅰendometrial carcinoma, 1 case was mucinous adenocarcinoma (MSS status), and the other 326 cases were endometrioid adenocarcinoma. Of the 72 patients with MSI, 71 cases were endometrioid carcinoma and the other was 1 of 3 mixed carcinomas in type Ⅱ endometrial carcinoma. There was a negative correlation between MSI and mutant p53 ( φ coefficient was -0.11, P = 0.031), and φ coefficient of the correlation of MSI with ER and PR was -0.03 and -0.06, while there were no statistically significant differences ( P value was 0.578 and 0.255, respectively). Conclusions:Endometrioid adenocarcinoma is the main type of endometrial cancer patients with MSI. MSI in endometrial cancer is correlated with age, FIGO staging, tumor diameter and histological type of patients, while negatively correlated with mutant p53.

Correlation of gene mutations and microsatellite instability in colorectal cancer tissues with clinicopathological features of patients / 肿瘤研究与临床

Objective:To explore KRAS, NRAS, BRAF gene mutations and microsatellite instability(MSI) in colorectal cancer tissues as well as their correlation with the clinicopathological characteristics of patients.Methods:The clinicopathological data of 473 colorectal cancer patients in Shanxi Province Cancer Hospital from October 2020 to May 2021 were retrospectively analyzed. The mutation status of KRAS, NRAS and BRAF gene in the paraffin tissues were detected by using amplification refractory mutation system (ARMS) method. Polymerase chain reaction (PCR)-capillary electrophoresis was used to analyze MSI status, and the correlation of the clinicopathological characteristics of patients with gene mutations and MSI status was analyzed.Results:The mutation rates of KRAS, NRAS and BRAF were 45.03% (213/473), 2.96% (14/473) and 5.50% (26/473), respectively in 473 patients with colorectal cancer. No case harbored both 2 gene mutations was detected. The mutation rate of KRAS gene in well differentiated adenocarcinoma was higher than that in poorly differentiated adenocarcinoma [47.4% (175/369) vs. 36.5% (38/104), χ2 = 3.89, P = 0.049]. NRAS mutation rate in female was higher than that in male [5.0% (10/202) vs. 1.5% (4/271), χ2 = 4.86, P = 0.027], and the NRAS mutation rate in patients with tumor diameter ≤ 3 cm was higher than that in those with tumor diameter >3 cm [7.1% (7/98) vs. 1.9% (7/375), P = 0.013]. BRAF mutation rate of tumors located in colon was higher than that in rectum [11.7% (20/171) vs.2.0% (6/302), χ2 = 19.81, P < 0.001]; BRAF mutation rate in poorly differentiated tumor was higher than that in well differentiated tumor [10.6% (11/104) vs. 4.1% (15/369), χ2 = 6.62, P = 0.010]; BRAF mutation rate in patients with mucus was higher than that in those without mucus [10.9% (11/101) vs. 4.0% (15/372), χ2 = 7.19, P = 0.007]; BRAF mutation rate in patients with lymphatic metastasis was higher than that in patients without lymphatic metastasis [8.2% (15/182) vs.3.8% (11/291), χ2 = 4.29, P = 0.038]. The incidence of high frequency MSI (MSI-H) in 473 colorectal cancer tissues was 7.19% (34/473). The incidence of MSI-H in colon was higher than that in rectum [14.0% (24/171) vs. 3.3% (10/302), χ2 = 18.82, P < 0.001]; the incidence of MSI-H in patient with poor differentiated tumor was higher than that in those with well differentiated tumor [17.3% (18/104) vs. 4.3% (16/369), χ2 = 20.46, P < 0.001]; the incidence of MSI-H in patients with mucus was higher than that in those without mucus [11.9% (12/101) vs. 5.9% (22/372), χ2 = 4.24, P = 0.039]; and the incidence of MSI-H in patients without lymphatic metastasis was higher than that in patients with lymphatic metastasis [10.0% (29/291) vs. 2.7% (5/182), χ2 = 8.75, P = 0.003]. In addition, the incidence of MSI-H was on the rise in patients with BRAF mutation ( P < 0.001). Conclusions:KRAS, NRAS, BRAF gene mutations and MSI status are correlated with the clinicopathological characteristics of patients with colorectal cancer; there is a close relationship between MSI-H and BRAF mutation.

Association of microsatellite instability with clinicopathological features and prognosis of colon cancer patients / 中华普通外科杂志

Objective:To investigate the relationship between microsatellite instability (MSI) , and clinicopathological features ,prognosis in patients with stage Ⅱ and Ⅲ colon cancer.Methods:Patients undergoing surgical resection for stage Ⅱ and Ⅲ colonic tumor in the Affiliated Hospital of Qingdao University from Dec 2016 to Nov 2018 were enrolled. All the 292 patients were with stage Ⅱ and Ⅲ colon cancer and MSI status. Propensity score matching method was used to match the two groups of patients according to 1:1. χ 2 analysis, Logistic Regression and COX regression was used to analyse the relationship between MSI status, the clinicopathological features and prognosis. Results:The risk of MSI-H in young patients ( OR=0.340, 95% CI: 0.126~0.921, P=0.034), right-sided colon cancer ( OR=7.985, 95% CI: 3.040-20.973, P<0.001), mucinous adenocarcinoma ( OR=4.285, 95% CI: 1.495-12.284, P=0.007), poorer differentiation ( OR=4.848, 95% CI: 1.597-14.716, P=0.005), N0 staging ( OR=0.235 , 95% CI: 0.077-0.719, P=0.011) increased . The total OS of colon cancer patients in the MSS group (66.7%) and the MSI-H group (86.9%) were statistically different( P=0.003). The MSI status ( HR=0.367, 95% CI: 0.151-0.891, P=0.027) is an independent factor affecting the prognosis of patients. Conclusions:In stage Ⅱ and Ⅲ colon cancer, patients with MSI-H have a better prognosis. MSI status is prognosis relevant factor for colon cancer patients.

Caracterización molecular de pacientes con cáncer colorrectal / Molecular characterization of colorectal cancer patients

Introducción. El cáncer colorrectal tiene una alta incidencia en la población mundial. Diversas vías moleculares están involucradas en su desarrollo, entre ellas, la inestabilidad cromosómica, la inestabilidad microsatelital y la epigenética. Objetivo. Hacer la caracterización molecular de 44 individuos con cáncer colorrectal esporádico. Materiales y métodos. El análisis de mutaciones en los genes APC, KRAS, TP53 y BRAF se hizo mediante secuenciación de Sanger; la inestabilidad microsatelital se determinó mediante electroforesis capilar utilizando cinco marcadores de repetición corta en tándem (Short Tandem Repeat) y el estado de metilación del promotor del gen MLH1 se hizo con la técnica MS-PCR (Methylation-Specific PCR). Resultados. La frecuencia de mutación de los genes APC, KRAS y TP53 fue del 18,1, 25 y 4,5 %, respectivamente; las mutaciones detectadas se localizaron con mayor frecuencia en el colon derecho. La frecuencia de inestabilidad microsatelital fue del 27,2 % y el 73,1 % en los tumores con metilación en el gen MHL1, y el 91,6 % de los tumores con inestabilidad microsatelital presentaba metilación en el gen MLH1. En el grupo de tumores con estabilidad microsatelital, las mutaciones en los genes APC, KRAS y TP53 fueron más frecuentes que en el grupo de tumores con inestabilidad microsatelital. La metilación del gen MLH1 fue la alteración más predominante. Conclusiones. En los pacientes con cáncer colorrectal evaluados se demostró la presencia de alteraciones moleculares en las diferentes vías genéticas, las cuales son comunes en su carcinogénesis. Los pacientes presentaron un perfil de mutaciones diferente al de otras poblaciones. Los hallazgos obtenidos en este estudio confirman la heterogeneidad molecular descrita en el desarrollo del cáncer colorrectal.

Introduction: Colorectal cancer has a high incidence in the world population. Different molecular pathways, such as chromosomal instability, microsatellite instability, and epigenetics are involved in its development. Objective: To perform molecular characterization in 44 individuals with sporadic colorectal cancer. Materials and methods: We conducted mutation analyses of the APC, KRAS, TP53 y BRAF genes using Sanger sequencing techniques; microsatellite instability was determined by capillary electrophoresis with five STR genetic markers while the methylation status of the MHL1 promotor gene was analyzed using methylation-specific PCR. Results: APC, KRAS, and TP53 genes mutation frequency was 18.1%, 25%, and 4.5%, respectively; the somatic mutations detected were located more frequently in the right colon. The frequency of microsatellite instability was 27.2% and 73.1% of the tumors had the MHL1 gene methylated while 91.6% of microsatellite instability-positive tumors had the methylated MLH1 gene. The mutation profile of microsatellite stability tumors APC, KRAS, and TP53 genes was more frequent than in the microsatellite instability-positive tumors. The methylation of the MLH1 gene was the most predominant molecular alteration. Conclusions: We identified molecular alterations in different genetic pathways of the colorectal cancer patients evaluated, which are common in the carcinogenesis of this cancer. These patients showed a different mutational profile compared to other populations. Our findings confirm the molecular heterogeneity described in the development of colorectal cancer.

Evaluation of microsatellite instability in routine examinations of surgical samples

Context: Approximately 20%–30% of colon cancer cases have a hereditary basis. The genetic defect may involve mismatch repair (MMR) genes, which results in microsatellite instability (MSI). MMR-deficient colorectal cancer may occur due to germline mutation (Lynch syndrome) or be a sporadic one. A tumor's histological features, supported by a panel of immunohistochemistry stains, enables pathologists to assess the MMR status, which in turn has beneficial effects on clinical management. Aims: We aimed to show the relations between histopathological features identified during routine examinations and MMR genes' mutations. Methods and Material: We reviewed retrospectively the material of the Department of Pathology fulfilling the revised Bethesda Guidelines. Statistical Analysis Used: We used Chi-square test, Spearman test, and epidemiological analysis. Results: For the PMS2 gene, the positive predictive value (PPV) indicates that 91% of cases neither present any histological lesions nor have genetic abnormalities. The negative predictive value (NPV) indicates that only 50% of cases have both histological and genetic changes. For the MSH6 gene, the PPV indicates that 85% of tumors without specific histological features do not have genetic abnormalities. Conclusions: We advise universal staining for MLH1, MSH2, MSH6, and PMS2 in every newly diagnosed colon cancer, but due to costly analyses we suggest a protocol for the selection of cases for MMR examinations.

Evaluation of a new detection method for microsatellite instability and its relationship with the expression of human epidermal growth factor receptor 2 and P53 in gastric cancer tissues / 中华老年医学杂志

Objective:To investigate the expression of human epidermal growth factor receptor 2(HER2)and P53 and their relationship with microsatellite instability(MSI)in gastric cancer tissues.Methods:A total of 103 patients diagnosed with gastric cancer between January 2018 and October 2020 at Yueyang Hospital were enrolled in this study.HER2, P53 and mismatch repair proteins in gastric cancer tissues were detected with immunohistochemical(IHC)methods, and MSI screening was conducted at 7 sites with a new Idylla MSI(multiple fluorescent PCR)method.Results:Of 103 gastric cancer patients in this study, 77(74.8%)showed microsatellite stability(MSS)and 26(25.2%)showed MIS via IHC, and PCR also detected 77 MSS cases and 26 MSI cases.In MSI, there was more low HER2 expression than high HER2 expression, and the rate of low HER2 expression in MSI was higher than the rate of high HER2 expression in MSI( P<0.05).Also in MSI, there was more low P53 expression than high P53 expression, and the rate of low P53 expression in MSI was higher than the rate of high expression in MSI( P<0.05). Conclusions:MSS may exist in the process of gastric carcinogenesis and in gastric cancer it may be accompanied by low expression of HER2 and p53 in cancer tissues.There may be a mutually exclusive relationship between MSI and expressions of HER2 and p53, suggesting that carcinogenic mechanisms involving MSI may be very different from those involving HER2 and p53.MSI detection is very valuable in guiding treatment drug selection and prognosis assessment.

Research progress and safety of immune checkpoint inhibitors in the treatment of gastrointestinal neoplasms / 中国医师杂志

Gastrointestinal neoplasms is the most common digestive tract neoplasms, and its incidence rate is increasing year by year. Compared with other solid tumors, the application of immune checkpoint inhibitors in gastrointestinal neoplasms is still in the stage of continuous exploration. This paper intends to review the relevant research and latest progress of immune checkpoint inhibitors in advanced gastric cancer, mismatch repair function defect/microsatellite high instability and mismatch repair function integrity/microsatellite stability or microsatellite low instability, and further evaluate the effectiveness and safety of immunotherapy combined with relevant studies.

Immunotherapy for microsatellite-instability-high advanced colorectal cancer / 中华胃肠外科杂志

Microsatellite instability-high (MSI-H) colorectal cancer accounts for approximately 10%-15% of all colorectal cancer patients, while in metastatic diseases the MSI-H population accounts for only 5% of patients. Previous studies have shown that early-stage MSI-H colorectal cancer patients have a good prognosis, but those with advanced disease have a poor prognosis and are not sensitive to chemotherapy. The advent of PD-1 antibodies has significantly improved the prognosis and changed treatment landscape in this population, not only achieving good outcomes in late-line therapy, but also significantly outperforming traditional chemotherapy combined with targeted therapy in first-line therapy. How to overcome primary and secondary drug resistance is a key issue in improving the outcome of MSI-H metastatic colorectal cancer, and commonly used approaches include changing chemotherapy regimens, combining with other immunotherapies, combining with anti-angiogenesis, and local treatments (surgery, radiotherapy, or interventional therapy). It is worth noting that immunotherapy has certain lifelong or even lethal toxicity, and the indications for neoadjuvant immunotherapy must be evaluated with caution. Neoadjuvant immunotherapy in MSI-H advantaged population can achieve high rates of pathological complete remission (pCR) and clinical complete remission (cCR). Therefore, for MSI-H patients with a strong intention to preserve anal sphincter and a strict evaluation of cCR after neoadjuvant immunotherapy, the Watch-and-Wait strategy offers an opportunity to preserve sphincter function and improve long-term survival quality in a subset of mid-to-low rectal cancers. Research on adjuvant immunotherapy in the field of colorectal cancer is also in full swing, and the results are worth waiting for.

Presencia de inestabilidad microsatélite en pacientes colombianos con adenocarcinoma colorrectal / Microsatellite instability in Colombian patients with colorectal adenocarcinoma

Resumen Introducción y objetivos: la vía de inestabilidad de microsatélites (IMS) está implicada en la carcinogénesis de un 15 % de carcinomas colorrectales (CCR). La detección de esta alteración tiene relevancia en el pronóstico y en el tratamiento de los pacientes con CCR. El objetivo del presente estudio es determinar la prevalencia de IMS en CCR en una cohorte de pacientes de Bogotá, Colombia. Materiales y métodos: se evaluó por inmunohistoquímica la presencia de homólogo MutL 1 (MLH1), segregación posmeiótica aumentada 2 (PMS2), homólogo mutS 2 (MSH2) y homólogo mutS 6 (MSH6) en muestras de CCR prevenientes de colectomías. Adicionalmente, se analizaron las variables clinicopatológicas. A los casos con pérdida de MLH1 y PMS2 se les evaluó la mutación del gen BRAF. Resultados: en total se incluyeron 86 casos. La mediana de edad de los pacientes con CCR fue de 69 años, 52,3 % fueron hombres. De los pacientes con CCR, 12 (13,9 %) presentaron IMS, de los cuales 10 (83,3 %) tenían ausencia de expresión MLH1/PMS2 y 2 (16,7 %), de MSH2/MSH6. La mediana de edad de los pacientes con CCR e IMS fue de 52 años (45-76,5), 9 eran hombres y el 66,7 % de estos casos se localizaron en el colon derecho. El tipo histológico más frecuente fue adenocarcinoma moderadamente diferenciado (67 %). Los linfocitos infiltrantes al tumor fueron observados en el 83 %, la presencia de infiltrado de tipo Crohn estaba presente en el 42 %. La mutación de BRAF se observó en el 30 % de los pacientes con pérdida de MLH1 y PMS2. Conclusión: la prevalencia de la IMS en nuestra población fue de 14 %, datos similares a los observados en la población norteamericana y europea. Sin embargo, se observa que el 83 % presentó pérdida de expresión del complejo MLH1/PMS2, una prevalencia mayor comparada con otras poblaciones.

Abstract Introduction: The microsatellite instability (MSI) pathway is involved in the carcinogenesis of 15% of colorectal carcinomas (CRC). The detection of this alteration is relevant for the prognosis and treatment of CRC patients. Objective: The aim of this study is to determine the prevalence of MSI in CRC in a cohort of patients in Bogotá, Colombia. Materials and methods: The presence of MLH1, PMS2, MSH2, and MSH6 was evaluated by immunohistochemistry in CRC samples collected during colectomy. Clinicopathological variables were analyzed as well. Cases with loss of MLH1 and PMS2 were evaluated for BRAF gene mutation. Results: A total of 86 cases were included. The median age was 69 years, 52.3% were male. 12 (13.9%) patients had IMS, 10 (83.3%) had absence of MLH1/PMS2 expression and 2 (16.7%) absence of MSH2/MSH6 expression. The median age of patients with IMS was 52 years (45-76.5), of which 9 were male. 66.7% of carcinomas were located in the right colon and the most frequent histological type was moderately differentiated adenocarcinoma (67%). Tumor infiltrating lymphocytes were observed in 83% of the cases, while the presence of Crohn's-like infiltrate was present in 42%. BRAF mutation was observed in 30% of patients with loss of MLH1 and PMS2. Conclusion: The prevalence of IMS in our population was 14%, similar to the data observed in the North American and European populations. However, we observed that 83% had loss of expression of the MLH1/PMS2 complex, a higher prevalence compared to other populations.

Inestabilidad microsatelital y cáncer gástrico / Microsatellite instability and gastric cancer

La inestabilidad microsatelital es causada por una alteración de los sistemas de reparación de apareamiento incorrecto, que puede afectar los microsatélites dentro de todo el genoma humano, produciendo errores en su replicación. Los estudios publicados, principalmente en la literatura inglesa, han encontrado que algunos tumores, como los gástricos, pueden expresar inestabilidad microsatelital. En la siguiente revisión de tema, se presenta una descripción de los sistemas de reparación de apareamientos incorrectos y su relación con la presencia de inestabilidad microsatelital en los tumores gástricos, así como su posible utilidad clínica, como factor asociado en la respuesta al tratamiento con inmunoterapia en los pacientes con dicha patología

Microsatellite instability is caused by an alteration of the mismatch repair systems, which can affect microsatellites within the entire human genome, causing errors in their replication. Published studies, mainly in the English literature, have found that some tumors, such as gastric ones, can express microsatellite instability. In this review, a description of the mismatch repair systems and their relationship with the presence of microsatellite instability in gastric tumors is presented, as well as its possible clinical utility, as an associated factor in the response to immunotherapy treatment, in patients with gastric cancer

The association between the histopathological features and microsatellite instability in young patients with urothelial carcinoma of the bladder

SUMMARY OBJECTIVE: Bladder cancer under the age of 40 is extremely rare. Bladder cancer development involves complex and multi-stage processes, one of which is the DNA damage repair mechanism. In this retrospective study, we aimed to evaluate the histopathological features of bladder urothelial carcinoma seen in patients under 40 years of age and tumor microsatellite instability status using immunohistochemistry. METHODS: A total of 50 patients under the age of 40 with urothelial bladder carcinoma from two different centers in the same country were included. Expression of the mismatch repair proteins MLH1, MSH2, MSH6, and PMS2 was analyzed by immunohistochemistry. RESULTS: Age at the time of diagnosis ranged from 17 to 40 years old. Most tumors were non-invasive papillary urothelial carcinoma. Two cases had nuclear loss of MSH-6 and PMS-2. We observed that tumor grade, tumor stage, presence of tumor differentiation, and infiltrative growth pattern of the tumor have significant impact on prognosis, but microsatellite instability does not have an effective role in bladder carcinogenesis in young patients. CONCLUSIONS: Our results indicate that the presence of microsatellite instability is not related to the low tumor grade and stage in urothelial neoplasms in young patients, suggesting that urothelial carcinoma of the bladder in young patients may represent a genetically stable form of neoplasia.

Analysis of Siewert classification, microsatellite instability and HER2 expression in 242 cases of adenocarcinoma of esophagogastric junction / 国际外科学杂志

Objective:To explore the characteristics of Siewert classification and microsatellite instability(MSI) and HER2 expression in adenocarcinoma of esophagogastric junction (AEG).Methods:The clinicopathological data of gastric adenocarcinoma from May 2019 to November 2020 were retrospectively analyzed. The patients were divided into two groups: AEG group and non AEG group. The composition ratio of Siewert type of AEG was counted, and the relationship between tumor size and Siewert type was analyzed. The MSI status and HER2 expression status of AEG and non AEG were statistically compared. The measurement data of normal distribution were expressed as mean ± standard deviation( Mean± SD), the comparison between groups were by t test, the comparison of count data between groups were by Chi-square test. Results:A total of 328 consecutive cases of gastric adenocarcinoma were collected, including 242 cases of AEG and 86 cases of non AEG. The Siewert classification of AEG was mainly type Ⅱ (151 cases, 62.40%), followed by type Ⅲ (86 cases, 35.54%) and type Ⅰ (5 cases, 2.07%). The analysis of the relationship between the size of the tumor length and the number of Siewert type showed that the number of Siewert type Ⅱ cases decreased and the number of Siewert type Ⅲ cases increased with the increase of the tumor size. MSI status was detected non selectively in 192 cases of gastric adenocarcinoma (140 cases of AEG and 52 cases of non AEG). There were 12 cases of MSI (6.25%), 2 cases of MSI-H (1.04%) and 10 cases of MSI-L (5.21%). There was no significant difference in MSI ratio between AEG group and non AEG group ( P>0.05). All MSI cases were negative or weakly positive for PMS2. The expression of HER2 was detected by immunohistochemistry in 313 cases of gastric adenocarcinoma, except 15 cases of PTIS/T1a. There were 30 cases (9.58%) with HER2 expression 3+ . Thirty-two cases (10.22%) expressed HER2 (2+ ), of which 7 cases were detected by fluorescence in situ hybridization (FISH), and 3 cases were positive. The proportion of HER2 (3+ ) in AEG was significantly higher than that in non AEG group ( P<0.05). Conclusions:The main type of AEG was Siewert type Ⅱ. AEG may mostly occur between 1 cm above the esophagogastric junction and 2 cm below the esophagogastric junction; For endoscopic screening of early AEG, more attention should be paid to this area of stomach. Siewert type Ⅲ may be derived from the development of Siewert type Ⅱ. The incidence of microsatellite instability in gastric cancer is low. Compared with other gastric adenocarcinoma, AEG has no specificity in MSI. The MSI of AEG was mainly the expression defect of PMS2. Compared with other gastric adenocarcinoma, there are more HER2 overexpression in AEG.

Research progress of MSI-CRC on anti-PD-1 therapy / 国际外科学杂志

The programmed cell death receptor 1 (PD-1) antibody has been used in the treatment of a variety of malignant tumors, in which colorectal cancer is considered immune " cold" tumor and is not sensitive to anti-PD-1 therapy. The molecular characteristics of mismatch repair deficient (dMMR)/high microsatellite instability (MSI-H) are important molecular markers for screening patients with immune checkpoint inhibitors therapy (ICIs). However, only some patients can benefit from ICIs treatment, and some patients even have disease progression. This article summarizes the research progress of anti-PD-1 immunotherapy of MSI-CRC in recent years, including the mechanisms of resistance, new efficacy biomarkers and treatment options, so as to provide ideas for expanding the application of immunotherapy in colorectal cancer.

Genome instability and lymphoma / 中南大学学报(医学版)

Lymphoma is one of the most common malignant tumor of the hematologic system. The genome instability is not only an important molecular basis for the development of lymphoma, but also has important value in the diagnosis and prognosis of lymphoma. There are 2 types of genome instability: Microsatellite instability (MSI/MIN) at gene level and chromosomal instability at chromosome level. Through the study on genes associated with lymphoma, the unstable genes associated with lymphoma could be found, meanwhile the mechanism of its occurrence and development of lymphoma could be explored, and the important basis of molecular biology could also be provided in the field of current hot lymphoma precision medical research.