Testing for deficient mismatch repair and microsatellite instability : A focused update

Testing to detect mismatch repair deficiency (dMMR) and high-grade microsatellite instability (MSI-H) has become an integral part of the routine diagnostic workup for colorectal cancer (CRC). While MSI was initially considered to be a possible indicator of a hereditary disposition to cancer (Lynch syndrome, LS), today the prediction of the therapy response to immune checkpoint inhibitors (ICI) is in the foreground. Corresponding recommendations and testing algorithms are available for use in primary diagnosis (reviewed in: Rüschoff et al. 2021).Given the increasing importance for routine use and the expanding indication spectrum of ICI therapies for non-CRCs, such as endometrial, small intestinal, gastric, and biliary tract cancers, an updated review of dMMR/MSI testing is presented. The focus is on the challenges in the assessment of immunohistochemical stains and the value of PCR-based procedures, considering the expanded ICI indication spectrum. A practice-oriented flowchart for everyday diagnostic decision-making is provided that considers new data on the frequency and type of discordances between MMR-IHC and MSI-PCR findings, and the possible role of Next Generation Sequencing in clarifying them. Reference is made to the significance of systematic quality assurance measures (e.g., QuIP MSI portal and multicenter proficiency testing), including regular continued training and education.

[Testing deficient mismatch repair and microsatellite instability : A focused update. German version]

Testing to detect mismatch repair deficiency (dMMR) and high-grade microsatellite instability (MSI-H) has become an integral part of the routine diagnostic workup for colorectal cancer (CRC). While MSI was initially considered to be a possible indicator of a hereditary disposition to cancer (Lynch syndrome, LS), today the prediction of the therapy response to immune checkpoint inhibitors (ICI) is in the foreground. Corresponding recommendations and testing algorithms are available for use in primary diagnosis (reviewed in: Rüschoff et al. 2021).Given the increasing importance for routine use and the expanding indication spectrum of ICI therapies for non-CRCs, such as endometrial, small intestinal, gastric, and biliary tract cancers, an updated review of dMMR/MSI testing is presented. The focus is on the challenges in the assessment of immunohistochemical stains and the value of PCR-based procedures, considering the expanded ICI indication spectrum. A practice-oriented flowchart for everyday diagnostic decision-making is provided that considers new data on the frequency and type of discordances between MMR-IHC and MSI-PCR findings, and the possible role of Next Generation Sequencing in clarifying them. Reference is made to the significance of systematic quality assurance measures (e.g., QuIP MSI portal and multicenter proficiency testing), including regular continued training and education.

Predictive factors based on the health belief model on cancer screening behaviour in first degree relatives of patients with Lynch syndrome-associated colorectal cancer

Objectives

This study aimed to investigate colorectal cancer-related knowledge, health beliefs, and screening behaviour in first-degree relatives (FDRs) of patients with Lynch syndrome-associated colorectal cancer (CRC) and explore the predictive factors of screening behaviour based on a health belief model.

Methods

This cross-sectional study was conducted in the colorectal department of a Class A tertiary hospital in Guangzhou from December 2017 to December 2019. A total of 265 FDRs of 96 patients with Lynch syndrome-related CRC were selected. The study was conducted in the colorectal department of a tertiary cancer centre in Guangzhou. The demographic questionnaire, the simplified CRC knowledge questionnaire, and the Champion's Health Belief Model Scale were used for evaluation. Data were analyzed using statistical description, between-group comparisons, and binary logistic regression.

Results

A total of 160 (60.4%), 61 (23.0%), and 44 (16.6%) of the participants had high, medium, and low levels of knowledge about CRC, respectively; the average overall score of health belief was 121.36 ± 13.02. Sixty-one participants (23.0%) underwent Lynch syndrome-associated cancer screening. The predictive factors of screening behaviour included sex (male), age (older), married status (married), multiple primary cancers of the index patients, and high levels of knowledge and health beliefs (P < 0.05).

Conclusions

The knowledge and health beliefs of cancer and cancer screening in FDRs of patients with Lynch syndrome-associated CRC should be improved. Both knowledge and beliefs are critical in promoting their cancer screening behaviour. Interventions should focus on health education and enhance health beliefs of the FDRs for better screening behaviour.

[S3 guidelines on the diagnosis and treatment of carcinoma of the endometrium : Requirements for pathology]

The present article summarises the relevant aspects of the S3 guidelines on endometrioid carcinomas. The recommendations include the processing rules of fractional currettings as well as for hysterectomy specimens and lymph node resections (including sentinel lymph nodes). Besides practical aspects, the guidelines consider the needs of the clinicians for appropriate surgical and radiotherapeutic treatment of the patients. Carcinosarcomas are assigned to the endometrial carcinoma as a special variant. For the first time, an algorithmic approach for evaluation of the tumour tissue for Lynch syndrome is given. Prognostic factors based on morphologic findings are summarised.

Validation of Prediction Models for Mismatch Repair Gene Mutations in Koreans

PURPOSE

Lynch syndrome, the commonest hereditary colorectal cancer syndrome, is caused by germline mutations in mismatch repair (MMR) genes. Three recently developed prediction models for MMR gene mutations based on family history and clinical features (MMRPredict, PREMM(1,2,6), and MMRPro) have been validated only in Western countries. In this study, we propose validating these prediction models in the Korean population.

MATERIALS AND METHODS

We collected MMR gene analysis data from 188 individuals in the Korean Hereditary Tumor Registry. The probability of gene mutation was calculated using three prediction models, and the overall diagnostic value of each model compared using receiver operator characteristic (ROC) curves and area under the ROC curve (AUC). Quantitative test characteristics were calculated at sensitivities of 90%, 95%, and 98%.

RESULTS

Of the individuals analyzed, 101 satisfied Amsterdam criteria II, and 87 were suspected hereditary nonpolyposis colorectal cancer. MMR mutations were identified in 62 of the 188 subjects (33.0%). All three prediction models showed a poor predictive value of AUC (MMRPredict, 0.683; PREMM(1,2,6), 0.709; MMRPro, 0.590). Within the range of acceptable sensitivity (> 90%), PREMM(1,2,6) demonstrated higher specificity than the other models.

CONCLUSION

In the Korean population, overall predictive values of the three models (MMRPredict, PREMM(1,2,6), MMRPro) for MMR gene mutations are poor, compared with their performance in Western populations. A new prediction model is therefore required for the Korean population to detect MMR mutation carriers, reflecting ethnic differences in genotype-phenotype associations.

Clinicopathological Features and Type of Surgery for Lynch Syndrome: Changes during the Past Two Decades

Purpose

The Korean Hereditary Tumor Registry, the first and one of the largest registries of hereditary tumors in Korea, has registered about 500 families with hereditary cancer syndromes. This study evaluates the temporal changes in clinicopathologic features and surgical patterns of Lynch syndrome (LS) patients.

Materials and Methods

Data on 182 unrelated LS patients were collected retrospectively. The patients were divided into the period 1 group (registered in 1990-2004) and 2 (registered in 2005-2014). The clinical characteristics of the two groups were compared to identify changes over time.

Results

The period 1 group included 76 patients; the period 2 group, 106 patients. The mean ages at diagnosis were 45.1 years (range, 13 to 85 years) for group 1 and 49.7 years (range, 20 to 84 years) for group 2 (p=0.015). The TNM stage at diagnosis did not differ significantly—period 1 group: stage 0-I (n=18, 23.7%), II (n=37, 48.7%), III (n=19, 25.0%), and IV (n=2, 2.6%); period 2 group: stage 0-I (n=30, 28.3%), II (n=35, 33.0%), III (n=37, 34.9%), and IV (n=4, 3.8%). Extended resection was more frequently performed (55/76, 72.4%) in the period 1 group than period 2 (49/106, 46.2%) (p=0.001).

Conclusion

Colorectal cancer in patients with LS registered at the Korean Hereditary Tumor Registry is still diagnosed at an advanced stage, more than two decades after registry’s establishment. Segmental resection was more frequently performed in the past decade. A prompt nationwide effort to raise public awareness of hereditary colorectal cancer and to support hereditary cancer registries is required in Korea.