Maternal ancestry and hematological cancer risk: case-control study in an Argentinean population.

Aim: We investigated the role of maternal ancestry in neoplastic hematological malignancies (HMs) risk in a population from Central Argentina. Materials & methods: We analyzed 125 cases with HMs and 310 controls from a public hospital, and a set of 202 colorectal, breast, lung, and hematologic cancer patients from a private hospital. Results: A decreased risk for HMs was associated with the Native American haplogroup B2 (odds ratio = 0.49; 95% CI: 0.25-0.92; p = 0.02). The sub-Saharan African parahaplogroup L was associated with higher susceptibility for disease (odds ratio = 3.10; 95% CI: 1.04-9.31; p = 0.043). Although the mean ancestral proportions in the total studied population was as published (61.7% Native American, 34.6% European and 3.7% African), an unequal distribution was observed between hospitals. Conclusion: We confirmed the tri-hybrid nature of the Argentinean population, with proportions varying within the country. Our finding supports the notion that associated haplogroup is population and cancer specific.

The colorectal cancer-associated faecal microbiome of developing countries resembles that of developed countries.

BACKGROUND: The incidence of colorectal cancer (CRC) is increasing in developing countries, yet limited research on the CRC- associated microbiota has been conducted in these areas, in part due to scarce resources, facilities, and the difficulty of fresh or frozen stool storage/transport. Here, we aimed (1) to establish a broad representation of diverse developing countries (Argentina, Chile, India, and Vietnam); (2) to validate a 'resource-light' sample-collection protocol translatable in these settings using guaiac faecal occult blood test (gFOBT) cards stored and, importantly, shipped internationally at room temperature; (3) to perform initial profiling of the collective CRC-associated microbiome of these developing countries; and (4) to compare this quantitatively with established CRC biomarkers from developed countries. METHODS: We assessed the effect of international storage and transport at room temperature by replicating gFOBT from five UK volunteers, storing two in the UK, and sending replicates to institutes in the four countries. Next, to determine the effect of prolonged UK storage, DNA extraction replicates for a subset of samples were performed up to 252 days apart. To profile the CRC-associated microbiome of developing countries, gFOBT were collected from 41 treatment-naïve CRC patients and 40 non-CRC controls from across the four institutes, and V4 16S rRNA gene sequencing was performed. Finally, we constructed a random forest (RF) model that was trained and tested against existing datasets from developed countries. RESULTS: The microbiome was stably assayed when samples were stored/transported at room temperature and after prolonged UK storage. Large-scale microbiome structure was separated by country and continent, with a smaller effect from CRC. Importantly, the RF model performed similarly to models trained using external datasets and identified similar taxa of importance (Parvimonas, Peptostreptococcus, Fusobacterium, Alistipes, and Escherichia). CONCLUSIONS: This study demonstrates that gFOBT, stored and transported at room temperature, represents a suitable method of faecal sample collection for amplicon-based microbiome biomarkers in developing countries and suggests a CRC-faecal microbiome association that is consistent between developed and developing countries.

Risk-reducing hysterectomy and bilateral salpingo-oophorectomy in female heterozygotes of pathogenic mismatch repair variants: a Prospective Lynch Syndrome Database report.

PURPOSE: To determine impact of risk-reducing hysterectomy and bilateral salpingo-oophorectomy (BSO) on gynecological cancer incidence and death in heterozygotes of pathogenic MMR (path_MMR) variants. METHODS: The Prospective Lynch Syndrome Database was used to investigate the effects of gynecological risk-reducing surgery (RRS) at different ages. RESULTS: Risk-reducing hysterectomy at 25 years of age prevents endometrial cancer before 50 years in 15%, 18%, 13%, and 0% of path_MLH1, path_MSH2, path_MSH6, and path_PMS2 heterozygotes and death in 2%, 2%, 1%, and 0%, respectively. Risk-reducing BSO at 25 years of age prevents ovarian cancer before 50 years in 6%, 11%, 2%, and 0% and death in 1%, 2%, 0%, and 0%, respectively. Risk-reducing hysterectomy at 40 years prevents endometrial cancer by 50 years in 13%, 16%, 11%, and 0% and death in 1%, 2%, 1%, and 0%, respectively. BSO at 40 years prevents ovarian cancer before 50 years in 4%, 8%, 0%, and 0%, and death in 1%, 1%, 0%, and 0%, respectively. CONCLUSION: Little benefit is gained by performing RRS before 40 years of age and premenopausal BSO in path_MSH6 and path_PMS2 heterozygotes has no measurable benefit for mortality. These findings may aid decision making for women with LS who are considering RRS.

Risk-Reducing Gynecological Surgery in Lynch Syndrome: Results of an International Survey from the Prospective Lynch Syndrome Database.

PURPOSE: To survey risk-reducing hysterectomy and bilateral salpingo-oophorectomy (BSO) practice and advice regarding hormone replacement therapy (HRT) in women with Lynch syndrome. METHODS: We conducted a survey in 31 contributing centers from the Prospective Lynch Syndrome Database (PLSD), which incorporates 18 countries worldwide. The survey covered local policies for risk-reducing hysterectomy and BSO in Lynch syndrome, the timing when these measures are offered, the involvement of stakeholders and advice regarding HRT. RESULTS: Risk-reducing hysterectomy and BSO are offered to path_MLH1 and path_MSH2 carriers in 20/21 (95%) contributing centers, to path_MSH6 carriers in 19/21 (91%) and to path_PMS2 carriers in 14/21 (67%). Regarding the involvement of stakeholders, there is global agreement (~90%) that risk-reducing surgery should be offered to women, and that this discussion may involve gynecologists, genetic counselors and/or medical geneticists. Prescription of estrogen-only HRT is offered by 15/21 (71%) centers to women of variable age range (35-55 years). CONCLUSIONS: Most centers offer risk-reducing gynecological surgery to carriers of path_MLH1, path_MSH2 and path_MSH6 variants but less so for path_PMS2 carriers. There is wide variation in how, when and to whom this is offered. The Manchester International Consensus Group developed recommendations to harmonize clinical practice across centers, but there is a clear need for more research.

MLH1 intronic variants mapping to + 5 position of splice donor sites lead to deleterious effects on RNA splicing.

Germline pathogenic variants in the DNA mismatch repair genes (MMR): MLH1, MSH2, MSH6, and PMS2, are causative of Lynch syndrome (LS). However, many of the variants mapping outside the invariant splice site positions (IVS ± 1, IVS ± 2) are classified as variants of unknown significance (VUS). Three such variants (MLH1 c.588+5G>C, c.588+5G>T and c.677+5G>A) were identified in 8 unrelated LS families from Argentina, Brazil and Chile. Herein, we collected clinical information on these families and performed segregation analysis and RNA splicing studies to assess the implication of these VUS in LS etiology. Pedigrees showed a clear pattern of variant co-segregation with colorectal cancer and/or other LS-associated malignancies. Tumors presented deficient expression of MLH1-PMS2 proteins in 7/7 of the LS families, and MSI-high status in 3/3 cases. Moreover, RNA analyses revealed that c.588+5G>C and c.588+5G>T induce skipping of exon 7 whereas c.677+5G>A causes skipping of exon 8. In sum, we report that the combined clinical findings in the families and the molecular studies provided the evidences needed to demonstrate that the three MLH1 variants are causative of LS and to classify c.588+5G>C and c.677+5G>A as class 5 (pathogenic), and c.588+5G>T as class 4 (likely-pathogenic). Our findings underline the importance of performing clinical and family analyses, as well as RNA splicing assays in order to determine the clinical significance of intronic variants, and contribute to the genetic counseling and clinical management of patients and their relatives.

Universal determination of microsatellite instability using BAT26 as a single marker in an Argentine colorectal cancer cohort.

Microsatellite instability (MSI) is a hallmark tool for Lynch syndrome (LS) screening and a prognostic marker for sporadic colorectal cancer (CRC). In regions with limited resources and scarce CRC molecular characterization as South America, the implementation of universal MSI screening is under debate for both its purposes. We sought to estimate the frequency of BAT26 in colorectal adenocarcinomas and to determine associated clinical and histological features. Consecutive patients from a CRC registry were included. BAT26 determination was performed in all cases; if instability was found, immunohistochemistry (IHC) and BRAF mutation analyses were done, as appropriate. Differences were assessed by chi-squared or Fisher's exact test, or by T test or Mann-Whitney. Multiple logistic regression was used to identify factors independently associated with BAT26-unstable tumors. We included 155 patients; mean age was 65.6 (SD 14.4) and 56.1% were male. The frequency of BAT26-unstable tumors was 22% (95% CI 15.7-29.3). Factors independently associated with BAT26-unstable tumors were right colon localization (OR 3.4, 95% CI 1.3-8.7), histological MSI features (OR 5.1, 95% CI 1.9-13.6) and Amsterdam criteria (OR 23.2, 95% CI 1.9-286.7). IHC was altered in 85.3% BAT26-unstable tumors and 70.6% lacked MLH1 expression; 47.8% of these harbored BRAF V600E mutation. We provide evidence to link the frequency of BAT26 to an increased diagnostic yield (up to 1.4-folds) of suspected LS cases in comparison to the revised Bethesda guidelines alone. In regions with limited resources, clinical and histological features associated with BAT26-unstable status could be useful to direct MSI screening in sporadic CRCs and may help guide clinical care and future research.

A survey of the clinicopathological and molecular characteristics of patients with suspected Lynch syndrome in Latin America.

BACKGROUND: Genetic counselling and testing for Lynch syndrome (LS) have recently been introduced in several Latin America countries. We aimed to characterize the clinical, molecular and mismatch repair (MMR) variants spectrum of patients with suspected LS in Latin America. METHODS: Eleven LS hereditary cancer registries and 34 published LS databases were used to identify unrelated families that fulfilled the Amsterdam II (AMSII) criteria and/or the Bethesda guidelines or suggestive of a dominant colorectal (CRC) inheritance syndrome. RESULTS: We performed a thorough investigation of 15 countries and identified 6 countries where germline genetic testing for LS is available and 3 countries where tumor testing is used in the LS diagnosis. The spectrum of pathogenic MMR variants included MLH1 up to 54%, MSH2 up to 43%, MSH6 up to 10%, PMS2 up to 3% and EPCAM up to 0.8%. The Latin America MMR spectrum is broad with a total of 220 different variants which 80% were private and 20% were recurrent. Frequent regions included exons 11 of MLH1 (15%), exon 3 and 7 of MSH2 (17 and 15%, respectively), exon 4 of MSH6 (65%), exons 11 and 13 of PMS2 (31% and 23%, respectively). Sixteen international founder variants in MLH1, MSH2 and MSH6 were identified and 41 (19%) variants have not previously been reported, thus representing novel genetic variants in the MMR genes. The AMSII criteria was the most used clinical criteria to identify pathogenic MMR carriers although microsatellite instability, immunohistochemistry and family history are still the primary methods in several countries where no genetic testing for LS is available yet. CONCLUSION: The Latin America LS pathogenic MMR variants spectrum included new variants, frequently altered genetic regions and potential founder effects, emphasizing the relevance implementing Lynch syndrome genetic testing and counseling in all of Latin America countries.