Targeted BRCA1/2 population screening among Ashkenazi Jewish individuals using a web-enabled medical model: An observational cohort study.

PURPOSE: This study aimed to evaluate uptake and follow-up using internet-assisted population genetic testing (GT) for BRCA1/2 Ashkenazi Jewish founder pathogenic variants (AJPVs). METHODS: Across 4 cities in the United States, from December 2017 to March 2020, individuals aged ≥25 years with ≥1 Ashkenazi Jewish grandparent were offered enrollment. Participants consented and enrolled online with chatbot and video education, underwent BRCA1/2 AJPV GT, and chose to receive results from their primary care provider (PCP) or study staff. Surveys were conducted at baseline, at 12 weeks, and annually for 5 years. RESULTS: A total of 5193 participants enrolled and 4109 (79.1%) were tested (median age = 54, female = 77.1%). Upon enrollment, 35.1% of participants selected a PCP to disclose results, and 40.5% of PCPs agreed. Of those tested, 138 (3.4%) were AJPV heterozygotes of whom 21 (15.2%) had no significant family history of cancer, whereas 86 (62.3%) had a known familial pathogenic variant. At 12 weeks, 85.5% of participants with AJPVs planned increased cancer screening; only 3.7% with negative results and a significant family history reported further testing. CONCLUSION: Although continued follow-up is needed, internet-enabled outreach can expand access to targeted GT using a medical model. Observed challenges for population genetic screening efforts include recruitment barriers, improving PCP engagement, and increasing uptake of additional testing when indicated.

Clonal relationship and directionality of progression of synchronous endometrial and ovarian carcinomas in patients with DNA mismatch repair-deficiency associated syndromes.

Sporadic synchronous endometrial (ECs) and ovarian cancers (OCs), although clinically considered to be independent primaries, have been shown to be clonally related and likely constitute metastases from each other. We sought to define whether synchronous ECs/OCs in patients with DNA mismatch repair (MMR)-deficiency syndromes would be clonally related. We subjected synchronous ECs/OCs from four patients (LS3-LS6) with clinically confirmed Lynch syndrome (LS) and one patient with constitutional mismatch repair-deficiency syndrome (CMMRD) to massively parallel sequencing targeting 468 cancer-related genes. Somatic mutations, copy number alterations (CNAs), clonal relatedness and clonal decomposition analyses were performed using previously described bioinformatics methods. All synchronous ECs/OCs analyzed were considered independent primaries based on clinicopathologic criteria. Sequencing analysis revealed that the ECs/OCs of three cases (LS2-CMMRD, L3, L4) harbored similar repertoires of somatic mutations and CNAs and were clonally related. In these three cases, a subset of subclonal mutations in the EC became clonal in the OC, suggesting that the EC was likely the substrate from which the OC developed. LS5's EC/OC had distinct mutational profiles but shared specific CNAs. In contrast, LS6's EC/OC harbored distinct somatic mutations and lacked CNAs, consistent with each tumor constituting an independent primary lesion. In LS5 and LS6, PTEN mutations and PTEN loss of protein expression were found to be restricted to the EC. Finally, re-analysis of sequencing data of sporadic synchronous ECs/OCs supported the observations made in the current study that the directionality of progression is likely from the endometrium to the ovary. In conclusion, contrary to sporadic synchronous ECs/OCs, which are almost invariably clonally related, ECs/OCs simultaneously involving the uterus and ovary in LS patients may represent distinct primary tumors. A subset of MMR-deficiency syndrome-related synchronous ECs/OCs, however, may originate from a single primary tumor at variance with their clinical diagnosis, with the endometrium being the likeliest site of origin.

Cascading After Peridiagnostic Cancer Genetic Testing: An Alternative to Population-Based Screening.

PURPOSE: Despite advances in DNA sequencing technology and expanded medical guidelines, the vast majority of individuals carrying pathogenic variants of common cancer susceptibility genes have yet to be identified. An alternative to population-wide genetic screening of healthy individuals would exploit the trend for genetic testing at the time of cancer diagnosis to guide therapy and prevention, combined with augmented familial diffusion or "cascade" of genomic risk information. METHODS: Using a multiple linear regression model, we derived the time interval to detect an estimated 3.9 million individuals in the United States with a pathogenic variant in 1 of 18 cancer susceptibility genes. We analyzed the impact of the proportion of incident patients sequenced, varying observed frequencies of pathogenic germline variants in patients with cancer, differential rates of diffusion of genetic information in families, and family size. RESULTS: The time to detect inherited cancer predisposing variants in the population is affected by the extent of cascade to first-, second-, and third-degree relatives (FDR, SDR, TDR, respectively), family size, prevalence of mutations in patients with cancer, and the proportion of patients with cancer sequenced. In a representative scenario, assuming a 7% prevalence of pathogenic variants across cancer types, an average family size of 3 per generation, and 15% of incident patients with cancer in the United States undergoing germline testing, the time to detect all 3.9 million individuals with pathogenic variants in 18 cancer susceptibility genes would be 46.2, 22.3, 13.6, and 9.9 years if 10%, 25%, 50%, and 70%, respectively, of all FDR, SDR, and TDR were tested for familial mutations. CONCLUSION: Peridiagnostic and cascade cancer genetic testing offers an alternative strategy to achieve population-wide identification of cancer susceptibility mutations.