The yield of full BRCA1/2 genotyping in Israeli Arab high-risk breast/ovarian cancer patients.

PURPOSE: While the spectrum of germline mutations in BRCA1/2 genes in the Israeli Jewish population has been extensively studied, there is a paucity of data pertaining to Israeli Arab high-risk cases. METHODS: Consecutive Israeli Arab breast and/or ovarian cancer patients were recruited using an ethically approved protocol from January 2012 to February 2019. All ovarian cancer cases were referred for BRCA genotyping. Breast cancer patients were offered BRCA sequencing and deletion/duplication analysis after genetic counseling, if the calculated risk for carrying a BRCA mutation by risk prediction algorithms was ≥10%. RESULTS: Overall, 188 patients participated; 150 breast cancer cases (median age at diagnosis: 40 years, range 22-67) and 38 had ovarian cancer (median age at diagnosis: 52.5 years, range 26-79). Of genotyped cases, 18 (10%) carried one of 12 pathogenic or likely-pathogenic variants, 12 in BRCA1, 6 in BRCA2. Only one was a rearrangement. Three variants recurred in more than one case; one was detected in five seemingly unrelated families. The detection rate for all breast cancer cases was 4%, 5% in bilateral breast cancer cases and 3% if breast cancer was diagnosed < 40 years. Of patients with ovarian cancer, 12/38 (32%) were carriers; the detection rate reached 75% (3/4) among patients diagnosed with both breast and ovarian cancer. CONCLUSIONS: The overall yield of comprehensive BRCA1/2 testing in high-risk Israeli Arab individuals is low in breast cancer patients, and much higher in ovarian cancer patients. These results may guide optimal cancer susceptibility testing strategy in the Arab-Israeli population.

The yield of full BRCA1/2 genotyping in Israeli high-risk breast/ovarian cancer patients who do not carry the predominant mutations.

PURPOSE: BRCA1 and BRCA2 genotyping results have clinical implications for cancer risk assessment and targeted therapy. Current practice in Israel is to genotype for the predominant BRCA1/2 mutations first, followed by full gene analysis in eligible mutation-negative individuals. This work assessed the rate of non-predominant mutations in BRCA1/2 in ethnically diverse high-risk cases. METHODS: Breast and/or ovarian cancer patients who tested negative for the predominant BRCA1/2 mutations were referred for comprehensive BRCA1/2 genotyping if calculated risk for carrying a BRCA mutation was ≥ 10%. RESULTS: Of 1258 eligible patients, 41 (3.3%) carried one of 38 mutations: 3% of Ashkenazi Jews and 3.4% of mixed ethnicities. Detection rate was < 5% among patients diagnosed with cancer younger than 40 or with bilateral breast cancer, and was 5.5% of ovarian cancer patients. Three of the carriers (7.3%) carried gene rearrangements. Three mutations were reported in more than one case. CONCLUSIONS: The overall yield of comprehensive BRCA1/2 testing in ethnically diverse high-risk Israeli individuals is 3.3%. This is lower than expected by probability models. A slightly higher rate of BRCA1/2 carriers was seen among ovarian cancer cases. These data should guide BRCA1/2 optimal testing strategy in Israel.

Screening for germline mutations in breast/ovarian cancer susceptibility genes in high-risk families in Israel.

We evaluated the clinical utility of screening for mutations in 34 breast/ovarian cancer susceptibility genes in high-risk families in Israel. Participants were recruited from 12, 2012 to 6, 2015 from 8 medical centers. All participants had high breast/ovarian cancer risk based on personal and family history. Genotyping was performed with the InVitae™ platform. The study was approved by the ethics committees of the participating centers; all participants gave a written informed consent before entering the study. Overall, 282 individuals participated in the study: 149 (53 %) of Ashkenazi descent, 80 (28 %) Jewish non-Ashkenazi descent, 22 (8 %) of mixed Ashkenazi/non-Ashkenazi origin, 21 (7 %) were non-Jewish Caucasians, and the remaining patients (n = 10-3.5 %) were of Christian Arabs/Druze/unknown ethnicity. For breast cancer patients (n = 165), the median (range) age at diagnosis was 46 (22-90) years and for ovarian cancer (n = 15) 54 (38-69) years. Overall, 30 cases (10.6 %) were found to carry a pathogenic actionable mutation in the tested genes: 10 BRCA1 (3 non-founder mutations), 9 BRCA2 (8 non-founder mutations), and one each in the RAD51C and CHEK2 genes. Furthermore, actionable mutations were detected in 9 more cases in 4 additional genes (MSH2, RET, MSH6, and APC). No pathogenic mutations were detected in the other genotyped genes. In this high-risk population, 10.6 % harbored an actionable pathogenic mutation, including non-founder mutations in BRCA1/2 and in additional cancer susceptibility genes, suggesting that high-risk families should be genotyped and be assigned a genotype-based cancer risk.

Constitutional Mismatch Repair Deficiency in Israel: High Proportion of Founder Mutations in MMR Genes and Consanguinity.

BACKGROUND: Heterozygous germline mutations in any of the mismatch repair (MMR) genes, MLH1, MSH2, MSH6, and PMS2, cause Lynch syndrome (LS), an autosomal dominant cancer predisposition syndrome conferring a high risk of colorectal, endometrial, and other cancers in adulthood. Offspring of couples where both spouses have LS have a 1:4 risk of inheriting biallelic MMR gene mutations. These cause constitutional MMR deficiency (CMMRD) syndrome, a severe recessively inherited cancer syndrome with a broad tumor spectrum including mainly hematological malignancies, brain tumors, and colon cancer in childhood and adolescence. Many CMMRD children also present with café au lait spots and axillary freckling mimicking neurofibromatosis type 1. PROCEDURE: We describe our experience in seven CMMRD families demonstrating the role and importance of founder mutations and consanguinity on its prevalence. Clinical presentations included brain tumors, colon cancer, lymphoma, and small bowel cancer. RESULTS: In children from two nonconsanguineous Ashkenazi Jewish (AJ) families, the common Ashkenazi founder mutations were detected; these were homozygous in one family and compound heterozygous in the other. In four consanguineous families of various ancestries, different homozygous mutations were identified. In a nonconsanguineous Caucasus/AJ family, lack of PMS2 was demonstrated in tumor and normal tissues; however, mutations were not identified. CONCLUSIONS: CMMRD is rare, but, especially in areas where founder mutations for LS and consanguinity are common, pediatricians should be aware of it since they are the first to encounter these children. Early diagnosis will enable tailored cancer surveillance in the entire family and a discussion regarding prenatal genetic diagnosis.

Clinical Characteristics and Prognosis of Gastric Cancer Patients with BRCA 1/2 Germline Mutations: Report of Ten Cases and a Literature Review.

BACKGROUND: The prognosis of gastric cancer (GC) is poor with a median overall survival (OS) of less than 12 months in advanced-stage disease. The search for distinct genetic subgroups of GC patients and predictive biomarkers is ongoing. While BRCA1 or BRCA2 germline mutations (gBRCAm) have potential therapeutic implications in ovarian, breast and pancreatic cancers, their significance in GC patients has not been established. PATIENTS AND METHODS: A retrospective multi-center data analysis of GC patients with gBRCAm was conducted, detailing the clinical characteristics and disease course in this unique subset of patients. RESULTS: Ten GC patients with gBRCAm were identified, six of them with metastatic disease. The median OS of all ten GC patients was 47.5 (13-192) months. Median OS for patients diagnosed with operable disease was 55.5 (13-192) months and of the patients with metastatic disease (calculated from metastatic disease diagnosis) 32 (15-52) months with an exceptional 1-, 2- and 3-year survival rate of 100%, 83.3% and 50%, respectively. CONCLUSION: These preliminary data suggest that gBRCAm in GC patients are associated with a favorable prognosis. Furthermore, gBRCAm might be a predictive biomarker to DNA-damaging agents response in GC patients, similarly to its established role in other malignancies. Further research is needed to confirm our findings.

A familial gastrointestinal cancer clinic: organization, aims and activities, 2004-2007.

BACKGROUND: Dedicated, organ-specific screening clinics have been shown to significantly reduce cancer morbidity and mortality. OBJECTIVES: To establish a dedicated clinic for Clalit Health Service patients at high risk for hereditary gastrointestinal cancer and to provide them with clinical and genetic counseling, diagnostic screening and follow-up. RESULTS: During the 3 years of the clinic's activity, 634 high risk families, including 3804 at-risk relatives, were evaluated. The most common conditions were hereditary colorectal syndromes, Lynch syndrome (n=259), undefined young-onset or familial colorectal cancer (n=214), familial adenomatous polyposis (n=55), and others (n=106). They entered follow-up protocols and 52 underwent surgical procedures. CONCLUSIONS: Consistent public and professional education is needed to increase awareness of hereditary colorectal cancer and the possibility of family screening, early diagnosis and therapy. The public health services--i.e., the four health management organizations--should provide genetic testing for these patients who, at present, are required to pay for almost all of these available but costly tests. Dedicated colorectal surgical units are needed to provide the specialized therapeutic procedures needed by patients with familial colorectal cancer. Our future plans include adding psychosocial support for these at-risk patients and their families as well as preventive lifestyle and dietary intervention.

Constitutional mismatch repair deficiency and Lynch syndrome among consecutive Arab Bedouins with colorectal cancer in Israel.

We assessed the molecular characteristics and the frequency of mutations in mismatch-repair genes among Bedouin patients with colorectal cancer (CRC) in Israel. Bedouin patients with a diagnosis of CRC at a major hospital in the southern part of Israel were deemed eligible for this study. The primary screening method was immunohistochemical staining for mismatch-repair proteins (MLH1, MSH2, MSH6, and PMS2). For subjects with abnormal immunohistochemical staining, we performed microsatellite instability (MSI) analyses, and for tumors with a loss of MLH1 expression we also performed BRAF testing. In MSI high cases we searched further for germline mutations. Of the 24 patients enrolled, four subjects (16.7%) had MSI high tumors: one subject was found to harbor a biallelic PMS2 mutation, one subject had Lynch syndrome (LS) with MSH6 mutation and two subjects had a loss of MLH1/PMS2 proteins/BRAF wild type/normal MLH1 sequence. Ten patients (41.7%) were younger than 50 at the time of diagnosis and none had first degree relatives with CRC. In conclusion, in this cohort of 24 consecutive Arab Bedouins with CRC, one patient was found to harbor a constitutional mismatch repair deficiency, one patient had LS with MSH6 mutation, and two patients had unresolved loss of MLH1/PMS2 proteins/BRAF wild type phenotype.

Counseling the at risk patient in the BRCA1 and BRCA2 Era.

The 5-year experience since the identification of the BRCA1 and BRCA2 genes has shown that genetic evaluation and testing can increase understanding of cancer risks for individuals with a personal or family history of early onset breast cancer and ovarian cancer. However, testing needs to be undertaken in a clinical setting where pretest counseling, including likelihood of identifying a mutation and risks and benefits of the process are provided. Identifying women who carry mutations in either BRCA1 or BRCA2 has implications for prevention, screening and treatment of these cancers.