Genetic testing approaches for hereditary breast cancer: Perspectives from a private diagnostic laboratory
SAMJ SOUTH AFRICAN MEDICAL JOURNAL
Authors: Smith, D. C.; Gardiner, S. A.; Conradie, M.; Gerber, J.; Loubser, F.
Abstract
Breast cancer is highly prevalent in South Africa, and up to 10% of breast cancer cases may be hereditary. The landscape of genetic testing options for hereditary breast cancer (HBC) has changed significantly over the past decade, and healthcare providers are faced with multiple options when referring breast cancer patients for genetic testing. We have performed a retrospective study of 3 years' worth of breast cancer genetic testing referrals to our laboratory. While Afrikaner and Ashkenazi Jewish founder screens may be appropriate as first-line tests in a limited subset of patients, we have shown that in the majority of cases it is more effective to adopt a multigene panel approach. While variants in the BRCA1 and BRCA2 genes still account for a significant proportion of cases, close to 40% of pathogenic variants were found in genes other than BRCA1 or BRCA2. There are many factors that healthcare providers should consider when requesting genetic testing for breast cancer patients and families, including family history, ancestral background, cost, medical aid scheme reimbursement and scope of testing. We summarise our findings and provide advantages and disadvantages of each approach, with the aim of assisting clinicians and genetic counsellors to make appropriate testing decisions.
Prevalence of Suspected Hereditary Cancer Syndromes and Germline Mutations Among a Diverse Cohort of Probands Reporting a Family History of Prostate Cancer: Toward Informing Cascade Testing for Men
EUROPEAN UROLOGY ONCOLOGY
Authors: Chandrasekar, Thenappan; Gross, Laura; Gomella, Leonard G.; Hegarty, Sarah E.; Leong, Joon Yau; Giri, Veda N.
Abstract
Background: Prostate cancer (PCa) is increasingly recognized as part of hereditary cancer syndromes (HCSs). HCS prevalence among diverse probands seeking genetic evaluation with PCa family history (FHx) has not been reported and has implications for cascade genetic testing. Objective: To evaluate the rates of HCSs among probands reporting PCa FHx and germline mutations among probands. Design, setting, and participants: A prospective genetic testing database queried for individuals with PCa FHx. Pedigrees analyzed for three HCSs: hereditary breast and ovarian cancer (HBOC), hereditary PCa, and Lynch syndrome. Outcome measurements and statistical analysis: Associations between HCS overall, and with plausible link to PCA FHx and race evaluated using Fisher's exact test. Germline mutation rates described among probands with a suspicion of an HCS connected with PCa FHx. Results and limitations: A total of 345 probands reported PCa FHx: 53 African American (AA) and 292 Caucasian (Wh). Overall, 220 probands (63.8%) met the criteria for at least one HCS with a potential link to PCa FHx (75.5% AA; 61.6% Wh). HBOC linked to PCa FHx was identified in a higher percentage of AA than Wh probands (90.2% vs 74.6%, p = 0.04). Among probands who underwent genetic testing with any HCS potentially linked to PCa FHx (n = 169), 19.5% had germline mutations identified; five AA probands had germline mutations (all in BRCA1/2), while 28 Wh probands had mutations in a spectrum of genes. Conclusions: A significant percentage of AA probands with PCa FHx meet the criteria for HCSs, with HBOC identified at the highest rate. Although limited in sample size, our findings implicate BRCA mutations in AA families with HCSs linked with PCa, underscoring the need for greater enrollment of AA participants in genetic studies. Patient summary: Hereditary cancer syndromes potentially linked to prostate cancer are common in patients reporting a family history of prostate cancer. African-American patients may need special attention with regard to testing for hereditary breast and ovarian cancer syndrome, which may impact men with prostate cancer in these families. (C) 2019 European Association of Urology. Published by Elsevier B.V. All rights reserved.