Detection of germline variants in Brazilian breast cancer patients using multigene panel testing.

Genetic diversity of germline variants in breast cancer (BC) predisposition genes is unexplored in miscegenated populations, such those living in Latin America. We evaluated 1663 Brazilian BC patients, who underwent hereditary multigene panel testing (20-38 cancer susceptibility genes), to determine the spectrum and prevalence of pathogenic/likely pathogenic (P/LP) variants and variants of uncertain significance (VUS). Associations between P/LP variants and BC risk were estimated in a case-control analysis of BC patients and 18,919 Brazilian reference controls (RC). In total, 335 (20.1%) participants carried germline P/LP variants: 167 (10.0%) in BRCA1/2, 122 (7.3%) in BC actionable non-BRCA genes and 47 (2.8%) in candidate genes or other cancer predisposition genes. Overall, 354 distinctive P/LP variants were identified in 23 genes. The most commonly mutated genes were: BRCA1 (27.4%), BRCA2 (20.3%), TP53 (10.5%), monoallelic MUTYH (9.9%), ATM (8.8%), CHEK2 (6.2%) and PALB2 (5.1%). The Brazilian variant TP53 R337H (c.1010G>A, p.Arg337His), detected in 1.6% of BC patients and 0.1% of RC, was strongly associated with risk of BC, OR = 17.4 (95% CI: 9.4-32.1; p < 0.0001); monoallelic MUTYH variants c.1187G>A and c.536A>G, detected in 1.2% (0.9% RC) and 0.8% (0.4% RC) of the patients, respectively, were not associated with the odds of BC, the former with OR = 1.4 (95% CI: 0.8-2.4; p = 0.29) and the latter with OR = 1.9 (95% CI: 0.9-3.9; p = 0.09). The overall VUS rate was 46.1% for the entire patient population. Concluding, the use of multigene panel testing almost doubled the identification of germline P/LP variants in clinically actionable predisposition genes in BC patients. In Brazil, special attention should be given to TP53 P/LP variants.

Câncer de mama hereditário e rastreamento em população de alto risco / Hereditary breast cancer and screening in high-risk population

Estima-se que para o câncer de mama, assim como para grande parte dos tumores malignos conhecidos, 5 a 10% sejam de caráter hereditário. A história de câncer em familiares de primeiro grau e a presença de alguns fatores específicos de risco, como câncer de mama bilateral, história familiar de câncer de mama e ovário, e câncer de mama em indivíduo do sexo masculino, são indicadores importantes de risco de câncer de mama hereditário. Os avanços em técnicas de biologia molecular nas últimas décadas resultaram na identificação de genes que, quando alterados, aumentam significativamente o risco de desenvolver câncer de mama, de ovário e outros tumores. Destacam-se os genes supressores tumorais BRCA1 e BRCA2, além de outros genes de predisposição ao câncer de mama identificados, que são igualmente importantes no risco da doença, embora correspondam a uma parcela menor dos casos hereditários. A possibilidade de identificar pacientes e familiares com elevado risco de desenvolvimento de câncer torna possível o emprego de uma abordagem preventiva e de detecção precoce do câncer. Além disso, a identificação de um indivíduo não portador de uma alteração genética em uma família de risco permite a tranquilização dele e elimina gastos/complicações com intervenções preventivas desnecessárias. Famílias de alto risco de desenvolvimento de câncer hereditário apresentam alta prevalência de câncer de mama, além de neoplasia com instalação precoce e com maior agressividade. Dessa forma, o rastreamento nesses casos deve ser diferente, objetivando alcançar a redução da morbidade e mortalidade associadas ao câncer nessa população.

It is estimated that for breast cancer, as well as for the great majority of malignant tumors, 5 to 10% are due to an inherited predisposition. Family history of cancer in first degree relatives and the presence of some specific risk factors, such as bilateral breast cancer, family history of breast and ovarian cancer, and breast cancer in a male person, are important indicators of risk for hereditary breast cancer. Advances in molecular biology in recent decades have resulted in the identification of genes that, when altered, increase significantly the risk of developing breast cancer, ovarian cancer and other tumors, for example, the tumor suppressor genes BRCA1 and BRCA2, as well as other genes predisposing to breast cancer identified, which are equally important in the risk for the disease, although a smaller portion of match cases hereditary. The ability to identify patients and relatives with high risk for developing cancer makes possible the use of a preventive approach and an early detection of cancer. In addition, the identification of a non-carrier individual in a family of high risk allows him to reassures the modification individual and eliminates expenses/complications with unnecessary preventive interventions. The typical profile of a patient with higher risk is high prevalence of breast cancer, earlier ages at cancer diagnosis and the worst prognosis and evolution of the tumor. In this way, follow up for these patients must be different in order to achieve the reduction of morbidity and mortality associated with cancer in this population.