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Simple Summary: The role of gender in oncology is an issue that is starting to be recognized as being of extreme importance in the last few years. While breast cancer is commonly perceived as a female-only disease, it does also occur in men, although rarely, thus opening relevant gender issues. Breast cancer in men is much less studied, with most knowledge coming from research on female breast cancer; however, several crucial differences have begun to be discovered between male and female patients. For example, the gender-specific impact and magnitude of risks conferred by breast cancer genetic risk factors are emerging, and they should be taken into consideration for a proper personalized clinical management. Overall, addressing all the challenges and the open issues regarding breast cancer genetic predisposition, including gender, will have an important clinical impact on the management of patients of both sexes. Among neoplastic diseases, breast cancer (BC) is one of the most influenced by gender. Despite common misconceptions associating BC as a women-only disease, BC can also occur in men. Additionally, transgender individuals may also experience BC. Genetic risk factors play a relevant role in BC predisposition, with important implications in precision prevention and treatment. The genetic architecture of BC susceptibility is similar in women and men, with high-, moderate-, and low-penetrance risk variants; however, some sex-specific features have emerged. Inherited high-penetrance pathogenic variants (PVs) in BRCA1 and BRCA2 genes are the strongest BC genetic risk factor. BRCA1 and BRCA2 PVs are more commonly associated with increased risk of female and male BC, respectively. Notably, BRCA-associated BCs are characterized by sex-specific pathologic features. Recently, next-generation sequencing technologies have helped to provide more insights on the role of moderate-penetrance BC risk variants, particularly in PALB2, CHEK2, and ATM genes, while international collaborative genome-wide association studies have contributed evidence on common low-penetrance BC risk variants, on their combined effect in polygenic models, and on their role as risk modulators in BRCA1/2 PV carriers. Overall, all these studies suggested that the genetic basis of male BC, although similar, may differ from female BC. Evaluating the genetic component of male BC as a distinct entity from female BC is the first step to improve both personalized risk assessment and therapeutic choices of patients of both sexes in order to reach gender equality in BC care. In this review, we summarize the latest research in the field of BC genetic predisposition with a particular focus on similarities and differences in male and female BC, and we also discuss the implications, challenges, and open issues that surround the establishment of a gender-oriented clinical management for BC. [ABSTRACT FROM AUTHOR]

Breast cancer (BC) in men is rare and genetic predisposition is likely to play a relevant role in its etiology. Inherited mutations in BRCA1/2 account for about 13% of all cases and additional genes that may contribute to the missing heritability need to be investigated. In our study, a well‐characterized series of 523 male BC (MBC) patients from the Italian multicenter study on MBC, enriched for non‐BRCA1/2 MBC cases, was screened by a multigene custom panel of 50 cancer‐associated genes. The main clinical‐pathologic characteristics of MBC in pathogenic variant carriers and non‐carriers were also compared. BRCA1/2 pathogenic variants were detected in twenty patients, thus, a total of 503 non‐BRCA1/2 MBC patients were examined in our study. Twenty‐seven of the non‐BRCA1/2 MBC patients were carriers of germline pathogenic variants in other genes, including two APC p.Ile1307Lys variant carriers and one MUTYH biallelic variant carrier. PALB2 was the most frequently altered gene (1.2%) and PALB2 pathogenic variants were significantly associated with high risk of MBC. Non‐BRCA1/2 pathogenic variant carriers were more likely to have personal (p = 0.0005) and family (p = 0.007) history of cancer. Results of our study support a central role of PALB2 in MBC susceptibility and show a low impact of CHEK2 on MBC predisposition in the Italian population. Overall, our data indicate that a multigene testing approach may benefit from appropriately selected patients with implications for clinical management and counseling of MBC patients and their family members. What's new? While multigene panel testing for breast cancer predisposition has been performed extensively in females, its use in male breast cancer (MBC) patients has been much more limited, despite a likely role for genetic predisposition in MBC. In this multicenter study in Italy, panel testing involving 50 cancer‐associated genes identified germline pathogenic variants in about 5 percent of BRCA1/2‐negative MBC patients. In non‐BRCA1/2 MBC, the most frequently mutated genes were PALB2 and ATM, with PALB2 mutations having a major impact on MBC risk. By comparison, mutations in CHEK2 had little impact on MBC predisposition in the Italian population. [ABSTRACT FROM AUTHOR]

Background: Male breast cancer (MBC) is a rare disease whose etiology appears to be largely associated with genetic factors. BRCA1 and BRCA2 mutations account for about 10% of all MBC cases. Thus, a fraction of MBC cases are expected to be due to genetic factors not yet identified. To further explain the genetic susceptibility for MBC, whole-exome sequencing (WES) and targeted gene sequencing were applied to high-risk, BRCA1/2 mutation-negative MBC cases.Methods: Germ-line DNA of 1 male and 2 female BRCA1/2 mutation-negative breast cancer (BC) cases from a pedigree showing a first-degree family history of MBC was analyzed with WES. Targeted gene sequencing for the validation of WES results was performed for 48 high-risk, BRCA1/2 mutation-negative MBC cases from an Italian multicenter study of MBC. A case-control series of 433 BRCA1/2 mutation-negative MBC and female breast cancer (FBC) cases and 849 male and female controls was included in the study.Results: WES in the family identified the partner and localizer of BRCA2 (PALB2) c.419delA truncating mutation carried by the proband, her father, and her paternal uncle (all affected with BC) and the N-acetyltransferase 1 (NAT1) c.97C>T nonsense mutation carried by the proband's maternal aunt. Targeted PALB2 sequencing detected the c.1984A>T nonsense mutation in 1 of the 48 BRCA1/2 mutation-negative MBC cases. NAT1 c.97C>T was not found in the case-control series.Conclusions: These results add strength to the evidence showing that PALB2 is involved in BC risk for both sexes and indicate that consideration should be given to clinical testing of PALB2 for BRCA1/2 mutation-negative families with multiple MBC and FBC cases. Cancer 2017;123:210-218. © 2016 American Cancer Society. [ABSTRACT FROM AUTHOR]

Germline pathogenic variants (PVs) in BRCA1/2 genes are associated with breast cancer (BC) risk in both women and men. Multigene panel testing is being increasingly used for BC risk assessment, allowing the identification of PVs in genes other than BRCA1/2. While data on actionable PVs in other cancer susceptibility genes are now available in female BC, reliable data are still lacking in male BC (MBC). This study aimed to provide the patterns, prevalence and risk estimates associated with PVs in non- BRCA1/2 genes for MBC in order to improve BC prevention for male patients. We performed a large case-control study in the Italian population, including 767 BRCA1/ 2-negative MBCs and 1349 male controls, all screened using a custom 50 cancer gene panel. PVs in genes other than BRCA1/2 were significantly more frequent in MBCs compared with controls (4.8% vs 1.8%, respectively) and associated with a threefold increased MBC risk (OR: 3.48, 95% CI: 1.88–6.44; p < 0.0001). PV carriers were more likely to have personal (p = 0.03) and family (p = 0.02) history of cancers, not limited to BC. PALB2 PVs were associated with a sevenfold increased MBC risk (OR: 7.28, 95% CI: 1.17–45.52; p = 0.034), and ATM PVs with a fivefold increased MBC risk (OR: 4.79, 95% CI: 1.12–20.56; p = 0.035). This study highlights the role of PALB2 and ATM PVs in MBC susceptibility and provides risk estimates at population level. These data may help in the implementation of multigene panel testing in MBC patients and inform gender-specific BC risk management and decision making for patients and their families. • About 5% of MBC cases are carriers of pathogenic variants in genes other than BRCA1/2 • PALB2 and ATM are associated with increased MBC risk • CHEK2 is not associated with MBC risk in the Italian population • Multigene panel test should be implemented in MBC patients [ABSTRACT FROM AUTHOR]

Increasing evidence indicates that common genetic variants may contribute to the heritable risk of breast cancer (BC). In this study, we investigated whether single nucleotide polymorphisms (SNPs), within the 8q24.21 multi-cancer susceptibility region and within BC-associated loci widespread in the genome, may influence the risk of BC in men, and whether they may be associated with specific clinical-pathologic characteristics of male BC (MBC). In the frame of the ongoing Italian Multicenter Study on MBC, we performed a case-control study on 386 MBC cases, including 50 BRCA1/2 mutation carriers, and 1105 healthy male controls, including 197 unaffected BRCA1/2 mutation carriers. All 1491 subjects were genotyped by Sequenom iPLEX technology for a total of 29 susceptibility SNPs. By logistic regression models, we found a significant association with MBC risk for five SNPs: rs1562430 ( p = 0.002) and rs445114 ( p = 0.026) both within the 8q24.21 region; rs1011970/9p21.3 ( p = 0.011), rs614367/11q13.3 ( p = 0.016) and rs1314913/14q24.1 ( p < 0.0001). Differences in the distribution of rs614367/11q13.3 genotypes according to oestrogen receptor (ER) status ( p = 0.006), and of rs1011970/9p21.3 genotypes according to human epidermal growth factor receptor 2 (HER2) status ( p = 0.002) emerged. Association of rs1011970/9p21.3 risk genotype with HER2+ MBC was confirmed by a multivariate analysis. rs1314913/14q24.1 was associated with increased MBC risk in analyses restricted to male BRCA1/2 mutation carriers ( p = 0.041). In conclusion, we provided the first evidence that the 8q24.21 region is associated with MBC risk. Furthermore, we showed that the SNPs rs1562430/8q24.21 and rs1314913/14q24.1 strongly influence BC risk in men and suggested that the SNP rs1314913/14q24.1 may act as a risk modifier locus in male BRCA1/2 mutation carriers. [ABSTRACT FROM AUTHOR]