Molecular profiling of male breast cancer by multigene panel testing: Implications for precision oncology

Assessing DNA Degradation through Differential Amplification Efficiency of Total Human and Human Male DNA in a Forensic qPCR Assay

The assessment of degradation is crucial for the analysis of human DNA samples isolated from forensic specimens. Forensic quantitative PCR (qPCR) assays can include multiple targets of varying amplicon size that display differential amplification efficiency, and thus different concentrations, in the presence of degradation. The possibility of deriving information on DNA degradation was evaluated in a forensic qPCR assay not specifically designed to detect DNA fragmentation, the Plexor HY (Promega), by calculating the ratio between the estimated concentrations of autosomal (99 bp) and Y-chromosomal (133 bp) targets ("[Auto]/[Y]"). The [Auto]/[Y] ratio measured in 57 formalin-fixed, paraffin-embedded samples was compared to a quality score (QS) calculated for corresponding STR profiles using quantitative data (allele peak height). A statistically significant inverse correlation was observed between [Auto]/[Y] and QS (R = -0.65, p < 0.001). The [Auto]/[Y] values were highly correlated (R = 0.75, p < 0.001) with the "[Auto]/[D]" values obtained using the PowerQuant (Promega) assay, expressly designed to detect DNA degradation through simultaneous quantification of a short (Auto) and a long (D) autosomal target. These results indicate that it is possible to estimate DNA degradation in male samples through Plexor HY data and suggest an alternative strategy for laboratories lacking the equipment required for the assessment of DNA integrity through dedicated qPCR assays.

Gender-Specific Genetic Predisposition to Breast Cancer: BRCA Genes and Beyond

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.

HER2-Low Expression in Male Breast Cancer: Results from a Multicenter Series in Italy

In the field of breast cancer care, a significant breakthrough has occurred with the recognition of HER2-low expression as a target for novel anti-HER2 antibody-drug conjugates (ADC). This discovery is reshaping the treatment landscape, challenging previous perceptions that considered HER2-low as clinically insignificant. The ability to target HER2-low expression is expected to have substantial clinical implications, irrespective of gender, including in cases of male breast cancer (MBC). However, an estimate of the prevalence of the HER2-low subtype in MBC is missing. This retrospective, observational, multicenter study was aimed at characterizing the HER2-low subtype in MBC. For the purpose of this study, the three-tiered categorization of HER2 (HER2-0, HER2-low, and HER2-positive) was used to reclassify the HER2-negative group into HER-0 or HER2-low subtypes. In the whole series of 144 invasive MBCs, 79 (54.9%) were HER2-0 (IHC scores of 0), 39 (27.1%) HER2-low (IHC scores of 1+/2+ with negative ISH), and 26 (18.0%) HER2-positive (IHC scores of 3+/2+ with positive ISH). Specifically, among hormone receptor-positive (HR+) HER2-negative invasive MBCs, 34.8% were HER2-low and 65.2% HER2-0. Compared with HER2-0, HER2-low subtype was associated with a positive lymph node involvement (p = 0.01). Other pathologic characteristics including histology, staging, and grading did not show notable variations between the two subtypes. The presence of germline BRCA1/2 pathogenic variants (PVs) did not significantly differ between HER2-0 and HER2-low MBCs. However, about 13% of HER2-low MBCs had germline PVs in BRCA1/2 genes, mainly BRCA2, a clinically relevant observation in the context of combined target therapy. Overall, our data, which focused on the largest gender-specific breast cancer series, to our knowledge, confirm that the emerging three-tiered categorization of HER2 (HER2-0, HER2-low, and HER2-positive) can also be considered in MBC, to mitigate both the gender gap and the underrepresentation of males in clinical trials.

Male Breast Cancer: a Review on Diagnosis, Treatment, and Survivorship

PURPOSE OF REVIEW

Male breast cancer is a relatively uncommon and rare disease that is often managed based on evidence adopted from trials pertaining to female breast cancer due to low accrual rates or exclusion of males. This is despite the known differences in the biology and epidemiology of this condition. This review provides an update regarding the management and surveillance of male breast cancer.

RECENT FINDINGS

Men with breast cancer tend to undergo more extensive surgery in the breast and axilla. The outcomes of male breast cancer compared to a similar subtype of female breast cancer appear worse when matched for stage. Systemic therapies remain predominantly based on recommendations for female breast cancer, although tamoxifen is the more optimal endocrine therapy for men than women. Surveillance with mammograms is recommended for patients harboring a breast cancer susceptibility gene but is otherwise not advised for men who have undergone a mastectomy. Notably, the role of other imaging modalities, including ultrasound and magnetic resonance imaging, is minimal. Although the focus on survivorship care among men is low, it is abundantly clear that this is a stigmatizing diagnosis for men, and they suffer from long-term physical and psychological sequelae following a diagnosis and treatment of breast cancer. In summary, providing more gender-inclusive care and advocating for increased representation of men in prospective breast cancer studies and clinical trials may help improve outcomes and provide enhanced support for this population.