Hereditary cancer predisposition syndromes are responsible for approximately 5–10% of all diagnosed cancer cases. In the past, single-gene analysis of specific high risk genes was used for the determination of the genetic cause of cancer heritability in certain families. The application of Next Generation Sequencing (NGS) technology has facilitated multigene panel analysis and is widely used in clinical practice, for the identification of individuals with cancer predisposing gene variants. The purpose of this study was to investigate the extent and nature of variants in genes implicated in hereditary cancer predisposition in individuals referred for testing in our laboratory. In total, 1197 individuals from Greece, Romania and Turkey were referred to our laboratory for genetic testing in the past 4 years. The majority of referrals included individuals with personal of family history of breast and/or ovarian cancer. The analysis of genes involved in hereditary cancer predisposition was performed using a NGS approach. Genomic DNA was enriched for targeted regions of 36 genes and sequencing was carried out using the Illumina NGS technology. The presence of large genomic rearrangements (LGRs) was investigated by computational analysis and Multiplex Ligation-dependent Probe Amplification (MLPA). A pathogenic variant was identified in 264 of 1197 individuals (22.1%) analyzed while a variant of uncertain significance (VUS) was identified in 34.8% of cases. Clinically significant variants were identified in 29 of the 36 genes analyzed. Concerning the mutation distribution among individuals with positive findings, 43.6% were located in the BRCA1/2 genes whereas 21.6, 19.9, and 15.0% in other high, moderate and low risk genes respectively. Notably, 25 of the 264 positive individuals (9.5%) carried clinically significant variants in two different genes and 6.1% had a LGR. In our cohort, analysis of all the genes in the panel allowed the identification of 4.3 and 8.1% additional pathogenic variants in other high or moderate/low risk genes, respectively, enabling personalized management decisions for these individuals and supporting the clinical significance of multigene panel analysis in hereditary cancer predisposition.

Background: Hereditary cancer predisposition syndromes are responsible for approximately 5–10% of all diagnosed cancer cases. In order to identify individuals at risk in a cost-efficient manner, family members of individuals carrying pathogenic alterations are tested only for the specific variant that was identified in their carrier relative. The purpose of this study was to investigate the clinical use and implementation of cascade family testing (CFT) in families of breast cancer patients with pathogenic/likely pathogenic variants (PVs/LPVs) in cancer-related predisposition genes. Methods: Germline sequencing was carried out with NGS technology using a 52-gene panel, and cascade testing was performed by Sanger sequencing or MLPA. Results: In a cohort of 1785 breast cancer patients (families), 20.3% were found to have PVs/LPVs. Specifically, 52.2%, 25.1%, and 22.7% of patients had positive findings in high-, intermediate-, and low-penetrance breast cancer susceptibility genes, respectively. Although CFT was recommended to all families, only 117 families (32.3%) agreed to proceed with genetic testing. Among the first-degree relatives who underwent CFT, 70.3% were female, and 108 of 121 (89.3%) were cancer free. Additionally, 42.7%, 36.7%, and 20.6% were offspring, siblings, and parents of the subject, respectively. Our data suggest that CFT was mostly undertaken (104/117, 88.8%) in families with positive findings in high-risk genes. Conclusions: Cascade family testing can be a powerful tool for primary cancer prevention by identifying at-risk family members. It is of utmost importance to implement genetic counseling approaches leading to increased awareness and communication of genetic testing results.

Background: Risk-reducing mastectomy (RRM) and risk-reducing salpingo-oophorectomy (RRSO) are established strategies for women carrying pathogenic or likely pathogenic (P/LP) variants in high-risk cancer susceptibility genes. However, real-world uptake remains variable and is influenced by clinical, demographic, and psychosocial factors. This study evaluated adherence to guideline-recommended surgical risk-reduction strategies following positive genetic testing. Materials and Methods: We conducted a retrospective observational study of 13,069 women who underwent hereditary cancer testing using a multigene next-generation sequencing panel between 2020 and 2025. Among them, 1,255 carriers of P/LP variants in genes with established recommendations for RRM and/or RRSO were identified. Physician-reported questionnaires were available for 203 individuals and captured data on counseling, acceptance, and implementation of risk-reducing surgery. Genes were grouped according to NCCN guideline recommendations: (i) BRCA1/2; (ii) PALB2, PTEN, TP53; and (iii) BRIP1, RAD51C, RAD51D. Results: Of the 203 women, 83% had a personal history of cancer. Overall, 83.7% were offered at least one risk-reducing intervention, with 64.9% accepting. RRM was more frequently discussed in higher breast cancer–risk genes, while RRSO discussion varied by gene group; these differences were statistically significant. Acceptance rates were moderate for RRM but consistently high for RRSO across groups. Younger age and advanced-stage disease were key factors limiting uptake or discussion, and 22 patients postponed surgery despite initial agreement. Conclusions: In this real-world cohort, physician counseling largely aligned with gene-specific guidelines, and acceptance of risk-reducing surgery was high once discussed, particularly for RRSO. However, uptake was influenced by age, disease stage, and clinical context. These findings highlight the importance of early genetic testing and multidisciplinary counseling to optimize timely decision-making and improve adherence to preventive strategies.