Prevalence of Homologous Recombination Deficiency Among Patients With Germline RAD51C/D Breast or Ovarian Cancer.

Importance: RAD51C and RAD51D are involved in DNA repair by homologous recombination. Germline pathogenic variants (PVs) in these genes are associated with an increased risk of ovarian and breast cancer. Understanding the homologous recombination deficiency (HRD) status of tumors from patients with germline PVs in RAD51C/D could guide therapeutic decision-making and improve survival. Objective: To characterize the clinical and tumor characteristics of germline RAD51C/D PV carriers, including the evaluation of HRD status. Design, Setting, and Participants: This retrospective cohort study included 91 index patients plus 90 relatives carrying germline RAD51C/D PV (n = 181) in Spanish hospitals from January 1, 2014, to December 31, 2021. Genomic and functional HRD biomarkers were assessed in untreated breast and ovarian tumor samples (n = 45) from June 2022 to February 2023. Main Outcomes and Measures: Clinical and pathologic characteristics were assessed using descriptive statistics. Genomic HRD by genomic instability scores, functional HRD by RAD51, and gene-specific loss of heterozygosity were analyzed. Associations between HRD status and tumor subtype, age at diagnosis, and gene-specific loss of heterozygosity in RAD51C/D were investigated using logistic regression or the t test. Results: A total of 9507 index patients were reviewed, and 91 patients (1.0%) were found to carry a PV in RAD51C/D; 90 family members with a germline PV in RAD51C/D were also included. A total of 157 of carriers (86.7%) were women and 181 (55.8%) had received a diagnosis of cancer, mainly breast cancer or ovarian cancer. The most prevalent PVs were c.1026+5_1026+7del (11 of 56 [19.6%]) and c.709C>T (9 of 56 [16.1%]) in RAD51C and c.694C>T (20 of 35 [57.1%]) in RAD51D. In untreated breast cancer and ovarian cancer, the prevalence of functional and genomic HRD was 55.2% (16 of 29) and 61.1% (11 of 18) for RAD51C, respectively, and 66.7% (6 of 9) and 90.0% (9 of 10) for RAD51D. The concordance between HRD biomarkers was 91%. Tumors with the same PV displayed contrasting HRD status, and age at diagnosis did not correlate with the occurrence of HRD. All breast cancers retaining the wild-type allele were estrogen receptor positive and lacked HRD. Conclusions and Relevance: In this cohort study of germline RAD51C/D breast cancer and ovarian cancer, less than 70% of tumors displayed functional HRD, and half of those that did not display HRD were explained by retention of the wild-type allele, which was more frequent among estrogen receptor-positive breast cancers. Understanding which tumors are associated with RAD51C/D and HRD is key to identify patients who can benefit from targeted therapies, such as PARP (poly [adenosine diphosphate-ribose] polymerase) inhibitors.

Recurrent genetic variants and prioritization of variants of uncertain clinical significance associated with hereditary breast and ovarian cancer in families from the Region of Murcia.

Objectives: Hereditary breast and ovarian cancer (HBOC) follows an autosomal dominant inheritance pattern of cancer susceptibility genes. The risk of developing this disease is primarily associated with germline mutations in the BRCA1 and BRCA2 genes. The advent of massive genetic sequencing technologies has expanded the mutational spectrum of this hereditary syndrome, thereby increasing the number of variants of uncertain clinical significance (VUS) detected by genetic testing. Methods: A prevalence study of HBOC was performed within 2,928 families from the Region of Murcia, in southeastern Spain. Genetic testing enabled the identification of recurrent pathogenic variants and founder mutations, which were mainly related to the BRCA1 and BRCA2 genes. VUS testing was performed using a prioritization algorithm designed by our working group. Results: Variants c.68_69del, c.212+1G>A, and c.5123C>A were detected in 30 % of BRCA1 carriers, whereas exon 2 deletion concurrent with c.3264dupT, c.3455T>G and c.9117G>A variants were found in 30 % of BRCA2 carriers. A total of 16 VUS (15 %) were prioritized. Conclusions: The genotype-phenotype correlation observed in our study is consistent with the scientific literature. Furthermore, the founder effect of c.1918C>T (BRCA1) and c.8251_8254del (ATM) was verified in the Murcian population, whereas exon 2 deletion (BRCA2) was proven to be a Spanish founder mutation. Our algorithm enabled us to prioritize potentially pathogenic VUS that required further testing to determine their clinical significance and potential role in HBOC.

Next step in molecular genetics of hereditary breast/ovarian cancer: Multigene panel testing in clinical actionably genes and prioritization algorithms in the study of variants of uncertain significance.

INTRODUCTION: BRCA1 and BRCA2 are the two main genes causing hereditary breast and ovarian cancer (HBOC). However, thanks to the development of Next Generation Sequencing (NGS), other genes linked to this syndrome (CHEK2, BRIP1, ATM and PALB2 among others) can be analysed. MATERIAL AND METHODS: an analysis by multigene panel testing was performed in 138 index cases (ICs) from HBOC Spanish families with a previous non-informative result for BRCA1/2. The BRCA Hereditary Cancer Master™ Plus kit, including 26 actionable and candidate genes related to HBOC was employed. Once classified, an algorithm was employed to prioritized those variants of unknown significance with a higher risk of having a deleterious effect. Moreover, a mRNA splicing assay was performed for the prioritized VUS c.3402+3A > C in ATM, located at intron 23. RESULTS: A total of 82 variants were found: 70 VUS and 12 pathogenic or probably pathogenic variants. The diagnostic yield in actionable genes non-BRCA was 7.97% of the total tested ICs. Overall, 19 VUS were prioritized, which meant 27% of the 70 total VUS. RNA analysis of the variant 3402+3A > C confirmed a deleterious impact on splicing. DISCUSSION: The implementation of a multigene panel in HBOC studied families improved the diagnostic yield, concordant with results obtained in previous publications. Due to the important number of VUS obtained in NGS, the application of a prioritization algorithm is needed in order to select those variants in which it is necessary to conduct further studies.

Molecular characterization and clinical interpretation of BRCA1/BRCA2 variants in families from Murcia (south-eastern Spain) with hereditary breast and ovarian cancer: clinical-pathological features in BRCA carriers and non-carriers.

This is the first study performed in Murcia (south-eastern Spain) in which 592 families with hereditary breast and ovarian cancer were identified thanks to Genetic Counselling Units from this area over 6 years. Diagnostic performance was 18.1% and 194 different genetic variants were obtained. Variants with uncertain significance accounted for only 5.6% of the total number of reports, so our population has been well characterised. In BRCA1 gene, two novel variants were found (c.1859delT and c.3205C > T) and the most frequently detected mutations were c.68_69delAG, c.212 + 1G > A, c.5123C > A, c.211A > G and c.1918C > T, which together represented 56.67% of total pathogenic mutations. In BRCA2 gene, four recurrent variants were described (deletion of entire exon 2, c.9117G > A, c.3264dupT and c.3455T > G) representing 43.5% of the mutations in this gene. Mutation c.68_69delAG and deletion of entire exon 2 in BRCA1 and BRCA2 genes respectively were the most prevalent variants in our population. Regarding the genotype-phenotype relation, mutation c.212 + 1G > A appeared in an important percentage of breast and ovarian cancer cases, c.5123C > A in bilateral breast cancer and c.9117G > A in bilateral breast cancer and ovarian cancer. With respect to clinical-pathological characteristic, BRCA1/BRCA2 mutation carriers showed earlier onset age of breast tumour and higher risk of developing contra lateral breast cancer than non-informative cases. Moreover, association between either molecular subtype triple negative breast cancer or ovarian cancer and BRCA1 carriers was obtained.

Novel BRCA1 deleterious mutation (c.1918C>T) in familial breast and ovarian cancer syndrome who share a common ancestry.

Mutations in breast cancer susceptibility (BRCA) genes lead to defects in DNA repair processes resulting in elevated genome instability and predisposing to breast and ovarian cancer. We report a novel mutation (c.1918C>T) in the exon 11 of the BRCA1 gene that consists of a nonsense mutation that causes a stop codon downstream in the 640 position of the protein. The mutation was present in two Spanish unrelated families and was associated with four breast cancer cases, including two bilateral breast cancer (one of them synchronous). The median age/mean age (range) was 48.5/44.25 years (27-53). This finding led us to perform haplotype analysis in all family carriers. Four highly polymorphic microsatellite markers were used (17-3858, 17-3930, D17S855, D17S1326) to establish whether or not all these families had a common ancestor. This analysis showed that all mutation carriers of these families had a common haplotype. None of the noncarriers of the mutation or of the 24 healthy controls showed this haplotype. Therefore, the c.1918C>T mutation carriers from these two families allows us to assert that all analyzed mutation carriers share a common ancestry.

An unusual case of locally advanced glycogen-rich clear cell carcinoma of the breast.

Glycogen-rich clear cell (GRCC) is a rare subtype of breast carcinoma characterized by carcinoma cells containing an optically clear cytoplasm and intracytoplasmic glycogen. We present the case of a 55-year-old woman with a palpable mass in the right breast and clinical signs of locally advanced breast cancer (LABC). The diagnosis of GRCC carcinoma was based on certain histopathological characteristics of the tumor and immunohistochemical analysis. To our knowledge, this is the first case of GRCC LABC with intratumoral calcifications. There is no evidence of recurrence or metastatic disease after 14 months' follow-up.

Intertrigo-like eruption caused by pegylated liposomal doxorubicin (PLD).

Pegylated liposomal doxorubicin (PLD) is a drug whose use is increasingly common. It has been associated with a lower rate of haematologic and cardiac side effects than its nonencapsulated form. However, mucocutaneous toxicity is quite frequent and can be severe. Here we provide a case report of a patient who developed an intertrigolike eruption during treatment with PLD.