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The subset of ovarian cancer (OC) diagnosed ≤ 30yo represents a distinct subgroup exhibiting disparities from late-onset OC in many aspects, including indefinite germline cancer predisposition. We performed DNA/RNA-WES with HLA-typing, PRS assessment and survival analysis in 123 early-onset OC-patients compared to histology/stage-matched late-onset and unselected OC-patients, and population-matched controls. Only 6/123(4.9%) early-onset OC-patients carried a germline pathogenic variant (GPV) in high-penetrance OC-predisposition genes. Nevertheless, our comprehensive germline analysis of early-onset OC-patients revealed two divergent trajectories of potential germline susceptibility. Firstly, overrepresentation analysis highlighted a connection to breast cancer (BC) that was supported by the CHEK2 GPV enrichment in early-onset OC(p = 1.2 × 10 -4 ), and the presumably BC-specific PRS 313 , which successfully stratified early-onset OC-patients from controls(p = 0.03). The second avenue pointed towards the impaired immune response, indicated by LY75-CD302 GPV(p = 8.3 × 10 -4 ) and diminished HLA diversity compared with controls(p = 3 × 10 -7 ). Furthermore, we found a significantly higher overall GPV burden in early-onset OC-patients compared to controls(p = 3.8 × 10 -4 ). The genetic predisposition to early-onset OC appears to be a heterogeneous and complex process that goes beyond the traditional Mendelian monogenic understanding of hereditary cancer predisposition, with a significant role of the immune system. We speculate that rather a cumulative overall GPV burden than specific GPV may potentially increase OC risk, concomitantly with reduced HLA diversity., (© 2024. The Author(s).)

Ovarian cancer (OC) is the deadliest gynecologic malignancy with a substantial proportion of hereditary cases and a frequent association with breast cancer (BC). Genetic testing facilitates treatment and preventive strategies reducing OC mortality in mutation carriers. However, the prevalence of germline mutations varies among populations and many rarely mutated OC predisposition genes remain to be identified. We aimed to analyze 219 genes in 1333 Czech OC patients and 2278 population-matched controls using next-generation sequencing. We revealed germline mutations in 18 OC/BC predisposition genes in 32.0% of patients and in 2.5% of controls. Mutations in BRCA1/BRCA2 , RAD51C/RAD51D , BARD1 , and mismatch repair genes conferred high OC risk (OR > 5). Mutations in BRIP1 and NBN were associated with moderate risk (both OR = 3.5). BRCA1/2 mutations dominated in almost all clinicopathological subgroups including sporadic borderline tumors of ovary (BTO). Analysis of remaining 201 genes revealed somatic mosaics in PPM1D and germline mutations in SHPRH and NAT1 associating with a high/moderate OC risk significantly; however, further studies are warranted to delineate their contribution to OC development in other populations. Our findings demonstrate the high proportion of patients with hereditary OC in Slavic population justifying genetic testing in all patients with OC, including BTO.

Background: Currently, more than 200 hereditary cancer syndromes have been described, yet, in most countries genetic testing is restricted to a narrow spectrum of genes within a limited group of people tested., Methods: For this retrospective study we used the TruSight cancer panel (Illumina)--NGS panel targeting 94 cancer predisposition genes in order to analyze 50 high-risk cancer patients with significant personal and family history of cancer who did not carry mutations in BRCA1, BRCA2, MLH1, MSH2, MSH6, TP53 or APC genes. All pathogenic and potentially pathogenic mutations detected by NGS technology have been confirmed by Sanger sequencing., Results: There were several deleterious (frame-shift/nonsense) mutations detected in ATM, BAP1, FANCC, FANCI, PMS2, SBDS, ERCC2, RECQL4 genes. Various pathogenic or potentially pathogenic (missense, predicted splice site, in-frame insertion/deletion) mutations were detected in ATM, BRIP1, CDH1, CHEK2, ERCC2, ERCC3, ERCC4, FANCA, MC1R, MEN1, MRE11A, MUTYH, PALB2, RAD51C, RET, SDHB, STK11. These mutations affect highly conserved protein domains and affect their function as proved by the available functional assays. They were confirmed to be pathogenic as an "Parent No2 " in serious recessive diseases such as Ataxia telangiectasia or Fanconi anemia. The clinical significance of the majority of detected missense variants still remains to be identified., Conclusion: Moderate or low penetrance variants are of limited clinical importance. Panel genetic testing in high-risk individuals with cancer provides important information concerning the cause of the investigated cancer, and may assist in the risk assesment and optimal management of the cancer, as well as in further preventive care.

Hereditary cancer syndromes are frequently seen in young cancer patients and patients with a positive family history. Genetic testing is important for the identification of high-risk individuals, and for the early introduction of specialized preventive care or prophylactic surgeries. High-risk tumour suppressor genes (BRCA1 and BRCA2) and DNA repair genes (MLH1, MSH2 and MSH6) are responsible for a substantial part of hereditary breast, ovarian and colorectal cancer. Other hereditary cancers are seen less frequently, but genetic testing has increased for many other site-specific cancers and complex syndromes. Genetic centres and molecular genetic laboratories are located mostly within university or regional hospitals. Some genetic centres are private. It is highly recommended (Czech Society for Medical Genetics) that all laboratories are accredited according to ISO 15,189 and that genetic testing of hereditary cancer syndromes is indicated by medical geneticists. The indication criteria and prevention strategies were published in Supplement 22 of Clinical Oncology 2009 (in Czech). Preventive care for high-risk individuals is organized by thirteen Oncology Centres, which provide most of the oncology care in the Czech Republic. Genetic testing and preventive care for high-risk individuals and mutation carriers is covered by health insurance. The molecular genetic laboratory at the MMCI provides molecular genetic testing of BRCA1, BRCA2, CHEK2 for hereditary breast/ovarian cancer, MLH1, MSH2, MSH6 for Lynch syndrome,TP53 for Li-Fraumeni syndrome, CDKN2A for familial malignant melanoma syndrome and CDH1 gene for hereditary diffuse gastric cancer. Other syndromes are tested in specialized laboratories elsewhere.The use of genetic testing is increasing because of more frequent referrals from oncologists and other specialists and the increasing variety of genes tested. However, in some patients the testing is not recommended and other family members are dying because of the late diagnosis of hereditary syndrome. Greater awareness of the importance of genetic testing in oncology is needed.