Philipp Harter, Jan Hauke, Florian Heitz, Alexander Reuss, Stefan Kommoss, Frederik Marmé, André Heimbach, Katharina Prieske, Lisa Richters, Alexander Burges, Guido Neidhardt, Nikolaus de Gregorio, Ahmed El-Balat, Felix Hilpert, Werner Meier, Rainer Kimmig, Karin Kast, Jalid Sehouli, Klaus Baumann, Christian Jackisch, Tjoung-Won Park-Simon, Lars Hanker, Sandra Kröber, Jacobus Pfisterer, Heidrun Gevensleben, Andreas Schnelzer, Dimo Dietrich, Tanja Neunhöffer, Mathias Krockenberger, Sara Y. Brucker, Peter Nürnberg, Holger Thiele, Janine Altmüller, Josefin Lamla, Gabriele Elser, Andreas du Bois, Eric Hahnen, Rita Schmutzler

• Background Identification of families at risk for ovarian cancer offers the opportunity to consider prophylactic surgery thus reducing ovarian cancer mortality. So far, identification of potentially affected families in Germany was solely performed via family history and numbers of affected family members with breast or ovarian cancer. However, neither the prevalence of deleterious variants in \(BRCA1/2\) in ovarian cancer in Germany nor the reliability of family history as trigger for genetic counselling has ever beenBackground Identification of families at risk for ovarian cancer offers the opportunity to consider prophylactic surgery thus reducing ovarian cancer mortality. So far, identification of potentially affected families in Germany was solely performed via family history and numbers of affected family members with breast or ovarian cancer. However, neither the prevalence of deleterious variants in \(BRCA1/2\) in ovarian cancer in Germany nor the reliability of family history as trigger for genetic counselling has ever been evaluated. Methods Prospective counseling and germline testing of consecutive patients with primary diagnosis or with platinum-sensitive relapse of an invasive epithelial ovarian cancer. Testing included 25 candidate and established risk genes. Among these 25 genes, 16 genes (\(ATM\), \(BRCA1\), \(BRCA2\), \(CDH1\), \(CHEK2\), \(MLH1\), \(MSH2\), \(MSH6\), \(NBN\), \(PMS2\), \(PTEN\), \(PALB2\), \(RAD51C\), \(RAD51D\), \(STK11\), \(TP53\)) were defined as established cancer risk genes. A positive family history was defined as at least one relative with breast cancer or ovarian cancer or breast cancer in personal history. Results In total, we analyzed 523 patients: 281 patients with primary diagnosis of ovarian cancer and 242 patients with relapsed disease. Median age at primary diagnosis was 58 years (range 16–93) and 406 patients (77.6%) had a high-grade serous ovarian cancer. In total, 27.9% of the patients showed at least one deleterious variant in all 25 investigated genes and 26.4% in the defined 16 risk genes. Deleterious variants were most prevalent in the \(BRCA1\) (15.5%), \(BRCA2\) (5.5%), \(RAD51C\) (2.5%) and \(PALB2\) (1.1%) genes. The prevalence of deleterious variants did not differ significantly between patients at primary diagnosis and relapse. The prevalence of deleterious variants in \(BRCA1/2\) (and in all 16 risk genes) in patients <60 years was 30.2% (33.2%) versus 10.6% (18.9%) in patients \(\geq\)60 years. Family history was positive in 43% of all patients. Patients with a positive family history had a prevalence of deleterious variants of 31.6% (36.0%) versus 11.4% (17.6%) and histologic subtype of high grade serous ovarian cancer versus other showed a prevalence of deleterious variants of 23.2% (29.1%) and 10.2% (14.8%), respectively. Testing only for \(BRCA1/2\) would miss in our series more than 5% of the patients with a deleterious variant in established risk genes. Conclusions 26.4% of all patients harbor at least one deleterious variant in established risk genes. The threshold of 10% mutation rate which is accepted for reimbursement by health care providers in Germany was observed in all subgroups analyzed and neither age at primary diagnosis nor histo-type or family history sufficiently enough could identify a subgroup not eligible for genetic counselling and testing. Genetic testing should therefore be offered to every patient with invasive epithelial ovarian cancer and limiting testing to \(BRCA1/2\) seems to be not sufficient.…