Somatic mutations in BRCA1&2 in 201 unselected ovarian carcinoma samples - single institution study.

Ovarian cancer (OC) is the most lethal among gynecologic malignancies worldwide. Unfortunately, in around 70% of cases cancer is diagnosed in late stages (III-IV) which decreases the 5-year survival rate to 25%. The standard of care in ovarian cancer is debulking surgery followed by chemotherapy regimens based on platinum salts. Since 2014 PARP inhibitors became available for OC patients with germline or/and somatic mutations in BRCA1/2, including maintenance therapy. BRCA1/2 Next Generation Sequencing (NGS)-based analysis of formalin-fixed paraffin-embedded (FFPE) ovarian cancer samples becomes the standard of care. The aim of the present study was to evaluate the frequency of mutations in 201 unselected ovarian cancer tissues using the NGS method. In total, pathogenic mutations in both genes were detected in 24% (49/201) of the ovarian cancer cases tested. For 41 patients the results of testing of DNA isolated from blood sample revealed that 17% (35/201) mutations were germline origin, whereas 3% (6/201) mutations were somatic. In 4% (8/201) cases blood sample was inaccessible. The presence of pathogenic mutations was correlated with younger age at diagnosis and serous subtype. Close cooperation between many specialists (gynecologist, pathologist, oncologist, clinical genetics and molecular biologist) is indispensable for efficient and on-time BRCA1/2 ovarian tumor tissue testing.

BRCA1 founder mutations and beyond in the Polish population: A single-institution BRCA1/2 next-generation sequencing study.

Hereditary mutations in BRCA1/2 genes increase the risk of breast cancer by 60-80% and ovarian cancer by about 20-40% in female carriers. Detection of inherited mutations in asymptomatic carriers allows for the implementation of appropriate preventive measures. BRCA1/2 genotyping is also important for poly(adenosine diphosphate)-ribose polymerase (PARP) inhibitor administration. This work addresses the need for next-generation sequencing (NGS) technology for the detection of BRCA1/2 mutations in Poland where until recently mostly founder mutations have been tested, and whether BRCA diagnostics should be extended beyond the panel of founder mutations in this population. The study comprises 2931 patients who were referred for genetic counseling and tested for founder and recurrent mutations in BRCA1 (5382insC (c.5266dupC; p.Gln1756Profs), c.5370C>T (c.5251C>T; p.R1751*), 300T>G (c.181T>G; p.Cys61Gly), 185delAG (c.68_69delAG; p.Glu23Valfs), and 4153delA (c.4035delA; p.Glu1346Lysfs)) by high-resolution melting/Sanger sequencing. A total of 103 (3.5%) mutations were detected, including 53 (51%) in healthy subjects and 50 (49%) in cancer patients. Then, based on more stringent clinical and pedigree criteria, sequencing of all BRCA1/2 exons was performed in 454 (16%) patients without founder mutations by NGS, which detected 58 mutations (12.8%), 40 (8.8%) of which were pathogenic. In 14 (3.1%) subjects, variants of uncertain significance (VUS) were detected, and in four (0.9%) subjects, the detected mutations were benign. In total, 161 mutations were detected using our two-step algorithm (founder test and NGS), of which 64% were founder mutations, 25% were NGS-detected pathogenic mutations, 9% were VUS, and 2% were benign. In addition, 38 mutations not yet reported in the Polish population were detected. In total, founder mutations accounted for only 64% of all detected mutations, and the remaining mutations (36%) were dispersed across the BRCA1/2 gene sequences. Thus, in Poland, testing for constitutional mutations in BRCA1/2 should be carried out in two stages, where NGS is performed in qualifying subjects if founder mutations are not identified.