Identification of BRCA1-deficient ovarian cancers.

Objective. It is believed that 24 - 40% of ovarian cancers have dysfunction in the BRCA1 or BRCA2 (BRCAness) genes, either due to inherited or somatic mutations or due to epigenetic inactivation. Demonstration of ovarian cancers with BRCAness is becoming important both due to the possibility of offering genetic counseling and due to beneficial effects of PARP inhibitor treatment in this group. Since DNA sequencing is expensive and time-consuming efforts have been devoted to develop more indirect methods for BRCA screening that can improve the selection of patients for sequence-based BRCA testing. Design. BRCA1-immunohistochemistry (IHC), fluorescence in-situ hybridization (FISH) and methylation analyses were performed on formalin-fixed, paraffin-embedded ovarian cancer tissue. Sample: 54 ovarian cancers; 15 BRCA1 cancers, 4 BRCA2 cancers, 10 cancers from patients with a family history but no mutation detected, and 25 ovarian cancers with unknown BRCA1 status. Results. Abnormal BRCA1 IHC was found to indicate BRCA mutations with a sensitivity of 80%, a specificity of 93%, and an estimated positive predictive value of 73%. FISH analyses supported the diagnosis in most cases. Methylation analyses could indicate BRCA deficiency in combination with one of the other methods. Conclusions. BRCA1 IHC is a promising screening method for BRCA1 mutation detection.