Primary antibodies were diluted in 1% goat serum/0.1% BSA/PBS (MAD2L1, Santa Cruz Biotechnology, 1:50 cat n. sc-374131, Clone C-10; cleaved PARP, Abcam 1:6,000 cat n. ab4830; BRCA1, Calbiochem, 1:100 cat n. OP92, clone MS110). All antibodies were incubated at 4 C overnight. The Novolink Polymer Detection Kit (cat n. RE7150-CE, Leica) was used according to the manufacturer's instructions. Sections were counterstained with hematoxylin and mounted using Leica Sub-X mounting medium (Leica). Images were taken on a Hamamatsu Nanozoomer Digital slide scanner. For BRCA1, automated staining has been performed on the Leica Bond III platform and the Leica Bond Polymer Refine DAB was used for detection.
The scoring was carried out by a pathologist with orthogonal validation using image process by Qupath (14) . BRCA1-positive tumors were defined as those demonstrating >10% of cells with nuclear staining (7) . MAD2L1-positive tumors were defined as those demonstrating >10% of cells with either nuclear or cytoplasmic staining (15) . IHC staining of cleaved PARP was scored as percentage of cells with nuclear staining.
The scoring was carried out by a pathologist with orthogonal validation using image process by Qupath (14) . BRCA1-positive tumors were defined as those demonstrating >10% of cells with nuclear staining (7) . MAD2L1-positive tumors were defined as those demonstrating >10% of cells with either nuclear or cytoplasmic staining (15) . IHC staining of cleaved PARP was scored as percentage of cells with nuclear staining.