Although PARPi-induced killing effect on tumor cells might contribute to the relative increase of the stromal component, desmoplastic histological characteristics, such as increased interstitial spaces, excessive ECM deposition, and obvious derangement of stromal cells, suggested that PARPis exerted a pro-activation role in stromal fibroblasts in both BRCA1/2-wild type and BRCA1/2-mutant xenograft models. This evidence concerns the gene BRCA1 and neoplasm.