In October 2020, clinical studies led to the registration by the European Regulatory Agency EMA (European Medicines Agency) of the PARP inhibitor olaparib “indicated, in monotherapy, for the treatment of adult patients with castration-resistant metastatic prostate cancer with BRCA1/BRCA2 gene mutations (germline PV and/or somatic PV), progressing after previous treatment including a new hormonal agent” (https://www.ema.europa.eu/en/documents/product-information/lynparza-epar-product-information_it.pdf (accessed on 30 March 2023)). This evidence concerns the gene BRCA2 and acquired polycythemia vera.