This study used linked, routinely-collected datasets to explore incidence, clinical characteristics and outcomes of prostate cancer (PC) patients who experience a rise in prostate-specific antigen (PSA) levels despite androgen deprivation therapy (ADT), without evidence of metastases in their patient record, termed non-metastatic castration-resistant PC (nmCRPC). This evidence concerns the gene KLK3 and pachyonychia congenita.