Prostate cancer incidence and mortality in most native Asian populations have gradually increased, but are around one-third lower than in corresponding Asian-American cohorts, which are themselves lower than the rates observed in other American cohorts. Although genetic and environmental factors, particularly a Western diet, could partially explain these differences, lower exposure to PSA screening in Asian individuals might be a major contributing factor. Genetic features and diet are, however, unlikely to differ substantially within the same region of Asia, and age-stratified PSA levels in men from various Asian countries are almost identical; therefore, variation in the epidemiology of prostate cancer among native Asian populations might be attributable to differences in access to PSA testing, urology clinics, and available therapies. Conversely, the proportion of patients with metastatic prostate cancer is substantially higher even in the more developed Asian countries than in migratory Asian populations residing in Western countries and in Westerners. Consequently, the most appropriate approaches to the management of prostate cancer in Asian countries probably also differ, and therefore individualized prostate cancer screening and treatment strategies based on the epidemiological features and socioeconomic status of each country are needed.

A B S T R A C T PurposeProstate cancer epidemiology has been marked overall by a downward risk migration over time. However, in some populations, both in the United States and abroad, many men are still diagnosed with high-risk and/or advanced disease. Primary androgen deprivation therapy (PADT) is frequently offered to these patients, and disease risk prediction is not well-established in this context. We compared risk features between large disease registries from the United States and Japan, and aimed to build and validate a risk prediction model applicable to PADT patients. MethodsData were analyzed from 13,740 men in the United States community-based Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) registry and 19,265 men in the Japan Study Group of Prostate Cancer (J-CaP) database, a national Japanese registry of men receiving androgen deprivation therapy. Risk distribution was compared between the two datasets using three well-described multivariable instruments. A novel instrument (Japan Cancer of the Prostate Risk Assessment [J-CAPRA]) was designed and validated to be specifically applicable to PADT patients, and more relevant to high-risk patients than existing instruments. ResultsJ-CaP patients are more likely than CaPSURE patients to be diagnosed with high-risk features; 43% of J-CaP versus 5% of CaPSURE patients had locally advanced or metastatic disease that could not be stratified with the standard risk assessment tools. J-CAPRA-scored 0 to 12 based on Gleason score, prostate-specific antigen level, and clinical stage-predicts progression-free survival among PADT patients in J-CaP with a c-index of 0.71, and cancer-specific survival among PADT patients in CaPSURE with a c-index of 0.84. ConclusionThe novel J-CAPRA is the first risk instrument developed and validated for patients undergoing PADT. It is applicable to those with both localized and advanced disease, and performs well in diverse populations.