Age at diagnosis on prostate cancer survival undergoing androgen deprivation therapy as primary treatment in daily practice: Results from Japanese observational cohort

Objectives: Primary androgen deprivation therapy (PADT) had been used extensively in Japan than in the USA and European countries regardless of the disease risk or patient's age. To illustrate the consequence of PADT from daily clinical practice, we evaluated the relationship among age, disease risk, and survival of patients with prostate cancer treated by PADT in largest Asian cohort. Patients and methods: The 19,246 men subjected to PADT enrolled in the Japan Study Group of Prostate Cancer were enrolled for the present analysis. Patients were divided into four groups based on age at diagnosis: age <66, 66-70, 71-75, and >75. Risk was stratified according to the Japan Cancer of the Prostate Risk Assessment (J-CAPRA). Multivariate competing risks regression analysis was performed for OS and PFS. Results: There was downward stage migration over age. Among men aged >75 years, 34.1 % had nodal or distant metastatic disease. In contrast, 56.0 % of patients aged <66 years presented with advanced disease. The modality of hormonal therapy varied with age across risk groups; the younger age group showed a higher proportion of maximal androgen blockade, while the proportion of monotherapy use was higher in older men. The likelihood of low-risk disease by J-CAPRA classification increased significantly with increasing age (p < 0.0001 by Pearson's chi-square test). The same as OS, the PFS rate increased with age until after the age of 75. Men aged 71-75 had better survival rates even after adjustments for treatment modality alone, or for treatment modality plus disease risk. Conclusions: Age cohorts do affect orientation toward favorable disease course after PADT with men aged 71-75 being benefiting more from PADT than other age groups.