Primary androgen deprivation therapy as monotherapy in unfavourable intermediate- and high-risk localised prostate cancer: a Singaporean single-centre perspective.

PURPOSE: Primary ADT (pADT) monotherapy is used significantly for patients with clinically localised disease in Asia and is acceptable even by guidelines, especially in intermediate- and high-risk disease. This occurs despite controversy in the West and data suggesting association with adverse effects, notably cardiovascular events. We therefore sought to assess the impact of pADT on all-cause mortality and prostate cancer-specific mortality (PCSM) in Asian men with high-risk and unfavourable intermediate-risk PCa.

METHODS: With cancer registry data, men from a single centre in Singapore with clinically localised high-risk/unfavourable intermediate-risk PCa diagnosed between 2004 and 2014 and either treated conservatively with no therapy or started on pADT within 1 year of diagnosis were followed up through January 2017. Patients with non-localised PCa (clinical stage T4, regional/distant lymph node involvement, metastases), or receipt of local therapy (radical prostatectomy/radiotherapy) were excluded. The primary outcomes of all-cause mortality and PCSM were analysed with Cox proportional hazards regression models.

RESULTS: Three hundred and forty Asian men were analysed, and 177 (52.1%) were started on pADT, with mean age of 77 (49-98) years. There were 119 deaths in the cohort, and 68 (38.4%) occurred in patients treated with pADT (median follow-up, 4.4 years). After adjusting for comorbidities and clinical characteristics, pADT did not provide benefit to all-cause mortality, PCSM or cardiovascular mortality.

CONCLUSION: For clinically localised unfavourable intermediate-risk and high-risk PCa, starting pADT within 12 months of diagnosis is not associated with improved 5-year all-cause mortality or PCSM compared to patients treated conservatively with no therapy and should be discouraged due to lack of mortality benefit.