Should androgen-deprivation therapy be given at the same time or before radiotherapy in the treatment of localized prostate cancer?

The study looked at the sequence of dose-escalated radiotherapy (RT) and androgen-deprivation therapy (ADT) in the treatment of local prostate cancer (LPCa). The study found that treatment with ADT before RT had the same outcome as treatment with ADT and RT at the same time. 

LPCa is a form of cancer that is localized to the prostate gland. The current treatment for LPCa is dose-escalated RT. This means giving increasing doses of radiation to kill cancer cells. Despite initial success, LPCa has a high recurrence rate. 

ADT is the standard care for advanced prostate cancer. ADT is a hormonal therapy used to reduce the amount of androgens (male sex hormones such as testosterone) that are produced or decrease their effect on cancer cells. Bicalutamide (Casodex) and goserelin (Zoladex) are both used in ADT.

ADT is added to a dose-escalated RT regime in order to reduce the recurrence rate of LPCa. However, the order these therapies should be given for the best outcomes is still unknown.

This study included 432 patients with newly diagnosed LPCa. 215 patients were assigned to arm A. These patients received 4 months of ADT, followed by 2 months of both RT and ADT. The other 217 patients in arm B received ADT and RT together for the first 2 months and continued another 4 months with ADT. The average follow-up period was 146 months. ADT included bicalutamide 50mg once daily plus goserelin injections. Patients received 38 RT doses over 7.5 weeks. 

The average 10-year biochemical relapse-free survival (bRFS) between both groups was 83.6%. BRFS is the percentage of patients alive without signs of prostate cancer blood markers rising. There was no significant difference in the bRFS between both groups (80.5% – arm A vs 87.4% – arm B). The 10-year overall survival rate was 76.4% in arm A and 73.7% in arm B.

The occurrence of side effects related to RT was also similar between arms. 2.5% of patients in arm A and 3.9% in arm B experienced serious bowel-related side effects after 3 years. 2.9% of patients in each group experienced serious urinary side effects after 3 years.

The authors concluded that ADT before beginning treatment with RT had the same outcome as ADT given at the same time as RT. 

This study was supported by AstraZeneca which manufactures bicalutamide and goserelin.