To describe patterns of initiation of androgen deprivation therapy (ADT) in a population-based cohort of patients with prostate cancer.
All patients with prostate cancer in Ontario, Canada, who started =90 days of ADT at age =66 years in 1995-2005 were classified by ADT regimen: medical castration [oestrogen and/or luteinizing hormone-releasing hormone (LHRH) agonist); orchidectomy; antiandrogen monotherapy; combined androgen blockade (CAB) medical (medical castration plus antiandrogen); CAB surgical (orchidectomy plus antiandrogen). Indications for ADT were as follows: neoadjuvant (short-term before prostatectomy or radiation therapy); adjuvant (long-term with prostatectomy or radiation therapy); metastatic disease; biochemical recurrence; primary (localized disease); other. We examined trends in ADT regimen and indication over time.
The number of patients initiating ADT increased from 1995 to 2001 (2106-2916 per year) and declined thereafter to 2200-2300 annually (total n= 26,809). However, prostate cancer prevalence doubled over these years, and the rate of ADT initiation decreased from 16 to 7 per 100 person-years. Patterns varied by regimen and indication. Medical castration increased from 12% of all ADT in 1995 to 47% in 2005; orchidectomy decreased from 17 to 4%. Use for metastatic disease remained stable, but adjuvant therapy increased from