Prevalent and incident use of androgen deprivation therapy among men with prostate cancer in the United States.

PURPOSE: Androgen deprivation therapy (ADT) for prostate cancer increased substantially through the 1990s, but more recent national trends regarding incident and prevalent use have been incompletely characterized.
METHODS: Linked Surveillance, Epidemiology, and End Results (SEER)-Medicare data were used to study patterns of ADT utilization. Prevalence of ADT in the male Medicare population was estimated by examining a cohort of prostate cancer patients and a 5% noncancer control population, from 1991 to 2005. ADT use across different indications was examined for men with incident cancers from 2000 to 2002. Nested logit models were used to examine determinants of ADT use in men with lower risk prostate cancer not treated definitively by surgery or radiation.
RESULTS: Prevalent ADT use increased through the 1990s, peaked in 2000 at 3.17% of all male Medicare beneficiaries, subsequently stabilized, then dropped in 2005 to 2.92%. Between 2000 and 2002, use in incident prostate cancer was stable, with 44.8% use in all cases, 15% of cases as an adjuvant with radiation, and 14% as a primary therapy. In the nested logit model, predictors of ADT use in a lower risk setting were older age, higher stage and grade, and elevated prostate-specific antigen levels.
CONCLUSIONS: Following a period of rapid expansion during the 1990s, incident and prevalent use of ADT has leveled, and may be starting to decline. Further research is needed to monitor how reductions in reimbursement for GnRH agonists will affect appropriate use of ADT as well as use in settings where its benefits may be marginal.