15635 Background: IADT is a therapeutic option frequently utilized in men with progressive non-castrate prostate cancer (PCa) which, compared to continuous ADT, may result in an improvement in quality of life while potentially prolonging time to androgen independence (AI). Methods: The records of 43 consecutive men with non-metastatic progressive non-castrate PCa treated with IADT were analyzed. 21 men had received no prior primary treatment (tx), and 22 had developed recurrent disease after previous local therapy. Therapy for this cohort of patients (pts) consisted of combined androgen blockade for 32 pts and a leutenizing hormone-releasing hormone agonist alone for 11. Pts were allowed to come off androgen deprivation (AD) when (a) PSA became undetectable, (b) after 9 to 12 months (mos) of receiving AD, (c) or per patient request. AD was re-initiated when (a) serum PSA reached 50% or greater of the pre-tx level, (b) at physician discretion, or (c) at patient's request. A tx cycle was defined as the number of months on tx plus the number of months off tx until the reinstitution of AD. Progressive disease and AI were defined by consensus criteria (climbing PSA despite AD). Results: Follow up ranged from 18 to 153 mos (median 68.2 mos) from the start of tx. Pts received from 1 to 10 cycles (median 4), with a median cycle length of 19 mos. The median pre-tx PSA value was 8.9, and the median nadir serum PSA level with ADT was 0.09 and was reached within an average of 6.4 mos (range 2–25) after beginning tx. Pts spent an average of 50.7% of time on hormones and 49.3% off hormones. Eleven pts developed AI progressive disease, with a median time to progression of 47 mos. When examining for potential characteristics that contributed to AI, such as duration of ADT, PSA at start of therapy, nadir PSA, stage, or Gleason score, no consistent patterns of failure emerged. Conclusions: IADT appears to be a viable tx option for men with non-metastatic progressive non-castrate PCa, resulting in prolonged duration of response. However, with a median follow up of nearly 6 years, AI still develops in over a quarter of pts, at a median of 47 months from starting ADT. No significant financial relationships to disclose.