Researchers at the The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, Maryland studied the relationship between the change of PSA doubling time (PSADT) and disease progression during intermittent androgen deprivation (IAD) therapy for prostate cancer.

They retrospectively analyzed the data from 96 men diagnosed with biochemically relapsed prostate cancer (BRPC) who were treated with IAD. The IAD consisted of LHRH-agonists?±?antiandrogen given usually at PSA threshold (ng/ml) of 10-20, for “on” periods of 6-9 months. Cycles were repeated until the development of castration resistance.

Mixed effects model was used to study PSADT change over cycles. Multivariate cox regression model was used to identify outcome-associated variables.

Men received a mean of 2.8 treatment cycles over a mean follow-up time of 71 months. Fifty-seven (59%) remain on treatment and 39 men (41%) developed PSA refractoriness (n?=?8) or positive scans (n?=?31).

1- First off treatment interval PSADT (median 2.3 months) was significantly shorter than the baseline (median 7.34) but remained stable in subsequent cycles.
2- Off treatment interval PSADT adjusted for testosterone recovery (median 3.7) was significantly longer than that based on all PSA determinations (median 2).
3- Factors associated with disease progression were pre-treatment PSADT (?6 vs. < 6), first off treatment interval PSADT (?3 vs. < 3), and PSA nadir during the first treatment interval (< 0.1 vs. ?0.1).During intermittent androgen therapy for biochemically recurring prostate cancer the PSA doubling time becomes shorter, and is associated with testosterone recovery.PSADT before treatment and during the first off treatment interval is associated with disease progression.These findings need to be prospectively validated, If validated this data may may be valuable in guiding both treatment with IAD and clinical trial design.Prostate. 2011 Mar 22. Epub ahead of print. doi: 10.1002/pros.21377; Keizman D, Huang P, Antonarakis ES, Sinibaldi V, Carducci MA, Denmeade S, Kim JJ, Walczak J, Eisenberger MA.PubMed Abstract PMID: 21432863Joel T Nowak, M.A., M.S.W.