1. Early development of castrate resistance varies with different dosing regimens of luteinizing hormone releasing hormone agonist in primary hormonal therapy for prostate cancer
- Author
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Jeremy M Blumberg, Judith Pacificar, Stephen G. Williams, Fang Niu, Gary W. Chien, Ronald K. Loo, Eric O. Kwon, T. Craig Cheetham, and Charles E. Shapiro
- Subjects
Male ,medicine.medical_specialty ,Time Factors ,Antineoplastic Agents, Hormonal ,Urology ,Lower risk ,Gonadotropin-Releasing Hormone ,Prostate cancer ,Prostate ,Internal medicine ,medicine ,Humans ,Dosing ,Testosterone ,Aged ,Retrospective Studies ,business.industry ,Prostatic Neoplasms ,medicine.disease ,Cancer registry ,Regimen ,Endocrinology ,medicine.anatomical_structure ,Drug Resistance, Neoplasm ,Hormonal therapy ,Leuprolide ,business - Abstract
Objectives Luteinizing hormone releasing hormone (LHRH) agonist therapy is one of the mainstays of prostate cancer treatment. Three dosing regimens currently exist: calendar-based, intermittent, and a testosterone (T)-based (T-based) regimen. We investigated the differences in development of early castrate resistance rates between these different regimens. Methods We evaluated 1617 patients with prostate cancer who received LHRH-agonist monotherapy in the Kaiser Permanente Southern California Cancer Registry between January 2003 and December 2006. Patients who had undergone surgery and/or radiation were excluded. Patients were grouped according to their dosing regimen: calendar-based, intermittent dosing, and T-based. Cox proportional hazard-regression analysis was used to estimate the hazards ratio (HR) for treatment failure. Results A total of 692 patients who received an LHRH agonist as primary monotherapy for prostate cancer fit our criteria. Calendar-based dosing was used in 325 patients; 252 received T-based dosing and 115 received intermittent dosing. On multivariate analysis controlling for demographic and prostate cancer–related variables, the T-based dosing group showed a significantly lower relative risk of treatment failure (HR = 0.65, P = .02). The intermittent-dosing group trended toward a lower risk treatment failure (HR = 0.80, P = .3). Among the variables analyzed, only a Gleason score >8 (HR = 2.05, P = .01) and a pretreatment prostate-specific antigen >20 (HR = 2.00, P
- Published
- 2010