title: Prior estrogen therapy as a predictor of response to subsequent estramustine-based chemotherapy in patients with androgen-independent prostate cancer.
abstract: BACKGROUND
  Hormone-refractory prostate cancer (HRPC) has modest response rates to second-line estrogenic agents such as diethylstilbestrol and the herbal product PC SPES. Estramustine phosphate (EMP) is a microtubule inhibitory agent with estrogenic properties commonly used in patients with metastatic HRPC. To determine whether previous response to second-line estrogen therapy would predict subsequent response to EMP-based chemotherapy, a retrospective study was conducted.
  
  
  METHODS
  Patients with HRPC previously treated with second-line estrogenic therapy who subsequently received EMP-based chemotherapy were enrolled in a retrospective analysis. The progression of disease or response to treatment was determined with use of standard prostate-specific antigen (PSA) criteria and Response Evaluation Criteria in Solid Tumors.
  
  
  RESULTS
  Seventy-eight patients were included in the analysis. Twenty-five patients with disease progression after receiving estrogen therapy received subsequent EMP-based chemotherapy. Overall, initial PSA response to any estrogen therapy was 54%. The overall PSA response to EMP-based chemotherapy was 60%, and the objective response was 36%. The PSA response to subsequent EMP-based chemotherapy was independent of patients having a previous response to estrogen therapy (70% vs. 53%; P = 0.68). The median overall survival for patients receiving estrogenic therapy and subsequent EMP-based chemotherapy was 12.7 months.
  
  
  CONCLUSIONS
  Previous response to second-line hormonal maneuvers with estrogen therapy does not predict subsequent response to EMP-based chemotherapy.
authors.affiliation: Department of Medicine, University of California San Francisco Comprehensive Cancer Center, USA. garciaj4@ccf.org
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Garcia
authors.forename: Vivian
authors.initials: V
authors.lastname: Weinberg
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Small
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000009:adverse effects / Q000627:therapeutic use*; D000972:Antineoplastic Agents, Phytogenic / Q000009:adverse effects / Q000627:therapeutic use; D004054:Diethylstilbestrol / Q000009:adverse effects / Q000627:therapeutic use*; D018450:Disease Progression; D004365:Drugs, Chinese Herbal / Q000009:adverse effects / Q000627:therapeutic use*; D004961:Estramustine / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000188:drug therapy*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D000972:Antineoplastic Agents, Phytogenic; D004365:Drugs, Chinese Herbal; C114209:herbal preparation PC-SPES; D004961:Estramustine; D004054:Diethylstilbestrol; D017430:Prostate-Specific Antigen