title: A multi-centre randomised phase III trial of Dexamethasone vs Dexamethasone and diethylstilbestrol in castration-resistant prostate cancer: immediate vs deferred Diethylstilbestrol.
abstract: BACKGROUND
  The role of further hormone therapy in castration-resistant prostate cancer (CRPC) remains unclear. We performed a multi-centre randomised phase III study comparing the use of Dexamethasone, Aspirin, and immediate addition of Diethylstilbestrol (DAiS) vs Dexamethasone, Aspirin, and deferred (until disease progression) addition of Diethylstilbestrol (DAdS).
  
  
  METHODS
  From 2001 to 2008, 270 men with chemotherapy-naive CRPC were randomly assigned, in a 1 : 1 ratio, to receive either DAiS or DAdS. They were stratified for performance status, presence of bone metastases, and previous normalisation of prostate-specific antigen (PSA) to androgen deprivation. The study end points were the proportion of patients achieving a 50% PSA response, progression-free survival (PFS), overall survival, and quality of life. Intention-to-treat analysis was carried out. The effect of treatment was studied first by Kaplan-Meier curves and log-rank test, and finally through multivariable stratified Cox's proportional hazards model adjusting for the effects of possible baseline prognostic factors. Quality of life was analysed using multivariate analysis of variance.
  
  
  RESULTS
  At study entry, the median age was 76 years (inter-quartile range: 70-80 years), the median PSA was 79 ng ml(-1), and 76% of the cohort had metastatic disease. The response rates for DAiS (68%) and DAdS (64%) were not significantly different (P=0.49). Similar to the response rate, neither the PFS (median=8.1 months for both arms) nor the overall survival (19.4 vs 18.8 months) differed significantly between the DAiS and DAdS groups (P>0.20). However, the response rate for the DAiS (68%) was significantly higher than the response rate of DA (before adding Diethylstilbestrol) (50%) (P=0.002). Similarly, the median time to progression for DAiS (8.6 months) was significantly longer than that of DA (4.5 months) (P<0.001). Multivariable analysis showed that patients with previous haemoglobin ≥11 g dl(-1) decreased the risk of death significantly (hazard ratio: 0.44, 95% CI: 0.25-0.77). Patients treated with previous anti-androgens alone had more than 5 times more risk of death compared with patients treated with gonadorelin analogues throughout their castration-sensitive phase. Treatment sequencing did not affect the quality of life but pre-treatment performance status did. The incidence of veno-thromboembolic events was 22% (n=28) in DAiS and 11% (n=14) in the DA arm (P=0.02). Painful gynaecomastia occurred in only 1% on DA, whereas in 40% on DAiS (P=0.001).
  
  
  CONCLUSIONS
  Dexamethasone and immediate Diethylstilbestrol resulted in neither higher PSA response rate nor higher PFS compared with Dexamethasone with deferred Diethylstilbestrol. There was no suggestion of significantly improved overall survival or quality of life. Given the significantly higher toxicity of Diethylstilbestrol, deferring Diethylstilbestrol until failure of Dexamethasone is the preferred strategy when using these agents in CRPC.
authors.affiliation: St Bartholomew's Hospital, 7th Floor, Gloucester House, Little Britain, UK. jonathan.shamash@bartsandthelondon.nhs.uk
authors.forename: J
authors.initials: J
authors.lastname: Shamash
authors.forename: T
authors.initials: T
authors.lastname: Powles
authors.forename: S J
authors.initials: SJ
authors.lastname: Sarker
authors.forename: A
authors.initials: A
authors.lastname: Protheroe
authors.forename: N
authors.initials: N
authors.lastname: Mithal
authors.forename: R
authors.initials: R
authors.lastname: Mills
authors.forename: R
authors.initials: R
authors.lastname: Beard
authors.forename: P
authors.initials: P
authors.lastname: Wilson
authors.forename: N
authors.initials: N
authors.lastname: Tranter
authors.forename: N
authors.initials: N
authors.lastname: O'Brien
authors.forename: S
authors.initials: S
authors.lastname: McFaul
authors.forename: T
authors.initials: T
authors.lastname: Oliver
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000008:administration & dosage / Q000009:adverse effects; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage / Q000009:adverse effects; D002277:Carcinoma / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D003907:Dexamethasone / Q000008:administration & dosage* / Q000009:adverse effects; D004054:Diethylstilbestrol / Q000008:administration & dosage* / Q000009:adverse effects; D018450:Disease Progression; D004334:Drug Administration Schedule; D004338:Drug Combinations; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology; D006801:Humans; D008297:Male; D009919:Orchiectomy; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D017211:Treatment Failure; D016896:Treatment Outcome
chemical_list: D000726:Androgen Antagonists; D018931:Antineoplastic Agents, Hormonal; D004338:Drug Combinations; D004054:Diethylstilbestrol; D003907:Dexamethasone