Long-term data comparing oestradiol (tE2) patches with luteinising hormone releasing hormone agonists (LHRHa) show no evidence of a difference between treatments in cardiovascular mortality or morbidity, according to the latest findings from the Prostate Adenocarcinoma Transcutaneous Hormone (PATCH) trial.
PATCH is a phase 2/3, randomised, multicentre trial in which men with locally advanced or metastatic prostate cancer were randomly allocated to either LHRHa according to local practice or tE2 patches (four 100 μg patches per 24 h, changed twice weekly, reducing to three patches twice weekly if castrate at four weeks [testosterone ≤1.7 nmol/L]).
The primary outcome was cardiovascular morbidity and mortality.
Between 14 August 2007 and 30 July 2019, 1694 men were randomly allocated to LHRHa (n=790) or tE2 patches (n=904). Overall, median follow-up was 3.9 (IQR 2.4-7.0) years.
One- and three-month castration rates were 65% and 93% respectively, in the LHRHa group and 83% and 93% in the tE2 group.
A total of 157 events from 145 men met predefined cardiovascular criteria, with a further 10 sudden deaths with no post-mortem report. Twenty-six (2%) of the total cohort had fatal cardiovascular events - 15 (2%) with LHRHa and 11 (1%) with tE2.
The time to first cardiovascular event did not differ between treatments (hazard ratio [HR] 1.20; 95% CI 0.86-1.68; P=0.29). Thirty (34%) of 89 cardiovascular events in patients assigned tE2 occurred >3 months after tE2 was stopped or changed to LHRHa.
The most frequent adverse events were gynaecomastia and hot flushes.
The authors advise that transdermal oestrogens should be reconsidered for androgen suppression in the management of prostate cancer.
