Langley RE et al. (2008) Early hormonal data from a multicentre phase II trial using transdermal oestrogen patches as first-line hormonal therapy in patients with locally advanced or metastatic prostate cancer. BJU Int 102: 442–445

Preliminary results from a randomized, phase II trial have shown that the transdermal estrogen patch Fem7® (Merck KGaA, Darmstadt, Germany) can suppress testosterone to castrate levels in men with locally advanced or metastatic prostate cancer. This novel method of androgen deprivation might be preferable to administration of oral estrogens, which are associated with cardiovascular toxicity, and to luteinizing-hormone-releasing hormone (LHRH) analogs, which can result in osteoporosis.

The study included men who had not previously received hormone therapy, except in the adjuvant or neoadjuvant setting. Participants were randomly allocated (in a 2:1 ratio) to receive estrogen patches or an LHRH analog. At the release of these preliminary results, 13 patients had received Fem7® and had ≥12 weeks of follow-up. The median estradiol level for Fem7®-treated patients was 442 pmol/l; however, the timing of this blood test was not specified, and diurnal variation in levels could have influenced the results. The target testosterone level of ≤1.7 nmol/l was achieved by eight men, and another two had testosterone levels <2 nmol/l. All patients' PSA levels decreased, and nine men had a PSA level <4 ng/ml at 12 weeks.

These data confirm that estrogen patches can achieve castrate levels of testosterone and a concomitant reduction in PSA levels. The trial is still ongoing, and has recruited 126 out of a planned 200 patients. The final results will include an assessment of cardiovascular toxicity, as well as efficacy.