It has been long assumed that hormone therapy (ADT) used in the treatment of men with advanced prostate cancer increases a man’s risk for developing potentially live threatening thromboembolic disease (formation in a blood vessel of a clot (thrombus) that breaks loose and is carried by the blood stream to plug another vessel. The clot may plug a vessel in the lungs (pulmonary embolism), brain (stroke), gastrointestinal tract, kidneys, or leg).
Assuming something so serious, without good evidence, can lead to poor clinical decisions. In an attempt to evaluate this assumption, researchers have investigated the risk of developing thromboembolic disease (TED) in men with prostate cancer who are on androgen deprivation therapy (ADT).
They evaluated the TED risk for 42,263 men with prostate cancer who were on ADT. They compared these men to a matched, prostate cancer-free cohort of 190,930 men.
The researchers analyzed the associations between ADT and deep venous thrombosis (DVT) or pulmonary embolism (PE). In their analysis they accounted for previous prostate cancer-related surgeries and the following proxies for disease progression: transurethral resection of the prostate, palliative radiotherapy and nephrostomy.
In their study period that went from 1997 to 2013, they evaluated 11,242 men who received anti-androgen (AA) mono-therapy, 26,959 gonadotropin-releasing hormone (GnRH) agonists, 1,091 combined androgen blockade, and 3,789 men who underwent an orchiectomy.
They found that the GnRH agonist users and surgically castrated men were at increased TED risk versus the comparison cohort. Men on AA monotherapy were at decreased risk. TED risk was highest among those who switched from AA to GnRH agonists.
They also found that the TED incidence among men on ADT increased with the duration of therapy and risk was highest for those who switched from AA to GnRH agonists.
These findings strongly support the delayed use of systemic ADT. They also call into question the practice of starting ADT with AA and then moving to other ADT methods. Unfortunately, this study did not evaluate the effect of an intermittent ADT schedule on the risk factor of developing TED.
BJU international. 2015 Oct 24 [Epub ahead of print]; Sean O’Farrell, Karin Sandström, Hans Garmo, Pär Stattin, Lars Holmberg, Jan Adolfsson, Mieke Van Hemelrijck