How bad is the risk of blood clots for men on ADT?

This is a grand, data-mining paper, with data from 42,263 men, on various ADT protocols, versus 190,930 men matched with them, who had not been diagnosed with prostate cancer.  The data came from the National Prostate Cancer Register of Sweden, and is a credit to that country for having national cancer data registries.

The authors show that the LHRH agonist drugs, like Lupron and Zoladex, are associated with a increased risk of thromboembolic disease (TED) which are dangerous blood clots than can form in deep veins in the body then move to the lungs. The increase in risk is slight, but blood clots in the lungs are dangerous, so it is not surprising that the authors conclude with a cautionary note that LHRH drugs should only be used when there is good reason to believe that they will benefit patients.

Interestingly, men who were on anti-androgen (like Casodex) monotherapy—a treatment more popular in Europe than North America—actually had a slightly lower risk of TED than those not treated for prostate cancer. The highest risk was seen in men, who started on an anti-androgen and switched to an LHRH agonist. These differences may related in part to the fact that there are receptors for LHRH agonists in the cardiovascular system.


O'Farrell S, Sandstrom K, Garmo H, Stattin P, Holmberg L, Adolfsson J, Van Hemelrijck M. 2015. Risk of thromboembolic disease in men with prostate cancer undergoing androgen deprivation. BJU Int 118(3):391-398.