Estrogen therapy is sometimes used in men who have prostate cancer to reduce the size of the tumor, the American Cancer Society states. Although estrogen therapies were once used as an alternative to orchiectomy (a procedure that removes one or both testicles), other hormone therapies are now available, and they have fewer side effects.
The aim of estrogen and other hormone therapies is to deprive the prostate cancer cells of the androgens that cause them to grow. As a result, they usually shrink. Hormone therapies usually take place when surgery and radiation are not options because the cancer has spread, when there is a high risk of the cancer returning following surgery or radiotherapy, to shrink the tumor before applying radiation and when the cancer returns following surgery or radiotherapy.
As estrogen therapy has side effects such as loss of libido and breast growth, doctors no longer commonly use it in place of orchiectomy to treat prostate cancer. Instead, they interrupt the production of androgens using therapies such as luteinizing hormone-releasing hormone (LHRH) analogs, which disrupt the release of LHRH, which in turn reduces androgen levels. This does initially induce a spike in androgen levels, but this is temporary.
Some doctors may choose to introduce anti-androgens alongside the LHRH analogs, but they do not often use them as a standalone treatment. Men undergoing hormone therapies may experience side effects, including shrinkage of the testicles and penis and impotence.