Someone just posted this article about use of estrogen patches as an alternative to castration or ADT in a new thread. People following this thread might find it of interest... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4052190/
Basically, it says that the current ability to provide estrogen in a new way might provide the benefits of testosterone suppression without some of the complications and side effects.
However, it's also cheaper using already available medications, so it probably would have very low impetus to be studied or promoted by drug companies....
The key phrase is "parenteral estrogen." (A phrase I have never ever heard until today.)