This was Diethyl Stilbestrol, a synthetic estrogen, which was the first hormone therapy drug.
Diethyl Stilbestrol is given orally (tablet), and drugs taken orally do what's called "first pass through the liver" to process toxins the same as all other nutrients you eat, to make them suitable for you body before they go into your normal blood circulation. It turns out that estrogens doing this "first pass through the liver" mess up the liver's generating of clotting agents, and long term on oral estrogens generates a significant risk of blood clots. This was a significant cause of death back when Diethyl Stilbestrol was the only hormone therapy drug, hence the switch to Zoladex and the others which have come along later, which are not estrogens.
Diethyl Stilbestrol is still used occasionally when all other ADT medications have stopped working, and it's usually given with Asprin too now.
The key thing about using Estradiol patches is that they are absorbed directly into the blood stream and don't do the "first pass through the liver", so don't have the blood clotting risk which oral Diethyl Stilbestrol does.
Edited by moderator 29 Mar 2026 at 18:04
| Reason: Slight rewording