Masteron is a derivative of Dihydrotestosterone (DHT) with an added 2a-methyl group. As with any DHT derivative, it is structurally incapable of conversion to estrogen and progesterone. Masteron is unique as it is one of the rare anabolic steroids that is not clinically used for weight gain. It’s never used for treatment of anemia or wasting diseases like Cancer or AIDS. Masteron is clinically treating certain forms of breast cancer,at which it is reasonably effective. It has, however, been largely replaced by third generation Aromatase Inhibitors such as Arimidex and Aromasin. However, in at least one study, Masteron & Tamoxifen outperformed than Chemotherapy with regards to producing immediate objective responses from ’s actually a weak anti-estrogen, and that’s where a lot of its “hardening” properties probably come from, and why it’s so useful in precontest cycles. If you aren’t using a lot of aromatizable drugs (and are using them in low doses), then Masteron may actually be the only anti-estrogen you need.
Masteron may actually interact with the aromatase enzyme to inhibit aromatization (conversion/metabolism) of other steroids into estrogen. Additionally, Masteron seems to be able to interact with estrogen at the receptor site.
Masteron stacks well with testosterone, and typically I like to stack it with something with a similar ester length. One of my favorite cycles included Masteron, Nandrolone (Phenylpropionate), and of course Testosterone Propionate. Trenbolone and Equipoise are popular additions to cycles including Masteron, as is Testosterone (always a must) and Anavar. Sometimes Winstrol is used instead of Anavar, to keep costs down.