Tamoxifen abuse?

Holy crap.

Just when I thought I had heard or seen it all, something comes up that proves me wrong. This time, the “something” comes to my attention via Corpus Callosum. It’s a story about people abusing a drug. Only it’s not just any drug, but a drug commonly used to treat breast cancer (which, given that a large part of my practice is the treatment of breast cancer patients, is why this item caught my attention).

They’re abusing tamoxifen.

A survey of male and female gym attendees found not only growing rates of steroid abuse but also greater misuse of prescription drugs.

Prescription drugs used included the breast cancer treatment tamoxifen and the diabetes medication insulin, the study – published in the Journal of the Royal Society of Medicine – said.


The study also found a 22% rise in the numbers using tamoxifen, and the chief researcher, Professor Bruce Davis, discovered that male bodybuilders were using the breast cancer drug to counteract the adverse side effects of steroids.

“When men take testosterone in large doses, it changes into oestrogen and they can develop a condition known as gynaecomastia, which causes them to grow breasts. Some even produce milk,” he said.

“Taking tamoxifen prevent this by repressing the body’s production of oestrogen.”

One minor quibble, Professor Davis: Tamoxifen does not repress the body’s production of estrogen. It is a selective estrogen receptor modulator and inhibits the activity of estrogen in specific tissues by blocking certain types estrogen receptors without activating them. It is used as a hormonal therapy for estrogen receptor-positive cancer and is very effective at decreasing the risk of recurrence in these patients. It is also used in patients at very high risk of developing breast cancer, whether from family history or known genetic mutation, for chemoprevention. Tamoxifen is also sometimes used in the treatment of gynecomastia in males not due to steroid abuse.

It’s a fairly safe drug by and large, but its use can lead to blood clots leading to pulmonary embolus (less than 1%) and stroke (also less than 1%), endometrial cancer (not a problem in males), among other things. It used to be thought that tamoxifen increases the risk of liver cancer, but later studies appear not to show that.

Still, it’s an odd drug to be abusing, and it’s odder still that I had never heard of its abuse, given what I do for a living. Of course I don’t see very many male bodybuilders in my practice. In fact, come to think of it, I don’t know if I’ve ever seen one in the nearly 7 years since I finished my fellowship. In any case, if these body builders weren’t abusing steroids in the first place, it wouldn’t even be an issue.