Q. I’ve been diagnosed with ER-receptive breast cancer, and once I finish chemo my doctor is considering two hormone drugs: tamoxifen, and Zoladex. I know all about tamoxifen, but what’s Zoladex?    

A. Zoladex (goserelin) and Lupron (leuprolide) are both drugs that prevent your brain from sending signals to your ovaries telling them to make estrogen. (This is called ovarian function suppression, or OFS; and the drugs themselves are called gonadotropin releasing hormones, GnRH, should you ever hear those acronyms mentioned.) The result: the amount of estrogen in your body is reduced significantly. Since you have estrogen-receptive cancer (i.e., it requires estrogen to grow), lowering your supply of the hormone obviously impacts the breast cancer cells in a negative way, preventing their growth and the subsequent spread of cancer.

While tamoxifen prevents estrogen from latching onto breast cancer cells, thus preventing their growth, Zoladex and Lupron cut estrogen out of the loop completely. GnRH drugs such as Zoladex are only prescribed for pre-menopausal women with ER/PR-receptive breast cancer. Since women who’ve been through menopause no longer produce estrogen via their ovaries, a GnRH isn’t effective for them.

Q. So, do most women in my situation take Zoladex, then, or tamoxifen?  

A. Suppressing a woman’s ovary function brings on the same major and serious side effects as menopause. So in pre-menopausal women, it’s a decision that’s not made lightly. Estrogen, though it unfortunately helps your particular breast cancer grow, also does a lot of good things in your body; its loss will affect your bones, your skin, and probably your mood, among other things.

If you’re very fearful of cancer coming back, and want to do everything possible to prevent it–even at the risk of going into menopause, with all the challenges that brings–then you may want to consider having your ovaries removed surgically, an operation called an oophorectomy.  If, on the other hand, you’d rather avoid permanent menopause–say, you’re still in your childbearing years, and might want to get pregnant–you might want to take Zoladex, either alone, or in combination with tamoxifen. Zoladex stops your period–but usually only temporarily. Once you stop taking Zoladex, your ovaries should start producing estrogen again (if you’re young enough, and haven’t been pushed into permanent menopause).

Q. That actually sounds like a good plan, since I’m still in my 30s. How do I decide whether I should take just the Zoladex, or the Zoladex and tamoxifen both?

A. Like much of the newer hormonal therapies, there just isn’t enough data yet to be able to give clearcut answers. Your oncologist may recommend taking both; another may recommend one or the other alone. To set your mind at ease about this decision, discuss with your doctor his or her recommendation, and the reasons behind it. If you disagree, get a second opinion.