Hormonal Therapy Choices

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A number of new effective hormonal therapies have recently become available. These treatments help stop the hormone estrogen from fueling the growth of breast cancer cells. So which one do you try first? Your best option depends on how you've responded in the past to hormonal therapy, and whether you are still menstruating (having periods regularly).

If the cancer grew or otherwise got worse while you were taking one type of hormonal therapy, your doctor may switch you to a different type of hormonal treatment. But if more than two years has passed since you took the hormonal therapy and had a recurrence, you may still respond to that first medication you were taking. To find out all your choices, read the section below that applies to you.

Premenopausal options

If you are still having a period each month, you have several choices of hormonal therapy:

  • tamoxifen
  • treatments that stop your ovaries from making estrogen (ovary shutdown)
  • tamoxifen AND ovary shutdown
  • Megace (chemical name: megestrol)
  • Halotestin (chemical name: fluoxymesterone)

Tamoxifen is usually the first choice, followed by treatments that stop your ovaries from making estrogen:

  • surgical removal of the ovaries
  • radiation treatment to stop the ovaries from working
  • the drugs Zoladex (chemical name: goserelin acetate), Lupron (chemical name: leuprolide), or Trelstar (chemical name: triptorelin), which are injected into the muscle

Get as much information about these options as you can so that you can discuss them with your doctor.

Hormonal therapies that are now used only occasionally are Megace and Halotestin:

  • Megace, a progesterone-like hormonal therapy, is generally less effective than tamoxifen, and causes bloating and weight gain. But it still can be highly effective in some women.
  • Halotestin is a male hormone that is not as effective as tamoxifen and Megace. It also causes facial hair growth and other masculine traits to develop. Despite its unpleasant side effects, halotestin can be very beneficial for some women because it can increase their numbers of red blood cells.

Premenopausal women who have had treatments to shut down their ovaries or who have gone into early menopause as a side effect of chemotherapy have some other options. These women can use hormonal therapies that are only for postmenopausal women:

  • Arimidex (chemical name: anastrozole), Femara (chemical name: letrozole) or Aromasin (chemical name: exemestane)
  • Faslodex (chemical name: fulvestrant)

Postmenopausal options

Very often, treatments for breast cancer stop the menstrual cycle temporarily. If you have not been menstruating for several months after treatment ends, you may think you have gone into menopause. But that's not necessarily the case. Your doctor must test you to be sure that you are in fact postmenopausal. If you are, you have a greater variety of options for hormonal treatment:

  • Arimidex (chemical name: anastrozole)
  • Femara (chemical name: letrozole)
  • Aromasin (chemical name: exemestane)
  • tamoxifen (if you have never before been treated with it)
  • Faslodex (chemical name: fulvestrant), an ERD (or estrogen receptor down-regulator)
  • Fareston (chemical name: toremifene), which is very closely related to tamoxifen
  • Megace (chemical name: megestrol)
  • Halotestin (chemical name: fluoxymesterone)
  • some combination of the above therapies

All these treatments are medicines that you take as a daily pill except for Faslodex, which is given as a monthly injection.

It's helpful to have so many choices, but which one do you consider first?

For over 20 years, tamoxifen was the best medicine available. But recent studies have shown that, in women who are postmenopausal, the aromatase inhibitors work better than tamoxifen. "Better" means more effective with fewer side effects. So, if you are faced with hormone-receptor-positive (ER+ or PR+) metastatic breast cancer, probably the best medicine to try first is one of the three aromatase inhibitors:

  • Arimidex (chemical name: anastrozole)
  • Femara (chemical name: letrozole)
  • Aromasin (chemical name: exemestane)

These three aromatase inhibitors haven't yet been compared to one another in a study, so we don't know if one is any better than the others. Which one you use first depends on your doctor's recommendation, medicines you may have already used, and how well you tolerate one medicine compared to the others.

Tamoxifen may still be a good option after Femara, Arimidex, or Aromasin. If this doesn't work, then Faslodex is the next best choice. Doctors have less experience with Faslodex, but one study found it was as effective as Arimidex in postmenopausal women who no longer respond to tamoxifen.

Combining tamoxifen with Arimidex provides no extra benefit and may result in more side effects. Researchers are testing the effectiveness of Arimidex combined with Faslodex, but results are not yet available.

When to switch

If you have metastatic disease and are doing well with a hormonal treatment, stick with it for as long as it works well and the side effects are acceptable to you. Hormonal therapy may be able to produce excellent results, with relatively mild side effects. But if the cancer comes back, enlarges, or spreads while you are taking this medication, it should be stopped. Cancer cells may have figured out how to grow despite the medication. They may have even learned to thrive on it. In this case, sometimes simply stopping the medication helps by "starving" the tumor.

Your doctor will probably also recommend you try a different hormonal therapy. Most women with hormone-receptor-positive metastatic breast cancer will use different hormonal therapies over time—usually one at a time. You stick with what works, only changing to another if the cancer gets worse.

Side effects of hormonal treatments

All hormonal therapies can cause a "flare" reaction shortly after they are started. This is a temporary increase of pain or increased calcium levels in the blood as the tumor reacts to being starved of what it needs to grow. Although uncomfortable, the flare reaction is a sign that the treatment is working. About two out of 10 women have this flare reaction, which pain medicines can help relieve. Symptoms usually occur within the first month of treatment and go away within two months.

Hormonal treatments can also cause a number of menopause-like symptoms, including:

  • hot flashes
  • vaginal dryness
  • pain during sex
  • mood swings

You can deal with menopausal side effects in a variety of ways, some medical and some involving lifestyle change.

The aromatase inhibitors and the medications and surgery that shut down the ovaries are all associated with mild bone loss during treatment. Bone strength can be monitored before treatment and throughout, as needed. You can also get bone-strengthening medicines to protect and build bone strength.

In rare cases, tamoxifen has been associated with blood clots and cancer of the uterus or its lining. But studies show that the benefits of the treatment far outweigh these risks for most women.

Next step

Eventually—months or many years from now—the cancer may progress despite hormonal therapy. At this point you may be offered chemotherapy. Some women continue with their hormonal therapy and add chemotherapy. Others stop hormonal therapy when they start chemotherapy. Herceptin, alone or with chemotherapy, or new treatments not yet on the market may also be an option.

And remember, scientists are actively investigating new and effective drugs with fewer side effects for tomorrow.

Hormonal therapies may take a few months to give you a response. Having estrogen or progesterone receptors in your metastatic breast cancer cells usually predicts a good response to hormonal (anti-estrogen) therapy. In general, the more receptors you have, the better your response to hormonal therapy will be:

  • If both estrogen and progesterone receptors are positive, your chance of responding to hormonal therapy is about 70%.
  • If only the estrogen or the progesterone receptors are positive, your chance of responding is about 33%.
  • If your receptor status is unknown, there is still a 10% chance that your condition will improve.

The chance of an encouraging response also increases if you are older and if at least two years have passed between the time when you were first diagnosed with breast cancer and when it came back.

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