Staying on Track with Hormonal Therapy

Hormonal, or anti-estrogen, therapy protects your whole body by blocking the effects of hormones (mainly estrogen) on cancer cells. This type of treatment only works against breast cancers that have hormone receptors (called hormone-receptor-positive).

Hormonal therapies are used to lower the chance of the cancer coming back, lower the chance of a new cancer developing, and lower the risk of breast cancer for women who have not had the disease but are at a high risk for it.

Most hormonal therapies—including tamoxifen and aromatase inhibitors—are taken orally (by pill), every day. ERDs are given by monthly injections.

Hormonal therapies are usually taken for five years or longer, depending on the stage of your disease and the type of therapy you're taking. Some women start with one type of hormonal therapy and switch to another after 2-3 years. After finishing the full five years, some women may choose to take another hormonal therapy for another five years.

You get the best results with hormonal therapy when you take the medications as prescribed, year after year. Following the dosing schedule—both the prescribed dose and the recommended length of time—is very important because:

• The more you stick to the program, the more benefit you'll get from the treatment in terms of lowering your risk of the disease developing or recurring.
• If you regularly miss doses of hormonal therapy, it's harder for your doctor to see how the drug is really working for you, which will make it harder for you to decide whether to stick with it or possibly switch to something else.

Many women have trouble sticking to hormonal therapy for the full five years of treatment. One study, co-authored by Dr. Ann H. Partridge at the Dana-Farber Cancer Institute in Boston, showed that 23% of patients missed taking tamoxifen more than 20% of the time.

The study also found that adherence rates declined with years of treatment, from 87% in the first year to only 50% by the fourth year.

According to Dr. Partridge, Missing a dose of hormonal medication every now and then probably doesn't make a big difference. But she adds that you shouldn't miss several months' worth of medication, because this may lower the protection you're getting from the therapy.

Problems you might have with sticking to your hormonal therapy plan:

• Skipping or forgetting doses, which may happen when you take medication every day for years.
• Feeling that the treatment isn't worth the trouble, especially if you've never had breast cancer and are taking treatment to lower your risk of developing future disease. Studies have shown that women taking tamoxifen to lower their risk of getting breast cancer are more likely to discontinue use than women who take it to prevent recurrence.
• Side effects of tamoxifen include hot flashes, nausea, premature menopause and vaginal changes. Less common, more serious side effects can occur, including blood clots, and cancer in the lining or wall of the uterus.
• Side effects of aromatase inhibitors include hot flashes, joint and muscle aches, nausea, constipation, diarrhea, headache, back pain, and slight bone loss.
• Side effects of ERDs are similar to those of aromatase inhibitors.
• If you have unpleasant side effects from hormonal medications taken by pill, you might stop taking them without telling your healthcare providers. You then lose the protection these medications can provide.

Ways to overcome these problems:

• Use pill organizers to keep track of your doses. For more on remembering to take medications, go to Forgetting to Take Medication or Missing Appointments.
• If side effects of hormonal treatments are bothering you, talk with your doctor or nurse immediately. Don't try to "tough it out" or suffer in silence. This will just make you less likely to stick to the treatment in the long run.
• You'll find more detailed information in the Breastcancer.org section Side Effects of Tamoxifen.