Will Your Doctor Want You to Switch Therapies?

In certain situations your doctor may suggest that you switch from one type of hormonal therapy to another, or take a break from therapy. This is true no matter what type of hormonal therapy you start with.

Switching if you are pre-menopausal

For pre-menopausal women with hormone-receptor-positive breast cancer, five years of tamoxifen is the standard of care. But under some special circumstances you may decide to stop taking tamoxifen for a while and then start again.

For example, you should not try to get pregnant while taking tamoxifen. However, if you are hoping to get pregnant within the next three years or so, you and your doctor might come up with a plan to address both your anti-cancer therapy and your strong desire to have a family. In that case, you may decide to take tamoxifen for two years and then—if the cancer is not growing—take a break from hormonal therapy, and try to get pregnant.

Later on, after the pregnancy, you can go back on tamoxifen and finish the full five years. Five years of continuous tamoxifen—with no breaks in treatment—is better than two years, but two years is better than no tamoxifen. And five years of tamoxifen, with a break in the middle, might be better than only two years.

Switching if you are post-menopausal

For post-menopausal women with hormone-receptor-positive breast cancer, five years of an aromatase inhibitor is the standard of care, although tamoxifen is also a very good medicine.

Your doctor may have you switch from one hormonal treatment to another, depending on your situation.

If you started with tamoxifen:

• You can stay on tamoxifen for two to three years, then switch over to an aromatase inhibitor such as Aromasin, Arimidex or Femara.
• You can stick with tamoxifen for the full five years, then switch to Femara for another five years (for a total of 10 years).

If you haven't started hormonal therapy yet:

• You can start out with either of the aromatase inhibitors Arimidex or Femara.
• After the full five years of Arimidex, you can stop your hormonal therapy, or you can consider participating in a clinical trial that looks at the possible value of extending your hormonal therapy beyond five years.

Switching if you have advanced (metastatic) disease

As long as one hormonal therapy works well, stick with it. But over time, if the treatment stops working as well, your doctor will probably suggest that you switch to another form of hormonal therapy.

The reason for switching: Studies of aromatase inhibitors vs. tamoxifen

Here are some of the studies that changed the standard of care for post-menopausal women, from tamoxifen to aromatase inhibitors. These studies compared aromatase inhibitors to tamoxifen in post-menopausal women who had hormone-receptor-positive breast cancer:

• Women who switched to Aromasin after two to three years of tamoxifen, for a total of five years of hormonal therapy, lived longer without the cancer coming back compared to women who took tamoxifen for the full five years.
• Women who switched to Arimidex after two to three years of tamoxifen, for a total of five years of hormonal therapy, had a reduced risk of recurrence and of getting a new cancer compared to women who took tamoxifen for five years.
• Women who took five years of Femara after five years of tamoxifen had a reduced risk of cancer coming back and of cancer spreading compared to women who didn't take Femara.

After five years of an aromatase inhibitor, it's not clear if switching to another hormonal therapy would provide extra protection against breast cancer coming back. There are studies under way to help address this important question.

Many women ask, "If the aromatase inhibitors are so good, why consider tamoxifen at all?" The answer is that tamoxifen is still the standard of care for pre-menopausal women, who cannot take aromatase inhibitors. And it's a very good treatment for post-menopausal women. There is still not enough data to support starting on or switching to an aromatase inhibitor for ALL patients, especially those with bone or joint problems, such as osteoporosis or arthritis.

Working with your doctor to design the best hormonal therapy for YOU

How do you work with your doctor to make the best decisions about sticking to one hormonal therapy or switching from one hormonal therapy to another? You'll choose one treatment to start with. Then, over the years, you'll see your doctor regularly and review your care. The main benefit you want is to remain cancer-free. You'll weigh the benefits of treatment against any side effects you may have. If side effects remain a problem, it's possible to switch hormonal therapies. For example, hot flashes that you get from taking tamoxifen may decrease if you switch to an aromatase inhibitor.

Because aromatase inhibitors have been associated with bone loss, before starting or switching to an aromatase inhibitor, get a bone test called a DEXA scan to check your bone strength. Repeat the scan once a year to monitor your bone health. You may need to take a bone-strengthening medicine at the same time as the aromatase inhibitor to maintain your bone strength.

Changes in bone health—loss, stabilization, and strengthening—take six months to a year to show up on your bone density test. If your doctor is concerned that you may be losing bone quickly (for example, if you have lost height over a few months), a different type of test can get answers more quickly. Testing the urine for bone changes will show differences in just a few months.

If a bone-building treatment plan isn't effective over a year while you're on an aromatase inhibitor, despite careful planning, then your doctor may want to switch you to another hormonal therapy. Early results of a Swedish study suggest that Aromasin may be associated with only slightly less bone loss than other aromatase inhibitors. Tamoxifen, on the other hand, usually helps build up bone strength.

Joint aches and discomforts with aromatase inhibitors might respond well to anti-arthritis medications. If this symptom is really troubling to you and you haven't gotten relief from anti-inflammatory medicines such as ibuprofen (brand names: Motrin, Advil), your doctor might suggest a switch from one aromatase inhibitor to another. And if that doesn't work, and this symptom continues to trouble you, then your doctor might suggest a switch to tamoxifen.

If your menopausal status changes during your treatment, you and your doctor may want to switch your hormonal therapy. For example, you may have been pre-menopausal when you started taking hormonal therapy, but now you're through menopause. You might then switch from tamoxifen to an aromatase inhibitor.

Or you might have been pre-menopausal when you were diagnosed and then gone through chemotherapy, which might have put you into menopause temporarily. Then, while you were on tamoxifen, your menstrual periods might have started up again. If this has happened to you, and if you had an aggressive form of breast cancer (a high-grade cancer that was big or involved a significant number of lymph nodes), then your doctor might suggest a change in your hormonal treatment. He or she might advise adding ovarian shutdown or removal to tamoxifen.