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New Study on Tamoxifen Efficacy

This touches on some very confusing medication issues and decisions that patients must make. When it comes to new information and data that actually might change the course of therapy in real time, I always turn to an expert.
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Almost every day, I hear from friends and acquaintances that I have met through BFFL Co., and I feel very fortunate to be a trusted sounding board for their questions and concerns. Here's one email I received just a few days ago from a 40-year-old premenopausal woman who has completed chemo and lumpectomy/radiation for Stage 2 breast cancer:

"Hi Elizabeth, I was curious to know your thoughts regarding this study. I am currently on tamoxifen and will be undergoing a hysterectomy by the end of the year, as per my gynecological oncologist, because I'm at higher risk now not just for recurrence of breast cancer, but other cancers as well."

This touches on some very confusing medication issues and decisions that patients must make. When it comes to new information and data that actually might change the course of therapy in real time, I always turn to an expert.

The study my friend asked me about is a trial conducted in Scotland that compared the effects of tamoxifen vs. exemestane -- two drugs that block the activation of the hormone estrogen. The study analyzed the effects of administering either medication in conjunction with the suppression of ovarian function (with a separate drug) or removal of the ovaries altogether.

Before we go any further, let's explain how the hormone estrogen relates to breast cancer:

Estrogen is an important "fuel" for breast cancers. When young women who are premenopausal develop breast cancer and their tumors are referred to as "Estrogen (ER) and Progesterone (PR) receptor positive," this means that those hormones can essentially cause growth in the cancerous tumors. In this situation, an effective treatment includes reducing the amount and effect of estrogen in the body. This can be accomplished in several ways:

  1. blocking the activation of estrogen "receptors" (proteins found inside cells that are fueled by the hormone estrogen)
  2. blocking the production of active estrogen in the body
  3. removing or "knocking out" the ovaries

The study results were as follows:

Adding ovarian suppression to tamoxifen or exemestane did not provide a significant benefit in the overall study population. However, for women who were (1) at risk for recurrence and therefore received chemotherapy before undergoing ovarian suppression and; (2) who remained premenopausal after chemotherapy (their ovaries still worked), ovarian suppression added to both of the drugs' positive disease outcomes. Of the two drugs, exemestane seemed to be more effective than tamoxifen on high risk patients when administered in conjunction with ovarian suppression.

Dr. Bruce Chabner of Massachusetts General Hospital agrees:

Combination therapy is possibly better than tamoxifen alone for high-risk patients with premenopausal breast cancer. With respect to improving the outlook for breast cancer, the benefits of removing ovarian estrogen were not striking overall but were most helpful for premenopausal patients with a high risk of recurrence after chemotherapy. Further, it appears that exemestane may be more effective than tamoxifen as the primary anti-estrogen combined with ovarian suppression. Patients should discuss this option of ovarian suppression with their medical oncologists.

There are three important points here:

  • Know your risk. For certain subgroups -- young women who have ER-positive cancers and, despite chemotherapy, still retain some ovarian function and estrogen production, removal of the ovaries will likely improve their survival. For a young mother in her early 40s, this is essential information to have.

  • Discuss all options and situations with your medical oncologist. There is a host of important information available, but it can be confusing and difficult to apply to your situation, particularly when stress levels are high. If you read or hear about a new therapy, mention it to your doctor -- bring the study to your appointment and discuss it. You are your own best advocate.
  • Ask about side effects. Remember that any treatment that shuts down your ovaries when you are still menstruating will have significant side effects. These may include not only hot flashes, changes in skin texture and moisture, but also endometrial, cardiac and blood-related changes that must be monitored. Ask questions and know the risks.
  • Elizabeth Chabner Thompson, MD, MPH, is a radiation oncologist and founder of BFFL Co (Best Friends for Life), which provides a wide range of products for patients undergoing various surgical procedures or cancer treatments. One such product is the Axillapilla® post-surgery pillow featured on the Katie Couric Show. This heart-shaped pillow provides support and stability for a patient recovering from surgery, especially cardiac surgery.