After surgery, women diagnosed with hormone-receptor-positive breast cancer usually take hormonal therapy medicine to reduce the risk of the cancer coming back (recurrence). Hormonal therapy medicines work in two ways:
- by lowering the amount of estrogen in the body
- by blocking the action of estrogen on breast cancer cells
There are several types of hormonal therapy medicines. Tamoxifen, a selective estrogen receptor modulator (SERM), is one of the most well-known. Tamoxifen can be used to treat both premenopausal and postmenopausal women. In 2005, the aromatase inhibitors:
- Arimidex (chemical name: anastrozole)
- Aromasin (chemical name: exemestane)
- Femara (chemical name: letrozole)
were shown to be more effective at reducing recurrence risk in postmenopausal women and are now used more often than tamoxifen to treat women who’ve gone through menopause. Aromatase inhibitors aren’t used to reduce recurrence risk in premenopausal women.
Hormonal therapy usually is prescribed for 5 years after surgery. Still, research that was published in December 2012 found that taking tamoxifen for 10 years instead of 5 years after surgery reduced the number of recurrences and improved overall survival.
Both tamoxifen and aromatase inhibitors can cause side effects. Tamoxifen may cause hot flashes and increase the risk of blood clots and stroke. Aromatase inhibitors may cause muscle and joint aches and pains. Less common but more severe side effects of aromatase inhibitors are heart problems, osteoporosis, and broken bones.
A study suggests that about 25% of women who are prescribed hormonal therapy to reduce the risk of recurrence after surgery either don’t start taking the medicine or stop taking it early.
The research was published online on March 31, 2013 by Breast Cancer Research and Treatment. Read the abstract of “Adjuvant endocrine therapy initiation and persistence in a diverse sample of patients with breast cancer.”
(Treatment that comes after surgery or another initial treatment is called adjuvant treatment.)
The most common reason the women said they stopped or never started hormonal therapy was side effects. Women who said they got less information about hormonal therapy from their doctors were less likely to begin taking it compared to women who got quite a bit of information from their doctors.
Women who were more worried about breast cancer coming back and women who already took some type of medicine regularly were more likely to complete the full course of hormonal therapy.
"It was particularly interesting that greater fear of recurrence was associated in our patient sample with greater adherence to endocrine therapy," said Jennifer J. Griggs, M.D., M.P.H., a medical oncologist who is a member of the Breastcancer.org Professional Advisory Board and professor of internal medicine at the University of Michigan Medical School. She was the senior author of the study.
"We don't want our patients living under a cloud of fear, so we need to develop creative ways to both reassure and motivate them," she added. “This means providing better education about the importance of staying on these medications and partnering with primary care and cancer doctors to help patients manage symptoms.”
While the side effects of hormonal therapy can be bothersome, they’re overshadowed by the reality that hormone-receptor-positive breast cancer can come back. Hormonal therapy after surgery reduces that risk. If you’ve been prescribed hormonal therapy after surgery, you must remember this.
There are good ways to get rid of any obstacles stopping you from doing all you can to lower your recurrence risk. If side effects are a major problem for you, talk to your doctor about ways to manage them. You also may be able to switch to a different hormonal therapy.
For more information, visit the Breastcancer.org pages on Staying on Track with Treatment. You can read about why it’s so important to stick to your treatment plan, as well as ways to manage side effects after radiation, chemotherapy, and hormonal therapy. If you’re taking hormonal therapy after surgery now, stick with it as prescribed. If you’re thinking of stopping early, talk to your doctor first. Together, you can find a solution that is best for you.