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
Doctors call treatments given after surgery “adjuvant” treatments.
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 the early 2000s, 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 commonly used to reduce recurrence risk in premenopausal women.
Most women take hormonal therapy for 5 to 10 years after breast cancer surgery.
American Society of Clinical Oncology (ASCO) guidelines on adjuvant hormonal therapy recommend that:
- premenopausal women diagnosed with hormone-receptor-positive disease with a high risk of recurrence for whom chemotherapy is recommended should be treated with ovarian suppression along with adjuvant hormonal therapy
- women diagnosed with stage I hormone-receptor-positive disease that doesn’t warrant chemotherapy or node-negative cancers that are 1.0 cm or smaller in size should be treated with adjuvant hormonal therapy alone, without ovarian suppression
ASCO is a national organization of oncologists and other cancer care providers. ASCO guidelines give doctors recommendations for treatments and testing that are supported by much credible research and experience.
Researchers wondered if women diagnosed with breast cancer in the United States were being treated according to the ASCO hormonal therapy guidelines.
A study suggests that guideline-use of hormonal therapy has improved since 2004, but still isn’t optimal.
The research was published online on Feb. 2, 2017 by JAMA Oncology. Read “Evaluation of the Quality of Adjuvant Endocrine Therapy Delivery for Breast Cancer Care in the United States.”
To do the study, the researchers looked at the records of 981,729 women diagnosed with and treated for stage I to stage III breast cancer from 2004 to 2013. The records are part of the National Cancer Data Base, a nationwide database created by the American Cancer Society and the American College of Surgeons Commission on Cancer:
- 818,435 had hormone-receptor-positive breast cancer
- 163,294 had hormone-receptor-negative breast cancer
Using computer models, the researchers analyzed the information and the relationships between type of treatment, the characteristics of the cancer, the type of cancer treatment facility, and the demographics of the patients.
- Overall, adjuvant hormonal therapy treatment of women diagnosed with hormone-receptor-positive disease went up from 69.8% in 2004 to 82.4% in 2013.
- Adjuvant hormonal therapy treatment of women diagnosed with hormone-receptor-negative disease dropped from 5.2% in 2004 to 3.4% in 2013.
- Non-Hispanic white women between the ages of 50 and 69 were the most likely to be treated with adjuvant hormonal therapy.
- Women younger than 40 or older than 80 were less likely to be treated with adjuvant hormonal therapy, as were Hispanics.
- Women who lived in the New England area and women who lived in rural areas were more likely to be treated with adjuvant hormonal therapy than women who lived in other areas.
- Women treated with mastectomy followed by radiation therapy and lumpectomy followed by radiation therapy were the most likely to be appropriately treated with adjuvant hormonal therapy.
- Women diagnosed with estrogen-receptor-positive/progesterone-receptor-positive disease were the most likely to be treated with adjuvant hormonal therapy compared to women diagnosed with cancer with a different hormone receptor status.
- Women diagnosed with estrogen-receptor-negative/progesterone-receptor-positive disease were the least likely to be treated with adjuvant hormonal therapy. The researchers said this shows that doctors place more value on the estrogen receptor and that women diagnosed with estrogen-receptor-negative/progesterone-receptor-positive disease are being undertreated if they are not treated with adjuvant hormonal therapy.
- Compliance with the ASCO guidelines varied among treatment centers. In 2004, only 40% of treatment centers were considered compliant. By 2013, nearly 70% were compliant.
"The use of adjuvant endocrine therapy slowly gained popularity over this time," said Dezheng Huo, M.D., Ph.D., associate professor of public health sciences at the University of Chicago and senior author of the study. "It improved after 2004, rising from 70% in 2004 to almost 84% in 2011. Then it declined slightly to 82% in 2013, when the study ended.
"Our results suggest that it is still underused," Huo added, "and in some cases, misused, offered to patients who lack hormone receptors."
The researchers also argued that if adjuvant hormonal therapy were used appropriately, an estimated 14,630 lives would have been saved over the decade of the study.
Still, the results of the study may be slightly off. Even though the researchers found that the appropriate use of adjuvant hormonal therapy was increasing, it’s known that adjuvant hormonal therapy often isn’t reported to the National Cancer Data Base because outpatient treatments aren’t always included in hospital records, according to the researchers. It’s also not known how many of the women stuck to the full course of their treatment plan.
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. Research has shown 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, in many cases because of side effects.
If you’ve been diagnosed with early-stage, hormone-receptor-positive breast cancer, it’s likely that your doctor will recommend hormonal therapy after surgery. If you know that the cancer is either estrogen-receptor-positive or progesterone-receptor-positive and your doctor doesn’t recommend hormonal therapy, it’s a good idea to ask why. Similarly, if you’ve been diagnosed with hormone-receptor-negative disease and your doctor recommends hormonal therapy after surgery, it’s also a good idea to ask why.
Based on the characteristics of the cancer and your personal preferences, you and your doctor will develop a treatment plan that’s right for you and your unique situation.
While the side effects of hormonal therapy can be troubling, 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 steps you can take 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. Studies have shown that exercise and acupuncture may reduce hormonal therapy side effects. Visit the Breastcancer.org Staying on Track With Treatment pages to learn more about how to ease side effects.