For decades, tamoxifen has made it possible for women to reduce the risk of a recurrence of breast cancer.
Dr. Kimberly Strickland, a breast medical oncologist at the Novant Health Cancer Institute in Charlotte, breaks down the facts and misconceptions about the drug, and explains why it’s not the only choice for women to prevent a recurrence of breast cancer.
What is tamoxifen?
Tamoxifen is a type of endocrine therapy, referring to drugs that block or lower the amount of hormones in the body. It’s taken in tablet form.
Tamoxifen and other drugs called selective estrogen receptor modulators, or SERMs, block the estrogen receptor in breast cells, which can fuel the growth of breast cancer cells. In other words, the drug stops estrogen from working in the breast which can help reduce the chance of recurrence.
Tamoxifen became one of the first drugs to safely do that when it was approved for use by the U.S. Food and Drug Administration in 1977, first as a treatment in later-stage breast cancer and then for reducing recurrence, known as adjuvant therapy.
The use of tamoxifen, and other forms of endocrine therapy, has drastically improved outcomes for patients. It can reduce your risk of dying from breast cancer by 30%, Strickland said.
Breast cancer care to support your every need.
It’s used for patients with estrogen receptor-positive tumors. “Two thirds of breast cancers are estrogen positive, and for that reason, tamoxifen is a commonly recommended treatment,” said Strickland, who also serves as investigator in the Southeast Clinical Oncology Research Consortium, which brings clinical trials to rural communities.
Who should take tamoxifen?
For postmenopausal women following breast cancer treatment, Strickland and other oncologists generally recommend taking aromatase inhibitors, which are superior in reducing risk of recurrence. They prevent an enzyme in fat tissue from changing other hormones into estrogen, according to the American Cancer Society. Drugs such as letrozole and anastrozole can be taken up to 10 years after surgery.
Strickland said patients weighing their decision about taking tamoxifen should learn about its common side effects: Hot flashes, muscle aches, joint aches, weight changes, sometimes mood changes. She said she always educates her patients about two very rare side effects, one being risk of blood clot and the other being risk of developing cancer of the uterus.
“When it comes to tamoxifen, you have to be careful because of risk of a blood clot,” Strickland said. “If somebody has a history of a blood clot, I talk to them about risks and benefits of using the medication.”
While tamoxifen does have the potential to cause unpleasant side effects, sometimes to a considerable degree, there are lots of things that doctors can do to help patients manage those.
It’s important to work with your clinician and share all of what you're experiencing. This can help your doctor formulate a plan to help manage side effects, hopefully making them tolerable, Strickland said.
Novant Health’s integrative medicine program — with nutritional counseling, exercise programs, stress management and other therapies like acupuncture — can help alleviate side effects.
The inventor of tamoxifen
One of the world’s most successful cancer drugs was originally developed as birth control. Pharmacologist V. Craig Jordan discovered a drug that was created to prevent pregnancy by blocking estrogen could stop the hormone's ability to unlock tumor cells and cause cancer. Jordan, affiliated with The University of Texas MD Anderson Cancer Center when he died in June 2024, first discovered that tamoxifen could prevent cancer without decreasing bone density.
Tamoxifen and other SERM (selective estrogen receptor modulator) drugs — raloxifene, toremifene, bazedoxifene and ospemifene — now are widely used, even in treatment of osteoporosis, painful intercourse and menopause symptoms.
