In several of our previous guides on breast cancer subtypes like Luminal A and Luminal B, hormone therapy has come up repeatedly as a cornerstone of treatment. But while we’ve explained how and when it’s used, we haven’t yet given hormone therapy the focused attention it deserves. What exactly is hormone therapy? How does it work? And perhaps most importantly—what are the benefits and side effects cancer patients should know about if hormone therapy is a treatment option for their illnes
How Does Hormone Therapy Work?
Hormones are chemical messengers that travel through the bloodstream to regulate everything from metabolism and mood to sexual function and tissue growth. Certain cancers — particularly major types of breast and prostate cancers — are hormone-sensitive. This means they rely on these hormonal signals to grow and multiply
Hormone therapy generally works by increasing or lowering specific hormone levels in the body or by activating or blocking hormone receptors on cells, depending on whether a patient requires more or less hormonal signaling. When applied to hormone receptor-positive cancers, hormone therapy treatments can effectively “starve” the tumor, slowing or even halting its growth by cutting the tumor off from estrogen, progesterone, or testosterone. Some hormone therapies suppress hormone production entirely, while others work more subtly by blocking receptors or inhibiting enzymes involved in hormone synthesis.
What is Hormone Therapy Used For?
Due to how integral hormones are to various bodily functions, hormone therapy is used for a wide variety purposes. These include menopause symptom relief, transgender hormone therapy, low testosterone treatment, thyroid disorders, adrenal insufficiencies, bone health, and growth disorders to name a few. This sampling shows that hormonal processes sometimes need to be slowed, while at other times, they need to be enhanced.
When it comes to cancer, it’s usually not the most immediate oncological procedure that comes to mind compared to radiotherapy and chemotherapy. Nonetheless, it can be just as effective as those more well-known operations depending on the situation as noted in the 2020 Annals of Oncology article “Prostate cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up”.
General applications of hormone for cancer patients include:
- Adjuvant therapy: To reduce the risk of recurrence after surgery or chemotherapy
- Neoadjuvant therapy: To shrink tumors before surgery
- Palliative therapy: To relieve symptoms in advanced or metastatic cancer
What Types of Cancer Can Be Treated with Hormone Therapy
Ideally, a cancer would only require a specific process, as the more procedures used compound the strain on a person’s body. Of course, there will be cases where utilizing a number of them in conjunction will be required to boost the probability of a promising outcome. By itself, and alongside other oncological processes, hormone therapy is most commonly used in the treatment of the following cancers:
- Breast cancer – Especially estrogen receptor-positive (ER+) or progesterone receptor-positive (PR+) types like Luminal A and B subtypes
- Prostate cancer – Androgen deprivation therapy (ADT) is widely used to lower testosterone
- Endometrial (uterine) cancer – Some forms respond to hormone therapy like progestins
- Ovarian cancer – In select cases, hormonal agents like tamoxifen are used
- Thyroid cancer – TSH suppression with levothyroxine may be employed post-surgery
Each cancer type requires a different strategy depending on which hormones are driving the disease. For instance, a woman with early-stage Luminal B breast cancer may receive five to ten years of estrogen-blocking therapy. In contrast, a man with advanced prostate cancer may be treated with medications that drastically lower testosterone.
The Risks of Hormone Therapy
While hormone therapy has helped extend survival and improve outcomes for millions of cancer patients, it’s not without its downsides. Hormones are intricately involved in many body systems, so interfering with them can cause a range of side effects—some mild, some more serious. Do keep in mind that the lists of hormone therapy side effects may not adequately stress how strong and volatile they can be.
For instance, over the course of the last decade, the manufactured leuprolide hormone Lupron was mired in controversy. You may have heard about its competencies as a prostate cancer treatment or as a puberty blocker. Additionally, it was so versatile and potent that it could be used for both chemical castration and as a fertility treatment.
Many were prescribed Lupron, and those same patients had to grapple with harsh side effects unique to how the treatment interacted with their hormones: bleeding gums, acne, difficulty urinating, protracted nausea, and migraines. Unsealed clinical trial results featured in “LUPRON LAWSUIT: Georgia woman says drug used to treat endometriosis led to series of health problems” showed that 62% of women who took Lupron did not regain normal estrogen levels even after they stopped taking it. Terry Paulen, the woman from that case, claimed to have had her appearance look prematurely aged from Lupron’s usage.
Common Side Effects of Hormone Therapy
Some common side effects of hormone therapy include:
- Hot flashes
- Mood changes
- Fatigue
- Weight gain
- Weight loss
- Decreased libido
- Bone thinning (osteopenia or osteoporosis)
- Cardiovascular risks (especially in older patients)
Long-term hormone therapy may also increase the risk of developing diabetes or blood clots, depending on the medication used and the patient’s overall health profile. Bone thinning is a particularly ironic side effect as hormone therapy is sometimes used to treat osteoporosis in postmenopausal women. Please note that many of the aches and tiredness caused by hormone therapies can potentially linger for months if not years after they conclude.
Cancer-Specific Hormone Therapy Side Effects
Breast cancer patients may experience joint pain, vaginal dryness, or a heightened risk of uterine cancer (in the case of tamoxifen usage). Prostate cancer patients may face muscle loss, breast enlargement, or metabolic changes linked to prolonged testosterone suppression. It’s essential for oncologists and patients to weigh the hormone therapy benefits against these risks—and to have a plan for managing side effects early in the treatment process.
Major Hormone Therapy Treatments for Cancer
A variety of medications are used in hormone therapy, each tailored to block specific hormonal pathways. Some of the most commonly prescribed include:
- Tamoxifen – A selective estrogen receptor modulator (SERM) used mainly in premenopausal women with ER+ breast cancer
- Aromatase inhibitors (e.g., letrozole, anastrozole, exemestane) – Used in postmenopausal women to block estrogen production
- Lupron (leuprolide) – A GnRH agonist that reduces testosterone in men and suppresses ovarian function in women
- Zoladex (goserelin) – Another injectable GnRH agonist used for both breast and prostate cancers
- Degarelix – A GnRH antagonist used for rapid testosterone suppression in prostate cancer
- Progestins (e.g., megestrol acetate) – Used in endometrial cancer and occasionally in breast cancer
- Levothyroxine – Used post-thyroidectomy to suppress TSH and prevent thyroid cancer recurrence
And now, a fairly recent name in the conversation is gaining momentum: Orgovyx (relugolix). Approved by the FDA in 2020 for prostate cancer, Orgovyx is an oral GnRH antagonist that offers a different path from traditional injections. It works by rapidly lowering testosterone without the initial hormone surge associated with older medications like leuprolide. In subsequent clinical trials listed in “Oral Relugolix for Androgen-Deprivation Therapy in Advanced Prostate Cancer”, Orgovyx showed fewer cardiovascular side effects compared to other ADT options.
We’ll be exploring Orgovyx— what it can do and how Encer may be able to help it —in our next article.
FAQ: Hormone Therapy for Cancer Treatment
Q: What is hormone therapy for cancer?
A: Hormone therapy is a treatment that alters hormone levels or blocks hormone receptors to slow or stop the growth of hormone-sensitive cancers, such as breast and prostate cancer. It works by “starving” tumors of hormones like estrogen, progesterone, or testosterone, which they need to grow.
Q: How does hormone therapy work for cancer?
A: Hormone therapy either increases or decreases specific hormone levels or activates/blocks hormone receptors on cells. For hormone receptor-positive cancers, it cuts off hormones like estrogen or testosterone, slowing tumor growth through methods like suppressing hormone production or inhibiting related enzymes.
Q: What is hormone therapy used for besides cancer treatment?
A: Beyond cancer, hormone therapy treats conditions like menopause symptoms, transgender hormone therapy, low testosterone, thyroid disorders, adrenal insufficiency, bone health issues, and growth disorders, either by slowing or enhancing hormonal processes depending on the patient’s needs.
Q: What types of cancer can be treated with hormone therapy?
A: Hormone therapy is commonly used for breast cancer (ER+/PR+ types like Luminal A and B), prostate cancer (via androgen deprivation therapy), endometrial cancer (with progestins), ovarian cancer (select cases with tamoxifen), and thyroid cancer (TSH suppression post-surgery).
Q: What are the general applications of hormone therapy in cancer care?
A: Hormone therapy serves as adjuvant therapy to reduce recurrence risk after surgery or chemotherapy, neoadjuvant therapy to shrink tumors before surgery, and palliative therapy to relieve symptoms in advanced or metastatic cancer, improving patient outcomes.
Q: What are the common side effects of hormone therapy for cancer?
A: Common side effects include hot flashes, mood changes, fatigue, weight gain or loss, decreased libido, bone thinning (osteopenia/osteoporosis), and cardiovascular risks. Long-term use may increase risks of diabetes or blood clots, with effects potentially lingering for months or years.
Q: What are cancer-specific side effects of hormone therapy?
A: Breast cancer patients may experience joint pain, vaginal dryness, or increased uterine cancer risk (e.g., with tamoxifen). Prostate cancer patients may face muscle loss, breast enlargement, or metabolic changes due to testosterone suppression, requiring careful management.
Q: Why is Lupron controversial in hormone therapy?
A: Lupron (leuprolide), used for prostate and breast cancer, has been linked to severe side effects like bone thinning and fatigue. A 2018 WSB-TV report noted that 62% of women treated for endometriosis didn’t regain normal estrogen levels post-treatment, sparking debate about its risks.
Q: What are the major hormone therapy drugs for cancer?
A: Common drugs include Tamoxifen (for ER+ breast cancer), aromatase inhibitors (e.g., letrozole), Lupron and Zoladex (GnRH agonists), Degarelix (GnRH antagonist), progestins (for endometrial cancer), levothyroxine (for thyroid cancer), and Orgovyx (a newer oral option for prostate cancer).
Q: What is Orgovyx, and how does it differ from other hormone therapies?
A: Orgovyx (relugolix), FDA-approved in 2020 for prostate cancer, is an oral GnRH antagonist that rapidly lowers testosterone without the initial hormone surge seen in drugs like Lupron. Clinical trials show it has fewer cardiovascular side effects, offering a safer alternative.