Hormonal (Endocrine) Therapy

What hormonal therapy is — in plain words

Some cancers grow because a hormone in the body sticks to them and tells them to multiply. Most breast cancers carry oestrogen and progesterone receptors — they grow in response to oestrogen. Almost all prostate cancers grow in response to testosterone. Hormonal therapy doesn't kill the cancer with a punch like chemotherapy does. Instead, it removes the signal the cancer was relying on, and the cancer goes quiet.

This is sometimes called endocrine therapy, anti-hormone therapy, or hormone-blocking treatment. The names mean the same thing.

"Hormonal therapy is the most underrated treatment in oncology. It's gentle. It's tablets. It's not dramatic. But it prevents more breast cancer recurrences than anything else we do — provided the patient actually takes it, every day, for years."

Hormonal therapy in breast cancer

About two out of every three breast cancers are hormone receptor positive. For those cancers, blocking oestrogen is one of the most important things we can do. The choice of drug depends on whether you are pre- or post-menopausal.

Hormonal therapy is usually started after surgery and chemotherapy (if chemotherapy was needed), and it runs in the background of your normal life for years. The benefit isn't seen immediately — it shows up later, as the years pass and the cancer simply does not come back.

Why 5, 7, or 10 years?

The longer you take it, the more recurrences you prevent — but the benefit flattens over time, and side effects accumulate. For low-risk cancers, 5 years is often enough. For higher-risk cancers — large tumours, node-positive disease, younger patients — extending to 7 or 10 years offers extra protection. The decision is individualised and reviewed at the 5-year mark, not made once and forgotten.

Hormonal therapy in prostate cancer

Prostate cancer depends on testosterone the way most breast cancers depend on oestrogen. Lowering testosterone — sometimes called androgen deprivation therapy, or ADT — is the cornerstone of treatment for prostate cancer that has spread, that is high-risk and being treated with radiation, or that has come back after surgery.

For high-risk localised prostate cancer treated with radiation, hormonal therapy is typically given for 2 to 3 years. For advanced or metastatic prostate cancer, it's usually long-term, and now almost always combined with a second-generation anti-androgen or chemotherapy from the start — a combination that adds years of life compared with hormonal therapy alone.

Side effects — and how we manage each one

Hormonal therapy is taken for a long time, so side effects matter. Most are manageable. None of them should be ignored or just endured silently — there's almost always something we can do.

• Hot flashes and night sweats — the most common complaint. Layered clothing, a fan by the bed, cutting back on caffeine and spicy food help. If they're disrupting sleep, medications like venlafaxine or gabapentin can settle them considerably.
• Joint pain and stiffness — especially with aromatase inhibitors. Worst on waking. Regular movement, walking, swimming, and sometimes a switch to a different drug in the class help. Vitamin D levels are worth checking.
• Bone thinning (osteopenia, osteoporosis) — both aromatase inhibitors and androgen deprivation accelerate bone loss. A baseline DEXA scan, calcium and vitamin D supplementation, weight-bearing exercise, and sometimes a bone-protecting injection (zoledronic acid or denosumab) are part of the plan.
• Fatigue — real but often improved by exercise, paradoxically. Even a 20-minute daily walk makes a measurable difference.
• Low libido and sexual side effects — common in both men and women on long-term hormonal therapy. This is worth bringing up; vaginal moisturisers, lubricants, and sometimes low-dose local oestrogen (used carefully in breast cancer survivors) help women. Men may experience erectile dysfunction; this can be managed with medication, devices, or referral.
• Mood and cognitive changes — some patients describe a "fog" or low mood. Sleep, exercise, and where needed, counselling or an antidepressant help.
• Weight gain and metabolic changes — common with ADT in men. Diet, resistance training, and monitoring blood sugar and cholesterol are part of survivorship care.
• Hot flashes, gynaecomastia (breast tenderness or growth) in men — sometimes prevented with a small dose of radiation to the chest before starting anti-androgens.
• Risk of blood clots, uterine changes (tamoxifen) — uncommon but important. Any unusual vaginal bleeding on tamoxifen needs investigation. Calf swelling or sudden breathlessness needs urgent attention.

What a typical year on hormonal therapy looks like

1. You start the medication — a tablet at home, or an injection at the clinic.
2. The first review is at 4 to 6 weeks — to check tolerance and answer the questions that always come up.
3. Routine follow-up settles into every 3 to 6 months. Blood pressure, weight, blood tests, and a conversation about how you're really doing.
4. A bone density scan at baseline and every 1 to 2 years for those at risk of bone loss.
5. For breast cancer, an annual mammogram and clinical exam. For prostate cancer, regular PSA tests.
6. At year 5, a careful discussion about whether to continue, switch, or stop — based on your individual risk and how you've tolerated treatment.

What hormonal therapy is not

• Not chemotherapy. You won't lose your hair. You won't have the cyclical pattern of feeling unwell after each dose. There are no neutropenic infections.
• Not optional, for most patients. When the cancer is hormone-driven, this is the treatment with the largest absolute benefit over the longest time.
• Not a small thing to live with. Five to ten years of any medication affects daily life. Your symptoms are real, they deserve attention, and they can almost always be improved.
• Not the same drug for everyone. If one drug doesn't suit you, there is almost always another in the same family that will.

Fertility, pregnancy, and family planning

Tamoxifen and other hormonal therapies must not be taken during pregnancy. For younger women who hope to have children, we plan ahead — sometimes pausing treatment for a defined window after at least two years (an approach supported by recent evidence), with careful monitoring. This conversation belongs at the start of treatment, not the end. Read about long-term survivorship →