Hormone therapy

What is hormone therapy?

This form of treatment works against cancers that need particular hormones to keep growing, breast and prostate cancer being the clearest examples. You might come across it under a few different names: hormonal therapy, sometimes just hormone treatment, or, in more clinical settings, endocrine therapy.

It isn't the same thing as hormone replacement therapy (HRT), which eases menopause symptoms instead. The two names sound alike, which understandably causes some confusion, but they refer to entirely different treatments.

What conditions does hormone therapy treat?

This treatment is mostly reserved for breast and prostate cancers that lean on hormones to keep multiplying.

Whether it's offered for breast cancer comes down to lab results from a tissue sample: if oestrogen turns out to be fuelling the cancer's growth, this gets labelled oestrogen receptor positive, or ER-positive. A separate check looks at whether progesterone plays a similar role, labelled PR-positive if so. Most PR-positive cancers turn out ER-positive too, and the case for this treatment weakens somewhat where PR-positive stands alone.

For prostate cancer, the target instead is testosterone, a hormone capable of pushing this particular cancer forward.

What are the benefits of hormone therapy?

This treatment can:

• hold back or halt a cancer's growth, lowering the odds of it returning later
• shrink a tumour ahead of surgery or radiotherapy
• wipe out cancer cells that have resurfaced or travelled to a different part of the body
• lower the odds of breast cancer developing at all, for women whose baseline risk sits well above average.

With prostate cancer specifically, it can also settle symptoms for men who aren't in a position to undergo surgery or radiotherapy.

Are there different types of hormone therapy?

Broadly speaking, treatments either shut down hormone production somewhere in the body, or work by disrupting how those hormones behave once they're already present.

For breast cancer, the names you might encounter include:

• tamoxifen
• an aromatase inhibitor, anastrozole, exemestane and letrozole among the options, generally suited to those who’ve already gone through menopause
• goserelin or leuprorelin, generally suited to those who haven't reached menopause yet
• Fulvestrant.

Prostate cancer has its own version of the surgical route too, removing the testicles, alongside medication designed to bring testosterone down. Removing the ovaries can achieve something comparable for women.

What happens before hormone therapy?

A piece of the tumour typically gets examined beforehand, checked for the hormone-linked markers mentioned earlier, since this is what tells your team whether the treatment is worth pursuing.

For breast cancer, surgery usually happens first, with this treatment starting afterwards. There are exceptions though, occasionally it's brought forward to shrink a tumour down first, or relied on by itself where an anaesthetic would pose too much risk.

How is hormone therapy given?

A few different delivery methods exist:

• swallowed as a tablet
• injected, either into muscle or just beneath the skin
• delivered surgically, removing whichever organs are producing the hormones in question, ovaries for women or testicles for men.

Tablets are generally something you take at home, while injections happen at a surgery, clinic or hospital. Where tamoxifen or one of the aromatase inhibitors follows breast cancer surgery, a run of five to ten years is typical, the precise length shaped by your particular cancer and how likely it is to return.

What does recovery and monitoring look like?

How this treatment feels day to day varies enormously, shaped by your cancer, how far it's progressed, and which drug and dose you've been given.

Prostate cancer treatment gets tracked through regular PSA blood tests, steady or falling numbers being a good sign, rising ones suggesting things may no longer be working as well as they should. Breast cancer treatment instead means routine check-ups, an examination covering your neck, underarm and chest, along with the breast itself, plus mammograms on a regular schedule.

Tapering off gradually isn't usually necessary here, and coming off the treatment doesn't bring problems of its own. For breast cancer, the protective effect against recurrence can carry on for five years or more after finishing, sometimes called a carryover effect.

What are the side effects of hormone therapy?

What you experience depends on the specific drug, the dose, and whether you’re male or female.

Men being treated for prostate cancer commonly notice:

• hot flushes
• a drop in sexual interest or ability
• bones becoming weaker
• diarrhoea and feeling sick
• breast swelling or tenderness
• Tiredness.

Women being treated for breast cancer commonly notice:

• hot flushes, night sweats and vaginal dryness
• a lower sex drive alongside mood changes
• aching, stiff joints
• tiredness, headaches, feeling sick and diarrhoea.

These menopause-like effects from breast cancer treatment tend to hit harder than a natural menopause would. Prostate cancer treatment can bring on weight gain too, worth flagging to your doctor, nurse or a dietitian if it starts becoming an issue.

Where side effects prove genuinely difficult to live with, your team might propose pausing treatment briefly, or trying a different drug in this same category instead.

Medication Risks:

• Thromboembolism (Blood Clots): Certain treatments, particularly Tamoxifen , carry a statistically significant risk of causing dangerous blood clots. You must monitor your limbs closely.
• Uterine changes: Tamoxifen can very rarely cause thickening of the womb lining, which presents as unexpected vaginal bleeding.