Tamoxifen is a key part of hormone therapy for many people recovering from hormone receptor-positive breast cancer. If you’ve completed surgery, chemotherapy or radiotherapy, you might be wondering how long you need to stay on Tamoxifen 20mg, and what the long-term plan looks like.

What does Tamoxifen do?

Tamoxifen works by blocking oestrogen receptors on breast cancer cells, preventing the hormone from fuelling cancer growth. This reduces the risk of the cancer coming back and can also help prevent it in the other breast.

It is most commonly used for pre-menopausal women, but can also be beneficial for some postmenopausal patients, depending on the type and stage of their cancer.

Typical duration of treatment

In the UK, the current guidelines often recommend taking Tamoxifen for 5 to 10 years, depending on individual risk factors. The exact length will be determined by your oncologist, based on factors such as:

• The size and grade of your tumour
• Lymph node involvement
• Age and menopausal status
• Family history of breast cancer

You may initially be prescribed Tamoxifen for 5 years, and then your consultant may recommend continuing for another 5 years or switching to another hormone therapy such as an aromatase inhibitor.

Why longer treatment may be better

Research has shown that taking Tamoxifen for 10 years can provide better long-term protection than stopping at 5 years. It may reduce the risk of recurrence and improve overall survival rates, particularly for premenopausal women.

One large study (ATLAS trial) found that women who took Tamoxifen for 10 years had lower breast cancer mortality rates than those who took it for only 5 years.

Are there long-term side effects?

Some people experience side effects such as:

• Hot flushes
• Vaginal dryness or discharge
• Tiredness
• Mood changes
• Irregular periods (for premenopausal women)

While these side effects can be unpleasant, many are manageable. Your doctor can suggest lifestyle changes, complementary therapies or, in some cases, medications to help ease symptoms.

Less commonly, Tamoxifen can slightly increase the risk of blood clots and endometrial cancer. Regular check-ups are important to monitor for any complications.

Regular check-ins are important

You’ll have regular follow-up appointments to monitor:

• Bone health (especially in premenopausal women who may experience bone thinning)
• Menstrual changes (if premenopausal)
• Any signs of recurrence
• Liver function and overall wellbeing

Empowering yourself through treatment

Staying on Tamoxifen can feel like a long journey, but many women find reassurance in knowing they’re taking steps to protect their health. Talk openly with your medical team, ask questions and seek support if needed.

In summary

Tamoxifen is a long-term treatment, and for many, it’s worth taking for up to 10 years. While side effects can occur, they’re often manageable with support from your medical team. Always discuss any concerns with your consultant, and never stop the medication without advice. Staying consistent with your hormone therapy is one of the most powerful ways to reduce the risk of breast cancer recurrence and protect your future health.