Preventing Breast Cancer — What the Evidence Says

What the evidence supports

According to Cancer Research UK, around 23% of breast cancers in the UK are linked to lifestyle factors that could potentially be modified. The evidence-based factors that lower risk are:

• Maintaining a healthy weight after the menopause — excess body fat produces oestrogen, which can fuel hormone receptor-positive breast cancers
• Regular physical activity — at least 150 minutes of moderate activity per week
• Limiting or avoiding alcohol — risk increases with each unit consumed regularly; there is no "safe" level for breast cancer risk
• Breastfeeding — the longer you breastfeed, the greater the protective effect
• Attending NHS screening — early detection isn't prevention, but it dramatically improves survival

Chemoprevention for high-risk individuals

For women at high risk (particularly those with BRCA mutations or a strong family history), NICE recommends considering preventive drug therapy:

• Tamoxifen: Reduces risk by around 30–40% in premenopausal high-risk women
• Anastrozole: Reduces risk in postmenopausal high-risk women
• Risk-reducing mastectomy: For women at very high risk (BRCA1/2 mutation carriers), surgical removal of both breasts reduces lifetime risk by up to 97%

What does NOT prevent breast cancer

Avoiding specific foods, taking particular supplements, or using "anti-cancer" products have no proven benefit in preventing breast cancer. The NHS does not recommend any supplement specifically for breast cancer prevention.

The limits of prevention

It is important to acknowledge that the majority of breast cancers cannot be attributed to modifiable lifestyle factors. Most women who develop breast cancer lead healthy lives. Prevention matters, but so does early detection — which is why regular screening and self-examination are equally important parts of the story.