--- title: "What Is Breast Cancer? Causes, Risks & Early Detection" description: "Breast cancer starts when breast cells grow out of control. How it develops, spreads, and why catching it early still changes survival in the UK." url: https://breastcancer-charity.org/about-breast-cancer/what-is-breast-cancer/ robots: noindex --- # What Is Breast Cancer? Causes, Risks & Early Detection Breast health information Breast cancer starts when breast cells grow out of control. How it develops, spreads, and why catching it early still changes survival in the UK. ## Quick answer Breast cancer starts when cells in the breast begin to grow uncontrollably. It is the most commonly diagnosed cancer in women worldwide — and caught early, it is highly treatable. **Your next step:** see a GP (or your doctor, if you live outside the UK) about any new breast or chest change. These guides explain general information; your care team can advise on your own situation. **Content updated:** 28 May 2026 . Independent clinical review has not yet been recorded for this page. [How we prepare health information](https://breastcancer-charity.org/editorial-policy/) · [Report an error](https://breastcancer-charity.org/corrections/) At a glance 2.4 million new breast cancer cases are diagnosed globally each year (WHO) 56,000 people are diagnosed with breast cancer in the UK annually The UK five-year survival rate is almost 90% — one of the highest in the world Most cases are diagnosed in women over 50 ## What is breast cancer? Breast cancer is a disease in which cells in the breast grow uncontrollably and form a tumour. The breast is made up of three main parts: lobules (glands that produce milk), ducts (tubes that carry milk to the nipple) and connective tissue. Most breast cancers begin in the ducts or lobules. Breast cancer is the most commonly diagnosed cancer in women worldwide, with around 2.4 million new cases diagnosed each year according to the World Health Organization. In the UK, around 56,000 people are diagnosed with breast cancer annually — the vast majority of them women, though around 400 men are also diagnosed each year. ## How does breast cancer develop? Cancer begins when the DNA inside normal breast cells mutates or changes, causing the cells to grow and divide faster than they should and to continue living when healthy cells would normally die. These abnormal cells accumulate and form a mass of tissue — a tumour. Some breast tumours are benign (not cancerous) and do not spread. Others are malignant (cancerous) and can grow into nearby tissue or spread to other parts of the body. Breast cancer can spread when cancer cells travel through the lymphatic system or the bloodstream to other parts of the body — most commonly the bones, liver, lungs and brain. This is called secondary or [metastatic breast cancer](https://breastcancer-charity.org/about-breast-cancer/secondary-breast-cancer/). ## Who is at risk? Any woman can develop breast cancer. The biggest risk factor is simply being female and getting older — most cases are diagnosed in women over 50. Other risk factors include a [family history of breast cancer](https://breastcancer-charity.org/about-breast-cancer/breast-cancer-genes-and-family-history/), inherited gene mutations (especially BRCA1 and BRCA2), having had previous breast cancer, dense breast tissue, and certain lifestyle factors such as alcohol consumption, being overweight after the menopause, and not having children. However, the majority of women who develop breast cancer have no obvious risk factors beyond age and sex. This is why general screening — not just high-risk monitoring — matters. ## Why early detection matters The stage at which breast cancer is detected is the single biggest predictor of survival. When breast cancer is found at Stage 1 (small, localised tumour), the NHS five-year [survival rate](https://breastcancer-charity.org/about-breast-cancer/breast-cancer-survival-statistics/) is almost 100%. By Stage 4, when the cancer has spread to distant organs, that figure falls to more than 30%. In the UK, widespread NHS mammography screening and good public awareness mean that many cancers are caught early. In low-income countries, the absence of screening programmes and poor health literacy mean that most cases are found at an advanced stage — which is why survival rates in countries such as Pakistan and Indonesia are far lower than in the UK. ## Common myths — and the truth - Myth: "A lump that doesn't hurt can't be cancer." Truth: Most early breast cancer lumps are painless. - Myth: "Cancer is caused by a blow or bruise." Truth: Injuries do not cause cancer — they may draw attention to a pre-existing lump. - Myth: "If no one in my family has had it, I won't get it." Truth: Most women who develop breast cancer have no family history of the disease. - Myth: "Deodorant or underwired bras cause breast cancer." Truth: There is no scientific evidence for either claim. ## Frequently asked questions What is breast cancer in simple terms? Breast cancer is a disease where cells in the breast grow uncontrollably and form a tumour. Most breast cancers start in the milk ducts or lobules. It is the most commonly diagnosed cancer in women worldwide, with around 2.4 million new cases each year according to the WHO. How common is breast cancer in the UK? Breast cancer is the most common cancer in the UK. Around 56,000 people are diagnosed every year — roughly 150 every day. About 1 in 7 women will develop breast cancer at some point in their lifetime. Overall five-year survival now is almost 90%, having more than doubled over the past 40 years thanks to earlier detection and improved treatments. Is breast cancer curable? When caught early, breast cancer is highly treatable. The NHS five-year survival rate at Stage 1 is almost 100%. Even at more advanced stages, treatment has improved significantly. Secondary (Stage 4) breast cancer cannot currently be cured but can often be controlled for months or years with modern treatments. What is the most common type of breast cancer? Invasive ductal carcinoma (IDC) is the most common type, accounting for around 80% of all breast cancers. It starts in the milk ducts and grows into surrounding breast tissue. Other types include invasive lobular carcinoma, triple-negative breast cancer, HER2-positive breast cancer, and the rarer inflammatory breast cancer. Can men get breast cancer? Yes. Around 400 men are diagnosed with breast cancer in the UK each year. All men have some breast tissue and can develop breast cancer, though it is much rarer than in women. The symptoms and treatments are similar to those for women. How quickly does breast cancer grow? Growth rate varies widely. Some breast cancers double in size every 180 days; others grow far more slowly. High-grade (Grade 3) cancers tend to grow faster than low-grade (Grade 1) ones. This is why acting quickly on any symptom matters — and why NHS screening catches cancers at smaller, more treatable sizes before symptoms appear. ## Sources and further reading - [NHS: what is breast cancer in women](https://www.nhs.uk/conditions/breast-cancer-in-women/what-is-breast-cancer-in-women/) - [NHS: symptoms of breast cancer in women](https://www.nhs.uk/conditions/breast-cancer-in-women/symptoms-of-breast-cancer-in-women/) - [NHS: causes of breast cancer in women](https://www.nhs.uk/conditions/breast-cancer-in-women/causes-of-breast-cancer-in-women/) - [WHO: breast cancer fact sheet](https://www.who.int/news-room/fact-sheets/detail/breast-cancer) - [Cancer Research UK: breast cancer incidence statistics](https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/breast-cancer/incidence-invasive) - [Cancer Research UK: breast cancer survival statistics](https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/breast-cancer/survival) This content is for educational purposes and does not constitute medical advice. Always consult a qualified healthcare professional for personal medical guidance. Source links do not imply endorsement by the NHS or another organisation. See our [editorial policy](https://breastcancer-charity.org/editorial-policy/). ## Keep reading [Support ### Where can I get breast cancer support in the UK?](https://breastcancer-charity.org/breast-cancer-support/) [🎗️ ### What are the symptoms of breast cancer?](https://breastcancer-charity.org/about-breast-cancer/breast-cancer-symptoms/)[⚠️ ### What causes breast cancer and who is at risk?](https://breastcancer-charity.org/about-breast-cancer/breast-cancer-causes-and-risk-factors/)[📊 ### What do the stages of breast cancer mean?](https://breastcancer-charity.org/about-breast-cancer/breast-cancer-stages/)