Breast Cancer: Symptoms, Risk Factors, Screening and Early Detection
Breast cancer is one of the most common cancers worldwide and can affect people in every country.
It develops when abnormal cells in the breast begin growing uncontrollably. These cells can form a tumour and, if the cancer becomes invasive, may spread into surrounding breast tissue, nearby lymph nodes or other parts of the body.
Breast cancer mainly affects women, but men can develop it too.
Finding breast cancer early and receiving appropriate treatment can substantially improve outcomes.
However, early detection involves more than looking for a lump. It includes knowing what is normal for your breasts, reporting unusual changes promptly and participating in appropriate screening when recommended.
How Common Is Breast Cancer?
Breast cancer represents a major global health challenge.
According to the World Health Organization, an estimated 2.4 million women were diagnosed with breast cancer worldwide in 2024, and approximately 694,000 women died from the disease.
Breast cancer occurs in women in every country and can occur at any age after puberty, although rates increase later in life.
Approximately 0.5% to 1% of breast cancers occur in men.
What Happens in Breast Cancer?
Breasts contain structures including milk-producing lobules and ducts that carry milk towards the nipple.
Breast cancer most commonly begins in cells lining these ducts or lobules.
Some abnormal cells initially remain within the structure where they developed. This is known as in situ disease.
When cancer cells grow into surrounding breast tissue, the cancer becomes invasive.
Cancer cells can eventually travel through the lymphatic system or bloodstream to other parts of the body.
When cancer spreads to distant organs, this is called metastatic breast cancer.
Can Breast Cancer Develop Without Symptoms?
Yes.
Breast cancer may cause no noticeable symptoms during its early stages.
This is one reason mammography can be valuable for people who meet screening criteria: it may identify breast cancer before a lump can be felt or other symptoms appear.
However, this does not mean that breast cancer never causes early warning signs.
Some cancers are first discovered because a person notices a change in their breast.
Both symptom awareness and appropriate screening are therefore important.
What Are the Warning Signs of Breast Cancer?
Different people can experience different symptoms.
Possible warning signs include:
- a new lump or thickened area in the breast,
- a new lump or swelling in the armpit,
- change in the size or shape of a breast,
- dimpling or puckering of the breast skin,
- redness or other unusual skin changes,
- changes in the appearance of a nipple,
- a nipple that becomes newly pulled inward,
- abnormal nipple discharge, including bloody discharge,
- flaky, crusted or irritated skin around the nipple,
- and persistent unusual breast or nipple pain.
Having one of these symptoms does not automatically mean you have breast cancer.
Many non-cancerous breast conditions can cause similar changes.
Nevertheless, a new or unexplained breast change should be properly assessed.
Does a Breast Cancer Lump Always Hurt?
No.
A cancerous breast lump is often painless, although pain can occur.
Do not assume that a painless lump is harmless.
Likewise, breast pain by itself is commonly caused by conditions other than cancer.
The important point is to have a new, persistent or unusual breast change evaluated rather than attempting to diagnose it yourself.
Most Breast Lumps Are Not Cancer
Finding a breast lump can be frightening, but most breast lumps are caused by conditions other than cancer.
Examples include cysts and other benign breast changes.
The way a lump feels cannot reliably establish whether it is cancerous.
A healthcare professional may recommend clinical examination and imaging to determine what the lump represents.
What Is Inflammatory Breast Cancer?
Inflammatory breast cancer is an uncommon but aggressive form of breast cancer.
Unlike many breast cancers, it may not initially produce a clearly defined lump.
Possible symptoms can include:
- rapid breast swelling,
- redness or discolouration,
- warmth,
- thickening of the skin,
- skin resembling the surface of an orange,
- tenderness,
- and nipple changes.
These symptoms can resemble an infection such as mastitis.
A breast infection is much more common than inflammatory breast cancer, particularly during breastfeeding, but symptoms that are unexplained, severe or do not improve as expected require further assessment.
Know What Is Normal for Your Breasts
Breasts naturally differ from person to person.
They can also change because of:
- menstrual cycles,
- pregnancy,
- breastfeeding,
- ageing,
- changes in body weight,
- hormonal medicines,
- and menopause.
There is no single appearance or texture that represents a “normal breast” for everyone.
The useful approach is breast awareness—becoming familiar with how your own breasts normally look and feel.
That makes it easier to recognise a new change.
Do You Need a Formal Monthly Breast Self-Examination?
Routine breast self-examination should not be treated as a substitute for evidence-based screening.
Research has not established formal breast self-examination alone as an adequate screening test that reduces breast-cancer mortality.
However, being familiar with your breasts remains useful.
If you notice a new lump, skin change, nipple change or another unusual symptom, report it rather than waiting for your next scheduled mammogram.
Who Is at Risk of Breast Cancer?
Anyone with breast tissue can potentially develop breast cancer.
However, certain factors increase risk.
Having a risk factor does not mean that you will definitely develop breast cancer.
Similarly, having no obvious risk factors does not guarantee that you will never develop it.
WHO reports that approximately 80% of breast cancers occur in women without a specific identifiable risk factor other than sex and age.
Age
Breast-cancer risk increases with age.
Although younger women can develop breast cancer, the disease becomes increasingly common later in life.
Age is therefore an important factor when deciding who should participate in population screening programmes.
Sex
Being female is the strongest breast-cancer risk factor.
Approximately 99% of breast cancers occur in women.
But because men have breast tissue, breast cancer can occur in men as well.
Family History
Having a close relative with breast cancer can increase risk.
This can be especially relevant when several close relatives have had breast or ovarian cancer, particularly at younger ages.
However, most women diagnosed with breast cancer do not have a known family history of the disease.
Never assume that you cannot develop breast cancer simply because nobody in your family has had it.
Inherited Genetic Changes
Some inherited genetic variants substantially increase breast-cancer risk.
The best known include changes in:
- BRCA1
- BRCA2
- PALB2
Other genes can also influence risk.
Genetic testing is not automatically necessary for everyone.
People with strong personal or family histories may be referred for genetic counselling so their risk and the potential benefits and limitations of testing can be assessed.
Previous Breast Cancer
Someone who has previously had breast cancer may have an increased risk of developing another breast cancer.
Certain non-cancerous breast conditions can also be associated with increased future risk.
Follow-up recommendations should be individualized.
Dense Breasts
Breasts are made of different proportions of fatty, glandular and fibrous tissue.
Having dense breasts can:
- increase breast-cancer risk,
- and make some cancers more difficult to see on a mammogram.
Breast density is determined through mammography rather than simply by how the breasts feel.
Reproductive and Hormonal Factors
Lifetime exposure to reproductive hormones can influence breast-cancer risk.
Factors associated with risk can include:
- starting menstruation at a younger age,
- experiencing menopause at an older age,
- reproductive history,
- and certain forms of menopausal hormone therapy.
These are risk factors, not guarantees that cancer will develop.
Alcohol
Alcohol consumption increases breast-cancer risk.
Risk generally increases with greater consumption.
Reducing alcohol consumption—or not drinking alcohol—can therefore reduce one modifiable risk factor.
Body Weight
Having excess body weight, particularly after menopause, is associated with increased breast-cancer risk.
This does not mean people with obesity will necessarily develop cancer, and weight should never be used to blame someone for developing breast cancer.
Risk is influenced by many factors, including those that cannot be changed.
Physical Activity
Regular physical activity is associated with a lower risk of breast cancer.
Exercise also supports cardiovascular health, metabolic health, bone health and general wellbeing.
Choose activities appropriate for your health and physical abilities.
Tobacco
Tobacco use is associated with numerous cancers and other serious diseases.
WHO also includes tobacco use among factors associated with breast-cancer risk.
Avoiding tobacco is therefore an important part of overall cancer prevention and health protection.
Previous Radiation Exposure
Previous exposure to significant ionising radiation, particularly radiation involving the chest at a younger age, can increase later breast-cancer risk.
This is particularly relevant to some people who previously received radiation therapy for another cancer.
Medical imaging uses radiation carefully because doctors balance potential risks against expected benefits.
Do not avoid medically necessary imaging because of fear of radiation without discussing your concerns with a healthcare professional.
Breastfeeding and Breast-Cancer Risk
Breastfeeding is associated with a reduction in breast-cancer risk.
However, decisions about breastfeeding are personal and can be influenced by health, circumstances, milk supply, medicines, work and many other factors.
Someone who cannot or chooses not to breastfeed should not be made to feel responsible for future cancer risk.
Breast cancer has many causes and risk factors.
Can Breast Cancer Be Completely Prevented?
No.
There is currently no guaranteed way to prevent every breast cancer.
Some important risk factors—such as age, sex and inherited genetic changes—cannot be modified.
However, certain behaviours may help reduce risk.
These include:
- maintaining regular physical activity,
- avoiding tobacco,
- reducing or avoiding alcohol,
- maintaining metabolic health and an appropriate body weight,
- breastfeeding where possible and desired,
- and discussing menopausal hormone therapy with a healthcare professional when relevant.
Risk reduction is not the same as guaranteed prevention.
Someone can follow a healthy lifestyle and still develop breast cancer.
What Is Breast-Cancer Screening?
Screening means testing people who do not currently have symptoms to look for cancer before it becomes clinically apparent.
This is different from diagnostic testing.
If you already have a breast lump, abnormal nipple discharge or another concerning breast symptom, you need medical evaluation, not simply routine screening.
What Is a Mammogram?
A mammogram is a low-dose X-ray image of the breast.
It can detect some breast cancers before they are large enough to feel.
Mammography is the standard breast-cancer screening method for many women.
However, it is not perfect.
A mammogram can sometimes:
- miss a cancer,
- produce an abnormal result when cancer is not present,
- lead to additional imaging or biopsy,
- or detect a cancer that might never have caused harm during a person's lifetime.
Despite these limitations, appropriate mammography screening can reduce deaths from breast cancer.
Should Every Woman Have a Mammogram Every Year?
Not necessarily.
This is an important correction to the original KandyWandy article.
There is no single worldwide screening schedule appropriate for every woman.
Recommendations differ according to:
- age,
- individual breast-cancer risk,
- family history,
- genetic risk,
- previous breast conditions,
- national screening programmes,
- healthcare resources,
- and recommendations from local health authorities.
For example, WHO describes organized mammography screening commonly targeting women approximately 50–69 years old in settings where appropriate health systems and treatment services are available.
Other national organisations begin routine screening at younger ages.
The appropriate approach is to follow the breast-screening recommendations in your country and discuss your personal risk with an appropriate healthcare professional.
Screening Is for People Without Symptoms
This distinction is extremely important.
Do not wait until your scheduled screening appointment if you discover:
- a new breast lump,
- unusual nipple discharge,
- skin dimpling,
- nipple retraction,
- unexplained breast-shape changes,
- or another concerning symptom.
Screening programmes are designed primarily for people without symptoms.
A new symptom requires diagnostic assessment.
What Happens If a Mammogram Is Abnormal?
An abnormal mammogram does not automatically mean breast cancer.
Further assessment may include:
- additional mammogram images,
- ultrasound,
- breast MRI in selected situations,
- clinical examination,
- and/or biopsy.
A biopsy involves taking a small tissue sample for examination.
A biopsy can determine whether suspicious cells are cancerous and provide information that helps guide treatment.
How Is Breast Cancer Diagnosed?
Diagnosis may involve a combination of:
- medical history,
- clinical breast examination,
- mammography,
- ultrasound,
- MRI in selected circumstances,
- and biopsy.
Imaging can identify suspicious abnormalities, but tissue examination through biopsy is often necessary to confirm a cancer diagnosis.
Are All Breast Cancers the Same?
No.
Breast cancer is not one single biological disease.
Tumours can differ according to characteristics such as:
- hormone receptors,
- HER2 status,
- genetic features,
- tumour grade,
- and stage.
These differences help doctors determine which treatments are most likely to work.
For example, some breast cancers respond to hormone therapy, while HER2-positive cancers may respond to medicines specifically targeting HER2.
How Is Breast Cancer Treated?
Treatment depends on the type of cancer, its biological characteristics, its size, whether it has spread and the person's overall circumstances.
Treatment may include:
Surgery
Surgery may remove the tumour while preserving much of the breast (breast-conserving surgery or lumpectomy) or remove the entire breast (mastectomy).
The appropriate operation depends on individual circumstances.
Radiation Therapy
Radiotherapy uses high-energy radiation to destroy cancer cells.
It is commonly used after breast-conserving surgery and in some other situations to reduce the risk of cancer returning.
Chemotherapy
Chemotherapy uses medicines that kill or control rapidly dividing cancer cells.
It may be given before surgery, after surgery or as part of treatment for advanced disease.
Hormone Therapy
Some breast cancers depend on hormones such as oestrogen for growth.
Hormone-receptor-positive cancers can often be treated with medicines that block hormonal effects or reduce hormone production.
Targeted Therapy
Certain medicines target specific characteristics of cancer cells.
HER2-targeted therapies are an important example.
Other Systemic Treatments
Depending on the cancer subtype and stage, other treatments, including immunotherapy in selected situations, may be considered.
Cancer treatment is increasingly personalised according to the biological characteristics of the tumour and the individual patient.
What Does Breast-Cancer Stage Mean?
Staging describes how much cancer is present and how far it has spread.
Doctors consider factors including:
- tumour size,
- involvement of nearby lymph nodes,
- spread to distant organs,
- and biological characteristics of the cancer.
Earlier-stage breast cancers have generally not spread to distant parts of the body.
Metastatic breast cancer means cancer has spread to distant organs such as bones, lungs, liver or brain.
Treatment goals and options differ according to stage.
Does Early Detection Matter?
Yes.
Breast cancers identified and treated before they have spread widely are generally easier to treat successfully.
WHO emphasizes early diagnosis, timely evaluation and comprehensive treatment as major components of reducing deaths from breast cancer.
However, “early detection” should not be interpreted as a promise that every early cancer will be cured or that every advanced cancer could have been prevented.
Cancer biology differs between individuals.
What About Headaches and Weight Loss?
The old KandyWandy article listed headaches, reduced appetite and weight loss among the general warning signs of breast cancer.
That presentation was misleading.
These are not the main breast changes used to recognise early breast cancer.
In advanced disease that has spread elsewhere in the body, symptoms can depend on the organs involved.
For example, metastatic disease may sometimes cause:
- persistent bone pain,
- neurological symptoms,
- breathing problems,
- or other systemic symptoms.
But headaches should not be presented as though they are a typical early symptom of breast cancer.
Can Men Get Breast Cancer?
Yes.
Although uncommon, men can develop breast cancer.
WHO estimates that approximately 0.5–1% of breast cancers occur in men.
Men should seek medical assessment for symptoms such as:
- a new breast or chest lump,
- nipple discharge,
- nipple inversion,
- skin changes around the breast or nipple,
- or unexplained swelling in the armpit.
Breast cancer should not be dismissed solely because the patient is male.
When Should You Seek Medical Advice?
Arrange appropriate medical assessment if you notice a new or unexplained change such as:
- a breast or armpit lump,
- thickening or swelling,
- nipple discharge other than breast milk,
- bloody nipple discharge,
- new nipple inversion,
- persistent unusual breast or nipple pain,
- change in breast size or shape,
- skin dimpling,
- persistent redness or unusual skin thickening,
- or another change that is not normal for you.
Do not wait for the change to become painful.
And do not wait for your next routine mammogram if you already have a concerning symptom.
A Breast Change Does Not Automatically Mean Cancer
Many breast changes are caused by benign conditions.
This is worth remembering because discovering a lump can create considerable anxiety.
But the fact that most lumps are not cancer is not a reason to ignore one.
The safest approach is:
Notice the change → get it evaluated → establish the cause.
Seven Things to Remember
1. Know what is normal for you.
Breast awareness can help you recognise changes.
2. A lump is not the only warning sign.
Look for nipple, skin, shape and underarm changes too.
3. Most breast lumps are not cancer.
But a new lump still deserves assessment.
4. Breast cancer can occur without a family history.
Most people diagnosed do not have a known family history.
5. Men can develop breast cancer.
It is uncommon but possible.
6. Screening schedules differ internationally.
Follow recommendations based on your age, risk and country.
7. Symptoms should not wait for routine screening.
A new breast change needs appropriate medical assessment.
The Bottom Line
Breast cancer develops when abnormal breast cells grow uncontrollably and can eventually invade surrounding tissue or spread elsewhere in the body.
Possible warning signs include a new breast or armpit lump, thickening, changes in breast size or shape, skin dimpling, nipple changes and abnormal nipple discharge.
Many breast changes are not cancer, but it is impossible to determine the cause reliably from appearance or touch alone.
Breast awareness can help people notice changes, while mammography can detect some cancers before symptoms develop.
Screening recommendations differ around the world, so there is no universal rule that every woman should have a mammogram every year.
The most important principles are to understand your personal risk, follow appropriate screening guidance where you live and seek medical assessment promptly when you notice an unusual breast change.
Medical Disclaimer
This article provides general health information for an international audience and is not a substitute for medical diagnosis, cancer screening advice or treatment. Breast-cancer screening recommendations vary according to age, individual risk and country. Anyone with a new or concerning breast change should seek assessment from an appropriately qualified healthcare professional rather than waiting for routine screening.
Sources and Further Reading
World Health Organization — Breast cancer
https://www.who.int/news-room/fact-sheets/detail/breast-cancer
World Health Organization — Cancer
https://www.who.int/news-room/fact-sheets/detail/cancer
National Cancer Institute — Breast Cancer Screening
https://www.cancer.gov/types/breast/screening
National Cancer Institute — Mammograms
https://www.cancer.gov/types/breast/screening/mammograms
Centers for Disease Control and Prevention — Symptoms of Breast Cancer
https://www.cdc.gov/breast-cancer/symptoms/index.html
Centers for Disease Control and Prevention — Breast Cancer Risk Factors
https://www.cdc.gov/breast-cancer/risk-factors/index.html
