Breast Cancer: Causes, Symptoms, Risk Factors & Prevention

Introduction

Breast cancer is a type of cancer that develops when abnormal cells in the breast grow and divide uncontrollably. It is the most common cancer in women worldwide, although men can also develop breast cancer. According to the World Health Organization (WHO), an estimated 2.3 million women were diagnosed with breast cancer globally in 2022.

Breast cancer does not usually have one single cause. A person’s risk can be influenced by factors such as age, family history, inherited gene mutations, reproductive and hormonal factors, alcohol use, physical activity, body weight, and previous exposure to radiation. Having one or more risk factors does not mean that someone will definitely develop breast cancer.

Recognizing possible breast changes and following appropriate screening recommendations can help with early detection. This guide explains what breast cancer is, its main types, risk factors, symptoms, diagnosis, screening, and ways that may help reduce the risk.

What Is Breast Cancer?

Breast cancer develops when abnormal cells in the breast grow and divide in an uncontrolled way. These cells can form a tumor and, in some cases, invade nearby tissues or spread to other parts of the body.

Breast cancer can begin in different parts of the breast. Many breast cancers start in the cells lining the milk ducts, while others begin in the lobules, which are the glands that produce breast milk. Less common types can develop in other breast tissues.

If cancer cells spread beyond the breast to nearby lymph nodes or other parts of the body, the disease is known as metastatic breast cancer. Cancer can spread through the lymphatic system or bloodstream.

Not every breast lump or breast change is caused by cancer. Many breast conditions are benign, meaning they are not cancerous. However, a new or unusual breast change should be evaluated by a healthcare professional so that its cause can be determined.

Types of Breast Cancer

Breast cancer can be classified in several ways, including where it begins, whether it has invaded surrounding tissue, and certain biological features that can affect treatment. Some common types and subtypes include:

• Ductal carcinoma in situ (DCIS): DCIS is not invasive breast cancer because the abnormal cells have not spread beyond the milk duct, but some cases can develop into invasive breast cancer if untreated.
• Invasive ductal carcinoma (IDC): IDC begins in the cells lining a milk duct and then grows beyond the duct into nearby breast tissue. It is the most common type of invasive breast cancer.
• Invasive lobular carcinoma (ILC): ILC begins in the lobules, the glands that produce breast milk, and can spread into nearby breast tissue.
• Inflammatory breast cancer: This is a rare and more aggressive form of breast cancer that can cause redness, swelling, warmth, or a peau d’orange appearance of the breast. It may not produce a distinct lump.
• Triple-negative breast cancer: This type of breast cancer does not have receptors for estrogen or progesterone and does not have excess HER2 protein. Because it lacks these three common treatment targets, treatment options can differ from those used for some other breast cancers.

Doctors use imaging, biopsy, and laboratory testing to determine the type and characteristics of breast cancer. These findings help healthcare professionals determine the most appropriate treatment approach.

Causes and Risk Factors

Breast cancer does not usually have one identifiable cause. It develops when genetic changes cause breast cells to grow and divide abnormally. Researchers have identified many factors that can increase the likelihood of developing breast cancer, but having a risk factor does not mean that a person will definitely develop the disease. Some people develop breast cancer without having any known risk factors other than age and sex.

Genetic and Biological Risk Factors

• Age: The risk of breast cancer generally increases with age. Most breast cancers are diagnosed in older adults, although breast cancer can occur at any age.
• Family history: Having a close relative, such as a mother, sister, or daughter, with breast cancer can increase risk. A family history of ovarian cancer may also be relevant because some inherited genetic mutations can increase the risk of both cancers.
• Inherited gene mutations: Inherited changes in genes such as BRCA1 and BRCA2 can substantially increase the risk of breast and ovarian cancers. People with a strong family history or other features suggesting inherited risk may benefit from discussing genetic counseling with a healthcare professional.
• Personal history of breast cancer: People who have previously had breast cancer may have an increased risk of developing another breast cancer.
• Dense breasts: Having dense breast tissue can increase breast cancer risk and can also make some abnormalities more difficult to detect on a mammogram.

Lifestyle and Environmental Risk Factors

• Alcohol use: Drinking alcohol is associated with an increased risk of breast cancer. In general, the risk increases as alcohol consumption increases.
• Body weight after menopause: Having overweight or obesity after menopause is associated with a higher risk of breast cancer, partly because fat tissue can affect hormone levels.
• Physical inactivity: Regular physical activity is associated with a lower risk of breast cancer. Being physically active also supports healthy body weight and overall health.
• Previous radiation exposure: Radiation treatment involving the chest, particularly at a young age, can increase the risk of developing breast cancer later in life.
• Smoking: Smoking is linked to many cancers and other serious health conditions. Some research also suggests a relationship between cigarette smoking and breast cancer risk, although this association is less established than some other breast cancer risk factors.

Reproductive and Hormonal Factors

Some reproductive and hormonal factors can affect breast cancer risk because they influence lifetime exposure to certain hormones.

• Early menstruation: Beginning menstrual periods at a younger age can be associated with a slightly higher breast cancer risk.
• Later menopause: Reaching menopause at an older age can also be associated with increased risk.
• Age at first full-term pregnancy: Having a first full-term pregnancy at an older age is associated with a higher risk compared with having a first full-term pregnancy at a younger age.
• Breastfeeding: Breastfeeding may modestly lower breast cancer risk, although it does not eliminate the possibility of developing breast cancer.
• Menopausal hormone therapy: Some forms of hormone therapy used during or after menopause, particularly combined estrogen-progestin therapy, can increase breast cancer risk. The effect can depend on the type of therapy, duration of use, and individual circumstances.

Having one or more of these risk factors does not mean that breast cancer will develop. Likewise, many people diagnosed with breast cancer do not have a strong family history or another obvious risk factor. A healthcare professional can help assess individual risk and determine whether additional screening or genetic counseling may be appropriate.

Signs and Symptoms of Breast Cancer

Early breast cancer may not cause noticeable symptoms, which is one reason screening is important for people who meet the recommended screening criteria. When symptoms do occur, they can vary from person to person.

Possible signs and symptoms of breast cancer include:

• A new lump or thickened area: A new lump in the breast or underarm can be a possible sign of breast cancer. However, many breast lumps are caused by non-cancerous conditions.
• A change in breast size or shape: A noticeable change in the size, shape, or appearance of one breast or both breasts should be evaluated.
• Skin changes: The skin of the breast may become dimpled, puckered, red, swollen, or thicker than usual. In some cases, the skin can develop an appearance similar to the peel of an orange.
• Nipple changes: The nipple may become newly inverted or change in appearance. Scaling, crusting, or other unusual changes around the nipple should also be checked.
• Nipple discharge: Unusual discharge from the nipple, particularly discharge that is bloody or occurs without squeezing the nipple, should be evaluated by a healthcare professional.
• Changes in the breast or nipple area: Persistent changes in the appearance or texture of the breast or nipple can have several causes, but they should not be ignored.
• Breast pain: Breast pain is common and is usually caused by conditions other than cancer. However, persistent or unexplained breast pain, especially when accompanied by another breast change, should be discussed with a healthcare professional.

These symptoms do not necessarily mean that a person has breast cancer. Many breast changes have non-cancerous causes. However, a new, unusual, or persistent change should be evaluated rather than ignored.

Diagnosis and Detection

If a person notices a new breast change or has an abnormal result on a screening test, a healthcare professional may recommend additional evaluation. The tests used depend on the person’s symptoms, age, breast characteristics, personal history, and other risk factors.

Clinical Breast Examination

A healthcare professional may examine the breasts and nearby areas for lumps, swelling, skin changes, nipple changes, or other abnormalities. A clinical examination can help determine whether further testing is needed.

Mammography

Mammography uses low-dose X-rays to create images of the breast. Screening mammography is performed in people who do not have signs or symptoms, while diagnostic mammography may be used to investigate a breast symptom or an abnormal finding from a screening test.

Breast Ultrasound

Breast ultrasound uses sound waves to produce images of breast tissue. It may be used to evaluate a breast lump or other abnormality and can help distinguish some fluid-filled cysts from solid masses. Ultrasound may also be used alongside mammography in certain situations.

Breast MRI

Breast magnetic resonance imaging (MRI) uses magnetic fields and radio waves to create detailed images of breast tissue. It may be recommended for some people who have a substantially higher risk of breast cancer or when additional imaging is needed to evaluate a particular finding.

Biopsy

A biopsy involves removing a sample of breast tissue or cells so that they can be examined under a microscope. A biopsy is generally needed to determine whether a suspicious breast abnormality is cancerous and, if cancer is present, to identify important characteristics of the cancer.

The healthcare professional will determine which tests are appropriate based on the individual’s symptoms, medical history, risk factors, and previous test results. An abnormal mammogram or other imaging result does not necessarily mean that a person has breast cancer.

Prevention and Risk Reduction

There is no guaranteed way to prevent breast cancer. Some risk factors, such as age, inherited gene mutations, and family history, cannot be changed. However, certain lifestyle choices and medical approaches may help reduce the risk of developing breast cancer.

Lifestyle-Based Risk Reduction

• Maintain a healthy weight: Maintaining a healthy weight, particularly after menopause, may help lower the risk of breast cancer. If you are trying to manage your weight, focus on sustainable eating habits and regular physical activity rather than rapid or extreme weight-loss methods.
• Stay physically active: Regular physical activity is associated with a lower risk of breast cancer. For general health, adults are generally advised to get at least 150 minutes of moderate-intensity aerobic activity each week, along with muscle-strengthening activities on at least two days a week.
• Limit alcohol: Alcohol consumption is associated with an increased risk of breast cancer. The less alcohol a person drinks, the lower their breast cancer risk is likely to be. People who do not drink alcohol do not need to start drinking for health reasons.
• Choose a balanced diet: A balanced eating pattern that includes vegetables, fruits, whole grains, legumes, and other nutrient-rich foods can support overall health and help with healthy weight management. No specific food or diet has been proven to prevent breast cancer on its own.
• Do not smoke: Avoiding tobacco is an important part of overall cancer prevention and general health. If you smoke, quitting can provide substantial health benefits.
• Breastfeed when possible: Breastfeeding may provide a modest reduction in breast cancer risk. However, breastfeeding is a personal decision and is not a guarantee against breast cancer.

Screening and Medical Risk Reduction

• Follow appropriate screening recommendations: Breast cancer screening recommendations vary by country, age, and individual risk. People at average risk should discuss the appropriate screening schedule with a healthcare professional, while people at higher risk may need earlier or additional screening.
• Discuss your personal risk: A healthcare professional can consider factors such as family history, previous breast conditions, inherited gene mutations, and other risk factors to help determine whether additional assessment is appropriate.
• Consider genetic counseling when appropriate: People with a strong family history of breast or ovarian cancer, certain patterns of cancer in their family, or known inherited mutations may benefit from genetic counseling. A genetic counselor can explain potential risks and testing options.
• Ask about risk-reducing treatments if you are at very high risk: Some people at substantially increased risk may be offered medications or, in selected situations, preventive surgery. These decisions involve potential benefits and risks and should be discussed with an appropriate healthcare professional.

Breast Cancer Screening and Early Detection

Early detection can identify some breast cancers before they have spread extensively. When breast cancer is found at an earlier stage, treatment may be more effective and the chances of successful treatment may be better. However, screening does not prevent breast cancer and cannot detect every cancer.

For people at average risk, screening recommendations vary by country and health organization. In the United States, the U.S. Preventive Services Task Force recommends screening mammograms every two years for women ages 40 to 74. Other organizations and countries may recommend different starting ages or screening intervals.

People with a higher-than-average risk may need a different screening approach. Factors such as a strong family history, certain inherited gene mutations, a personal history of breast cancer, or previous radiation treatment to the chest can affect screening recommendations.

It is also important to pay attention to new or unusual breast changes. Screening recommendations are intended for people who do not have symptoms. If you notice a new lump, nipple change, unusual discharge, skin change, or another persistent breast change, contact a healthcare professional rather than waiting for your next routine screening appointment.

Regular breast self-awareness can help people become familiar with the normal appearance and feel of their breasts. However, routine breast self-examination is not considered a substitute for recommended screening mammography.

Living With and Beyond Breast Cancer

A breast cancer diagnosis can affect a person’s physical health, emotional well-being, relationships, work, and daily life. The experience can also continue to affect someone after treatment has ended.

Support from family members, friends, support groups, counselors, and healthcare professionals can help people cope with the emotional and practical challenges of diagnosis and treatment. Some people may experience anxiety, sadness, fatigue, changes in body image, or concerns about the cancer returning.

After treatment, follow-up care can help monitor health and address ongoing or new concerns. Survivorship care may include follow-up appointments, management of treatment-related side effects, emotional support, healthy lifestyle habits, and guidance about returning to normal activities.

Everyone’s experience with breast cancer is different. People who are struggling emotionally or having difficulty managing symptoms after treatment should discuss their concerns with their healthcare team so they can receive appropriate support.

Conclusion

Breast cancer can develop for many reasons, and risk is influenced by factors such as age, family history, inherited gene mutations, reproductive history, alcohol use, body weight, physical activity, and previous radiation exposure. Having a risk factor does not mean that breast cancer will develop, and some people develop the disease without an obvious risk factor.

Knowing the possible signs and symptoms, following appropriate screening recommendations, and discussing personal risk factors with a healthcare professional can support early detection and informed decisions about breast health. Maintaining a healthy weight, staying physically active, limiting alcohol, avoiding tobacco, and following a balanced diet may also help reduce risk.

If you notice a new or unusual breast change, do not wait for a routine screening appointment to have it evaluated. A healthcare professional can help determine the cause and recommend appropriate testing when needed.

Disclaimer

This article is intended for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. If you have a new breast lump, breast change, concerning symptom, or questions about your breast cancer risk or screening, speak with a qualified healthcare professional. Do not delay or avoid medical care because of information presented in this article.

Frequently Asked Questions

How old should I be when I start getting mammograms?

Screening recommendations vary by country, organization, and individual risk. In the United States, the U.S. Preventive Services Task Force recommends screening mammograms every two years for women ages 40 to 74 who are at average risk. People with a higher risk of breast cancer may need to begin screening earlier or have additional screening. Discuss your personal risk and screening schedule with a healthcare professional.

Can men get breast cancer?

Yes. Although breast cancer is much less common in men than in women, men can develop breast cancer. A new lump, nipple change, skin change, or unusual nipple discharge should be evaluated by a healthcare professional.

Does every breast lump mean cancer?

No. Many breast lumps are caused by non-cancerous conditions, such as cysts or fibroadenomas. However, a new, persistent, or unusual lump should be evaluated by a healthcare professional to determine its cause.

How often should I perform a breast self-exam?

Routine breast self-examination is not a substitute for recommended breast cancer screening. Instead, people can practice breast self-awareness by becoming familiar with the normal appearance and feel of their breasts and reporting new or unusual changes to a healthcare professional. If you notice a concerning change, seek medical advice rather than waiting for your next screening appointment.

Does having a BRCA1 or BRCA2 mutation mean I will develop breast cancer?

No. Certain inherited BRCA1 or BRCA2 mutations can substantially increase the lifetime risk of breast cancer, but they do not mean that cancer will definitely develop. People who have a known mutation or a strong family history may benefit from genetic counseling and a personalized risk-management plan.

Can underwire bras or antiperspirants cause breast cancer?

There is no good scientific evidence that wearing an underwire bra or using antiperspirants or deodorants causes breast cancer. These products have been studied because of common concerns about their possible effects, but major cancer organizations have not found convincing evidence that they increase breast cancer risk.

References

• World Health Organization (WHO). Breast Cancer
• Centers for Disease Control and Prevention (CDC). Breast Cancer Risk Factors.
• Centers for Disease Control and Prevention (CDC). Symptoms of Breast Cancer.
• National Cancer Institute (NCI). Breast Cancer Causes and Risk Factors.
• National Cancer Institute (NCI). Mammograms.

Zaheer Abbas

Hello, I’m Zaheer Abbas, founder and main contributor to JustHealthyLine. I created this website to share practical, evidence-based information about nutrition, fitness, wellness, skin care, and everyday health.

I focus on researching health topics using reliable medical and nutritional sources and presenting the information in a clear, practical way. Health information on this website is intended for general education and is not a substitute for professional medical advice.