Breast cancer is one of the most common types of cancer among women, but there is no single cause that can be considered directly responsible for the disease in every case. Breast cancer develops when changes occur in the genetic material within breast cells, causing some cells to grow and divide abnormally. A combination of genetic, hormonal, health-related, and lifestyle factors may increase the likelihood of these changes. Therefore, when discussing the causes of breast cancer, it is important to distinguish between a direct cause and risk factors that increase the likelihood of developing the disease without making it inevitable.
This article was medically reviewed by Dr. Alaa Mahfouz, Consultant and Lecturer of Oncology Surgery at the National Cancer Institute, Cairo University, to ensure the accuracy of the medical information provided.
What Are the Causes of Breast Cancer and Risk Factors?
A single cause of breast cancer cannot be identified in most cases, as the disease usually results from the interaction of several factors that affect breast cells over time. Medical sources explain that having a risk factor does not necessarily mean that a woman will develop breast cancer. Some women with breast cancer may also have no clear risk factor other than age and being female.
The main breast cancer risk factors include:
Increasing age.
A family history of breast cancer.
Certain inherited genetic changes, such as BRCA1 and BRCA2.
A previous history of breast cancer or certain high-risk breast changes.
Previous exposure to radiation doses to the chest area, particularly at a young age.
Overweight and obesity, especially after menopause.
Lack of physical activity.
Certain factors related to hormonal and reproductive history.
Is Breast Cancer Hereditary?
Breast cancer may be linked to hereditary factors in some families, but not all breast cancer cases are hereditary. The likelihood of a genetic predisposition increases when there are multiple cases of breast or ovarian cancer in the family, when cancer occurs at a young age, or when inherited changes are found in genes associated with the disease, most notably BRCA1 and BRCA2.
Having a family history does not mean that cancer is certain, but it may warrant an assessment of the individual's risk level with a doctor. Genetic counseling and genetic testing may be appropriate for some people based on their medical and family history, rather than simply because there is one case of breast cancer in the family. Some breast cancer cases also occur in people with no known family history. Therefore, each case should be assessed individually rather than relying solely on genetic factors.
How Do Age and Hormones Increase the Risk of Breast Cancer?
Increasing age is one of the most important risk factors for breast cancer, as the likelihood of genetic changes occurring in cells increases over time. The risk of developing breast cancer may also be associated with the length of time breast tissue is exposed to female hormones, particularly estrogen and progesterone.
Factors associated with longer hormonal exposure include:
Starting menstruation at an early age.
Reaching menopause at a later age.
Never having a full-term pregnancy.
Having the first pregnancy at a later age.
Certain types of hormone therapy after menopause.
Having these factors does not mean that a woman will develop breast cancer, but they may be associated with an increased likelihood of developing the disease. Therefore, hormonal and reproductive history should be discussed with a doctor when assessing an individual's risk level.
Is Lifestyle One of the Causes of Breast Cancer?
Lifestyle alone cannot be considered a cause of breast cancer, but it may affect the level of risk. Some habits are associated with an increased likelihood of developing the disease, while others may help reduce certain modifiable risk factors. Key factors to consider include lack of physical activity and excess weight, while alcohol consumption is also associated with an increased risk of breast cancer.
Risk reduction can be supported by:
Maintaining a healthy weight.
Engaging in regular physical activity.
Avoiding smoking.
Limiting or avoiding alcohol consumption.
Following a balanced diet.
Discussing hormone therapy after menopause with a doctor before using it.
These measures cannot prevent the disease completely because some risk factors cannot be changed, but they may help reduce certain risks and improve overall health.
Can Breast Cancer Be Prevented?
There is no method that guarantees 100% prevention of breast cancer because some risk factors, such as age, genetics, and family history, cannot be changed. However, certain risk factors can be reduced by maintaining a healthy weight, engaging in physical activity, avoiding smoking, and limiting alcohol consumption. Evidence also suggests that breastfeeding may have a protective effect, particularly when continued for several months.
The prevention plan varies according to each woman's level of risk. If there is a strong family history or a known genetic change, specialized assessment may be needed to develop an appropriate follow-up plan or determine which screening tests are more suitable for the individual. Therefore, one prevention plan should not be applied to all women. Instead, it should be based on age, medical and family history, and other risk factors.
When Should You See a Doctor?
Understanding the causes of breast cancer and its risk factors is important, but paying attention to any new breast changes is equally important. A lump or breast change does not necessarily mean cancer, as there are many benign causes. However, any new or persistent change should be medically evaluated rather than trying to determine its cause at home.
You should see a doctor if you notice:
A new lump in the breast or under the arm.
A noticeable change in the shape or size of the breast.
Unusual changes in the breast skin.
A new change in the nipple or nipple inversion.
Unusual nipple discharge, especially if it is blood-stained.
A persistent and unexplained change in the breast.
The timing of screening tests also varies according to age, risk level, and applicable guidelines. A doctor can therefore determine the appropriate screening test and timing for each individual case.
Reassure Yourself About Your Health and Get the Right Evaluation
If you have a family history of breast cancer or have noticed a new change in your breast, do not rely solely on searching for the causes of breast cancer to determine your level of risk. A medical evaluation can help identify your existing risk factors and determine whether you need additional tests or regular follow-up. You can contact Dr. Alaa Mahfouz for a specialized evaluation and to determine the appropriate next step based on your condition and medical history.
Frequently Asked Questions About the Causes of Breast Cancer
Is Family History a Risk Factor for Breast Cancer?
Yes. Having a first-degree relative with breast cancer, such as a mother, sister, or daughter, may increase the risk of developing the disease. Assessing family history becomes even more important when there are multiple cases or when cancer occurs at a young age.
Is Breast Cancer Always Hereditary?
No. Some cases are associated with inherited genetic changes, such as BRCA1 and BRCA2, but many breast cancer cases do not result from a known inherited genetic mutation.
Does Obesity Increase the Risk of Breast Cancer?
Yes. Overweight and obesity are associated with an increased risk of breast cancer, and this association is more evident among women after menopause. Maintaining a healthy weight is therefore one measure that may help reduce certain risk factors.
Can Breast Cancer Be Completely Prevented?
There is no way to guarantee complete prevention of breast cancer, but certain risk factors can be reduced through physical activity, maintaining a healthy weight, avoiding smoking, and limiting alcohol consumption, along with following appropriate screening based on individual risk level.
Can Men Develop Breast Cancer?
Yes. Men can develop breast cancer because they have breast tissue, although the condition is much less common than in women. Any unusual lump or change in a man's breast should be medically evaluated.
