Breast cancer is a disease that begins when cells in the breast grow out of control. These abnormal cells can form a tumor and may spread to nearby lymph nodes or other parts of the body if not detected and treated. Breast cancer can form in one or both breasts and affects both women and men. Hundreds of thousands of people are diagnosed with breast cancer every year, and there are over 4 million breast cancer survivors in the United States.
Early detection and advances in treatment have helped improve outcomes for many people diagnosed with the disease. Understanding what breast cancer is is the first step toward early detection and informed decision-making.
Breast cancer is one of the most common cancers in the United States and around the world. In the U.S., 1 in 8 women—or approximately 13%—will be diagnosed with breast cancer in their lifetime. While it is much less common, men can also develop breast cancer, accounting for about 1% of all breast cancer cases.
This year, approximately 382,640 women in the United States will be diagnosed with breast cancer. Thanks to advances in early detection and treatment, more than 4 million breast cancer survivors are living in the U.S. today. Many people diagnosed with breast cancer go on to complete treatment and live long, healthy lives.
Anyone can get breast cancer. Although breast cancer is most common in women, with the median age at diagnosis being 62, it can also affect younger women, older women, and men. A person’s risk of developing breast cancer is influenced by many factors, including age, genetics, family history, breast density, hormone exposure, and lifestyle. However, having one or more risk factors does not mean someone will develop breast cancer, and many people diagnosed with the disease have no known risk factors. Understanding who is at risk for breast cancer can help individuals make informed decisions about screening, early detection, and breast health.
Breast cancer is a type of cancer that begins when abnormal cells in the breast grow uncontrollably, forming a malignant tumor. Cancer develops when the normal process of cell growth breaks down, causing damaged cells to survive and new cells to form when they aren’t needed. As these abnormal cells multiply, they can invade nearby tissue and spread through the bloodstream or lymphatic system to other parts of the body. This spread of cancer beyond the breast is known as metastasis.
Understanding the facts and statistics surrounding breast cancer can empower people to take charge of their breast health and recognize the importance of early detection. Learning who is affected, how common the disease is, and how risk and outcomes can vary across different populations helps raise awareness and encourages informed conversations with healthcare providers. Breast cancer can affect anyone, regardless of age, race, or gender, making education and regular screening important for everyone.
Breast cancer does not grow at the same rate for everyone. How quickly a tumor develops and spreads depends on many factors, including the type of breast cancer, its biology, and individual characteristics. Some breast cancers grow slowly over many years, while others are more aggressive and can spread more rapidly. Because it is impossible to predict exactly how a particular cancer will grow, routine screening and early detection are essential for finding breast cancer as early as possible, when treatment is often most effective.
Many factors can influence a person’s risk of developing breast cancer, but having one or more risk factors does not mean someone will develop the disease. Some risk factors, such as age, family history, inherited gene mutations, and breast density, cannot be changed, while others, like maintaining a healthy weight, staying physically active, and limiting alcohol consumption, may help reduce risk. It’s also important to remember that many people diagnosed with breast cancer have no known risk factors other than being female and getting older.
The exact cause of breast cancer is not fully understood, and in many cases, there is no single reason why it develops. Researchers believe breast cancer is caused by a combination of genetic, hormonal, environmental, and lifestyle factors that can lead to changes in breast cells over time. While certain risk factors may increase the likelihood of developing breast cancer, many people who are diagnosed have no known risk factors, and many people with risk factors never develop the disease.
The breast is made up of lobes, lobules, milk ducts, fatty tissue, connective tissue, blood vessels, and lymph vessels, with most breast cancers beginning in the ducts or lobules. The lymphatic system also plays an important role because it is one of the primary pathways through which breast cancer can spread. Understanding the anatomy of the breast can help you better recognize changes, communicate with your healthcare provider, and understand how breast cancer develops.
Breast tumors are abnormal growths of cells that can be either benign (noncancerous) or malignant (cancerous). Some tumors form breast lumps that can be felt within the breast tissue. While most breast lumps are not cancer, it’s important to have any new or unusual breast change evaluated by a healthcare provider. Understanding the difference between benign and malignant tumors can help reduce uncertainty and reinforce the importance of timely evaluation and diagnosis.
Genetic testing can identify inherited gene mutations that increase the risk of developing breast cancer. It is typically recommended for people with a personal or family history that suggests an inherited cancer risk and is often paired with genetic counseling to help interpret the results. While a positive test result does not mean you will develop breast cancer, it can help guide personalized screening, risk-reduction strategies, and early detection plans for you and your family.
BRCA genes are BReast CAncer genes that normally help repair damaged DNA and protect against cancer. All people have BRCA genes, which typically prevent cells from growing and dividing uncontrollably. But if a person inherits a harmful mutation in either the BRCA1 or BRCA2 gene, their risk of developing breast, ovarian, and certain other cancers increases significantly. Understanding whether you carry a BRCA mutation can help you and your healthcare provider make informed decisions about screening, risk reduction, and early detection strategies.
While BRCA1 and BRCA2 are the most well-known genes linked to breast cancer, several other inherited gene mutations can also increase a person’s risk. Genes such as PALB2, CHEK2, ATM, TP53, PTEN, and others play important roles in cell growth and DNA repair, and mutations in these genes may increase the likelihood of developing breast cancer. Identifying these inherited mutations through genetic testing can help guide personalized screening, risk-reduction strategies, and conversations with healthcare providers.
A positive genetic test result means you have inherited a gene mutation that increases your risk of developing breast cancer. It does not mean you currently have cancer or that you will definitely develop it. Knowing your genetic risk allows you and your healthcare provider to create a personalized plan that may include earlier or more frequent screenings, medications to reduce risk, or, in some cases, preventive surgery.
