Every two minutes, someone in the United States is diagnosed with breast cancer, one of the most common cancers worldwide. This disease affects millions of people, but thanks to advances in research, treatments, and early detection, survival rates are steadily improving, allowing more people to thrive after a breast cancer diagnosis.

This article explains what breast cancer is, explores its causes, and discusses factors that contribute to its prevalence. It also covers the history of breast cancer, the impact of genetics, common symptoms, and current treatment options.

What Is Breast Cancer?

Like every tissue in the body, the breast is made up of individual cells. Normally, the cells in your body grow, divide, and eventually die in an orderly way. But sometimes, mutations (variants, or changes) in certain genes cause breast cells to grow out of control, leading to cancer. These cells can form a lump or mass in the breast tissue and, over time, might spread to other parts of the body.

There are many types of breast cancer, depending on where the disease starts in the breast and the genetic makeup of the cancer cells. Some types grow and spread quickly, while others develop more slowly. Doctors use terms like “stage” and “grade” to describe how far the cancer has spread and how fast it’s likely to grow. Understanding the type, stage, and grade of your breast cancer helps your oncologist (cancer doctor) recommend the best treatment options for you.

The History of Breast Cancer

Breast cancer has been recognized and studied for thousands of years. Ancient Egyptians were among the first to document cases, as far back as 1600 BCE. The Greek physician Hippocrates, often called the “father of medicine,” used the term “karkinos” (Greek for “crab”) because tumors and their surrounding blood vessels reminded him of crabs, with their hard shells and spread-out legs. We still use the term “carcinoma” for certain cancers.

Throughout history, people have come up with ideas about what causes breast cancer. In the 1700s, an Italian doctor named Bernardino Ramazzini noticed that breast cancer was more common in nuns and thought it might be linked to their celibacy. We now know that not experiencing childbirth and not breastfeeding can slightly increase the risk of breast cancer, likely due to hormonal factors.

Surgery

By the 1800s, surgery became the primary method for treating breast cancer. Scottish surgeon John Hunter observed that, if the cancer hadn’t spread to nearby tissues, it could sometimes be removed through surgery. This insight laid the groundwork for more advanced surgical techniques.

In 1894, Dr. William Stewart Halsted introduced the radical mastectomy, which involved removing the breast, nearby lymph nodes, and chest muscles. Although effective, it was very disfiguring. In 1972, Dr. John Madden described the modified radical mastectomy, which preserved the chest muscles and became a more common and less extreme option.

Then, in the early 1980s, professor Umberto Veronesi in Italy and Dr. Bernard Fisher in the United States developed the quadrantectomy, a breast-conserving surgery that allowed surgeons to remove the tumor while preserving most of the breast. This approach became the gold standard for small breast cancers and marked a shift toward less invasive procedures that balance disease control with quality of life.

Radiation Therapy

In 1896, just a year after Wilhelm Röntgen discovered X-rays, Emil Grubbe used radiation to treat breast cancer that couldn’t be surgically removed. By today’s standards, the radiation he used was only strong enough to treat surface-level skin cancers.

In the 1930s, English surgeon Geoffrey Keynes pioneered the use of radium needles for treating breast cancer. His approach allowed doctors to target cancer cells directly while sparing healthy breast tissue. Over the years, radiation technology has made important improvements that allow a more precise treatment, reducing side effects such as burns and skin damage.

Today, radiation therapy is a key component in breast cancer treatment, often used after surgery to target any remaining cancer cells and reduce the risk of recurrence (return of cancer).

Imaging Diagnosis

Advances in imaging technology, including ultrasound, computed tomography (CT) scans, magnetic resonance imaging (MRI), and positron emission tomography (PET), have made it easier to detect breast cancer. Since the late 20th century, radiology has become increasingly precise, making it possible to detect nonpalpable breast tumors (those too small or deep to be found in a physical exam). Early diagnosis through these methods can be lifesaving, allowing for timely and targeted treatment.

Chemotherapy

A major breakthrough came in 1953, when researchers at the National Cancer Institute found that chemotherapy could cure certain types of cancer, including breast cancer. This discovery laid the foundation for modern cancer treatments.

Chemotherapy is now widely used in breast cancer treatment, often given before or after surgery to destroy any remaining cancer cells. Using chemotherapy after surgery is called adjuvant therapy, a strategy first tested in breast cancer and later found effective for other types of cancer too.

Hormone Receptors

Doctors had long suspected that breast cancer growth was influenced by hormones. U.S. oncologist Elwood Jensen provided crucial evidence for this theory in 1967, when he discovered estrogen receptors and progesterone receptors on breast cancer cells. He found that hormones bind to these receptors, enabling them to interact with the cell’s nucleus (center), where gene regulation takes place. Jensen’s research later showed that tamoxifen can block the effects of estrogen on these receptors, slowing the cancer growth.

Genes Linked to Breast Cancer

By the 1990s, scientists had discovered that certain genes, such as BRCA1 and BRCA2, raise the risk of breast cancer. This finding led to new prevention strategies and personalized treatments, such as hormone therapy, for people with these genetic mutations. For example, doctors began using hormone-blocking drugs such as tamoxifen and recommending prophylactic (preventive) surgery to reduce the risk of aggressive breast cancer in people with BRCA mutations.

How Common Is Breast Cancer?

Aside from skin cancers, breast cancer is the most common cancer in U.S. women, according to the American Cancer Society. In the United States, about 13 percent of women, or 1 in 8, will develop invasive breast cancer. Hereditary (family history) and environmental factors may raise or lower that risk. More than 4 million people in the U.S. are either being or have been treated for breast cancer.

How Is Breast Cancer Diagnosed?

Breast cancer may initially be detected during either a regular manual (hands-on) breast exam or a screening with a mammogram (breast X-ray). To diagnose breast cancer, a health care provider will perform a needle biopsy to collect a small tissue sample. Cells from the sample will be examined in a laboratory. Your health care provider may also order imaging tests such as a mammogram, an ultrasound, or MRI to better understand your cancer’s shape and structure.

Breast Cancer Symptoms

Early on, breast cancer may not cause detectable symptoms. The first symptom might be a change in how your breast looks or feels, such as tenderness or a lump. Breast cancer can also cause skin irritation and dimpling. Nipple changes such as discharge, pain, discoloration, scaly skin, or retraction (pointing inward instead of outward) also can indicate breast cancer.

Treatment Options for Breast Cancer

Doctors often use a combination of approaches to treat breast cancer. The main treatment options include:

• Surgery
• Chemotherapy
• Radiation therapy
• Hormonal therapy
• Targeted therapy

In recent years, advances in targeted therapies and immunotherapy have transformed breast cancer treatment. Understanding how these treatments work is essential for people navigating their treatment options.

Immunotherapy harnesses the body’s immune system to fight cancer. In the 1990s, researchers developed genetically modified antibodies that specifically target cancer cells. Trastuzumab (Herceptin) and pertuzumab (Perjeta) are examples of monoclonal antibodies that are used to treat certain types of breast cancer. New drugs and treatment strategies continue to be studied, offering hope for even more effective ways to combat the disease.

Breast Cancer Risk Factors

Age is a significant factor in breast cancer risk, with the likelihood of developing the disease increasing as a person gets older. Only 5 percent of breast cancers are diagnosed in people under 40, and most cases occur in those over 50.

The American Cancer Society recommends that women have the choice to start breast cancer screening between ages 40 and 45. Their guidelines state that women between ages 45 and 54 should have an annual mammogram. For people with a higher risk of breast cancer — due to factors such as a strong family history, HER2-positive status, or BRCA1 or BRCA2 gene mutations — earlier screening may be advisable. Be sure to talk with your health care team about your risk of breast cancer and the best age to start getting screened.

What Is the Prognosis for Breast Cancer?

The term “prognosis” refers to the likely outcome or course of a disease. For breast cancer, prognosis depends on factors like the type of breast cancer, the stage at diagnosis, and the treatments used.

Breast cancer is the second leading cause of cancer-related death among U.S. women, following lung cancer, according to the Centers for Disease Control and Prevention (CDC). Encouragingly, breast cancer death rates have been falling for years. Today, 90 percent of people are alive five years after their breast cancer diagnosis, and 84 percent are alive after 10 years.

By staying informed and working closely with your health care team, you can make the best choices for your health and continue to benefit from advances in breast cancer treatment.

Find Your Team

On MyBCTeam, the social network for people with breast cancer and their loved ones, more than 74,000 members come together to ask questions, give advice, and share their stories with others who understand life with breast cancer.

Have you or a loved one been diagnosed with breast cancer? Do you have more questions about diagnosis, risk factors, treatments, or other aspects of living with breast cancer? Share your thoughts in the comments below, or start a conversation by posting on your Activities page.