Breast Cancer in Women

Breast cancer is a condition where cells in breast tissue grow out of control and form tumors. While it is the most common cancer diagnosed in women and the second leading cause of cancer death among women worldwide, advances in early detection and treatment have significantly improved survival rates.

Table of contents

• What is breast cancer?
• Types of breast cancer
• Anatomy of the breast
• Risk factors
• Signs and symptoms
• Diagnosis
• Treatment options
• Survival and prognosis
• Life after treatment

What is breast cancer?

Breast cancer is a disease in which cells in the breast grow out of control and form tumors, which are abnormal masses of tissue^[1]. After skin cancer, breast cancer is the most common cancer diagnosed in women in the United States^[1]. Globally, there were approximately 2.3 million women diagnosed with breast cancer in 2022, causing an estimated 670,000 deaths^[5].

Although breast cancer typically affects women age 50 and older, it can also affect younger women^[1]. Everyone is born with some breast tissue, so anyone can develop breast cancer. Approximately 0.5 to 1% of breast cancers occur in men^[5].

Breast cancer occurs in every country of the world. The disease can begin silently, often discovered on routine screening in countries with established screening programs. Without screening, breast cancer is often detected as a noticeable lump in the breast^[6].

• Breast tissue
• Milk ducts
• Lobules (milk-producing glands)
• Lymph nodes

Types of breast cancer

The type of breast cancer depends on which cells in the breast turn into cancer. Most breast cancers begin in the ducts, which are tubes that carry milk to the nipple, or in the lobules, which are the glands that produce milk^[2].

Most common types

Invasive ductal carcinoma (IDC) is the most common type of breast cancer, accounting for about 70% to 80% of all breast cancer cases^[2]. The cancer cells start in the milk ducts and spread to other parts of the breast. A person with IDC may feel a lump in the breast or underarm, or the cancer may be seen on a mammogram, which is an X-ray of the breast tissue. IDC can also cause symptoms other than a lump, such as breast pain, a change in the shape of the breast, or discharge from the nipple^[2].

Invasive lobular carcinoma (ILC) is the second most common type, representing about 10% to 15% of breast cancers^[2]. Cancer cells begin in the lobules and spread to nearby breast tissues. ILC does not typically make a lump. Instead, it appears as thickened connective tissue in the breast, making it harder to see on a mammogram. ILC is more likely to form in both breasts than IDC^[2].

Less common types

Ductal carcinoma in situ (DCIS) starts in the milk ducts but does not spread beyond them. It is not life-threatening at this stage and can be detected early^[5].

Inflammatory breast cancer (IBC) is a rare, fast-growing cancer in which cancer cells block lymph vessels in the skin of the breast. This makes the breast feel warm and look red and swollen. The breast may also look dimpled, like an orange, and the nipple may turn inward^[2].

Triple-negative breast cancer (TNBC) does not have receptors for estrogen, progesterone, or the HER2 protein. This means doctors have fewer ways to treat this type of cancer, and it tends to be more aggressive^[2].

Breast cancer subtypes

Breast cancers are also classified by whether the cancer cells have certain proteins called receptors on their surfaces. These receptors can attract hormones like estrogen and progesterone, which help cancerous cells grow. Finding out if cancer cells have these receptors helps doctors plan treatment^[6].

Cancer cells may be ER-positive (ER+) if they have estrogen receptors, PR-positive (PR+) if they have progesterone receptors, or HR-positive (HR+) if they have both. Cancer cells that don’t have these receptors are called HR-negative (HR-). Some cancers have higher than normal levels of the HER2 protein, which also helps cancer cells grow. About 15% to 20% of all breast cancers are HER2-positive^[6].

Anatomy of the breast

Each breast is made up of three main parts: lobules, ducts, and connective tissue^[2]. The lobules are the glands that produce milk. The ducts are tubes that carry milk to the nipple. The connective tissue, which consists of fibrous and fatty tissue, surrounds and holds everything together.

Each breast contains 15 to 20 sections called lobes, arranged like the petals of a flower. Each lobe has many smaller sections called lobules^[1]. Each breast also has blood vessels and lymph vessels, which carry a fluid called lymph. Lymph vessels connect to small, bean-shaped structures called lymph nodes, which filter lymph and store white blood cells that help fight infection and disease. Groups of lymph nodes are found near the breast in the underarm area, above the collarbone, and in the chest^[11].

Risk factors

Female gender is the strongest breast cancer risk factor. Roughly half of all breast cancers occur in women with no specific risk factors other than sex and age^[5]. While risk factors can increase the chance of developing breast cancer, having a risk factor does not mean someone will definitely get cancer^[11].

Common risk factors include older age, early start of menstrual periods, late menopause, having no children, lack of breastfeeding, and a positive family history of breast cancer^[6]. Women with dense breast tissue have a higher risk. The use of hormone therapy and a history of radiation therapy to the chest also increase risk^[6].

Genetic changes associated with increased risk include mutations in the BRCA1 and BRCA2 genes, which are genes that normally help prevent cancer. Women with these genetic mutations have a much higher risk of developing breast cancer^[14].

Lifestyle factors that may affect risk include alcohol consumption and being overweight or obese. Staying physically active and maintaining a healthy weight can help lower the risk of breast cancer^[22].

Signs and symptoms

Some breast cancers do not cause noticeable symptoms. However, when symptoms do occur, they may include^[1]:

• A change in the size, shape, or contour of the breast
• A mass or lump in the breast, which may feel as small as a pea
• A lump or thickening in or near the breast or in the underarm that persists through the menstrual cycle
• A change in the look or feel of the skin on the breast or nipple
• Skin that looks dimpled, puckered, scaly, or inflamed
• Redness or darkening of the breast skin
• Changes to the nipple, such as turning inward
• Unusual discharge from the nipple

Finding a lump in the breast does not automatically mean it is cancer. Many breast lumps are not cancerous. However, any breast changes should be checked by a healthcare professional^[1].

Diagnosis

Breast cancer diagnosis often begins with an exam and a discussion of symptoms. Several tests are used to look at the breast tissue and confirm whether cancer is present^[10].

Breast examination

During a clinical breast exam, a healthcare professional looks at the breasts for anything unusual, such as changes in the skin or nipple. The professional then feels the breasts for lumps and also checks along the collarbones and around the armpits^[10].

Imaging tests

A mammogram is an X-ray of the breast tissue commonly used to screen for breast cancer. If a screening mammogram finds something concerning, additional imaging may be needed^[10].

A breast ultrasound uses sound waves to create images of breast tissue. An MRI (magnetic resonance imaging) uses magnets and radio waves to create detailed pictures of the inside of the breast. These tests can help doctors see abnormal areas more clearly^[10].

Biopsy

To confirm whether cancer is present, a sample of tissue is removed from the breast for testing. This procedure is called a biopsy. The tissue sample is sent to a laboratory where doctors called pathologists examine it^[10]. The pathology report will identify if cancer is present and provide information about the type of cancer and whether it has hormone receptors or HER2 protein^[6].

Treatment options

Treatment for breast cancer depends on several factors, including the stage of cancer, the type of cancer, whether the cancer cells have hormone receptors, the HER2 status, and the person’s overall health^[12]. Treatment is based on the person, the type of cancer, and how far it has spread. Many people with breast cancer receive more than one kind of treatment^[11].

Surgery

Surgery is the main treatment for breast cancer. There are two main surgical options with similar survival rates^[14]. A lumpectomy removes the tumor and a small amount of surrounding tissue. After a lumpectomy, radiation therapy is usually given. A mastectomy removes the entire breast. Some women may also need surgery to remove lymph nodes to check if the cancer has spread^[9].

Radiation therapy

Radiation therapy uses high-energy rays, similar to X-rays, to kill cancer cells. It is often used after surgery to destroy any remaining cancer cells and reduce the risk of the cancer coming back^[12].

Chemotherapy

Chemotherapy uses special medicines to shrink or kill cancer cells. The drugs can be pills taken by mouth or medicines given through a vein. Chemotherapy is sometimes given before surgery to shrink tumors or after surgery to reduce the risk of recurrence^[12].

Hormone therapy

Hormone therapy blocks cancer cells from getting the hormones they need to grow. This treatment is used when cancer cells have estrogen or progesterone receptors. Common hormone therapy medicines include tamoxifen^[12].

Targeted therapy

Targeted therapy uses drugs that target specific molecules on cancer cells. For example, drugs called HER2 inhibitors are used when cancer cells have high levels of the HER2 protein^[9].

Immunotherapy

Immunotherapy works with the body’s immune system to help it fight cancer cells. This treatment may be used for certain types of breast cancer, including triple-negative breast cancer^[9].

Survival and prognosis

Breast cancer survival rates have been increasing steadily, and the number of people dying from breast cancer is going down. Much of this improvement is due to widespread support for breast cancer awareness, funding for research, and advances in screening and treatment^[1].

Finding cancer earlier through screening makes it much more likely that the cancer can be cured. Even when breast cancer cannot be cured, many treatments exist to extend life. New discoveries in breast cancer research are helping doctors choose the most effective treatment plans^[1].

The outlook depends on many factors, including the stage at diagnosis, the type of breast cancer, how well the cancer responds to treatment, and the person’s overall health^[11].

Life after treatment

After finishing treatment, many breast cancer survivors face new challenges. The transition from active treatment to life after cancer can bring both relief and uncertainty^[19].

Follow-up care

Regular follow-up appointments are important to check for any signs that the cancer has come back and to manage any long-term effects of treatment. During follow-up visits, doctors may perform physical exams, order imaging tests, and discuss any new symptoms or concerns^[16].

Physical effects

Many survivors experience ongoing physical effects from treatment, including fatigue, pain, changes in weight, and problems with memory or concentration. Some women experience lymphedema, which is swelling in the arm or hand caused by fluid buildup after lymph nodes are removed^[19].

Physical activity and exercise can help reduce fatigue and improve overall well-being after treatment. Many survivors find that regular movement helps them feel stronger and more energetic^[19].

Emotional well-being

It is normal to experience a wide range of emotions after breast cancer treatment, including anxiety about the cancer coming back, changes in body image, and feelings of sadness or depression. Many survivors find it helpful to talk with other people who have had breast cancer or to work with a counselor or therapist^[18].

Some survivors feel pressure to feel happy immediately after treatment ends, but it is normal to need time to adjust. Learning to ask for help, talking openly with healthcare providers about symptoms, and finding support from others can all make a difference^[24].

Lifestyle changes

Many survivors make changes to their lifestyle after treatment, including eating a healthier diet, exercising regularly, limiting alcohol, and finding ways to reduce stress. While there is no proven way to prevent breast cancer from coming back, these healthy habits can help improve overall health and quality of life^[26].