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About Breast Cancer
Everyone, regardless of biological sex, has at least a small amount of breast tissue. The breast overlays your pectoral (chest muscles). It is largely composed of fatty tissue and some connective tissue that give the breast its shape. Breasts also contain lymph nodes, small, bean-shaped organs that help transport immune cells and remove waste from tissue. In women, the breast also has specialized glands that can produce milk. These glands are called lobules, and they are connected to the nipple by a series of small channels called ducts.
Breast cancer occurs when cells of the breast tissue grow and multiply uncontrollably. It primarily affects women but can also affect men. Several factors determine what type of breast cancer you have, your prognosis, and your treatment options. These factors include:
- Where the cancer starts
- Whether it is invasive or non-invasive
- Molecular receptor status of cancer cells
Breast cancer symptoms vary from person to person and there is no exact definition of what a lump or mass feels like. The best thing to do is to be familiar with your breasts so you know how “normal” feels and looks. If you notice any changes, tell your doctor. While regular self-exams are important, many breast cancers are found through regular screening mammograms before any symptoms appear.
Breast cancer symptoms may include:
- Lump or mass in the breast
- Lump or mass in the armpit
- Breast skin changes, including skin redness and thickening of the breast skin, resulting in an orange-peel texture
- Dimpling or puckering on the breast
- Discharge from the nipple
- Scaliness on nipple, which sometimes extends to the areola
- Nipple changes, including the nipple turning inward, pulling to one side or changing direction
- An ulcer on the breast or nipple, sometimes extending to the areola
- Swelling of the breast
These symptoms do not always mean you have breast cancer. However, it is important to discuss any symptoms with your doctor, since they may also signal other health problems.
Where breast cancer starts
While breast cancer can develop in several different tissue types within the breast, most cancers can be classified as either ductal carcinomas, which starts in the ducts, or lobular carcinomas, which starts in the lobule glands. See below for other types of breast cancer.
Non-invasive vs Invasive
Ductal and lobular carcinoma cancers can be further divided into non-invasive and invasive breast cancer, depending on if they have spread to the surrounding tissue. Non-invasive ductal carcinoma (also called ductal carcinoma in situ, or DCIS) is an early cancer stage that has not spread beyond the ducts. It is usually caught during a routine breast exam or mammogram. If ductal carcinoma spreads to the surrounding tissue, it is considered invasive. Invasive ductal carcinoma is the most commonly diagnosed form of cancer.
Non-invasive lobular carcinoma (also referred to as lobular carcinoma in situ) is less common, and it isn't actually classified as cancer. However, having lobular carcinoma in situ may put you at higher risk for developing breast cancer later on. (See below for other breast cancer risk factors.) Lobular carcinoma is considered invasive if it has spread to other tissue or lymph nodes within the breast. Invasive lobular carcinoma is less common than invasive ductal carcinoma.
Receptors are molecules that cancer cells produce on their surface. These receptors can interact or bind with specific proteins and hormones in the patient’s body. This is called recognition.
Researchers have identified certain receptors that fuel the growth and spread of breast cancer when they recognize a specific molecule. By interrupting this recognition with cancer drugs, the disease’s growth can be slowed or stopped.
Currently, three major receptor subtypes play important roles in the patient’s prognosis and treatment. As research into breast cancer continues, more receptor subtypes with different treatments may emerge. The three main subtypes follow.
Molecular receptor subtypes
HER2-positive breast cancer
HER2 (Human epidermal growth factor receptor 2) is a protein involved in cell growth. Breast cancers with high levels of HER2 on the surface of the cancer cells are considered HER2-positive. When two of these proteins bond they form a dimer, which sends a signal to the cell that promotes growth and multiplication Treatment includes anti-HER2 therapy that targets the HER2 protein. HER2-positive breast cancer accounts for about 15%-20% of all breast cancers.
About half of HER2-positive cancers are also hormone receptor-positive/ER positive (see below). These patients receive treatments that target both molecular receptors. They are classified as HER2-positive since doctors believe HER2 is the primary driver of the disease.
A HER2-positive diagnosis was at one time associated with a higher risk of recurrence. Recent treatment advances, particularly with targeted therapies, have made the disease more curable in its early stages. They have also extended the survival period for patients whose cancer metastasized, or has spread beyond the breast and nearby lymph nodes.
Hormone receptor-positive/ER-positive breast cancer
Hormone receptor-positive breast cancer is the most common type of breast cancer. This disease has receptors that bind with one of two naturally occurring hormones, estrogen and progesterone. These hormones fuel the growth of the cancer by binding to these receptors.
Endocrine therapy (also known as hormone therapy) targets this receptor/hormone recognition, thereby stopping or slowing the growth of cancer. These therapies can limit the body’s production of estrogen and progesterone or stop the receptors from recognizing the hormones.
Thanks to hormone therapy and the cancer’s tendency to spread relatively slowly, hormone receptor-positive breast cancer is considered the most treatable form of the three main subtypes.
Triple-negative breast cancer
Triple-negative breast cancer (sometimes called basal breast cancer) covers most breast cancers that do not have one of the molecular receptors listed above. Besides this, triple-negative breast cancers can have very little in common.
Since there’s no receptor in these cancers that has a major impact on the disease when targeted, triple-negative breast cancer is the most difficult subtype to treat. It also tends to be more aggressive, so the prognosis for this subtype is often worse than others.
Other types of breast cancer
Ductal carcinoma in situ
Ductal carcinoma in situ (DCIS) is a condition in which cancer cells have formed in the milk ducts but have not spread to nearby tissue. DCIS is the earliest possible form of ductal breast cancer. It is sometimes referred to as Stage 0 breast cancer.
For some patients, DCIS will advance and invade nearby tissue. Others can have DCIS for years without it moving outside the ducts. There is no way to distinguish between the two.
DCIS can be treated with surgery, radiation therapy or chemotherapy.
Inflammatory breast cancer
Inflammatory breast cancer accounts for 2-4% of all breast cancer diagnoses in the United States. It is commonly associated with invasive ductal cell carcinoma. The disease is aggressive and makes up about 10% of all breast cancer deaths in the U.S. In this disease, cancer cells block lymph vessels in the skin and soft tissue. Inflammatory breast cancer is more often triple-negative or HER2-positive than non-inflammatory breast cancer.
Male breast cancer
Each year about 2,500 men in the United States are diagnosed with breast cancer. Like female breast cancer, most cases fall into the three receptor subtype groups (HER2-positive, hormone receptor-positive and triple-negative).
Metaplastic breast cancer
Metaplastic breast cancer is rare, making up less than 1% of all breast cancers. Metaplastic breast cancer starts in the duct cells. In this disease, the duct cells transform from normal duct cells to cells that resemble soft or connective tissue. Most patients have a distinct breast lump that grows quickly. The disease is aggressive and usually has a triple-negative receptor type. It is difficult to treat successfully.
Metastatic breast cancer
Advanced breast cancer (also called metastatic breast cancer and stage IV breast cancer) is not a distinct type of cancer. Instead, it is any breast cancer that has spread beyond the breast and nearby lymph nodes to other parts of the body, such as the bones, brain, liver or lungs. Even though the disease may be found in other organs, it is still considered and treated like breast cancer.
Most cases of advanced breast cancer are not considered curable. Instead, they are treated like a chronic illness. The goal of care is to prolong life and maintain the patient’s quality of life. With emerging therapies and treatments, many metastatic breast cancer patients can live well for years. MD Anderson has an Advanced Breast Cancer Clinic dedicated to caring for these patients.
Paget disease of the breast
Paget disease is a rare form of breast cancer, making up 1-4% of all breast cancer cases, according to the National Cancer Institute. It arises when ductal carcinoma cancer cells invade the skin of the nipple. This can cause a rash or scaling of the nipple that may spread to the areola (the colored area surrounding skin).
A risk factor is anything that increases the chances of developing a specific disease. Key breast cancer risk factors and causes include:
- Age: As women age, their breast cancer risk increases. Most breast cancers are diagnosed after age 50. If you believe you may be more likely to develop cancer because of your personal or family medical history. Learn more about breast cancer screening.
- Inherited genetic mutations: Specific gene mutations increase the risk of developing cancer. These include BRCA1 and BRCA2 mutations. Normal BRCA1 and BRCA2 genes repair damaged DNA. When these genes are mutated in certain ways, they fail at DNA repair, which could lead to breast and/or ovarian cancer. Other mutations that can lead to breast cancer are to PALB2, another DNA repair gene; CHEK2, a tumor suppressor gene; and PTEN, which controls how quickly cells multiply. Learn more about hereditary cancer syndromes.
- Family history: A woman’s odds of developing breast cancer are higher if a parent, sibling or child has had the disease.
- Early menstruation: Women who began menstruating before age 12 have a higher risk of developing breast cancer.
- Women who have no full-term pregnancies or their first pregnancy after age 30 are at a higher risk of breast cancer.
- Previous breast cancer diagnosis: A woman who has had breast cancer once has a higher risk of developing cancer again.
- Previous radiation therapy: People who had radiation therapy to the chest in childhood or early adulthood to treat another cancer are at a higher risk of developing breast cancer. The benefits of these earlier radiation treatments far outweigh the risks, however.
- Obesity: Obesity, particularly after menopause, increases a woman’s breast cancer risk.
- Dense breast tissue: Based on its appearance in a mammogram is a known risk factor for breast cancer.
- Postmenopausal hormone therapy: Some women use hormone therapies containing estrogen and progesterone to treat the symptoms of menopause. This may increase the risk of breast cancer.
- Drinking alcohol
Some cases of breast cancer can be passed down from one generation to the next. Genetic counseling may be right for you. Learn more about the risk to you and your family in our prevention and screening section.
Learn more about breast cancer:
Breast cancer prevention related articles:
Why choose MD Anderson for your breast cancer treatment?
Choosing the right hospital may be the most important decision you make as a breast cancer patient. At MD Anderson you’ll get treatment from one of the nation’s top-ranked cancer centers. Our expertise starts with the ability to accurately diagnose and stage even extremely rare cancers, then carries on through groundbreaking treatment and into survivorship.
At other centers and hospitals, doctors may be expected to develop treatment plans or perform surgery on patients with several different types of cancer and/or non-cancerous conditions. At MD Anderson, our core mission is to eliminate cancer. The surgeons, radiation oncologists and medical oncologists with the Nellie B. Connally Breast Center are focused exclusively on curing breast cancer, extending the life of breast cancer patients and maximizing their quality of life.
This allows them to develop a tremendous amount of experience and skill in treating breast cancer patients, including those with rare forms of the disease. Each doctor brings their skills to our multidisciplinary teams, where they work together to develop treatment plans that address the unique nature of each breast cancer case and patient.
As a top-ranked cancer hospital, MD Anderson is also a leader in innovating new and better ways to care for patients. Our breast cancer doctors have helped develop new treatments and therapies that have improved survival rates, decreased side effects and resulted in better cosmetic outcomes for breast cancer patients.
This care is available beyond MD Anderson’s campus in the Texas Medical Center. Through our five Houston-area locations, patients throughout the region can get the same multidisciplinary care and personalized attention close to home.
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