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What are the types of breast cancer?
Traditionally, most breast cancers have been classified as either ductal or lobular. Lobular carcinomas start in the breasts’ milk-producing glands, called the lobules. Ductal carcinomas start in the cells of the milk ducts, which carry milk from the lobules to the nipples.
Both can be non-invasive, meaning the diseased cells have not spread into surrounding normal tissue. Non-invasive diseases are by definition early in the cancer development process. In fact, non-invasive lobular carcinoma is so early that it’s not even classified as cancer. Instead it is considered a cancer risk factor and may not even require surgery.
Both ductal and lobular carcinomas can also be invasive, meaning the cancer has spread beyond the lobule or duct where it first started into nearby tissue.
Breast cancer treatments are designed around several factors, including whether the cancer is ductal or lobular and invasive or non-invasive.
For invasive breast cancers, another key factor is the molecular receptor status of the cancer cells.
What are molecular receptors?
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 interaction is known as recognition.
Researchers have identified certain receptors that fuel the growth and spread of breast cancer when they recognize, or bind, with a specific molecule. By interrupting this recognition with new cancer drugs, the disease’s growth can be slowed or stopped.
Currently there are three major receptor subtypes that play important roles in the patient’s prognosis and treatment. As research into breast cancer continues, more subtypes with different treatments are likely to emerge. Today, the three main subtypes are:
HER2-positive breast cancer
HER2 is a protein that promotes cell growth and multiplication. It is found on the surface of all breast cells. A breast cancer is HER2-positive when it has much higher levels of the protein than normal.
About half of HER2-positive cancers are also hormone receptor-positive/ER positive. 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 has spread beyond the breast and nearby lymph nodes.
Hormone receptor-positive/ER-positive breast cancer
Hormone receptor-positive breast cancer (sometimes called Luminal A) 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 therapies target this receptor/hormone recognition. These therapies can limit the body’s production of estrogen and progesterone or stop the receptors from recognizing the hormones.
Thanks to this 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 don’t have one of the other three receptors. Besides this, triple-negative breast cancers can have very little in common.
Since there isn’t an established receptor to target in triple-negative breast cancer, this is the most difficult of the three receptor subytpes to treat. Triple-negative breast cancer also tends to be more aggressive, so the prognosis for this subtype is often worse than others. Some triple-negative breast cancers, however, do respond well to chemotherapy. In some cases, chemotherapy works so well that no cancer is found during surgery. This is called a pathological complete response.
Other types of breast cancer
Some breast cancers are grouped by special or unusual traits that are not related to the molecular receptors. These cancers may be categorized by their receptor status, but they are first classified by their special group.
Inflammatory breast cancer
Inflammatory breast cancer accounts for 2%-4% of all breast cancer diagnoses in the United States. 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 also classified by its receptor status and is more often triple-negative or HER2-positive than non-inflammatory breast cancer. Read more about inflammatory breast cancer.
Metaplastic breast cancer
Metaplastic breast cancer is rare, making up less than 1% of all breast cancers. Most patients have a distinct lump that grows quickly. The disease is aggressive and usually has a triple-negative receptor type. It is difficult to treat successfully.
Male breast cancer
While breast cancer is thought of as a disease impacting women, each year about 2,500 men in the United States are diagnosed with the disease. Like female breast cancer, most cases fall into the three receptor subtype groups (HER2-positive, hormone receptor-positive and triple-negative). Learn more about male breast cancer.
Male breast cancer related articles:
- Male breast cancer: What men should know
- What men should know about genetic breast cancer
- Male breast cancer survivor: Why I volunteer at MD Anderson
- Male breast cancer: patient and doctor discuss experience and treatment
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. The disease first appears on the nipple and often extends to the areola. Read more about Paget disease of the breast.
Advanced 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.
Breast cancer risk factors
A risk factor is anything that increases the chances of developing a specific disease. Key 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, please review our screening exams by age.
- Inherited genetic mutations: Specific gene mutations increase the risk of developing cancer. These include the 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 genes mutations associated with a higher risk of cancer include PALB2, another DNA repair gene; CHEK2, a tumor suppressor; and PTEN, which controls how quickly cells multiply. Learn more about hereditary cancer syndromes.
- Family history: A woman’s odds of developing breast cancer increase 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 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 a second cancer.
- Previous radiation therapy to the chest in childhood or early adulthood increases the risk of developing breast cancer.
- 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.
Learn more about breast cancer:
Breast cancer prevention related articles:
MD Anderson is #1 in Cancer Care
Did you know?
Why choose MD Anderson for your breast cancer treatment?
Choosing the right hospital may be the most important decision you can 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, eliminating cancer is our core mission. The surgeons, radiation oncologists and medical oncologists with the Nellie B. Connally Breast Center are focused 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 top-ranked care and personalized attention close to home. The breast specialists at the Texas Medical Center interact easily and often with the outstanding regional MD Anderson doctors to provide input on any rare or unusual case.
Cancer is mentally and physically challenging, but don't let it shut you down. Dust yourself off and get back up, even if you have to crawl. This is your life, after all, and it's worth fighting for.
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