Cancer occurs when changes called mutations take place in genes that regulate cell growth. The mutations let the cells divide and multiply in an uncontrolled, chaotic way. The cells keep multiplying, producing copies that get progressively more abnormal. In most cases, the cell copies eventually form a tumor.
Breast cancer is cancer that develops in breast cells. Typically, the cancer forms in either the lobules or the ducts of the breast. Lobules are the glands that produce milk, and ducts are the pathways that bring the milk from the glands to the nipple. Cancer can also occur in the fatty tissue or the fibrous connective tissue within your breast.
The uncontrolled cancer cells often invade other healthy breast tissue and can travel to the lymph nodes under the arms. The lymph nodes are a primary pathway that helps the cancer cells move to other parts of the body. See pictures and learn more about the structure of the breast.
According to the Centers for Disease Control and Prevention (CDC), breast cancer is the most common cancer in women. And according to statistics from the American Cancer Society (ACS), nearly 232,000 new cases of invasive breast cancer were expected to be diagnosed in the United States in 2015. Invasive breast cancer is cancer that has spread from the ducts or glands to other parts of the breast. More than 40,000 women were expected to die from the disease.
Breast cancer can also be diagnosed in men. The ACS also estimated that in 2015, more than 2,000 men would be diagnosed, and more than 400 men would die from the disease. Find out more about breast cancer numbers around the world.
There are several types of breast cancer, which are broken into two main categories: “invasive” (as mentioned above), and “noninvasive,” or in situ. While invasive cancer has spread from the breast ducts or glands to other parts of the breast, noninvasive cancer has not spread from the original tissue.
These two categories are used to describe the most common types of breast cancer, which include:
- Ductal carcinoma in situ. Ductal carcinoma in situ (DCIS) is a noninvasive condition. With DCIS, the cells that line the ducts in your breast change and look cancerous. However, DCIS cells haven’t invaded the surrounding breast tissue.
- Lobular carcinoma in situ. Lobular carcinoma in situ (LCIS) is cancer that grows in the milk-producing glands of your breast. Like DCIS, the cancer cells haven’t yet invaded the surrounding tissue.
- Invasive ductal carcinoma. Invasive ductal carcinoma (IDC) is the most common type of breast cancer. This type of breast cancer begins in your breast’s milk ducts and then invades nearby tissue in the breast. Once the breast cancer has spread to the tissue outside your milk ducts, it can begin to spread to other nearby organs and tissue.
- Invasive lobular carcinoma. Invasive lobular carcinoma (ILC) first develops in your breast’s lobules. If breast cancer is diagnosed as ILC, it has already spread to nearby tissue and organs.
Other, less common types of breast cancer include:
- Paget disease of the nipple. This type of breast cancer begins in the breasts’ ducts, but as it grows, it begins to affect the skin and areola of the nipple.
- Phyllodes tumor. This very rare type of breast cancer grows in the connective tissue of the breast.
- Angiosarcoma. This is cancer that grows on the blood vessels or lymph vessels in the breast.
The type of cancer you have determines your treatment options, as well as your prognosis (likely long-term outcome). Learn more about types of breast cancer.
Inflammatory breast cancer
Inflammatory breast cancer (IBC) is a rare but aggressive type of breast cancer. IBC makes up only between 1 and 5 percent of all breast cancer cases.
With this condition, cells block the lymph nodes near the breasts, so the lymph vessels in the breast can’t properly drain. Instead of creating a tumor, IBC causes your breast to swell, look red, and feel very warm. A cancerous breast may appear pitted and thick, like an orange peel.
IBC can be very aggressive and progress quickly. For this reason, it’s important to call your doctor right away if you notice any symptoms. Find out more about IBC and the symptoms it can cause.
Triple-negative breast cancer
Triple-negative breast cancer is another rare disease type, affecting only about 10 to 20 percent of people with breast cancer. To be diagnosed as triple-negative breast cancer, a tumor must have all three of the following characteristics:
- It lacks estrogen receptors. These receptors are cells that bind, or attach, to the hormone estrogen. If a tumor has estrogen receptors, it needs estrogen to grow.
- It lacks progesterone receptors. These receptors are cells that bind to the hormone progesterone. If a tumor has progesterone receptors, it needs progesterone to grow.
- It doesn’t have additional HER2 proteins on its surface. HER2 is a protein that fuels breast cancer growth.
If a tumor meets these three criteria, it’s labeled a triple-negative breast cancer. This type of breast cancer has a tendency to grow and spread more quickly than other types of breast cancer.
Triple-negative breast cancers are difficult to treat because traditional breast cancer treatments are not effective. Learn about treatments for triple-negative breast cancer, as well as survival rates.
There are several risk factors that increase your chances of getting breast cancer. However, having any of these doesn’t mean you will definitely develop the disease.
Some risk factors can’t be avoided, such as family history. Other risk factors, such as smoking, you can change. Risk factors for breast cancer include:
- Age. Your risk for developing breast cancer increases as you age. Most invasive breast cancers are found in women over age 55.
- Drinking alcohol. Drinking excessive amounts of alcohol raises your risk.
- Having dense breast tissue. Dense breast tissue makes mammograms hard to read. It also increases your risk of breast cancer.
- Gender. Women are 100 times more likely to develop breast cancer than men.
- Genes. Women who have the BRCA1 and BRCA2 gene mutations are more likely to develop breast cancer than women who don’t. Other gene mutations may also affect your risk.
- Early menstruation. If you had your first period before age 12, you have an increased risk for breast cancer.
- Giving birth at an older age. Women who don’t have their first child until after age 35 have an increased risk of breast cancer.
- Hormone therapy. Women who took or are taking postmenopausal estrogen and progesterone medications to reduce their signs of menopause symptoms have a higher risk of breast cancer.
- Inherited risk. If a close female relative has had breast cancer, you have an increased risk for developing it. This includes your mother, grandmother, sister, or daughter. If you don’t have a family history of breast cancer, you can still develop breast cancer. In fact, the majority of women who develop it have no family history of the disease.
- Late menopause start. Women who do not start menopause until after age 55 are more likely to develop breast cancer.
- Never being pregnant. Women who never became pregnant or never carried a pregnancy to full-term are more likely to develop breast cancer.
- Previous breast cancer. If you have had breast cancer in one breast, you have an increased risk of developing breast cancer in your other breast or in a different area of the previously affected breast.
In its early stages, breast cancer may not cause any symptoms. In many cases, a tumor may be too small to be felt, but an abnormality can still be seen on a mammogram. If a tumor can be felt, the first sign is usually a new lump in the breast that was not there before. However, not all lumps are cancer.
Each type of breast cancer can cause a variety of symptoms. Many of these symptoms are similar, but some can be different. Symptoms for the most common breast cancers include:
- a breast lump or tissue thickening that feels different than surrounding tissue and has developed recently
- breast pain
- red, pitted skin over your entire breast
- swelling in all or part of your breast
- a nipple discharge other than breast milk
- bloody discharge from your nipple
- peeling, scaling, or flaking of skin on your nipple or breast
- a sudden, unexplained change in the shape or size of your breast
- inverted nipple
- changes to the appearance of the skin on your breasts
- a lump or swelling under your arm
If you have any of these symptoms, it doesn’t necessarily mean you have breast cancer. For instance, pain in your breast or a breast lump can be caused by a breast cyst. Still, if you find a lump in your breast or have other symptoms, you should see your doctor for further examination and testing. Learn more about possible symptoms of breast cancer.
To determine if your symptoms are caused by breast cancer or a benign breast condition, your doctor will do a thorough physical exam in addition to a breast exam. They may also request one or more diagnostic tests to help understand what’s causing your symptoms.
Tests that can help diagnose breast cancer include:
- Mammogram. Perhaps the best way to see below the surface of your breast is with an imaging test called a mammogram. Many women get annual mammograms to check for breast cancer. If your doctor suspects you may have a tumor or suspicious spot, they will also request a mammogram. If an abnormal area is seen on your mammogram, your doctor may request additional tests.
- Ultrasound. A breast ultrasound creates a picture of the tissues deep in your breast. The ultrasound uses sound waves to do this. An ultrasound can help your doctor distinguish between a solid mass, such as a tumor, and a benign cyst.
Your doctor may also suggest tests such as an MRI or a breast biopsy. Learn about other tests that can be used to detect breast cancer.
If your doctor suspects breast cancer, they may order both a mammogram and an ultrasound. If both of these tests can’t tell your doctor if you have cancer, your doctor may do a test called a breast biopsy.
During this test, your doctor will remove a tissue sample from the suspicious area to have it tested. There are several types of breast biopsies. With some of these tests, your doctor uses a needle to take the tissue sample. With others, they make an incision in your breast and then remove the sample.
Your doctor will send the tissue sample to a laboratory. If the sample tests positive for cancer, the lab can test it further to tell your doctor what type of cancer you have. Learn more about breast biopsies, how to prepare for one, and what to expect.
Breast cancer can be divided into stages based on how severe it is. Cancers that have grown and invaded nearby tissues and organs are at a higher stage than cancers that are still contained to the breast. In order to stage a breast cancer, doctors need to know:
- if the cancer is invasive or noninvasive
- how large the tumor is
- whether the lymph nodes are involved
- if the cancer has spread to nearby tissue or organs
Breast cancer has five main stages: stages 0–5.
Stage 0 breast cancer
Stage 0 is DCIS. Cancer cells in DCIS remain confined to the ducts in the breast and have not spread into nearby tissue.
Stage 1 breast cancer
There are two types of stage 1 breast cancer:
- Stage 1A: The primary tumor is 2 centimeters wide or less and the lymph nodes are not affected.
- Stage 1B: Cancer is found in nearby lymph nodes, and either there is no tumor in the breast, or the tumor is smaller than 2 centimeters.
Stage 2 breast cancer
Stage 2 breast cancers are also divided into two categories:
- Stage 2A: The tumor is smaller than 2 centimeters and has spread to 1–3 nearby lymph nodes, or it’s between 2 and 5 centimeters and hasn’t spread to any lymph nodes.
- Stage 2B: The tumor is between 2 and 5 centimeters and has spread to 1–3 axillary (armpit) lymph nodes, or it’s larger than 5 centimeters and hasn’t spread to any lymph nodes.
Stage 3 breast cancer
There are three main types of stage 3 breast cancer.
- Stage 3A: This stage can have several types of cancer:
- The cancer has spread to 4–9 axillary lymph nodes or has enlarged the internal mammary lymph nodes, and the primary tumor can be any size.
- The tumor is bigger than 5 centimeters and small groups of cancer cells are found in the lymph nodes.
- Tumors are greater than 5 centimeters and the cancer has spread to 1–3 axillary lymph nodes or any breastbone nodes.
- Stage 3B: A tumor has invaded the chest wall or skin and may or may not have invaded up to 9 lymph nodes.
- Stage 3C: Cancer is found in 10 or more axillary lymph nodes, lymph nodes near the collarbone, or internal mammary nodes.
Stage 4 breast cancer
Stage 4 breast cancer can have a tumor of any size, and its cancer cells have spread to nearby and distant lymph nodes, as well as distant organs.
The testing your doctor does will determine the stage of your breast cancer, which will affect your treatment. Find out how different breast cancer stages are treated.
Metastatic breast cancer
Metastatic breast cancer is another name for stage 4 breast cancer. It’s breast cancer that has spread from your breast to other parts of your body, such as your bones, lungs, or liver.
This is the most serious type of breast cancer, and it requires immediate treatment. Your oncologist (cancer doctor) will create a treatment plan with the goal of stopping the growth and spread of the tumor, or tumors. Learn about treatment options for metastatic cancer, as well as factors that affect your outlook.
Your breast cancer’s stage, how far it has invaded (if it has), and how big the tumor has grown all play a large part in determining what kind of treatment you’ll need.
To start, your doctor will determine your cancer’s size, stage, and grade (how likely it is to grow and spread). After that, the two of you can discuss your treatment options. Surgery is the most common treatment for breast cancer. In addition to surgery, most women have a complementary treatment, such as chemotherapy, radiation, or hormone therapy.
Several types of surgery may be used to remove breast cancer, including:
- Lumpectomy. This procedure removes only the suspicious or cancerous spot, leaving most surrounding tissue in place.
- Mastectomy. In this procedure, a surgeon removes an entire breast. In a double mastectomy, both breasts are removed.
- Sentinel node biopsy. This surgery removes some of the lymph nodes that receive drainage from the tumor. These lymph nodes will be tested. If they don’t have cancer, you may not need additional lymph-removing surgery.
- Axillary lymph node dissection. If lymph nodes removed during a sentinel node biopsy test positive, your doctor may perform this procedure to remove additional lymph nodes.
- Contralateral prophylactic mastectomy. Even though breast cancer may be present in only one breast, some women elect to have a contralateral prophylactic mastectomy. This surgery removes your healthy breast to reduce your risk of developing breast cancer again.
With radiation therapy, high-powered beams of radiation are used to target and kill cancer cells. Most radiation treatments use external beam radiation. This technique uses a large machine on the outside of the body.
Advances in cancer treatment have also enabled doctors to irradiate cancer from inside the body. This type of radiation treatment is called brachytherapy. To conduct brachytherapy, surgeons place radioactive seeds, or pellets, inside the body near the tumor site. The seeds stay there for a short period of time and work to reduce cancer cells.
Chemotherapy is a drug treatment used to destroy cancer cells. Some people may undergo chemotherapy on its own, but this type of treatment is often used along with other treatments, especially surgery.
In some cases, doctors prefer to give patients chemotherapy before surgery. The hope is that the treatment will shrink the tumor, and then the surgery will not need to be as invasive. Chemotherapy has many unwanted side effects, so discuss your concerns with your doctor before starting treatment.
If your type of breast cancer is sensitive to hormones, your doctor may start you on hormone therapy. Estrogen and progesterone, two female hormones, can stimulate the growth of breast cancer tumors. Hormone therapy works by blocking your body’s production of these hormones. This action can help slow and possibly stop the growth of your cancer.
Certain medications are designed to attack specific abnormalities or mutations within cancer cells. For example, Herceptin (trastuzumab) can block your body’s production of the HER2 protein. HER2 helps breast cancer cells grow, so taking a medication to slow the production of this protein may help slow cancer growth.
Your doctor will tell you more about any specific treatment they recommend for you. Learn more about breast cancer treatments, as well as how hormones affect cancer growth.
Breast cancer doesn’t have an identifiable cause. For that reason, it can’t be prevented entirely. However, following a healthy lifestyle, getting regular screening, and taking any preventive measures your doctor recommends can help reduce your risk.
Lifestyle factors can affect your risk of breast cancer. For instance, women who are obese have a higher risk of developing breast cancer. Maintaining a healthy diet and getting more exercise could help you lose weight and lower your risk.
Drinking too much alcohol also increases your risk. This is true of having two or more drinks per day, and of binge drinking. However, a recent study found that even one drink per day increases your risk of breast cancer. If you drink alcohol, talk to your doctor about what amount they recommend for you.
Breast cancer screening
Having regular mammograms may not prevent breast cancer, but it can help reduce the odds that it will go undetected. The American Cancer Society provides the following general recommendations for mammograms:
- Women ages 40 to 44: An annual mammogram is optional.
- Women age 45 to 54: An annual mammogram is recommended.
- Women 55 and older: A mammogram every 1 or 2 years is recommended, for as long as you’re in good health and expected to live 10 more years or longer.
These are only guidelines. Specific recommendations for mammograms are different for each woman, so talk with your doctor to see if you should get regular mammograms.
Some women are at increased risk of breast cancer due to hereditary factors. For instance, if your mother or father has a harmful BRCA1 or BRCA2 gene mutation, you’re at higher risk of having it as well. This significantly raises your risk of breast cancer.
If you’re at risk for this mutation, talk to your doctor about your diagnostic and treatment options. You may want to be tested to find out if you definitely have the mutation. And if you learn that you do have it, discuss with your doctor any pre-emptive steps you can take to reduce your risk of getting breast cancer. These steps could include a prophylactic mastectomy (surgical removal of a breast).
In addition to mammograms, breast exams are another way to watch for signs of breast cancer.
Many women do a breast self-examination. It’s best to do this exam once a month, at the same time each month. The exam can help you become familiar with how your breasts normally look and feel, so that you’re aware of any changes should they occur.
Keep in mind, though, that the ACS considers these exams to be optional because current research hasn’t shown a clear benefit of physical exams, whether performed at home or by a doctor.
Breast exam by your doctor
The same is true for breast exams done by your doctor or other healthcare provider. They won’t hurt you, and your doctor may do a breast exam during your annual visit.
That said, if you’re having symptoms that concern you, it’s a good idea to have your doctor do a breast exam. During the exam, your doctor will check both of your breasts for abnormal spots or signs of breast cancer. Your doctor may also check other parts of your body to see if the symptoms you’re having could be related to another condition. Learn more about what your doctor may look for during a breast exam.
Male breast cancer
Although they generally have less of it, men have breast tissue just like women do. So, men can get breast cancer too. However, it’s much rarer. According to the ACS, breast cancer is 100 times less common in men than in women.
That said, the breast cancer that men get is just as serious as the breast cancer women get. It also has the same symptoms. Read more about breast cancer in men and the symptoms to watch for.
Breast cancer survival rates vary widely based on many factors. Two of the most important factors are the type of cancer you have, and the stage of the cancer at the time you receive a diagnosis. Other factors that may play a role include your age, gender, and race.
The good news is breast cancer survival rates are improving. According to the ACS, in 1975, the 5-year survival rate for breast cancer in women was 75.2 percent. But in 2008, it was 90.6 percent. Find out more about survival statistics and the factors that affect them.
Breast cancer can cause a range of symptoms, and these symptoms can appear differently in different people.
If you’re concerned about a spot or change in your breast, it can be helpful to know what breast problems that are actually cancer look like. Learn more about breast cancer symptoms, and see pictures of what they can look like.
Fortunately for women and men around the world, people today are increasingly aware of the issues associated with breast cancer. Breast cancer awareness efforts have helped people learn what their risk factors are, how they can reduce their level of risk, what symptoms they should look for, and what kinds of screening they should be getting.
Breast Cancer Awareness Month is held each October, but many people spread the word throughout the year. Check out these breast cancer blogs for first-person insight from women living with this disease with passion and humor.
Breast cancer care
If you detect an unusual lump or spot in your breast, or have any other symptoms of breast cancer, make an appointment to see your doctor. Chances are good that it’s not breast cancer. For instance, there are many other potential causes for breast lumps.
But if your problem does turn out to be cancer, keep in mind that early treatment is the key. Early-stage breast cancer can often be treated and cured if found quickly enough. The longer breast cancer is allowed to grow, the more difficult treatment becomes.
If you’ve already received a breast cancer diagnosis, keep in mind that cancer treatments continue to improve, as do outcomes. So follow your treatment plan and try to stay positive. Find out more about the outlook for different stages of breast cancer.