Breast cancer occurs when breast cells develop mutations and begin to divide and multiply. People may first notice a lump in the breast, discoloration, texture changes, or other symptoms.

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. Once the cancer enters the lymph nodes, it has access to a pathway to move to other body parts.

Although they generally have less of it, males have breast tissue just like females do. Males can develop breast cancer, too, but it’s much rarer.

Learn more about the signs of breast cancer, how it’s diagnosed, and what treatment options are available.

Signs and symptoms of breast cancer

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.

Symptoms of the most common breast cancers includeTrusted Source:

• a breast lump or tissue thickening that feels different from surrounding tissue and is new
• breast pain
• discolored and pitted skin on your 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 benign cyst.

Still, if you find a lump in your breast or have other symptoms, speak with a doctor for further examination and testing.

Learn more about breast cancer symptoms and see pictures of what they can look like.

Types of breast cancer

There are several types of breast cancer, which are broken into two main categories: invasive and noninvasive. Noninvasive breast cancer is also known as breast cancer 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.

Types of noninvasive breast cancer

• Ductal carcinoma in situ (DCIS): DCIS is a noninvasive cancer. With DCIS, the cancer cells are confined to the ducts in your breast and haven’t invaded the surrounding breast tissue.
• Lobular carcinoma in situ (LCIS): LCIS is cancer that grows in the milk-producing glands of your breast. Like DCIS, the cancer cells haven’t invaded the surrounding tissue.

Types of invasive breast cancer

• Invasive ductal carcinoma (IDC): IDC is the most common type of breast cancer. It 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 (ILC): ILC first develops in your breast’s lobules and then invades nearby tissue.
• Inflammatory breast cancer (IBC): IBC is a rare but aggressive type of breast cancer. According to the National Cancer Institute, IBC makes up only 1% to 5%Trusted Source of all breast cancer cases. It blocks the lymph nodes near the breasts, so the lymph vessels in the breast can’t properly drain.
• Paget disease of the nipple: This type of breast cancer begins in the ducts of the nipple, but as it grows, it begins to affect the skin and areola of the nipple.
• Triple-negative breast cancer: This is another rare disease type. It affects only about 10% to 15%Trusted Source of people with breast cancer.
• Angiosarcoma: This is cancer that grows on the blood vessels or lymph vessels in the breast.

The type of cancer you have helps guide your treatment options and long-term outcome.

Learn more about types of breast cancer.

How common is breast cancer?

According to the Centers for Disease Control and Prevention (CDC)Trusted Source, breast cancer is the second most common cancer in women.

Risk factors for breast cancer

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.

Risk factors you can change includeTrusted Source:

• Alcohol use: Drinking alcohol raises your risk.
• Hormone therapy: People who took or are taking postmenopausal estrogen and progesterone medications to help reduce their menopause symptoms have a higher risk of breast cancer.
• Not getting enough exercise: Those who are not physically active can often have a higher risk of cancer.

Risk factors you cannot change include:

• Age: Your risk of developing breast cancer increases as you age. Most invasive breast cancers are found in people over 55 years old.
• Having dense breast tissue: Dense breast tissue makes mammograms hard to read. It also increases your risk of breast cancer.
• Genes: People who have the BRCA1 and BRCA2 gene mutations are more likely to develop breast cancer than people who don’t. Other gene mutations may also affect your risk.
• Inherited risk: If a close female relative, such as your mother, sister, or grandmother, has had breast cancer, you have an increased risk of developing it.
• Never having been pregnant: People who have never been pregnant or carried a pregnancy to full term are more likely to develop breast cancer.

Learn more about the causes and risk factors of breast cancer.

Diagnosis of breast cancer

To determine whether your symptoms are caused by breast cancer or a benign breast condition, a 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.

These include:

Imaging tests

The most common way to see below the surface of your breast is with an imaging test called a mammogram. Many females over 40 years old get annual mammograms to check for breast cancer.

If a doctor suspects you may have a tumor or suspicious spot, they will also request a mammogram.

If an atypical area is seen on your mammogram, a doctor may request additional tests, such as a breast ultrasound. This method uses sound waves to create a picture of the tissues deep in your breast. An ultrasound can help your doctor distinguish between a solid mass, such as a tumor, and a benign cyst.

Breast biopsy

If your doctor suspects breast cancer based on tests like a mammogram or an ultrasound, they may do a test called a breast biopsy.

During this test, they remove a tissue sample from the suspicious area and test it in a lab.

If the sample tests positive for cancer, the lab can test it further to identify the type of breast cancer.

If you don’t already have a primary care doctor, you can browse doctors in your area through the Healthline FindCare tool.

Learn more about Healthline’s Newly Diagnosed with Breast Cancer.

Breast cancer stages

Doctors divide breast cancer into stages based on the size of the tumor and how much it has spread.

Cancers that are large or have invaded nearby tissues or organs are at a higher stage than cancers that are small or still contained in the breast.

To stage 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 stagesTrusted Source: stages 0 to 4.

Stage 0 breast cancer

Stage 0 is ductal carcinoma in situ (DCIS). Cancer cells in DCIS remain confined to the ducts in the breast and have not spread into nearby tissue.

Stage 1 breast cancer

• Stage 1A: The primary tumor is 2 centimeters (cm) wide or less. The lymph nodes are not affected.
• Stage 1B: Cancer is found in nearby lymph nodes. Either there is no tumor in the breast, or the tumor is smaller than 2 cm.

Stage 2 breast cancer

• Stage 2A: The tumor is smaller than 2 cm and has spread to one to three nearby lymph nodes, or it’s between 2 and 5 cm and hasn’t spread to any lymph nodes.
• Stage 2B: The tumor is between 2 and 5 cm and has spread to one to three axillary (armpit) lymph nodes, or it’s larger than 5 cm and hasn’t spread to any lymph nodes.

Stage 3 breast cancer

• Stage 3A:
  • The cancer has spread to four to nine axillary lymph nodes or has enlarged the internal mammary lymph nodes. The primary tumor can be any size.
  • Tumors are greater than 5 cm. The cancer has spread to one to three 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 nine 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 (metastatic breast cancer)

Stage 4 breast cancer can have a tumor of any size. Its cancer cells have spread to nearby and distant lymph nodes as well as distant organs.

The testing a doctor does will determine the stage of your breast cancer, which will affect your treatment.

Learn more about breast cancer stages and grades.

Breast cancer treatment

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, a doctor will determine your cancer’s size, stage, and grade. Your cancer’s grade describes how likely it is to grow and spread. After that, you can discuss your treatment options.

Surgery is the most common treatment for breast cancer. Many people have additional treatments, such as chemotherapy, targeted therapy, radiation, or hormone therapy.

Surgery

Several types of surgery may be used to remove breast cancer, including:

• Breast-conserving surgery:
  • Lumpectomy: This procedure removes the tumor and some surrounding tissue, leaving the rest of the breast intact.
• Surgery to remove lymph nodes:
  • Sentinel node biopsy: This surgery removes a few 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 surgery to remove more lymph nodes.
  • Axillary lymph node dissection: If lymph nodes removed during a sentinel node biopsy contain cancer cells, a doctor may remove additional lymph nodes.
• Removal of one or both breasts:
  • Mastectomy: In this procedure, a surgeon removes an entire breast. In a double mastectomy, they remove both breasts.
  • Contralateral prophylactic mastectomy: Even though breast cancer may be present in only one breast, some people elect to have a contralateral prophylactic mastectomy. This surgery removes your healthy breast to lower your risk of developing breast cancer again.

Radiation therapy

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 is known as brachytherapyTrusted Source.

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 destroy cancer cells.

Chemotherapy

Chemotherapy is a drug treatment used to destroy cancer cells. Some people may undergo only chemotherapy, but this type of treatment is often used alongside other treatments, especially surgery.

Some people will have surgery first followed by other treatments, such as radiation. This is called adjuvant therapy. Others may have chemotherapy first to shrink the cancer, called neoadjuvant therapy, and then surgery.

In some cases, doctors prefer to give chemotherapy before surgery. The hope is that the treatment will shrink the tumor, and then the surgery will not need to be as invasive.

Hormone therapy

If your type of breast cancer is sensitive to hormones, a 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 or by blocking the hormone receptors on the cancer cells. This action can help slow and possibly stop the growth of your cancer.

Learn more about treatment options for breast cancer.

Breast cancer prevention

While there are risk factors you can’t control, following a healthy lifestyle, getting regular screenings, and taking any preventive measures recommended by a doctor can help lower your risk of developing breast cancer.

Learn more about breast cancer prevention.

Lifestyle factors

Lifestyle factors can affectTrusted Source your risk of breast cancer.

For instance, people who have obesity have a higher risk of developing breast cancer. Maintaining a nutrient-dense diet and getting regular exercise as often as possible could help you lose weight and lower your risk.

According to the American Association for Cancer Research, drinking alcohol also increases your risk, especially drinking more than the recommended moderate amount. For females, moderate alcohol use is definedTrusted Source as one drink per day.

If you drink alcohol, consider talking with a 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 chance that it will go undetected.

The American Cancer SocietyTrusted Source provides the following general recommendations for those at average risk of breast cancer:

• Ages 40 to 44 years: an optional mammogram each year
• Ages 45 to 54 years: a mammogram every year
• Ages 55 years and older: can choose to continue with annual mammograms or switch to every other year

Specific recommendations for mammograms are different for everyone, so talk with a doctor to see if you should get regular mammograms.

Preventive treatment

You may have an increased risk of breast cancer due to hereditary factors.

For instance, if your parent has a BRCA1 or BRCA2 gene mutation, you’re at higher riskTrusted Source of having it as well. This significantly raises your risk of breast cancer.

If you’re at risk for this mutation, consider talking with a doctor about your diagnostic options. You may want to be tested to determine whether you have the mutation.

If you learn that you do have it, talk with a doctor about any preemptive steps you can take to reduce your risk of developing breast cancer. These steps could include a prophylactic mastectomy, or surgical removal of a breast.

You may also consider chemoprophylaxis, or taking medication, such as Tamoxifen, to potentially reduce your breast cancer risk.

Self-exams

Many people routinely conduct a breast self-examination. It’s best to do this exam once per month, at the same time each month. The exam can help you become familiar with how your breasts usually look and feel so that you’re aware of any changes that occur.

Breast exam by your doctor

If you’re having symptoms that concern you, it’s a good idea to have a doctor do a breast exam. During the exam, they will check both of your breasts for abnormal spots or signs of breast cancer.

Learn more about what your doctor may look for during a breast exam.

Breast cancer outlook

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
• your sex
• your race
• the growth rate of the cancer

Research from 2021Trusted Source shows there’s a higher mortality rate in people of color with breast cancer than white people with breast cancer. A key reason for this is healthcare disparities, such as a lack of access to quality care.

The good news is breast cancer survival rates are improving.

The 5-year relative survival rates for breast cancer differ depending on the stage at diagnosis. According to the American Cancer SocietyTrusted Source, the 5-year relative survival rates for breast cancer are:

• 99% for localized breast cancer
• 86% for regional breast cancer
• 31% for distant breast cancer
• 91% for all stages combined

Find out more about survival statistics and the factors that affect them.

Takeaway

Breast cancer occurs when breast cells develop mutations and begin to divide and multiply. Some people may notice symptoms such as a lump, discoloration, or texture changes.

There are several types of breast cancer, which are broken into two main categories: invasive and noninvasive. The type of cancer you have helps guide your treatment options and long-term outcome.

If you notice any changes to your breast, such as a lump, swelling, or pain, reach out to a healthcare professional for advice. They can run some tests to identify what could be causing your symptoms.

Remember, breast cancer survival rates are improving. The earlier the cancer is caught, the better your outlook may be.

Check out Healthline’s Breast Cancer Resource Center.