Breast surgeon Anita Mamtani treats people with breast cancer at MSK Bergen.
MSK's Guide To

Breast Cancer

Overview

No one should go through breast cancer alone. At MSK, our team of breast cancer experts is here for you.

You may be reading this because you or someone you care about learned they have breast cancer. Or maybe you’re curious about your risk of getting breast cancer. 

It’s important to get to know the signs of breast cancer. It’s best if we can catch it early, when it may be easier to treat. 

This guide is a good place to learn about what causes breast cancer, and how to prevent breast cancer. You can learn about the signs and symptoms of breast cancer.

This information can help you get ready to talk with your healthcare provider and understand your next steps. 

Meet MSK's breast cancer experts

What is breast cancer?

Breast cancer can happen when cells in your breast grow out of control. There are different types of breast cancer. The type depends on which cells in your breast turn into cancer. 

Breast cancer can start in many parts of the breast. This includes the ducts, the lobules, or the tissue in between.

Most breast cancers affect people who were assigned female at birth. But breast cancer can also happen to people assigned male at birth. This is rare, but it does happen. See our guide to Male Breast Cancer.

Screening exams can help find breast cancer early, when it may be easier to treat. This is also called early detection, and it can save your life. 

Treatments for breast cancer can include surgery, radiation, chemotherapy, hormone therapy, or targeted therapy

Dr. Lori H. Kelly, Director of Radiology at MSK Nassau, looks at breast images.
How is breast cancer diagnosed?

We use imaging tests, such as mammograms, to look for abnormal (not normal) signs and symptoms in your breasts. We may do more tests, such as a biopsy procedure to get tissue or cell samples for testing.

Anatomy of the breast

What’s inside your breasts? Knowing the breast’s anatomy can help you better understand where breast cancer starts. Anatomy (uh-NA-toh-mee) means the parts of a structure, such as the breast.

Breast cancers can start in the lobes and ducts.

The breast has fatty and fibrous tissue. Inside are 15 to 20 glands called lobes. Each lobe has many smaller lobules, or sacs, that make milk. Lobules are in clusters, like bunches of grapes.

Ducts are thin tubes that carry milk to the nipple. 

Lymph vessels filter and carry lymph fluid from the breast to the lymph nodes.

Lymph nodes are small, bean-shaped organs that help fight infection. They’re in the breast and throughout the body. Lymph nodes make and filter a colorless fluid called lymph. It has white blood cells (lymphocytes) that help fight infections and diseases such as cancer.

There are clusters of lymph nodes near the breast. They’re in the armpit (called axillary lymph nodes), above the collarbone, in the neck, and in the chest. 

Where does breast cancer start?
  • Lobules are sacs that make milk. Breast cancer that starts in your lobules is called lobular cancer. MSK has a Lobular Breast Cancer Program run by experts in this cancer type. 
  • Ducts are thin tubes that carry milk. Breast cancer that starts in your ducts is called ductal cancer. It’s the most common type of breast cancer.
  • Fibrous tissue is also called connective tissue. Fatty tissue fills the space between your lobules and ducts. Some rare forms of breast cancer start in fibrous and fatty tissue.
  • Lymph nodes are small organs in your armpit, collarbone, neck, and chest. Sometimes, breast cancer can spread to lymph nodes. 
This illustration shows what a breast looks like inside and outside.
This illustration shows what a breast looks like inside and outside.

What a breast looks like on the inside and outside.

What a breast looks like on the inside and outside.

How does breast cancer spread?

Breast cancer spreads when cancer cells break away from the first tumor. They move to other parts of your body through your blood. These cells can grow into new tumors in other places. This includes the lymph nodes, bones, liver, lungs, or brain.

When cancer spreads from where it started to another area, it’s called metastasis (meh-TAS-tuh-sis). 

What are dense breasts?

Dense breasts are normal. They have more fibrous or connective tissue. When you have a mammogram, the dense tissue looks white on the image of your breast. But cancer cells also look white on mammogram images. It can be hard to spot cancer cells in images of dense breasts.

Some people with dense breasts may need extra imaging tests, such as ultrasounds or MRIs, to help find any possible cancers.

You will know if you have dense breasts after getting a mammogram. In September 2024, the FDA ruled that breast density must be on your report after getting a mammogram. Having dense breasts can put you at a higher risk for breast cancer. Talk with your doctor about your risk.

How do lymph nodes affect breast cancer?

Lymph nodes act as filters in your body. They trap cancer cells and other things that can harm your body.

One job of the lymph nodes is to stop things that can harm your body from spreading. There are many lymph nodes close to your breasts, so it's easy for cancer cells to travel to them. 

Cancer cells in your lymph nodes may have spread from somewhere else. Your healthcare provider will choose a treatment option for cancer that has spread. 

Risk factors and prevention

What causes breast cancer?

A risk factor is anything that raises your chances of getting a disease. Some risk factors never change, such as your age or genes (DNA).

Research shows that having healthy habits can lower your risk for cancer.

A few risk factors can raise your risk for getting breast cancer. Examples are: 

  • Your personal and family health history
  • Genetic changes (mutations or variants) in genes such as BRCA1 or BRCA2
  • Lesions that are benign. These are areas that are not normal, but are not cancer. Examples are:
    • Atypical ductal hyperplasia (ADH)
    • Atypical lobular hyperplasia (ALH)
    • Lobular carcinoma in situ (LCIS) 
Your age and your sex assigned at birth

People assigned female at birth are more likely to get breast cancer than people assigned male at birth. 

As you get older, your risk goes up, too. This is because the cells in your body become less healthy over time. It’s harder for your body to fix them. That's why regular check-ups and screenings are important as you age. 

Your personal and family history

Your risk may be higher if you had breast cancer before.

It’s higher if people related to you by blood (such as your mother, sister, or daughter) have had breast cancer. It’s also higher if they’ve had another type of cancer, such as ovarian cancer. 

Certain genetic mutations you were born with also raise your risk. This includes the BRCA1, BRCA2, and PALB2 genes. It's important to know your family history of breast cancer. 

Your general health and health history

You can lower your breast cancer risk by living a healthy lifestyle. This includes eating a balanced diet and exercising regularly. You should also avoid or limit tobacco (smoking, vaping, and chewing tobacco) and alcohol. 

Your health history also can affect your risk. For example, radiation treatments to your chest or other breast conditions can raise your risk. 

Who is at high risk for breast cancer?

You’re at high risk if you were assigned female at birth (your gender now does not matter) and had:

  • A history of breast cancer in your family (blood relatives). This is different for everyone. Your healthcare provider will assess your risk.
  • Radiation to your chest before age 32.
  • A change (mutation or variant) in your BRCA or other genes.

You’re at high risk if you were assigned male at birth (your gender now does not matter) and had:

  • Radiation to your chest.
  • A disease linked to high levels of estrogen, such as cirrhosis (liver disease) or Klinefelter syndrome (a genetic disorder).
  • A history of breast cancer in your family. This is different for everyone. Your healthcare provider will assess your risk.
  • Changes in genes, such as BRCA1 or BRCA2.
  • Gender affirming therapy with feminizing hormones. More research is needed to understand how hormone therapy affects your risk for cancer. 
The MSK Difference

Our RISE Program is for people at high risk for breast cancer. We'll make a plan to watch you for early signs of breast cancer. You’ll get regular breast exams and imaging tests. This helps us find changes in your breasts early, often before you have symptoms. 

Can I lower my risk for breast cancer?

There are some steps you can take to lower your risk for breast cancer. There also are some risk factors that you cannot control. Research shows that some healthy habits can lower your risk. 

Lower your risk by taking care of your health in these ways:
  • Eat plenty of fruits and vegetables. Read our tips.
  • Limit the amount of sugar and fat you eat and drink.
  • Do not smoke or use tobacco products. Need help quitting?
  • Limit the amount of alcohol you drink.
  • Stay active and exercise regularly. Things to know.
  • Protect yourself from the sun and do not use tanning beds.
  • Get regular check-ups with your healthcare provider. 
MSK Recommends

Exercise can make your immune system stronger and keep your body at a healthy weight. This can help prevent cancer. Exercising 30 minutes a day, 5 days a week can lower your risk for breast cancer. 

Screening for breast cancer

What is breast cancer screening?

Breast cancer screening means getting regular tests to find breast cancer, even before you have any signs or symptoms. 

During a screening test you will have a mammogram, which takes images of your breasts. Sometimes to get a closer look at an area, you may need to have an ultrasound or MRI.

Your healthcare provider can do a clinical breast exam to feel for anything abnormal (not normal). Regular screenings help find cancer early, when it's easier to treat.

Medical oncologist Diana E. Lake, an expert in breast cancer, talks with a patient

Medical oncologist Diana E. Lake is an expert in breast cancer screening, diagnosis, and treatment.

What are the screening tests for breast cancer?

There are several types of screening tests and exams that look for breast cancer, including mammograms and breast MRIs. Here are the types of breast cancer screening tests and exams: 

Clinical breast exam

A clinical breast exam is when a healthcare provider checks your breasts for lumps or other changes. 

You will lie down for this exam. Your healthcare provider will use their hands to feel different parts of your breasts and underarms. They will look for any lumps or thickening that may need testing. 

It's a simple and quick exam that helps catch breast cancer early. Regular clinical breast exams are important for your overall breast health.

You may have also heard about breast self-exams and breast self-awareness. This can help you notice changes in your breasts. You should talk to your healthcare provider about any changes you notice. 

Mammogram

Mammography uses low-dose X-rays to take pictures of a breast to check for signs of breast cancer.  

MSK’s mammograms use tomosynthesis (toh-moh-SIN-thuh-sis), also called 3D mammography. It helps us see breast tissue and tumors more clearly. It’s helpful for people who have dense breasts. The pictures it takes are so detailed that most people will not need to come back for more images.

MSK also offers contrast-enhanced mammogram, or CEM. It uses contrast to show the blood flow in your breast. Tumors often have more blood flow than normal tissue. They show clearly on the images. 

Breast MRI

A breast MRI uses radio waves, a powerful magnet, and a computer to take detailed pictures of breast tissue. You lie face down on a special table, and your breasts fit into an opening in the table. The table then slides into an MRI machine to take the images.

This test helps doctors see more details than a regular mammogram. A breast MRI is helpful if you have dense breasts or a higher risk of breast cancer. 

Breast ultrasound

A breast ultrasound uses high-frequency sound waves to make pictures of the inside of your breasts. We use ultrasound to see both structure and movement.

For example, we can use it to check blood flow or see if a mass is solid or filled with liquid. Your care team can see what's inside a lump so they can suggest the right treatment for you.

During an ultrasound, the technician places a handheld probe close to the breast. The probe gives off sound waves that bounce off breast tissue and make echo patterns. These patterns are shown as images, called sonograms, on the ultrasound machine’s screen. 

When should you be screened for breast cancer?

Knowing your risk for getting breast cancer will help you choose when screening is right for you. Ask your healthcare provider about your risk of getting breast cancer in your life. This is called your lifetime risk. 

Your lifetime risk tells us if you have an average, intermediate (medium), or high risk for breast cancer. 

MSK has different guidelines for each level of risk. There are different types of screening, and screening schedules. 

Most breast cancers occur in people who were assigned female at birth. However, people of all genders can get breast cancer. For example, if you are a transgender man or a nonbinary person, you can still be at risk. This is true even if you had top surgery. People assigned male at birth also can get breast cancer

Average risk for breast cancer

You’re at average risk if you were assigned female at birth (your gender now does not matter) and you do not have:

  • A hereditary syndrome, such as a mutation (change or variant) in your BRCA or other genes. You may have a hereditary syndrome if your blood relatives had breast, ovarian, or other types of cancers.
  • A history of:
    • Invasive breast cancer or ductal carcinoma in situ (DCIS).
    • Atypical hyperplasia or lobular carcinoma in situ (LCIS). This is a type of breast disease that is not cancer.
    • Dense breasts. A mammogram will show if you have dense breasts.
    • Breast cancer in your family (blood relatives). This is different for everyone. Your risk will be assessed by your healthcare provider.
    • Radiation therapy to your chest when you were young. 
Intermediate risk for breast cancer

You’re at intermediate risk if you were assigned female at birth (your gender now does not matter) and you have or had:

  • A history of breast cancer and are over the age of 50.
  • A few relatives with breast cancer, but without abnormal genes.
  • Dense breasts. A mammogram will show if you have dense breasts.
  • A history of atypical hyperplasia (ADH) and lobular neoplasia. This includes lobular carcinoma in situ (LCIS) or atypical lobular hyperplasia (ALH).
High risk for breast cancer if you were assigned female at birth

You’re at high risk if you were assigned female at birth (your gender now does not matter) and have or had:

  • A history of breast cancer in your family (blood relatives). This is different for everyone. Your risk will be assessed by your healthcare provider.
  • Radiation to your chest before age 32.
  • A mutation (change or variant) in your BRCA or other genes.
  • Dense breasts. A mammogram will show if you have dense breasts.
  • A relative who carried a mutation but you have not had a genetic test.
High risk for breast cancer if you were assigned male at birth

You’re at high risk if you were assigned male at birth (your gender now does not matter) and have or had:

  • Radiation to your chest.
  • A disease linked to high levels of estrogen, such as cirrhosis (liver disease) or Klinefelter syndrome (a genetic disorder).
  • A history of breast cancer in your family (blood relatives). This is different for everyone. Your risk will be assessed by your healthcare provider.
  • Changes (mutations or variants) in genes, such as BRCA1 or BRCA2.
  • Gender affirming therapy with feminizing hormones. More research is needed to understand how hormone therapy affects your risk for cancer. You may be at high risk if you also:
    • Have been taking feminizing hormones for many years.
    • Have 1 or more relatives who had breast cancer.
MSK’s screening guidelines for breast cancer

Our screening guidelines may not be the same as those of other groups of experts. At MSK, we use an approach that saves the most lives. The type of screening you have and your screening schedule are based on your personal risk for breast cancer.

Signs and symptoms

What are the signs and symptoms of breast cancer?

Lumps, swelling, and redness are often the first symptoms of breast cancer. Everyone may not have the same symptoms. 

The most common signs and symptoms of breast cancer are:

  • A lump or thickness in or near the breast or under your arm.
  • Your breast has swelling (gets bigger) or shrinking (gets smaller), especially on 1 side.
  • Changes in your breast skin, such as redness, flaking, or thickening (skin gets hard).
  • Nipple discharge (fluid coming from your nipple) that is not breast milk.
  • A nipple that becomes sunken (dips inward), red, thick, or scaly.

Watch for these signs. Talk with your healthcare provider about them. We may be able to find breast cancer early. 

MSK Recommends

Talk with your healthcare provider right away if you notice any signs or symptoms. Look for lumps, swelling, redness, nipple discharge, or changes in your breast size or shape.

Breast cancer programs

MSK RISE: High Risk Breast Cancer Screening Program

MSK RISE is a breast cancer screening program. It’s for people considered at a high risk for getting breast cancer. We create a monitoring plan just for you, so we can watch for any early signs of breast cancer.

Learn more

Young Women with Breast Cancer

The Young Women with Breast Cancer program offers clinical care, support, education, and research. The program is for people with early on-set breast cancer and those aged 45 and younger.

Learn more

Rare Breast Cancer Program

Some types of breast cancer can be so rare that very few doctors have experience in diagnosing and treating them. MSK’s Rare Breast Cancer Program has that experience. Every year, we evaluate and treat about 200 people with rare breast cancer in early or advanced stages.

Learn more

Hereditary Breast Cancer Program

MSK understands the cancer care needs of people who have hereditary (genetic) breast cancer. Our experts choose treatments based on types of breast cancer caused by genetic mutations. The Hereditary Breast Cancer Program is for people with breast cancer linked to an inherited gene mutation.

Learn more

Healthy Living for People with Breast Cancer

Our experts in the MSK Healthy Living program will create a personal lifestyle plan for you. The program is for people who had surgery to treat breast cancer. We offer personal, one-on-one support. Based on many years of research, we connect you to MSK resources that support your health.

Learn more

Breast Cancer in Adults Over 65

MSK understands the needs of older people who have breast cancer. We offer cancer care and support when you learn you have breast cancer after the age of 65.

Learn more

Lobular Breast Cancer Program

Lobular breast cancer can be harder to diagnose and treat than other types of breast cancer. Our experts in the Lobular Breast Cancer Program provide an accurate diagnosis. We’ll create a complete, personal treatment plan. We’ll talk with you about whether joining a research study, also known as a clinical trial, is right for you. You may be able to have treatments not available at most other hospitals. 

Learn more

Innovations at MSK

Our experts always are discovering new information about breast cancer. We’re learning ways to diagnose the exact type and stage of breast cancer. We’re finding out how to find it early when it’s easier to treat. Explore breast cancer news from MSK. 

Dr. Shanu Modi
Podcast
A Game-Changing Cancer Drug Gives Stage 4 Breast Cancer Patients New Hope

For nearly half of all breast cancer patients – those with low levels of the HER2 protein – targeted treatment options have always been limited. Palliative chemo has been the standard of care in stage 4 metastatic patients – until now.