What Is Breast Cancer?

Breast cancer is a tumor that starts in the breast. It is the most common type of cancer in females, affecting approximately 12% of women over the course of their lifetime. While breast cancer is rare in men, the disease can affect men too. Breast cancer typically does not cause symptoms in the early stages and is often detected with screening mammograms. Treatment is always necessary.

There are a number of subtypes of breast cancer, and some may remain small and grow slowly, while others can enlarge or spread to other regions of the body, causing life-threatening complications. Different subtypes respond to different treatments. Breast cancer subtypes are identified with a microscopic examination of a biopsy sample.

Breast Cancer Symptoms

Most of the time, breast cancer does not cause any signs or symptoms. But in some instances, breast cancer can produce visible or other detectable changes in the breast.

Some of the signs of breast cancer can be the same as for other medical conditions, and it is important to get prompt medical attention if you develop any of these issues.

  • A lump: A breast lump is the most common sign of breast cancer. Doctors often recommend that you check for breast lumps by performing monthly mid-cycle self-checks (about two weeks after your period).
  • Breast pain: Breast cancer is usually painless during its early stages, but growths can stretch the skin and breast tissue, causing discomfort or pain.
  • Change in appearance: A tumor can cause a noticeable change in the size or shape of your breast. This may make your breasts appear different from each other/uneven.
  • Skin changes: Dimpling of skin on part of the breast (like an orange peel) or changes in the color of the breast require medical attention.
  • Itching: Redness or a rash-like appearance of the skin on the breast may resemble mastitis, an infection in the breast.
  • Nipple changes: Inward turning nipple or flaky or crusty looking skin around the nipple can occur with breast cancer.
  • Discharge: Nipple discharge can be milky or yellow, or may include tinges of blood.

Men can have breast lumps too, but because breast cancer is so rare, men are not usually reminded to check for them. If you are a man, you should get a prompt medical evaluation for any lump or change in the appearance of your chest or breast area.

breast cancer diagnosis
 Verywell / Gary Ferster

Are All Breast Lumps Cancer?

No. Not all lumps in the breast are breast cancer, and not all breast cancers present with a lump. However, all lumps or thickening in the breast need medical attention.


Breast cancer occurs when normal cells in the breast undergo major changes in their molecular characteristics, which makes them grow and multiply faster than they should.

There is no single specific cause of breast cancer, but there are risk factors that can make a person more likely to develop the disease.

  • Age: A woman’s chance of getting breast cancer increases with advancing age.
  • Family history: Having a mother, sister, or daughter diagnosed with breast cancer increases the chances of developing the disease. But about 85% of breast cancers occur in women who have no family history of breast cancer.
  • Genetics: Approximately 10% of all breast cancers can be linked with inherited gene mutations. The BRCA 1 and 2 genes are the most common, but there are many other genes that have been associated with breast cancer.
  • Breast density: Women who have dense breast tissue have a higher risk of breast cancer than women of similar age who have little or no dense breast tissue.
  • Race: In the United States, breast cancer is diagnosed more often in white women and least often in Alaska Native women.
  • Weight: Breast cancer is more common in women who are significantly overweight compared to peers who are of a healthy weight.
  • Smoking: There is an increased risk of breast cancer among women who smoke, especially those who started to smoke before having their first child.
  • Alcohol: Alcohol consumption is associated with an increased risk of breast cancer.
  • Inactive lifestyle: Women who are physically inactive throughout life may have an increased risk of breast cancer.


A definitive diagnosis of breast cancer usually involves several steps, including a physical examination, imaging, and a biopsy.

Breast cancer cells may form a solid tumor in the breast. Depending on its location, a breast cancer growth may be detected by a physical examination or by an imaging test, such as a mammogram—an X-ray designed to look at breast tissue. There are other imaging tests used to evaluate breast as well, including breast magnetic resonance imaging (MRI).

The only way to confirm a diagnosis of breast cancer is with a biopsy, which is a sample of tissue. The type of biopsy you may need depends on several factors, including the tumor's size and location.

Types of breast cancer biopsies include:

  • Fine needle aspiration: The procedure is performed by a breast surgeon or radiologist using a thin needle with a hollow center to extract a sample of cells.
  • Core needle biopsy: This type of biopsy uses a large hollow needle to obtain a larger sample from the area identified on an imaging test.
  • Surgical biopsy: To obtain a larger sample, a surgeon uses a scalpel to cut through the skin to remove a sample of the tissue.
  • Lymph node biopsy: Sometimes your doctor may need to take a sample of tissue from the lymph nodes near your breasts to see whether the cancer has spread. Lymph nodes are part of the lymphatic system, and breast cancer can spread to other areas of the body by traveling in the lymph nodes.

The sample needs to be examined under a microscope by a pathologist, a specialized medical doctor who examines tissue and cells.

Breast Cancer Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Woman

Breast Cancer Types and Staging

There are several ways of classifying breast cancer. The main ways of describing and classifying cancer include type/subtype, stage, and grade. The best treatment for an individual's breast cancer is based on these factors.


Breast cancer is described based on the type of breast tissue that the tumor came from. For example, breast cancer often originates in the breast ducts that carry milk to the nipple. These types, called ductal cancers, account for about 80% of all breast cancers. Lobular cancer begins in the glands (lobules) that produce breast milk and accounts for about 8% of all breast cancers.

Rarer forms of breast cancer include:


Breast cancer staging describes how far cancer has spread in the body. When cancer is confined within a breast duct or the cells of the lobules it is called in situ. Cancers that begin to spread into the surrounding breast tissue are described as invasive or infiltrating.

Metastatic breast cancer, which is also known as stage IV breast cancer, is cancer that begins in the breast and spreads to distant organs such as the brain, bones, lungs, and liver. About 6% to 10% of women and men have stage IV or metastatic cancer when first diagnosed.

Ultimately, based on tumor size, lymph node status, and metastasis, breast cancer is staged from 0 (indicating a precancerous condition) to IV (indicating metastasis).


Breast cancer grading is based on how aggressive the cells look under a microscope. The cells from a biopsy can have a well-differentiated appearance, which means that they resemble normal breast tissue (less aggressive, lower grade), or a poorly differentiated appearance, which is not as similar to normal breast tissue (more aggressive, higher grade).

A biopsy may also show characteristics of rapid growth or slow growth, which also affect the grade.


There are several options for the treatment of breast cancer. Your treatment is tailored to your cancer stage, grade, and type. Often, more than one type of treatment is necessary.

  • Surgery: Most women and men who are diagnosed with breast cancer have surgery to remove the growth. Surgery can include breast-conserving surgery, with the removal of the lump and a margin of tissue surrounding the lump, mastectomy (complete removal of the breast or breasts), or breast surgery as well as lymph node removal.
  • Chemotherapy: When cancer cells have traveled beyond the breast, powerful systemic therapy that destroys cancer cells and shrinks the tumor is often needed prior to surgery.
  • Hormonal therapy: Some breast cancer types respond to hormone therapy, which blocks cancer cells from getting the hormones they need to grow.
  • Biological therapy: Specialized anti-cancer treatment may be given to help your immune system fight cancer cells.
  • Radiation therapy: This treatment uses high-energy rays to kill cancer cells.

Women and men with early-stage cancer are often candidates for breast-conserving surgery, such as a lumpectomy, and may not need to have chemotherapy treatments.


Prevention of advanced breast cancer relies on early detection. Finding breast cancer while it is still at an early stage offers the best possible prognosis.

Early detection requires:

  • Knowing what your breasts normally look and feel like, and reporting any changes or symptoms to your physician
  • Seeing your physician annually for a comprehensive breast exam
  • If you are under 40 years of age and have a family history of breast cancer, speaking with your physician as to when you need to begin annual mammograms and discuss the need for genetic counseling
  • If you are over 40 with no family history of breast cancer, getting regular mammograms

A Word From Verywell

There is a strong chance that you may already know someone who has been diagnosed with breast cancer. Know that your breast cancer type may not be the same, and your treatment and prognosis might also be different.

Breast cancer can be treated. In most cases that are detected early, the outcome is good. And having a diagnosis and treatment of breast cancer does not mean that you won't have it again. After your treatment is completed, you need to be sure to maintain your screening schedule.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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