Breast cancer, which is the most common type of cancer in women in the United States, isn’t a single disease. There are, in fact, several different types of breast cancer. One of these is invasive breast cancer, in which cancer cells spread into surrounding breast tissues.

This article will go into detail about what invasive breast cancer is, how it’s diagnosed, and the potential treatment options.

Breast cancer most often begins in the milk producing glands (lobules, which are small sacs found inside the lobes) or the milk ducts. When cancer cells spread outside of these areas and into healthy breast tissue, it’s called invasive breast cancer.

Most breast cancers are invasive. In fact, according to the American Cancer Society, 81 percent of breast cancers are an invasive type.

Invasive breast cancer and staging

Whether or not invasive cancer cells are present can influence how breast cancer is staged after a diagnosis.

Breast cancer that remains isolated to the area in which it started and has not spread into healthy breast tissue is called cancer in situ. You may also see this referred to as non-invasive breast cancer or Stage 0 breast cancer.

When invasive cancer is detected, it can be staged as stage 1 through 4. Many of these stages also have subcategories.

Several factors are taken into consideration with the TNM staging system that’s used for invasive breast cancer. This includes:

  • Tumor (T): Tumor size and the extent to which it has spread
  • Lymph nodes (N): Whether or not the cancer has spread to the lymph nodes and if so, how many
  • Metastasis (M): If the cancer has spread (metastasized) to more distant organs and tissues

Other factors that can impact staging are:

  • Tumor grade. Tumor grading gives an indication of how quickly the cancer cells are likely to grow and spread. The higher the grade, the more aggressive the cancer likely is.
  • HER2 status. Human epidermal growth factor receptor 2 (HER2) proteins help control the growth and repair of breast cells. But too many HER2 proteins can cause breast cells to grow much faster than they should.
  • Estrogen receptor (ER) status. The most common type of breast cancer, ER-positive means that there are receptors on the surface of the breast cancer cells that bind to estrogen.
  • Progesterone receptor (PR) status. This means that the receptors on the surface of the cancer cells bind to the hormone progesterone.

There are different types of invasive breast cancer. Let’s examine some of the most common ones in more detail.

Invasive ductal carcinoma

Invasive ductal carcinoma (IDC) is the most common type of breast cancer overall. It also makes up about 80 percent of all invasive breast cancer diagnoses.

IDC begins in the cells lining the milk ducts. The milk ducts are the tubes in the breast that carry milk from the lobules to the nipple.

In IDC, cancerous cells break through the walls of the milk duct and begin to grow into the surrounding breast tissue. As time passes, IDC can spread to lymph nodes and other areas of the body.

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Invasive lobular carcinoma

Invasive lobular carcinoma (ILC) is the second most common type of invasive breast cancer. About 10 percent of invasive breast cancers are ILC.

Invasive lobular carcinoma begins in the lobules, which are the glands in the breast that make milk. In ILC, cancer cells have broken through the wall of the lobule and into neighboring breast tissue. Like invasive ductal carcinoma, ILC can also spread to other areas of the body.

Due to the way that it grows, ILC can sometimes be harder to detect through screening methods like a breast exam or mammogram. It’s also possible that about 1 in 5 women with ILC can have cancer that affects both breasts.

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Less common types

There are other types of invasive breast cancer that are less common. These can include inflammatory breast cancer and triple negative breast cancer.

Additionally, invasive ductal carcinoma has several subtypes that, together, make up fewer than 5 percent of all breast cancers. These are described based on how they look under a microscope and include:

It’s possible that invasive breast cancer may not have any noticeable symptoms. In these cases, it may be initially detected through routine screening techniques like a mammogram.

When symptoms are present, they can include:

There are a variety of tests to diagnose invasive breast cancer. These include:

  • Breast exam: During a breast exam, a healthcare professional will carefully feel your breasts for signs of lumps or other changes.
  • Mammogram: During a mammogram, a device presses your breasts between two plates. X-ray images of the breast tissue are then taken and evaluated for signs of cancer.
  • Imaging tests: A healthcare professional may order additional imaging tests to help them better visualize breast tissue. Some examples include ultrasound or magnetic resonance imaging (MRI).
  • Biopsy: During a biopsy, a sample of breast tissue is carefully removed and checked under a microscope for signs of cancer.
  • Blood tests: Blood tests use a sample your blood to check for various markers of disease or illness.

If cancer is detected, additional tests can be used to help characterize the cancer and determine its stage. These tests can include things like:

Treatment for invasive breast cancer depends on the stage of the cancer as well as other factors. Let’s examine the most common treatment options.

Surgery

Many women have surgery to remove the cancer cells and the lymph nodes that the cancer has spread to. The type of surgery recommended depends on the cancer stage, as well as the location of the tumor.

Types of surgery

  • Breast-conserving surgery: Breast-conserving surgery removes the tumor and some of the surrounding tissue, but it doesn’t involve removal of the breast. It’s also called a partial mastectomy or a lumpectomy.
  • Total mastectomy: A total mastectomy removes the entire breast. It may also remove some of the lymph nodes that are located close to the armpit.
  • Modified radical mastectomy: A modified radical mastectomy removes the entire breast, many of the surrounding lymph nodes, and some of the chest lining. Sometimes part of the chest muscle is removed as well.

Radiation therapy

Radiation therapy uses high-energy radiation to stop cancer cells from growing. It can either be given externally or internally (brachytherapy).

Radiation therapy is often recommended after surgery. That’s because it can help get rid of any cancer cells that may have remained behind at the surgical site.

Systemic therapies

Systemic therapies are treatments that can travel through your bloodstream, impacting different parts of your body. Systemic therapies can be given as a pill or infusion.

Examples of systemic therapies include:

  • Chemotherapy: Chemotherapy consists of strong drugs that can prevent cancer cells from growing.
  • Targeted therapy: Targeted therapy uses drugs that specifically target cancer cells. Because of this, they cause less harm to healthy cells in the body compared to chemotherapy and radiation therapy.
  • Hormone therapy: Hormone therapy blocks the actions of hormones that can cause breast cancer cells to grow. It can be used if breast cancer is positive for certain types of hormone receptors, such as estrogen or progesterone.
  • Immunotherapy: Immunotherapy works by stimulating immune cells to respond to cancer cells. It can be used to treat some types of invasive breast cancer, such as triple negative breast cancer.

Systemic therapies may be recommended before surgery to help shrink a tumor, particularly if the tumor is large. This is called neoadjuvant therapy.

Like radiation therapy, these treatments can also be used after surgery, to help remove any remaining cancer cells that may still be present at the surgical site. This is called adjuvant therapy.

Because systemic therapies can travel throughout the body, they’re also the main treatment option for people who have metastatic breast cancer.

Invasive breast cancer simply refers to breast cancer that has spread away from the tissue in which it originated and into healthy breast tissue. It can be either localized or metastatic.

For example, if a cancer that began in the milk ducts breaks through the lining of the milk ducts and spreads into healthy breast tissue, that cancer is considered to be invasive. However, it’s not metastatic because it’s still localized to the breast.

If cancer cells break away from that tumor and spread to other areas of the body, such as the liver or lungs, the cancer is now metastatic. In this case, the breast cancer is both invasive and metastatic.

Survival rates for breast cancer indicate the percentage of people, on average, that are still alive 5 years after their diagnosis.

According to the American Cancer Society, the 5-year survival rates for breast cancer are determined based on how far the cancer has spread at the time of diagnosis. For instance:

5-year survival rates for breast cancer

  • Localized: When breast cancer remains localized to the breast, the 5-year survival is 99 percent.
  • Regional: If breast cancer has spread to lymph nodes or to neighboring tissues, the 5-year survival rate is 86 percent.
  • Distant: If breast cancer has spread to more distant tissues of the body (metastasized), the 5-year survival rate is 28 percent.
  • Overall: The overall 5-year survival rate for breast cancer is 90 percent.

It’s important to remember that these numbers are derived from a great number of people diagnosed with breast cancer. While these numbers can be informative, they cannot predict what will happen to you.

Every person is different. While factors like stage and characteristics of the cancer certainly impact outlook, individual factors like age and overall health are also important. Additionally, newer, more effective treatments continue to be developed, which helps improve the prognosis for breast cancer.

The physical, mental, and emotional toll of breast cancer can sometimes feel overwhelming. While this is completely normal, there are many resources available to help, including the following:

  • The Breast Cancer Healthline app places a community of support right at your fingertips. Using the Healthline app, you can connect with other members who have similar interests, treatment plans, and questions to your own. Download it here.
  • The American Cancer Society provides a variety of services, including a 24/7 helpline (800-227-2345), connections with breast cancer survivors, and transportation to treatment centers.
  • Breastcancer.org provides information about breast cancer, treatment options, and daily topics like nutrition and exercise. Its discussion boards and podcast can help you connect with others who’ve been diagnosed with breast cancer.
  • Living Beyond Breast Cancer (LBBC) is dedicated to providing support services to people living with breast cancer, breast cancer survivors, and loved ones. You can connect with others in person, online, or by phone.
  • The Centers for Disease Control and Prevention (CDC) can help you find low-cost screenings. Additionally, it also offers podcasts and videos on a variety of breast cancer topics.

Invasive breast cancer is when cancer spreads from the area in which it began and into healthy breast tissue. This type of cancer can either be localized to the breast or it can spread to other areas of the body, both nearby and distant.

Most breast cancers are invasive. The two most common are invasive ductal carcinoma and invasive lobular carcinoma. There are also other, less common types of invasive breast cancer.

Make an appointment with a healthcare professional if you notice any possible signs of breast cancer. Generally, the outlook is better when invasive breast cancer remains localized to the breast or surrounding tissues.