Invasive ductal carcinoma (IDC)

Invasive ductal carcinoma, also called infiltrating ductal carcinoma or IDC, is the most common type of breast cancer. It starts in the cells that line the inside of a milk duct. Breast ducts are tubes that connect the milk-producing glands (also called lobules) to the nipple.

“Invasive” means that the cancer has spread beyond the duct into the surrounding breast tissue.

• In some cases, invasive ductal carcinoma may stay confined to the breast.
• In other cases, invasive ductal carcinoma can spread to nearby lymph nodes and possibly travel to other parts of the body through the lymph system or the bloodstream. If this happens, it becomes metastatic invasive ductal carcinoma.

About 80% of invasive breast cancers are classified as invasive ductal carcinoma. Invasive ductal carcinoma is different from ductal carcinoma in situ (DCIS). In DCIS, the cancer cells stay inside the milk duct; they don’t invade nearby breast tissue. DCIS is also called noninvasive breast cancer.

Invasive ductal carcinoma usually affects one breast. It’s rare for it to develop in both breasts at the same time. However, about 10% of people diagnosed with invasive ductal carcinoma will develop it in the opposite breast later on.

Most invasive ductal carcinomas are a single growth in one area of the breast. Still, about 10 to 20% of people can have two or more tumors within the same breast. The cancer may be:

• Multifocal: the tumors are close together, or
• Multicentric: the tumors are in different areas of the breast

Who gets invasive ductal carcinoma?

Women and men can get invasive ductal carcinoma. The biggest risk factors are age and sex at birth: Most cases occur in women age 55 and older.

Other risk factors for invasive ductal carcinoma

Additional factors that increase the risk of invasive ductal carcinoma include:

• Having dense breast tissue (the tissue is more glandular and fibrous than fatty)
• Starting menstrual periods early (before age 12)
• Giving birth to a first child at an older age
• Beginning menopause at an older age
• Previous radiation therapy to the chest
• Lack of exercise
• Drinking alcohol
• Weight gain after menopause
• Being diagnosed with ductal carcinoma in situ (DCIS), a noninvasive cancer that is contained within the breast ducts
• Being diagnosed with lobular carcinoma in situ (LCIS), a non-cancerous change in a breast lobule that can increase risk
• Being diagnosed with atypical ductal hyperplasia (ADH) or atypical lobular hyperplasia (ALH), an overgrowth of abnormal cells in the breast ducts or lobules
• Inherited gene mutations that increase breast cancer risk
• Long-term use of systemic hormone replacement therapy

Inherited gene mutations

Inherited gene mutations — unusual changes in genes passed through families — can also increase a person’s risk of invasive ductal carcinoma. Examples include inherited mutations in genes such as BRCA1, BRCA2, and TP53.

It’s important to know that most cases of invasive ductal carcinoma are not caused by inherited gene mutations.

Learn more about genetic testing for inherited mutations.

Long-term use of systemic hormone replacement therapy

Long-term use of hormone replacement therapy (HRT) after menopause also may increase the risk of invasive ductal carcinoma. HRT usually contains the hormones estrogen and progesterone.

This risk appears to be greatest if the hormone replacement therapy if it is given in a way that causes hormones travel throughout the body (systemic therapy). Examples include pills taken by mouth, patches worn on the skin, sprays, or gels absorbed into the bloodstream at levels that can affect many areas of the body. Long-term use means using it for more than 5 years.

While long-term use of systemic HRT appears to increase risk, vaginal estrogen, applied locally as a cream or tablet, has not been found to increase risk. In March of 2025, the American Journal of Obstetrics and Gynecology published research showing that low-dose vaginal estrogen does not appear to be associated with increased risk of recurrence in people with a history of breast cancer.

Learn more at What causes breast cancer?

Symptoms of invasive ductal carcinoma

Symptoms of invasive ductal carcinoma may include:

• A breast mass or lump that you can feel
• A lump or thickening near the breast or in the underarm area
• A change in breast shape or size
• A change in the breast skin or nipple, such as redness, scaling, or dimpling
• A discharge of clear fluid or blood from the nipple

Learn more about the symptoms of breast cancer.

How invasive ductal carcinoma is diagnosed

Several kinds of tests can help doctors learn more about whether breast cancer may be present:

• A clinical breast exam in your doctor’s office: This manual exam may find a lump or thickening that requires further testing.
• Mammogram: A test that uses low-dose X-rays to create images of the breast
• Breast ultrasound: An imaging test that uses high-frequency sound waves to detect lumps, cysts, and other changes in the breast
• Breast MRI: An imaging test that creates detailed, 3D pictures of breast tissue using a magnetic field and radio waves
• Biopsy: A procedure that removes a sample of the abnormal tissue so it can be looked at more closely

After a biopsy, a doctor trained to diagnose diseases (called a pathologist), examines the tissue under a microscope and tests it for certain proteins.

Subtypes of invasive ductal carcinoma

After biopsy, you and your doctor will receive a pathology report that provides more information about the features of invasive ductal carcinoma. These features include the grade (how different the cancer cells are from normal cells), hormone receptor status, HER2 status, and other characteristics. These are helpful in choosing treatments beyond surgery.

For example:

• The cancer is hormone receptor-positive if tests show that the cancer cells have proteins called hormone receptors. This means that the hormones estrogen and/or progesterone are fueling the cancer’s growth. Hormonal therapy and possibly other treatments, such as targeted therapy, will be part of the treatment plan.
• If the cells have too many copies of the HER2 gene, testing will show that extra HER2 receptors are present. The receptors receive signals that tell the breast cancer to grow and divide out of control. The cancer may be described as HER2-positive, HER2-low, or HER2-ultralow. These labels are based on the levels of HER2 found on cancer cells. Anti-HER2 targeted therapy can be used as part of the treatment plan.
• The cancer is called triple-negative if it does not have hormone receptors or HER2 receptors. Treatment may include targeted therapy and/or immunotherapy, often along with chemotherapy and possibly other treatments.

Your doctor also may describe the cancer as luminal A, luminal B, basal-like, or HER2-enriched. These classifications are based on combining features such as hormone and HER2 receptor status, grade, rate of growth, and other factors. Visit Molecular subtypes of breast cancer to learn more about these classifications.

Staging

While some features of the cancer are listed on the pathology report after your biopsy, the stage is confirmed after:

• Lumpectomy or mastectomy surgery to remove cancer from the breast
• Lymph node surgery to check for cancer in the lymph nodes

Learn more about How breast cancer is staged.

Additional testing after a diagnosis of invasive ductal carcinoma

Other tests are often recommended after invasive ductal carcinoma is diagnosed.

Testing for inherited genetic mutations

Certain genetic mutations — or abnormal changes in genes — increase cancer risk and can be passed through families. The American Society of Clinical Oncology (ASCO) recommends that all newly diagnosed patients under age 65 be tested for mutations in the BRCA1 and BRCA2 genes. It is also recommended for:

• People over 65, based on their personal and family history
• People who may be eligible for targeted therapies called PARP inhibitors
• People who develop a second breast cancer in the same breast or the other breast

Genetic test results can help you and your doctor make treatment decisions, as well as assess your risk of developing breast cancer again in the future. They also can help your family members understand whether they could be at increased risk.

Based on medical and family history, doctors also may recommend testing for mutations in other genes. Your team can help you understand whether the results could be helpful in planning your treatment and guiding family members concerned about risk. Visit Genetic testing for inherited mutations to learn more.

Genomic testing for early-stage breast cancer

Genomic tests look at the activity of certain genes, or groups of genes, to better understand the cancer and how it is likely to respond to treatments.

In early-stage invasive ductal carcinoma, genomic testing can look at specific groups of genes to learn more about the risk of recurrence. The tests also can predict response to treatments such as chemotherapy or hormonal therapy. Examples of these tests include Oncotype DX Recurrence Score and MammaPrint.

Next-generation sequencing tests for metastatic breast cancer

If you have been diagnosed with metastatic invasive ductal carcinoma, your doctor may recommend a next-generation sequencing test. These tests look at a large group of genes at once to see if there are mutations that can be targeted by available treatments. These mutations aren’t inherited; instead, they develop over time.

Rare types of invasive ductal carcinoma

There are some less common types of invasive ductal carcinoma. Your breast cancer pathology report will tell you whether or not you have one of these rare types of invasive ductal carcinoma.

These rare types include:

Medullary ductal carcinoma

• This often feels like a spongy area in the breast, rather than a distinct lump.
• Compared to invasive ductal carcinoma, medullary ductal carcinoma is more likely to be triple-negative (testing negative for hormone receptors and HER2) and diagnosed at a younger age.
• Medullary ductal carcinoma accounts for about 1 to 7% of breast cancers.

Mucinous ductal carcinoma

• The tumor is made up of cancer cells as well as mucous they produce.
• It’s usually hormone receptor-positive and HER2-negative, and diagnosed at a later age (in women, after menopause).
• Mucinous carcinoma makes up about 2% of breast cancers.

Papillary ductal carcinoma

• This type of tumor is made up of enlarged ducts and cysts that contain finger-like structures. In most cases, it grows under the nipple and causes a bloody discharge.
• Most are hormone receptor-positive, HER2-negative, and slow-growing.
• It is very rare, making up only about 0.5% of breast cancers.

Tubular ductal carcinoma

• Tubular carcinomas look like they are made up of hundreds of tiny tubes.
• They’re almost always hormone receptor-positive, HER2-negative, and low grade (slow-growing). Most are diagnosed in post-menopausal women.
• They make up about 1 to 2% of invasive breast cancers.

Learn more about rare types of IDC

You can learn more about how frequently these different types of invasive ductal carcinoma are diagnosed in the table on this page, presented by Komen.org: Prevalence and tumor characteristics of different types of invasive breast cancer.

Metastatic invasive ductal carcinoma

Metastatic invasive ductal carcinoma happens if cancer cells break away from the original tumor and move into other parts of the body, either through the lymph system or bloodstream. It’s also called stage IV breast cancer.

Invasive ductal carcinoma can move into the lungs, bone, liver, and/or brain.

Your doctor can use a combination of approaches to diagnose metastatic breast cancer. These may include:

• Imaging tests, such as x-rays, CT or PET scans, bone scans, and MRI
• Blood tests
• Physical exams
• Surgical biopsies

If you’re diagnosed with metastatic invasive ductal carcinoma, talk with your care team about biomarker testing, including next-generation sequencing tests. These are blood and tissue tests that may help match the cancer to a specific treatment.

Visit Tests for metastatic breast cancer to learn more.

Treatment for invasive ductal carcinoma

Treatment for invasive ductal carcinoma depends on the features of the cancer. Features such as stage and having (or not having) certain biomarkers, including hormone receptors and HER2 receptors, will play a role in your treatment plan.

The treatment plan may include:

• Surgery, including lumpectomy or mastectomy and lymph node removal to check for cancer in the lymph nodes
• Chemotherapy
• Targeted therapy
• Radiation therapy
• Hormonal therapy, if the cancer is hormone receptor-positive
• Immunotherapy

Surgery and radiation therapy are not usually recommended for metastatic breast cancer. They might be used In certain cases, though, if they can help with managing specific symptoms.

Learn more about treatment for metastatic breast cancer.

Protecting fertility

If you’re premenopausal (still having periods) and want to have biological children, it’s important to talk with your doctor about fertility preservation before starting treatment, if possible.

Some breast cancer treatments, such as chemotherapy and hormonal therapy, can interfere with fertility or pregnancy timing. However, there are still options for having a baby. You can ask your doctor to refer you to a fertility specialist who can help you understand those options.

Follow-up care for invasive ductal carcinoma

After treatment for invasive ductal carcinoma, you and your care team will decide on a follow-up plan. The timing and frequency often depend on the type and stage of cancer and whether you’re getting longer-term treatments, such as hormonal therapy.

Follow-up often includes:

• Physical exams two or more times a year
• Breast screenings with mammogram; in some cases, ultrasound and/or MRI may be recommended
• Test to monitor you for treatment side effects, such as impact on heart or bone health
• In cases of metastatic breast cancer, specific imaging, blood, and other tests, recommended as needed

Visit When to have follow-up visits to learn more.