Invasive Ductal Carcinoma

Invasive ductal carcinoma (IDC) — also called infiltrating ductal carcinoma — is the most common type of breast cancer. It accounts for more than 8 in 10 breast cancers in women. It happens when cancer cells in the milk ducts in your breast start to grow outside of the ducts.

Without treatment, the cancer cells can spread to nearby breast tissue. They can get into your bloodstream or lymph fluid and spread to other parts of your body. At this point, doctors consider IDC metastatic, or stage 4 breast cancer. This advanced form of the disease is hard to treat.

The good news is that healthcare providers diagnose most people with IDC before it spreads. Regular mammograms often detect invasive ductal carcinoma in the early stages, when it’s curable.

Types

There are different types of IDC. Healthcare providers classify them based on the features (biomarkers) of the cancer cells. Biomarkers provide clues about how the cancer will grow. For example, some cancer cells have receptors that attach to hormones, which fuel growth. Others have higher than normal levels of proteins that cause the cancer to grow.

Common types are:

• ER-positive (ER+) breast cancer (most common): Grows in response to the hormone estrogen
• HER2-positive (HER2+) breast cancer: Grows in response to high levels of HER2 protein
• Triple-negative breast cancer: Does not grow in response to estrogen, progesterone or HER2

Knowing this information helps providers choose the best treatments. Some therapies work by blocking the hormones and proteins.

Symptoms of invasive ductal carcinoma

Routine mammograms often detect invasive ductal carcinoma before symptoms start. But if you do notice changes, they may include:

• A painless lump in your breast
• A change in the size or shape of your breast
• A lump or thickening in or near your breast or armpit that lasts through your menstrual cycle
• Skin changes in your breast or nipple, including reddened, scaled or dimpled skin
• A nipple that pulls inward or to the side
• Bloody or clear fluid (discharge) from your nipple

Many of these symptoms, like breast lumps, are also common in noncancerous conditions. So it’s important not to assume you have cancer if you find a change. But you should make sure to see a healthcare provider to get checked. Early breast cancer diagnosis saves lives.

Invasive ductal carcinoma causes

In IDC, you develop gene changes (mutations) in the cells lining your milk ducts. The cells are called epithelial cells. The mutations turn the healthy epithelial cells into a cancer called carcinoma. Left untreated, carcinomas can invade healthy tissue.

Experts don’t know what triggers the mutations in the first place.

Risk factors

Researchers have found several factors that may increase the risk, including:

• Sex: Most diagnoses are in females. Still, more than 9 in 10 male breast cancers are IDC.
• Age: The risk increases as you get older. Most diagnoses happen in females over 55.
• Genetics: About 1 in 20 invasive breast cancers are linked to genes you inherit from your biological parents. For example, mutations in the BRCA genes greatly increase your risk.
• Hormone exposure: Getting your period early or starting menopause late in life increases your exposure to estrogen and progesterone. This may increase your breast cancer risk. Some forms of hormone replacement therapy may also increase your chances.
• Past treatments: This includes radiation therapy to your chest area.
• Obesity: Having a body mass index above 30, especially after menopause, is a risk factor.
• Tobacco and alcohol: Cancer risk is tied to smoking and drinking alcoholic beverages.

If you think your risk may be high, talk to your healthcare provider about doing a breast cancer risk assessment to learn more.

How doctors diagnose this condition

Your healthcare provider will review your medical history and ask about your family’s history of cancer. They’ll feel for breast lumps and swollen lymph nodes in your armpit. You’ll need one or more of the following imaging tests to look for a mass or suspicious tissue:

• Mammogram
• Breast ultrasound
• Breast MRI

To find out if a breast tumor is IDC, your provider will remove a tissue sample and test it for cancer cells. This happens during a breast biopsy. If they find cancer, they’ll check the cells for hormone receptors and high levels of HER2 protein. This helps them know the type of IDC.

Stages of IDC

Your cancer care team will use your test results to plan your treatment. They do that by identifying the cancer stage. They’ll assign a number from 0 to 4, where higher numbers mean more advanced disease:

• Stage 0: This stage is not IDC because it’s not invasive. But it’s important to know about because it’s a pre-cancer stage called ductal carcinoma in situ (DCIS). With stage 0, there are cancer cells that stay within the milk ducts and haven’t spread beyond. It’s almost always curable.
• Stages 1, 2 and 3: Invasive ductal carcinoma begins at stage 1. The cells have spread beyond your milk ducts and, in some cases, to the lymph nodes in your armpits.
• Stage 4: Cancer has spread to distant organs. Your healthcare provider may refer to it as metastatic.

Providers consider lots of factors to determine the stage. They consider the tumor’s size and location to see how advanced it is. They check to see whether the cancer has spread to lymph nodes or distant organs.

Biomarkers, like hormone receptor status and HER2 levels, provide clues about how aggressive IDC is. The grade — how much cancer cells resemble normal cells — matters, too. The scale ranges from 1 to 3. Grade 1 cells look close to normal and grow slowly. Grade 3 cells look abnormal and typically spread fast. Grade 2 is somewhere in between.

How is invasive ductal carcinoma treated?

Treatment options vary depending on factors like the cancer stage and your preferences. Treatments include:

• Breast cancer surgery: Surgery is often the main treatment. Options include removing the tumor (lumpectomy) or removing the affected breast (mastectomy). Surgery may involve breast reconstruction.
• Chemotherapy: You may need chemotherapy before surgery to shrink the tumor or afterward to kill any remaining cancer cells. It may be the main treatment if you have stage 4 disease.
• Radiation therapy: You may need this treatment after a lumpectomy to kill any remaining cancer cells. Radiotherapy may be the main treatment if surgery isn’t an option.
• Targeted therapy: This cancer treatment targets the gene changes that turn healthy cells into cancer. Therapy blocks proteins, like HER2, that cancer cells use to grow.
• Hormone therapy: Hormone therapy cuts off cancer cells’ access to hormones that help them grow. It’s used to treat hormone-receptor positive IDC.
• Immunotherapy: Immunotherapy helps your immune system find and destroy cancer cells.

As part of your breast surgery, your provider may also remove a few of your armpit lymph nodes, so they can test them for cancer. This happens during a sentinel node biopsy. If they find cancer, you may need surgery to remove more lymph nodes that contain cancer cells.

When should I see my healthcare provider?

You’ll see your provider regularly during treatment and after. In the meantime, let them know if you have new symptoms or side effects from treatment. Cancer therapies are excellent at fighting cancer, but they can cause unpleasant side effects. Some happen during treatment. But late effects can show up months or even years after treatment, too.

What is the life expectancy of someone with invasive ductal carcinoma?

In the U.S., researchers at the National Cancer Institute estimate life expectancy by measuring survival rates. They do this by tracking how many people are alive five years after their diagnosis. The five-year mark is important because most cancers that remain gone after five years don’t come back. IDC is often curable with early treatment.

Still, cancers can recur past this milestone. This is why you’ll need regular checkups with your provider to keep a close eye on your health.

The most recent five-year survival rates (from 2013-2019) from the National Cancer Institute are:

• Local (cancer hasn’t spread outside of the breast): 99%
• Regional (cancer has spread to nearby organs or lymph tissue): 86%
• Metastatic (cancer has spread to distant sites, like the liver or lungs): 31%

Remember that these numbers reflect others’ past experiences. They don’t take into account new treatments. And they don’t reflect your unique diagnosis or health status.

If you have questions about your prognosis, talk to your provider. They’re your best resource because they know your situation.

Is there anything I can do to feel better?

Living with invasive ductal carcinoma may not be easy. You may have days when you feel overwhelmed by not knowing what comes next.

Even though you can’t control your diagnosis, you can take charge of your health by taking advantage of every resource. This includes connecting with other people who have IDC. It’s also a good idea to ask your healthcare provider about cancer survivorship programs. These programs can help you manage the challenges that come with living with IDC, no matter where you are on the treatment/recovery timeline.

How serious is invasive ductal carcinoma?

IDC is a serious cancer that can spread and be fatal without treatment. But IDC that’s diagnosed and managed early is often curable. Most people who have been diagnosed with this cancer are living cancer-free thanks to screening mammograms that detected it early.

How fast does invasive ductal cancer spread?

This depends on lots of things, like the cell grade and type of disease. For example, high-grade IDC spreads faster than low-grade IDC. Triple-negative invasive ductal carcinomas spread faster than the other types.

Ask your provider how the type of cancer impacts how aggressive it may be.