What's the Difference Between Invasive and Non-invasive Breast Cancers?

7 min read

What's the Difference Between Invasive and Non-invasive Breast Cancers?

If you’ve received a diagnosis of breast cancer, you’re probably in the process of learning all you can about it. It will help with understanding the treatment plan that’s suggested for you and why it might be different from a relative or friend who was also diagnosed with breast cancer. 

One term that’s used when the biopsy report comes back is related to being “invasive” or “non-invasive” breast cancer. It’s important to understand the difference between these because it will play a role in what’s recommended for you along with other aspects of the cancer, including hormone receptors, HER2, ductal vs lobular, and lymph node status. 

Learn more in our blog: Understanding Your Breast Cancer Pathology Report

In short, breast cancer is considered non-invasive if it starts in a duct or lobe of the breast and the cancer cells remain only in that specific area when it’s diagnosed. Invasive breast cancer means the cancer cells have grown outside of the area where it started into other areas of the breast or beyond. Most breast cancers are invasive at the time they’re diagnosed. 

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Types of Invasive Breast Cancer

There are several types of invasive breast cancer, but the majority are either invasive ductal carcinoma or invasive lobular carcinoma. Inflammatory breast cancer is another form of invasive breast cancer. 

  • Invasive ductal carcinoma starts in the cells lining the breast’s milk ducts, which move breast milk into the nipples. Invasive ductal carcinoma has broken through the duct wall and invaded the surrounding breast tissue. It can spread (metastasize) beyond the breast via blood and the lymph system. At least 80% of invasive breast cancers are invasive ductal carcinomas.
  • Invasive lobular carcinoma about 10% of all invasive breast cancers. It starts in the milk glands (or lobules, where breast milk is produced) and can metastasize like IDC. It’s more likely to occur in both breasts, which happens in about 20% of IDC patients. Invasive lobular carcinoma is harder to detect than invasive ductal carcinoma.
  • Inflammatory breast cancer accounts for only about 5% of all breast cancers. It’s a less common type of invasive ductal carcinoma. It’s given this name because of the symptoms. Rather than a hard lump, this type of breast cancer makes the breast look inflamed, causing redness, puckering, and an unusual texture on the skin. It tends to be aggressive and will need treatment right away.

What is Non-invasive Breast Cancer?

Non-invasive breast cancer, also called in situ breast cancer, is referred to as Stage 0 breast cancer. Non-invasive breast cancer includes ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS). 

  • DCIS accounts for almost 20% of all new breast cancers diagnosed. It’s most often found during a screening mammogram and has an excellent chance of a cure. However, having DCIS increases your risk of breast cancer returning. Radiation therapy after surgery lowers this risk.
  • LCIS is considered by oncologists to be a precancerous condition rather than a true cancer. However, having LCIS increases your risk of developing invasive breast cancer in the future. Because LCIS has no symptoms, it’s usually discovered after a breast biopsy for another reason. 

The primary way the doctor knows what type of cancer is present is through the biopsy report and images such as mammograms, a breast MRI, or an ultrasound.

Visit the breast cancer education center for blogs, patient experiences and videos.

Other Traits of Breast Cancer That Must Be Considered When Creating a Treatment Plan

There is a lot that goes into deciding which treatments are going to work best for a specific patient with breast cancer. In addition to whether the cancer is invasive or non-invasive, the breast cancer doctor will also review information to determine:

  • The grade (aggressiveness) of the breast cancer. This is established by the pathologist when they look at the cancer cells under a microscope. Breast cancer grades range from 1 to 3, with 3 being the most aggressive grade and most likely to metastasize. This means the cells looked far from normal when viewed up close. The more aggressive the cancer, the sooner treatment needs to begin.
  • Hormone-receptor status of breast cancer is determined during a biopsy as well. The cells are tested to determine if there are extra estrogen or progesterone receptors on the breast cancer cells. Breast cancer can be estrogen-positive or negative and it can be progesterone positive or negative. Some women are positive for both and some are negative for both. If hormones are fueling the cancer cells, the oncologist will use specific drugs in the treatment process to counter this. Learn more.
  • HER2 status identifies whether there are extra receptors on the breast cancer cells for the HER2 protein to help the cancer grow. You can be positive, negative, or even considered HER2-low. Read more about what it means to be HER2-low.
  • Triple-negative status is what oncologists call this aggressive type of breast cancer when there are no estrogen receptors, progesterone receptors, and no extra HER2 receptors causing the cancer to grow. Read more about triple-negative breast cancer. 
  • Molecular subtype status identifies the genetic composition of your breast cancer that will be important when considering the right treatment options. 

With all of this information in hand, along with the status of whether the breast cancer is growing outside of where it started, a full treatment plan is created. 

How do Invasive and Non-invasive Breast Cancers Compare?

  • Most breast cancers are invasive; non-invasive is less common.
  • Location – invasive breast cancer spreads beyond the area where it began; non-invasive has not spread.
  • Symptoms – invasive cancer will sometimes develop symptoms such as a lump; non-invasive rarely has symptoms. However, in both cases they can be present without any symptoms

Treatment Options Based on the Type of Breast Cancer

Invasive breast cancer typically requires more treatment than non-invasive breast cancer because it’s more developed and usually growing faster than non-invasive. In fact some non-invasive breast cancer doesn’t need to be treated right away.

Invasive Breast Cancer Treatments

Surgery is usually required. This can be a lumpectomy or a mastectomy depending on how large the tumor is, if it’s in more than one location inside the breast, and the likelihood of the cancer coming back. Some, such as triple-negative breast cancer, are more likely to recur. Those patients may opt for a mastectomy even if the cancer is at an early stage.

Radiation therapy can be used to shrink a tumor before surgery and/or to be sure all the cancer cells in the breast have been destroyed after a lumpectomy. Mastectomies don’t usually require radiation afterwards.

Additional treatments are based on the other characteristics of the cancer that were identified:

  • Hormone positive breast cancer will include a recommendation for hormone therapy to block the receptors for allowing the cancer to grow.
  • HER2 positive breast cancer will include a targeted therapy that blocks the HER2 receptors on the breast cancer cells and slows the growth of the cancer.
  • Immunotherapy is now available for breast cancer patients, typically for more advanced stages.
  • Chemotherapy is used to kill cancer cells whether in the breast, lymph nodes, or distant areas of the body. Several types are available. The oncologist will determine which is most likely to work for the specific subtype of invasive breast cancer.

Some patients receive several of these therapies. Some are given before surgery and some are given after. The right timing of each is coordinated by the breast cancer oncologist. 

Non-invasive Breast Cancer Treatments

Lobular carcinoma in situ doesn’t usually require treatment because it’s a precancerous condition. Because LCIS can increase your risk for future breast cancer, you may have additional screenings and take estrogen-blocking medications to lower the likelihood of invasive cancer developing later.

The treatment objective with ductal carcinoma in situ is to remove the cancer before it can grow beyond the milk ducts. DCIS treatment has a very high degree of success. 

Surgery is the standard treatment for DCIS. Surgery may be a lumpectomy, which preserves the breast, plus radiation therapy to help prevent a recurrence. If the cancer tests as hormone receptor-positive, you may have a lumpectomy plus hormone therapy.

Because surgery is usually followed with radiation to kill any cancer cells that weren’t removed with surgery, patients who cannot have radiation may opt for a mastectomy, which doesn’t require radiation.

You may also want to read: Can Tamoxifen be Used to Reduce the Risk of Invasive Breast Cancer? 

The Importance of Breast Cancer Screening and Early Detection

Regular screening for breast cancer is the key to finding breast cancer when it’s early. If you’re not familiar with the recommendations for your age take our short quiz.

Physical exams of the breasts – self-exam and by your doctor – along with mammograms detect most breast cancers. Early detection provides the best prognosis as well as more treatment options. Early treatment is less invasive, causes less discomfort, and is less expensive.

Learn more in our breast cancer screening section

What to Do If Your Mammogram Shows Breast Cancer?

The breast cancer experts at Rocky Mountain Cancer Centers will be with you every step of your cancer-fighting journey. Request an appointment today at any of our convenient breast cancer centers in the greater Denver area, Colorado Springs, Boulder, and throughout the Front Range.

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