Invasive vs. Metastatic Breast Cancer: What’s the Difference

Understanding the specifics of a breast cancer diagnosis greatly impacts our approach to treatment options, healthcare planning and outlook. It’s easy to feel overwhelmed with unfamiliar medical terms – especially as we navigate the path ahead. Breast cancer that has spread beyond its original location is often referred to as both invasive and metastatic, but what do those terms actually mean? Can our condition fall into one category and not the other? Comprehending the key differences between these subtypes may help us stay better informed as we make choices about our treatment, care and support. 

Demystifying and Simplifying 

To put it simply, metastatic breast cancer is invasive cancer that has spread to another part of the body beyond the breast. This includes stage IV breast cancer. Regardless of where another tumor forms within our bodies, it is still referred to as breast cancer due to its place of origin. Invasive cancer refers to cancer cells that have invaded the surrounding breast tissue (usually beyond our milk ducts or lobules), yet are still contained within the breast tissue or surrounding area.

How Both Cancers Are Formed

As we look a little closer at how invasive and metastatic breast cancers develop and progress, it becomes easier to understand the differences. Our bodies are producing new cells every day. When abnormal, or atypical, cells are produced they may not be cause for alarm – unless they begin to spread. When and if they do they are then considered invasive. If an invasive cancer spreads into another part of the body, infecting other organs and systems, it is considered to be metastatic. In this way, metastatic breast cancer can be considered the most advanced stage of breast cancer.

Treating Metastatic Breast Cancer vs. Invasive Breast Cancer

Since both invasive and metastatic breast cancer cells have moved beyond their original origin, the treatment goals are usually to slow or stop any additional spread of the disease. Every person will have a unique path, but surgery, radiation (used locally) and chemotherapy (used systemically) are often used to shrink or remove tumors and slow additional cancer cell growth. Nearly 30% of women diagnosed with early-stage breast cancer develop metastatic disease. While this is not always the case, abnormal cells and tumors can return in another part of the body months or years after our original diagnosis. (Here’s a list of ways to try and naturally reduce our risk of breast cancer.)

Our Unique Journeys

Being diagnosed with any type of cancer is life-altering. It’s normal to have concerns about the origin, stage and outlook of any illness. While an enormous amount of information and research is being done to understand it, breast cancer is also a very personal and unique experience for each of us. Our own health history and medical circumstances will play a large role in the steps we can take toward treatment. 

“Courage doesn’t always roar. Sometimes courage is the little voice at the end of the day that says I’ll try again tomorrow.” – Mary Anne Radmacher