Home > Education > Statistics: StageIV vs MBC

sources are listed in brackets]


What is SEER Data?

SEER is part of the National Cancer Institute and stands for Surveillance, Epidemiology and End Results (SEER) Program, a premier source for cancer statistics in the United States.

The SEER program collects information on incidence, prevalence and survival from specific geographic areas representing 28 percent of the US population and compiles reports on all of these plus cancer mortality for the entire country. For more information, click HERE.


If We're NOT counted, do we still 'count'?

As you will learn, however, many statistics for metastatic breast cancer are NOT collected.  This is a major problem for the metastatic breast cancer community because if we are not counted, do we still matter? How can we  expect to have adequate attention and funding directed to the needs of the metastatic patient for support, treatment and research, if we lack fundamental statistics like incidence and prevalence?  We will try to put statistics in perspective for you on the following pages and explain what is known and what is estimated based on individual studies.  Here's another 'curve ball' of which you may not be aware:


Is metastatic breast cancer (mbc) the same as Stage IV cancer

when talking about statistics?

NO! Although Stage IV cancer and mbc are used interchangeably in the media and by the public, surprisingly, they mean very different things in the medical and statistical world.
Here's how American Cancer Society explains it:
A cancer's staging does not change over time: Stage IV and MBC are NOT the same.
An important point some people have trouble understanding is that the stage of a cancer does not change over time, even if the cancer progresses. A cancer that comes back or spreads is still referred to [in medical community] by the stage it was given when it was first found and diagnosed-information about the current extent of the cancer is added to it.
For example, let's say a woman was first diagnosed with stage II breast cancer and the cancer went away with treatment. But then it came back with spread to the bones. The cancer is still called a stage II breast cancer, now with recurrent disease in the bones. If the breast cancer did not respond to treatment and spread to the bones it's called a stage II breast cancer with bone metastasis. In either case, the original stage does not change and it's not called a stage IV breast cancer. A stage IV breast cancer refers to a cancer that has already spread to a distant part of the body when it's first diagnosed. A person keeps the same diagnosis stage, but more information is added to the diagnosis to explain the current state of the disease.
This is important to understand because survival statistics and information on treatment by stage for specific cancer types refer to the stage when the cancer was first diagnosed." [ACS website]

Does that mean I should NOT refer to my recurrent metastatic breast cancer as Stage IV?

NO! Most patients will never hear their metastatic breast cancer with bone mets, for example,  referred to as Stage II with recurrent disease to the bones. It is common to use the terms "metastatic breast cancer" and "Stage IV" breast cancer interchangeably. Even though this is statistically and technically incorrect, Stage IV is used synonymously with mbc in the media and in common usage, but not when we look at SEER data and breast cancer statistics.

WHY does MBCN raise this as an issue?

We at MBCN, like everyone else,  use the terms metastatic breast cancer and Stage IV interchangeably. We only raise it as an issue here because the narrower definition is what is often used when we look at data and breast cancer statistics. Especially if you will be speaking out as an advocate, you should have a basic understanding of breast cancer statistics and definitions.


What is the real number of people

diagnosed each year with metastatic breast cancer and

how many people are living with mbc in the US?

These are good questions, but first let's look at how we should define the entire metastatic breast cancer community.
Cases of metastatic breast cancer consist of two groups:
• those where the initial diagnosis was Stage IV and
• those where there was a metastatic recurrence after an early stage breast cancer

Statistics do not capture those with metastatic recurrence!

o The NCI/SEER (National Cancer Institute/Surveillance Epidemiology and End Results) databases record when a person is diagnosed with breast cancer and when a person dies. It does not record a metastatic recurrence for someone who had early stage breast cancer. Therefore the SEER databases collect only those with an initial Stage IV diagnosis, which represents only a small portion of metastatic breast cancer. Under the current system if everyone was reclassified as stage IV when their cancer metastasized, there would be no meaningful survival statistics because early stage cancers (I-III) would all have 100% survival and stage IV would have 0% survival.)

o If you were first diagnosed with an earlier stage cancer, you are not excluded from breast cancer statistics, but you are not counted as being metastatic





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