The subtypes of metastatic breast cancer

Breast cancer surgeon, Kristi Funk, MD, explains the subtypes of metastatic breast cancer to give a background for understanding the progress that is happening in MBC research.

Transcript

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Getting an idea for the types of strides we're making requires, I think, a little background on the kinds of subtypes that exist within metastatic breast

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cancers. [MUSIC PLAYING]

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The way we classify these subtypes is by determining two things, their hormone receptor-- or HR status--

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and their HER2 status. A patient's cancer can be positive or negative in either of these categories.

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Think of an estrogen receptor like a little antenna sitting on the outside of a cancerous cell.

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Whenever estrogen hits that receptor, it's going to send a signal to the cell to multiply and divide.

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Aha, so now, if we can block that receptor or knock it off the cell or stop the internal signaling

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connection or get rid of all the estrogen, without its cancer fuel, maybe that cell will peter out and die.

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So cancer cells either do or do not contain these receptors. If you have a receptor, it's called positive.

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If there is not a receptor, it's called negative. For hormone receptor status, we describe a patient as HR

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positive if the cancer contains either estrogen receptors or progesterone receptors or both.

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For HER2 status, it's the same idea but instead, the cancer is tested for a protein called human epidermal growth factor

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receptor 2 or HER2 for short. These receptors often act to promote the cancer's growth.

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So a patient's HR and HER2 status will likely determine their best treatment options. What if you don't have any of these three receptors?

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Well, that's what we term triple negative, meaning all three receptors-- estrogen, progesterone, and HER2 are absent.

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Just to give you an idea of which subtypes are most common, about 70% of patients diagnosed with metastatic breast cancer

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are HR positive, HER2 negative. This subtype can be referred to as Luminal A.

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Or when the division rate is fast, it joins the Luminal B group. Luminals are the most common among the four,

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with the other two types being triple negative-- also called basal type-- or HR negative, HER2 positive--

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called HER2 enriched. It's important to know that treatments overall are becoming more specialized, targeted, precise,

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and put it simply, more effective. And I think that's absolutely cause for some optimism.