We’ve covered most of the info in your pathology report, but there is one more incredibly important piece to that puzzle - the characteristics of your tumor. Namely, its hormone and HER2 receptor status.
Many people don’t realize that there are different kinds of breast cancer; I sure didn’t. So, when I was diagnosed as having “triple negative” breast cancer, I had no idea what that meant. Turns out, breast cancer is not one size fits all… who knew!?
Let’s get right into it.
Hormone Receptor Positive
Two out of three breast cancers are positive for hormone receptors; these hormone receptors send out signals which drive cancer cell growth.
When your pathology report shows that the cancer is estrogen-receptor (ER) positive, it means the cancer cells in the breast receive signals from the hormone estrogen which promotes their growth, just as if the cancer is progesterone-receptor (PR) positive, the hormone progesterone sends signals to the cancer cells that tells them to grow. Breast cancer cells may have one, both, or none of these receptors.
Testing for hormone receptors is crucial because the results inform whether or not to use hormone therapy as part of your treatment, which lowers the amount of, or blocks, the hormone driving the cancer.
HER2, human epidermal growth factor receptor 2, is a gene that makes a protein found on the surface of all breast cells. A normal HER2 receptor helps control cell growth and repair, but if the HER2 gene mutates, it makes extra copies, and, as such, too much HER2 protein. This, in turn, causes cells to divide and grow too fast.
About one in five breast cancers are HER2 receptor-positive, meaning that there is an overexpression of this protein, which promotes the growth of cancer cells.
While HER2-positive breast cancers tend to grow faster than HER2-negative, there is good news in that highly effective targeted immunotherapies are available and used as part of treatment.
If your tumor tests positive for all of the above (ER/PR/HER2), then you may hear the term “triple positive;” however, breast cancers can be any combo of the above, such as ER+/PR +, HER2-, and so forth.
Triple-negative breast cancer, therefore, means that the tumor is negative for all of the above – ER, PR, and HER2. This type accounts for 10-20% of all breast cancers and is more common in women under 50, black and Hispanic women, and those who carry the BRCA1 gene mutation. This kind of cancer tends to be a grade 3, and more aggressive.
This triple negative status will inform your doctor’s suggested protocol because the targeted therapies used for hormone and HER2 receptor-positive cancers are not relevant for triple-negative breast cancer. This explains why, for example, your new “breastie” is put on the hormonal therapy Tamoxifen and getting the HER2 immunotherapy Herceptin treatments, and you aren’t.
See? I told you breast cancer is not one size fits all! Your treatment plan may be different than others’ treatment plans, because your cancer’s characteristics may be different than others.’ And you know what that means? You’re special and unique, even in your breast cancer.