Understanding Triple Negative Breast Cancer
“I’ve been diagnosed with triple negative breast cancer. Is this a type of breast cancer like IDC or inflammatory breast cancer, or…? Find answers to your questions about triple negative breast cancer here.
What is triple negative breast cancer (TNBC)?
TNBC isn’t a type or sub-type of breast cancer. You can have IDC or another type of breast cancer, and be triple negative, too. This is because TNBC is a phenotype – that is, “triple negative” refers not to what the cancer is, but how it behaves.
“Triple negative” means your cancer cells are negative for estrogen and progesterone receptivity; and also negative for HER2-neu over-expression. Most women’s cancers are positive for at least one of those, giving them more treatment options.
How (un)common is TNBC?
About 17% of women with breast cancer have triple negative cancer. It’s generally considered more aggressive; and it’s more common in younger women; in African-American women, and in women with BRCA1 or BRCA2 gene abnormalities.
For most women, chemo is an option; for those with TNBC it’s pretty much a given, since it’s the most effective treatment available. If the cancer has spread to the lymph nodes, chemo will probably be administered prior to surgery, to track how effectively it shrinks the tumor.
Likewise, it doesn’t “over-express” the HER2-neu protein. And while this over-expression in and of itself isn’t a plus (HER2-neu over-expression signals a more aggressive cancer), it does mean women with this type of cancer can be successfully treated with the drug Herceptin – while those with TNBC can’t.
Bottom line: Most women have ER/PR-receptive breast cancer, and receive long-term hormone therapy to reduce their risk of recurrence. Women with HER2-neu positive breast cancer take Herceptin for a year, to reduce their risk of recurrence. For women with triple negative breast cancer, there’s no therapy beyond chemo that will help keep the cancer at bay.
Chemotherapy is key
Luckily, chemotherapy is generally quite effective for women with triple negative breast cancer – in fact, more effective than it is for most other diagnoses.
Most women with a triple-negative diagnosis receive ACT: Adriamycin (an anthracycline), Cytoxan (a cyclophosphamide), and Taxol (a taxane). Hopefully that’ll knock the cancer out for good.
Two newer drugs in the pipeline, carboplatin and cisplatin, are showing promise as perhaps being more effective than ACT. Currently, they’re only being used to treat metastatic TNBC; clinical trials continue.
How likely is a recurrence?
Women with a triple negative diagnosis are more likely to suffer a recurrence within the first three years than women with hormone-receptive or HER2-neu-positive cancer.
In fact, the recurrence rate for TNBC is about 32 percent in the first 5 years, compared to around 15 percent for women with other breast cancers. If you can get through those first 5 years after treatment cancer-free, then your chances are excellent that you’ve beat it.
If recurrence happens
There are other treatments on the horizon, some closer to becoming reality than others.
The use of the drug Avastin in conjunction with chemo has had good results in clinical trials. A co-called antiangiogenic drug, Avastin keeps tumors from growing the blood vessels they need to ensure a steady blood supply.
One of the most popular diabetic drugs in the U.S., metformin (a.k.a. Glucophage, Fortamet, et. al.), has had positive results fighting all types of breast cancer, including triple negative, when given at low levels with chemo drug Adriamycin. While still in clinical trials, the combination of these two drugs both eliminated tumors, and prevented their regrowth; while Adriamycin alone simply kept the tumors from growing, without fully eliminating them.
Another promising treatment is a class of drugs called PARP inhibitors. PARP1 is a gene involved in helping cells recover from the natural damage they incur as they grow. If this gene is inhibited – prevented from doing its job – cancer cells are unable to repair themselves, and they die.
A possible future treatment in clinical trials is the drug Tarceva®, an EGFR inhibitor. EGFR (epidermal growth factor receptor) helps cells grow and proliferate; when it’s “inhibited” (disabled), cancer cells can’t grow.
Finally, a trial using bisphosphonates – the drugs commonly used to treat osteoporosis – to inhibit the spread of TNBC to the bones has shown promising results.
Hope on the horizon
A diagnosis of triple negative breast cancer, with its lack of multiple treatment options, may seem devastating at first. But researchers are making huge strides in discovering new ways, beyond hormone therapy and Herceptin, to stop the spread of all breast cancers.
And treatment for triple negative cancers are definitely getting front-burner treatment. As oncologist Mark Pegram, M.D., of the Sylvester Comprehensive Cancer Center in Miami notes, once researchers discover what TNBC is, rather than what it isn’t, “We’ll stop calling it triple-negative and start calling it something positive.” Just as Herceptin was developed to treat HER2-neu cancers – once their “Achilles heel” was identified – the same will be true for TNBC.
For more information, check out the Triple Negative Breast Cancer Foundation.
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Breast cancer survivor and award-winning author PJ Hamel, a long-time contributor to the HealthCentral community, counsels women with breast cancer through the volunteer program at her local hospital. She founded and manages a large and active online survivor support network.