5 Things You Need to Know About Triple Negative Breast Cancer
By Shawna Rich-Ginsberg March 3 2019
Today is Triple Negative Breast Cancer (TNBC) Day – a day dedicated to raising funds and awareness for TNBC. You might be wondering why a specific type of breast cancer needs its own day? TNBC is an aggressive form of breast cancer that can be difficult to treat and targets specific populations. Read on to find out more about what you need to know.
Triple Negative Breast Cancer (TNBC) is not hormonally fuelled
Triple-negative breast cancer (TNBC) are tumours that test negative for estrogen receptors, progesterone receptors, and excess HER2 protein. These results mean the growth of the cancer is not fueled by the hormones estrogen and progesterone, or by the HER2 protein. About 10-20 percent of breast cancers are triple-negative breast cancers.
TNBC has a different treatment pathway
TNBC does not respond to hormonal therapy medicines or medicines that target HER2 protein receptors. TNBC is typically treated with a combination of surgery, radiation therapy, and chemotherapy. The following are typical treatment pathways:
Research has shown that when TNBC is treated with chemotherapy before surgery — what doctors call neoadjuvant chemotherapy — and there is a pathologic complete response, disease-free survival and overall survival improve. Disease-free survival is how long a person lives without the cancer recurring. Overall survival is how long a person lives whether or not the cancer recurs.
One way for oncologists to determine the effectiveness of neoadjuvant therapy is to look at the tissue removed during surgery to see if there are any active cancer cells. If no active cancer cells are present, doctors call it a “pathologic complete response” or pCR.
PARP inhibitors for hereditary TNBC
Poly ADP-ribose polymerase (PARP) inhibitors, enzymes that fix DNA damage in both healthy and cancer cells, have been approved to treat advanced-stage HER2-negative breast cancer in people with a BRCA1 or BRCA2 hereditary mutation. This is important because 70 percent of breast cancers diagnosed in people with an inherited BRCA1 mutation are triple-negative.
Research has shown that medicines that interfere or inhibit the PARP enzyme make it even harder for cancer cells with a BRCA1 or BRCA2 mutation to fix DNA damage. In other words, a PARP inhibitor makes some cancer cells less likely to survive.
Research also suggests that the immunotherapy medicines combined with chemotherapy may improve outcomes for metastatic TNBC patients, compared to chemotherapy alone.
Immunotherapy medicines work by helping your immune system work harder or smarter to attack cancer cells. This is still an emerging field in breast cancer and we are hoping to see more immunotherapies developed and approved for use in treating breast cancer.
Most TNBC patients undergo a mastectomy to reduce their chance of recurrence for breast cancer. Depending on your diagnosis (stage, grade of cancer), a unilateral or bilateral mastectomy may be recommended to reduce your risk.
TNBC targets specific populations
While TNBC can show up in anyone, researchers have found that it is more prevalent in the following populations:
Younger people. TNBC is more likely to be diagnosed in people younger than 50. Other types of breast cancer are more commonly diagnosed in people age 60 or older.
African-American and Hispanic women. TNBC is more likely to be diagnosed in African-Canadian and African-American women and Hispanic women. Asian women and non-Hispanic white women are less likely to be diagnosed with TNBC.
People with a BRCA1 genetic mutation. About 70 percent of breast cancers diagnosed in people with an inherited BRCA1 mutation are triple negative.
TNBC has unique features
TNBC is considered a more aggressive type of breast cancer, mainly because there are fewer targeted medicines that treat TNBC. Studies have shown that TNBC is more likely to spread beyond the breast and more likely to recur (come back) after treatment. That being said, when patients do have a complete response to treatment beyond five years, they have longer periods of NED (no evidence of disease).
TNBC tends to be a higher grade than other types of breast cancer. The higher the grade, the less the cancer cells resemble normal, healthy breast cells in their appearance and growth patterns. On a scale of 1 to 3, TNBC is usually grade 3.
TNBC is “basal-like.” “Basal-like” means that the cells resemble the basal cells that line the breast ducts. Basal-like cancers tend to be more aggressive, higher grade cancers — just like TNBC. Most but not all basal-like breast cancers are triple negative, and most but not all TNBC are basal-like.
TNBC can be scary
Being diagnosed with cancer is terrifying but a TNBC diagnosis can be exceptionally scary because it tends to be more aggressive with a poorer prognosis. Also, unlike other breast cancers, when you are done treatment there is no adjuvant therapies like Tamoxifen for estrogen receptive breast cancer or Herceptin for HER2 positive breast cancer. This means there is nothing left to take or “do” to reduce your risk of a recurrence and some people may feel powerless. Keep in mind that everyone is different and a complete response to TNBC treatment can produce an excellent prognosis.
For more info. on TNBC check out The Triple Negative Breast Cancer Foundation.