What is Triple Negative Breast Cancer?
The purpose of this page is to explain to you, and your family and friends, what triple negative breast cancer (or TNBC) is, how it differs from other types of breast cancer and what this means for you.
What is Triple Negative Breast Cancer?
Breast cancer is still the cancer most likely to affect women in the UK, being diagnosed in about 1 in 8 at some point in their life.
However, it can come as a surprise to learn that not all breast cancers are the same and there are differences in the ways these different types of breast cancer behave and are treated.
These different types of breast cancer are based on special tests usually done on the lump in the breast, either a biopsy taken with a needle passed through the skin or at an operation. In the laboratory doctors can look down a microscope and say whether or not the lump is a breast cancer and if so what type of breast cancer.
This includes looking for the presence, or absence, of three different ‘receptors’. These are tiny receivers on the cancer called the estrogen (ER), progesterone (PR), and human epidermal growth factor 2 (HER2) receptors. These receptors affect how a cancer develops and grows, and also which drugs are used to treat it.
If the ER and/or PR is present a cancer is said to be hormone receptor (HR) positive; if the HER2 receptor is present at a high level the cancer is HER2 positive.
But if none of the three receptors is present, or present only at low levels, the cancer is said to be “triple negative” and the diagnosis is of triple negative breast cancer (TNBC).
Are some people more likely to be diagnosed with TNBC than others?
TNBC is less common than other types of breast cancer, but still accounts for about 1 in 8 of people diagnosed with breast cancer.
With 50,000 people diagnosed with breast cancer in the UK each year there are thousands of people, mostly women, who have TNBC. This includes about 400 men diagnosed with breast cancer each year, a similar proportion of whom are triple negative.
Breast cancer usually affects older women, but those with TNBC tend to be younger (less than 40 years of age) than those with other types of breast cancer.
Black women and those of South Asian heritage appear more likely to be diagnosed with TNBC.
Finally, people with the inherited form of breast cancer caused by BRCA 1 or BRCA 2 gene mutations are more likely to have TNBC than other types of breast cancer.
Is it ‘worse’ to have Triple Negative Breast Cancer?
Any diagnosis of breast cancer is very difficult, but the diagnosis of TNBC can be especially hard because TNBC may come back and spread more often than other types of breast cancer.
This is why you may hear it said that TNBC is more ‘aggressive’, but it is important to understand that when first diagnosed, provided it is caught early and treated, many people with TNBC are cured.
Similarly, although breast cancer cannot be cured once it has spread to other parts of the body, TNBC can still be controlled with drug treatment.
How will having TNBC affect how I am treated?
Your surgeon and your oncologist (cancer doctor) will discuss with you what treatments are best for you and your particular cancer.
When breast cancer is first diagnosed it is usually visible only in the breast, and sometimes the lymph glands in the armpit. This is called “early” or “primary” breast cancer and treatment is usually with surgery, with or without radiotherapy; this is the same for HR positive, HER2 positive and triple negative breast cancers.
Drugs are often used before and/or after surgery (with or without radiotherapy) to treat people with early/primary triple negative breast cancer to reduce the risk of the cancer coming back or spreading.
If triple negative breast cancer does spread to other parts of the body, drugs can again be used to shrink or control “metastatic” or “secondary” breast cancer.
The drugs used to treat both early/primary breast cancer and metastatic/secondary breast cancer differ between the various types of breast cancer.
Which drugs are used to treat people with TNBC?
Because TNBC do not have ER/PR, hormone treatments such as tamoxifen are not helpful.
Similarly, because HER2 in not present at high levels drugs like trastuzumab (Herceptin) are not going to help.
There are, however, other drug treatments that can and do work in treating people with TNBC including chemotherapy, immunotherapy and new targeted therapy.
There is more information about these elsewhere on this website where the treatment of early/primary and advanced/metastatic breast cancer in greater detail.