What is triple negative breast cancer?

This blog post discusses triple negative breast cancer, including what it is, types, symptoms, and potential treatment options. Breast cancer happens when cells in different parts of the breast start to grow abnormally.¹ It can be a complicated disease with some types of breast cancer being harder to treat than others.¹ Triple negative breast cancer is one of the more complex types.¹

Within the cells of the breast there are special proteins called receptors. If the cells that are growing abnormally have certain receptors then it can impact how well the cancer may respond to treatment.¹ The three most important receptors to look for in breast cancer are the hormones estrogen (ER) and progesterone (PR), and human epithermal growth factor receptor 2 (HER2) which is a protein involved in cell growth.¹ Some types of breast cancer do not have any of the receptors, these cancers are called triple-negative breast cancers (TNBC).¹

Triple refers to the three receptors (ER, PR and HER2) and negative refers to the fact that the cancer cells don’t have these receptors.¹ Unlike other types of breast cancer, TNBC does not respond to treatments that target those specific receptors, like hormone therapy or drugs that target HER2.¹ Because of this, TNBC can be more challenging to treat, and doctors may turn to other methods, such as chemotherapy, to fight the cancer.¹ In addition, TNBC tends to grow faster and can be more aggressive than other breast cancers,¹ which is why early detection and treatment are especially important.

Knowing which receptors are present on the cancer cells can help determine which treatments will be used. For example, if the cancer cells have ER or PR receptors the cancer is called ‘hormone-receptor positive’ (ER+ and/or PR+) which tells your healthcare team to consider treatments targeting these specific receptors.¹ If the cancer cells have HER2 receptors present then it’s called ‘HER2 positive’ (or HER2+) then treatment targeting the HER2 receptors may be recommended.¹

The main symptom of TNBC is a hard lump, which is why it is important to be familiar with your breast by regularly checking your own breasts once a month.² Other less common symptoms include:²

• Swelling
• Skin dimpling
• Pain
• Nipple retraction
• Discharge
• Redness
• Swollen lymph nodes under the arm

Triple-negative breast cancer (TNBC) is diagnosed based on the characteristics of cells taken from a biopsy, rather than specific symptoms.² During the testing, the cells are checked for certain markers like estrogen and progesterone receptors and HER2. The absence of these three markers helps doctors classify the cancer as triple-negative.² In some cases, further testing using gene expression profiles can break down TNBC into different molecular subtypes, such as basal-like or those with specific gene mutations like BRCA1/2.²

Which treatment recommended depends on a combination of factors to do with you and your cancer, such as:¹

• Cancer type and stage – ER+, PR+, HER2+, triple negative, early or advanced
• Tumour characteristics – is it in the breast only or has it spread to other parts of the body?
• Your age and general health
• Your preferences for how you are treated
• Previous treatments – what treatments you have had before can affect what treatment options your team recommends next

Surgery is the most common option for TNBC and the aim is to remove tumour.¹ Your team may recommend treatment before surgery to shrink the cancer¹ – this is called neoadjuvant treatment and can include chemotherapy, immunotherapy, targeted therapy or a mix of treatments.³ Neoadjuvant treatments may allow for less complex surgery, such as breast-conserving surgery instead of a mastectomy (full removal of the breast tissue).⁴

After surgery your team may recommend treatment to help prevent the cancer from coming back.¹ This is called adjuvant treatment and can include radiation or chemotherapy which may be used to get rid of any remaining cancer cells.¹ Ask your doctor if neoadjuvant or adjuvant treatment is right for you.