Demystifying Triple Negative Breast Cancer: Understanding the Basics

Author: Rebecca Armstrong, Manager of Patient Education Programs for the Canadian Breast Cancer Network | Editors: Romina Garcia de leon, Janielle Richards (Blog coordinators) | Expert reviewer: Chloe White

Published: November 29, 2024 

Triple negative breast cancer (TNBC) is a term that might be unfamiliar to many, yet it represents 10-15% of breast cancer cases. Let’s break down what TNBC is, why it’s important to understand it, and what actions you can take to understand your risk and spread awareness.

What is TNBC?

Triple negative breast cancer is a subtype of breast cancer that does not have three common receptors known to drive the growth of breast cancer tumours– estrogen (ER), progesterone (PR), and HER2. Because TNBC lacks these receptors, it does not respond to targeted treatments (medicine given by pill or through IV to the entire body) that are common in treating hormone-positive (ER or PR) or HER2-positive breast cancers. This characteristic makes TNBC more challenging to treat and requires different therapeutic strategies. TNBC is also generally considered to be a more aggressive type of breast cancer with a higher risk of returning after treatment ends.

TNBC Stats: A Closer Look

As we mentioned above, triple negative breast cancer accounts for 10-15% of breast cancers. While anyone can be diagnosed with triple negative breast cancer, it can be more common in some groups. Breast cancer is more commonly diagnosed in people over 50, but TNBC is known to be more frequently diagnosed in younger women. Furthermore, Black and Hispanic women are more likely to be diagnosed with this subtype although there aren’t enough studies currently to say exactly why this is the case. Genetics is also associated with TNBC; 60-80% of breast cancer patients with a BRCA1 mutation have the triple negative subtype.

Awareness of TNBC is alarmingly low. According to the Canadian Breast Cancer Network’s (CBCN) TNBC Project Report published in 2023, a staggering 70.6% of triple negative patients had not heard of the term at the time of their diagnosis. Most (76.8%) were informed of the aggressive nature of the disease. Given that a breast cancer diagnosis is already a scary thing to face, one can only imagine the additional shock and surprise this news would bring. It paints a concerning and overwhelming picture of what their future will look like, leaving room for anxiety and grief in an already uncertain time. Improving awareness can give voice to those diagnosed with TNBC and hopefully increase research and the development of new, effective treatments.

Treatment and Support

One of the major challenges faced by TNBC patients is the limited range of treatment options. Unlike other breast cancer subtypes that can be treated with hormonal therapy and HER2 targeted therapies, TNBC requires a different approach. Chemotherapy is currently the standard systemic treatment for triple negative breast cancer, while newer treatments like immunotherapy and therapies that targeted BRCA genetic mutations may be additional options for some. These treatments can be effective, but the lack of targeted therapies means that there is a greater need for new research and treatment development.

There is also a lack of information and support dedicated to women with triple negative breast cancer. CBCN’s report found that patients with TNBC preferred to receive information tailored to their triple negative subtype (94.3%) but 74% said that triple negative tailored resources were not easy to find. Nor was support; 66.2% of TNBC patients found it was not easy or only somewhat easy to connect with other patients with triple negative breast cancer.

Taking Action: Knowing About Your Personal Risk for breast cancer and Available TNBC Resources

Now that you know more about TNBC, what can you do to better understand your own personal risk?

1. Learn about your family history: Knowing your family history of breast cancer can provide important clues about your risk, especially whether there are cases of genetic mutations.
2. Explore genetic counselling and testing: If you have a strong family history of breast cancer, talk to your doctor about genetic counselling and testing. This can help identify any genetic predispositions you might have. Even if you or your family members have been tested in the past, newly discovered mutations may be identified that weren’t known at the time of previous testing.
3. Learn about your breast density: Having dense breasts can increase your risk of developing breast cancer and can make detecting breast cancer on a mammogram more difficult.
4. Identify the breast screening guidelines in your province: Eligibility for mammogram screening varies by province. Discuss with your doctor about when you should begin screening based on your personal risk and the provincial guidelines.

If you or someone you love has been diagnosed with triple negative breast cancer, there are helpful resources available if you know where to look. The Canadian Breast Cancer Network (CBCN) can help you navigate these resources at their website.