Triple-Negative Breast Cancer (TNBC)

What is Triple-Negative Breast Cancer (TNBC)?

Triple-negative breast cancer is a rare form of breast cancer that affects 13 in 100,000 women each year. It is called “triple-negative” breast cancer because it does not have three markers that are associated with other types of breast cancer. It is one of the most challenging breast cancers to treat, but ongoing research is making efforts to create more effective treatments.

Triple-negative breast cancer can be an aggressive cancer, but other factors will determine the rate at which the tumor grows or spreads. Your provider will discuss the best treatment options to manage symptoms and slow growth and spread. Black and Latina women seem to be more impacted by triple-negative breast cancer than white women. TNBC also appears more frequently in women 40 or younger. Additionally, women who have the gene change BRCA1 are more likely to develop TNBC.

Signs and Symptoms

Symptoms of TNBC are like other types of breast cancer. However, there are many less serious conditions that also have similar symptoms to breast cancer. It is possible to have symptoms of breast cancer and not actually have breast cancer. Consulting with a healthcare professional when you notice any of these symptoms will allow them to determine or rule out a breast cancer diagnosis. Breast cancer symptoms may include:

  • A new lump or mass (can be hard with irregular edges or soft and round; most breast lumps or masses are NOT cancer; can be painless or painful)
  • Dimpled skin (may resemble an orange peel)
  • Swelling in part of the breast or the whole breast
  • Breast or nipple pain
  • Nipple retraction (nipple turns inward)
  • Nipple or breast skin that is dry, flaking, thickened, or red
  • Nipple discharge (other than breast milk)
  • Swollen lymph nodes (when the cancer has spread to the lymph nodes under your arm or near the collar bone)

If you have any of these symptoms, please consult with your healthcare provider so they can determine a diagnosis.


There is no known cause for TNBC, but research has theorized that a genetic mutation in BRCA1 may make a person more vulnerable to developing TNBC. The BRCA1 gene is meant to prevent cancer, but when it experiences a mutation, the gene makes your cells more susceptible to cancer.

Risk Factors

Although there are no known causes for TNBC, there are certain risk factors associated with developing TNBC. Triple-negative breast cancer typically develops more often in women who are 40 or younger. Black and Latina women are also more prone to developing TNBC. Additionally, if the BRCA1 gene mutates, it increases the risk of developing TNBC by making your body’s cells more susceptible to cancer.


A diagnosis for TNBC is usually made from a series of testing. Typically, a suspicion of breast cancer is found through a routine breast exam or mammogram. If a doctor determines that further testing is needed to rule out cancer, it may be recommended to get a biopsy or have imaging tests conducted (MRI, CT scan, ultrasound, or PET scan). A biopsy will help to determine if the cells are cancer and what subtype the cancer is. Imaging tests help to determine the size of the tumor or whether it has spread. Your doctor will make a diagnosis based on any findings from a biopsy or imaging test and will consult with you regarding next steps.


TNBC is a more aggressive cancer that can be difficult to treat. However, research continues to make progress in finding more effective treatments, including new combinations of treatments and different approaches to treatments that already exist. Treatments include:

  • Chemotherapy. This treatment is used to shrink a tumor before surgery or to destroy any remaining cancer cells throughout your body after surgery.
  • Radiation therapy. This is often used post-surgery to reduce the risk of the cancer returning.
  • Immunotherapy. This treatment helps to engage your immune system and helps it identify and fight the cancer cells. It also helps produce more cancer-fighting cells. This treatment can be used prior to surgery with chemotherapy to help shrink the tumor or may be administered for about a year after surgery and radiation therapy.
  • Surgery. There are different types of surgeries that your doctor may recommend, depending on the size and location of the cancer. A lumpectomy is used to remove an individual lump. A mastectomy removes an entire breast. Additionally, a doctor may recommend a sentinel node biopsy or axillary node surgery to determine if the cancer has spread to the lymph nodes.


There is no known cause for TNBC, which makes prevention measures difficult. One potential factor in developing TNBC is having the BRAC1 gene mutation, but because it’s an inherited gene there is no way to prevent yourself from having it. Although there are no known prevention measures to decrease the risk of developing TNBC, there are factors that can help decrease the risk of developing breast cancer. These include:

  • Maintaining a healthy weight
  • Regular exercise
  • Knowing your family’s medical history
  • Consistently monitoring your breast health (routine breast exams and mammograms)
  • Genetic testing for BRCA gene if there is a family history of cancer


Complications depend on the size of the tumor and if it has spread. Additionally, there can be several side effects from the treatments. Common side effects that may be experienced from chemotherapy or if the cancer has spread to your lymph nodes:

  • Hair loss
  • Fatigue
  • Nausea
  • Lymphedema (when the lymph fluid does not drain properly and causes swelling under the skin)
  • Skin changes
  • Pain

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