Triple-negative breast cancer

What is triple-negative breast cancer?

About 10 percent to 15 percent of all breast cancers are triple-negative. Its name signifies that cancer cells have tested negative for three molecular components of breast cancer cells—receptors for the hormones estrogen and progesterone, and the protein called human epidermal growth factor, or HER2. Triple-negative breast cancer is defined as progesterone receptor-negative, estrogen receptor-negative and HER2-negative.

What causes triple-negative breast cancer?

Scientists are uncertain about what causes TNBC, but some factors may increase a woman's risk of developing the disease.

Certain women are more likely to be diagnosed with triple-negative breast cancer:

• Black women
• Women younger than 40
• Women with a BRCA1 gene mutation

Triple-negative cancer may also be more common in Hispanic women.

The signs and symptoms of triple-negative breast cancer are the same symptoms all breast cancer patients may experience. It may cause a lump, which is more commonly hard, painless and irregular, but can also be soft, round and painful. Other signs include:

• Breast swelling
• Swelling or a lump under the arm or on the collarbone
• Dimpling of the skin, sometimes reminiscent of an orange peel
• Discharge from a nipple
• A nipple that turns inward
• Skin changes on the breast or nipple, including redness, dryness, thickening or flaking

How is triple-negative breast cancer diagnosed?

Imaging tests are usually the first tests done:

• Mammography, the most common screening tool for breast cancer, uses X-rays to take images of the breast and can uncover tumors that may be too small to feel.
• MRI (magnetic resonance imaging) uses a magnet, radio waves and a computer to make detailed images of the breast with a much greater resolution than a mammogram offers.

The next step is a biopsy to remove a sample of suspicious cells from the breast to analyze them. Techniques include:

• Fine-needle aspiration biopsy
• Core needle biopsy
• Surgical biopsy

The appropriate type of biopsy depends on factors such as the size and location of the tumor. The patient may also have a biopsy of her underarm lymph nodes at the same time to see if any cancer is there.

Triple-negative breast cancer treatment

Triple-negative cancers aren’t fueled by hormones that can be specifically targeted, but the primary types of cancer-fighting treatment are still options. These include:

• Surgery
• Chemotherapy
• Radiation

Surgery may be a breast-conserving type, such as a lumpectomy, or complete removal of the breast, known as a mastectomy, depending on the tumor's characteristics. In both cases, nearby lymph nodes would be removed and analyzed to see if the cancer has spread.

The patient may receive chemotherapy before surgery to shrink a tumor or after surgery to help prevent the cancer from returning. The patient may be a candidate for an oral chemotherapy drug called capecitabine, taken for 18 to 24 weeks, to help kill cancer cells. Chemotherapy for breast cancer appears to have more benefit for those with triple-negative cancer than it does for those who have hormone receptor-positive cancer.

Breast cancer radiation therapy involves targeting the breast with high-energy radiation to kill any cancer cells that might have been missed.

Additional treatments for more advanced stages of breast cancer include:

• PARP inhibitors, advanced forms of chemotherapy
• Platinum-based chemotherapy drugs, such as carboplatin and cisplatin
• Immunotherapy

Immunotherapy drugs known as checkpoint inhibitors can help the patient's immune system slow down or even stop the growth of tumor cells. These include the monoclonal antibody drugs atezolizumab and pembrolizumab.

• Combined with chemotherapy, atezolizumab is considered a first-line treatment for a type of triple-negative cancer that makes a protein called PD-L1, found in about 20 percent of these cancers.
• Pembrolizumab is primarily for recurrent tumors that make PD-L1 that can’t be surgically removed or when the cancer has spread.

Cancer that has metastasized may also be treated with an antibody drug conjugate—a drug that links a chemical toxic to cancer cells with an antibody that targets a receptor that helps cancer grow. Sacituzumab govitecan-hziy (Trodelvy^®) is FDA-approved for people whose triple-negative breast cancer has metastasized and who previously received two other cancer treatments.

Patients might want to consider enrolling in a clinical trial to possibly receive new treatments. Trials test new treatments and combinations of treatments along with standard treatments. The patient's care team can help her investigate appropriate trials and help her make a decision on if and when to join a trial. Trials are supported by several organizations, including the National Cancer Institute (NCI), and several listing search services are available online to help patients learn about current studies underway.

Triple-negative breast cancer survival rate and prognosis

The five-year relative survival rate for someone with localized triple-negative breast cancer, cancer that has not spread beyond the breast, is 91 percent (91 percent as likely as someone without cancer to survive during the five-year period). For cancer that has spread into nearby lymph nodes or nearby areas, the five-year survival rate is 65 percent. For cancer that has spread further into the body, such as into the bones, lungs or liver, survival is 12 percent.

Survival rates are averages determined by what’s happened in the past. As research and cancer treatment evolve, the outlook may improve.

These statistics are recorded in the SEER database, which is maintained by the NCI, and do not differentiate between stages of cancer or take into account variables such as patient age and overall health.