Triple-negative and basal-like breast cancers
Many breast cancer cells have receptors for estrogen or progesterone. They may also have receptors for a protein called HER2 (also called ERBB2). Triple-negative breast cancer means that the cancer cells don’t have any of these receptors. Because it doesn’t have any of these receptors, triple-negative breast cancer is considered a separate type of breast cancer with its own treatment options. Most triple-negative breast cancers are invasive ductal carcinoma. Ductal carcinoma in situ (DCIS) may also be triple negative.
Basal-like breast cancer is similar to triple-negative breast cancer because the cancer cells often don’t have receptors for estrogen, progesterone and HER2. But basal-like breast cancer cells have changes in the proteins that triple-negative breast cancers usually don’t have. Most basal-like breast cancers are invasive ductal carcinomas.
It is important to note that not all triple-negative breast cancers are basal-like. And not all basal-like breast cancers are triple negative. They are 2 similar, but distinct, subtypes of breast cancer. Scientists have not yet developed one internationally accepted definition of a basal-like breast cancer. But they know that it is different from other types of breast cancer.
Women under the age of 40 and women of African or Asian ancestry have a higher risk of developing triple-negative breast cancer. Basal-like breast cancers are more likely to be found in younger women and in women of African ancestry.
Many triple-negative and basal-like breast cancers may be called interval cancers because they can develop between regularly scheduled screening mammography.
Most triple-negative and basal-like breast cancers are high-grade, or aggressive, tumours. This means that they tend to grow and spread quickly. Many are diagnosed at a later stage when the cancer has already spread (metastasized) to lymph nodes or other organs. These tumours tend to spread to the bloodstream, brain or lungs more often than breast cancers that aren’t triple negative. They do not spread to the lymph nodes or the bones as often as other types of breast cancer.
Triple-negative breast cancer usually responds to chemotherapy. However, it does have a higher risk of coming back (recurrence) within 5 years of treatment, compared to breast cancer that is hormone-receptor positive or HER-2 positive. After 5 years, this risk decreases.
When you are diagnosed with breast cancer, your healthcare team will do certain tests to help them develop a treatment plan for you. They use hormone receptor status testing to see if the breast cancer cells have receptors for the hormones estrogen and progesterone. They also do HER2 status testing to see if the cancer cells make too much HER2 protein.
If you have triple-negative or basal-like breast cancer, your healthcare team will create a treatment plan just for you. It will be based on your health and specific information about the cancer.
Surgery is often used to treat triple-negative and basal-like breast cancer. The type of surgery done will depend on the type of tumour, the size of the tumour, where the cancer has spread and other factors.
Radiation therapy is sometimes offered after surgery.
Chemotherapy is used to treat triple-negative and basal-like breast cancer. You may be offered the same combinations of drugs used to treat the different types of breast cancer that aren’t triple negative. Cisplatin (Platinol AQ) or carboplatin (Paraplatin, Paraplatin AQ) are often added to chemotherapy regimens because research suggests that these drugs may work better against triple-negative and basal-like breast cancers.
Neither hormonal therapy nor targeted therapy is offered for triple-negative or basal-like breast cancer. Hormonal therapy isn’t used because these tumours do not have receptors for estrogen or progesterone. Targeted therapy isn’t offered if these tumours don’t have receptors for HER2.
Immunotherapy may be used to treat locally advanced or metastatic triple-negative breast cancer. Immunotherapy helps to strengthen or restore the immune system’s ability to fight cancer. Atezolizumab (Tecentriq) is an immune checkpoint inhibitor used in combination with nab-paclitaxel (Abraxane) to treat advanced or metastatic triple-negative breast cancer that expresses the PD-L1 protein.