Breast Cancer: Molecular Classifications

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At the Swedish Cancer Institute, our personalized medicine program can identify and target gene mutations that cause different forms of breast cancer.

In some cases, pinpointing your tumor’s genomic fingerprint can be useful in customizing treatment recommendations.

Every breast cancer has its own unique molecular fingerprint, and there are four primary molecular categories for breast cancer. Your healthcare team will use that molecular information, along with any gene mutations, to help determine the most effective and personalized treatment plan for you.

These are the primary molecular categories for breast cancer:

  • Luminal A: As the most common breast cancer type (nearly 50 percent), Luminal A cancers grow with the aid of estrogen and/or progesterone.
  • Luminal B: Also a common type of breast cancer (6 percent to 19 percent). Along with estrogen and/or progesterone, the protein HER2 (human epidermal growth factor receptor 2) also affects the growth of this cancer.
  • Triple Negative/Basal-Like: Fourteen percent to 20 percent of breast cancers are triple negative, meaning growth of the cancer is not affected by estrogen, progesterone or HER2. These cancers are more aggressive and tend to be found in younger women, those with BRCA1 or BRCA2 gene mutations and also African Americans.
  • HER2-Enriched: This breast cancer type is seen in 7 percent to 12 percent of those diagnosed and it is aggressive. HER2-Enriched cancers grow when HER2 proteins are present. Fortunately, these cancers respond well to targeted therapies.

Learn more about genomic testing