Levels of hormones, like estrogen and progesterone, vary from person to person, but everyone has some amount, including women who have gone through menopause and men. If your cancer is hormone receptor positive (HR+)—sometimes called estrogen or progesterone receptor positive— hormones in your blood attach to receptors on the outside of breast cancer cells, causing the cancer cells to grow more quickly. If you’re hormone receptor negative (HR-), you have very few, or none, of these receptors in your cancer cells. If you have had breast cancer in the past, have your hormone receptor status retested because it may have changed.

Everyone has HER2 genes that produce HER2 proteins to help healthy breast cells grow and divide. The HER2 gene makes HER2 proteins that sit on the outside of breast cells. If the HER2 genes don’t work correctly, they can make too many HER2 proteins and cause breast cells to become cancerous. If your cancer is HER2+, your breast cells have too many HER2 proteins. If breast cancer cells have a normal amount of HER2 proteins, the cancer is HER2-. If you have had breast cancer in the past, it is important to have your HER2 status retested because it may have changed.

Genetic and genomic mutations are changes in your DNA. Everyone’s DNA has changes that give people unique characteristics, but some changes are especially rare and some can be harmful. Genetic mutations, which can be hereditary, may be found in your cancer cells. These may be an important factor in determining which treatments your doctor recommends. If you’ve been tested for mutations that may provide information about your cancer, be sure to tell your doctor. If you’re uncertain whether you have mutations, talk to your doctor about testing as knowing could help your doctor with determining an appropriate treatment option for you.