Most of us learn about breast cancer from the news, from events and studies that get us closer to “the cure.” But in reality, researchers are looking for many cures because breast cancer is not one disease. Breast cancer is actually a group of diseases that are related because they involve the tissues of the breast and nearby lymph nodes. Research has shown that no two breast cancers are alike.

Breast cancers can be grouped into different types based on the way the cancer cells look under the microscope. They can also be categorized based on the biology and genetics of the tumor cells. Each cancer has a unique genetic profile that predicts how it will grow and what treatment will work best. The biology of the cancer is as important as how much cancer is present and where it’s located.

When you first receive your diagnosis, you will have little information about the cancer, how it grows or whether it has traveled beyond your breast. Your doctors must learn more about the traits of the cancer before you can decide on a treatment plan.

Tests will give your doctors information on the proteins that control your body’s cells. If specific proteins are present, missing or not working as they should, your doctors can predict how a cancer will react to certain medicines and tailor your treatment. Today, this is what is known as “personalized medicine.”

Your pathologist, a doctor who diagnoses diseases by looking at cells under a microscope, will look at samples of tissue or the tumor. The pathologist will then create your pathology report with information on the disease, including the type. Your pathology report becomes part of your medical record, and you are given a copy for yourself.

Sometimes a single breast tumor can have several different types of breast cancer cells. In some rare types of breast cancer, the cancer cells may not form a tumor in one place at all.

Understanding the breast cancer’s biology can help you make treatment decisions. As you learn more and begin to develop a treatment plan, don’t hesitate to seek a second opinion, especially if your diagnosis feels unclear to you or you have unanswered questions.

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