Larry Norton, MD, is attending physician and member, Memorial Hospital, and head of the solid tumor division, Memorial Sloan-Kettering Cancer Center, and president of the American Society of Clinical Oncology.
What is metastatic breast cancer?
Metastatic breast cancer refers to the capability of some cancer cells to grow in other parts of the body where they don't belong. We have very good ways of taking care of cancer in the breast—we can cut it out, we can irradiate the breast, we can remove the whole breast under certain circumstances — but the real problem with breast cancer is that cells can spread to other parts of the body and grow there.
Many people don't realize that many normal cells in your body travel to other parts of the body. Every time you brush your teeth you're putting some of your gum cells in your bone marrow, for example, and that can be measured, but those don't grow. They know they're in an abnormal place, they know they're in bone marrow when they belong in your gums, and they won't grow and they'll go on to die.
Breast cancer cells—cancer cells in general—often have the capacity of growing in a part of the body where they don't belong: lymph nodes under the arm, lung, liver, bone, brain. That's what we call metastatic breast cancer. Now metastatic cancer can only be treated by drugs that enter the blood stream and go to all parts of the body. Currently we have a number of medications that are extremely effective at killing cancer cells when we find them or depriving them of the hormones that they need to grow.
In each case what are doctors trying to achieve?
Oncologists are trying to preserve life and quality of life for every individual that we take care of. The treatments that we use depend upon what the problem is that we're facing. It's entirely appropriate to think of breast cancer as two diseases: we call the disease in the breast and the lymph nodes under the arm the local or regional disease; and we call the cells that might have spread to other parts of the body the metastatic disease.
Things like surgery to the breast, radiation to the breast, removal of the lymph nodes under the arm or radiation to the lymph nodes under the arm are very good treatments for the local disease. But we now know that many people, even at the time of first diagnoses with breast cancer, have cells that have spread to other parts of their body. For these patients we have to add other therapies that we call adjuvant or adjunctive therapies. These can kill cancer cells in all parts of the body.
These are chemotherapy, which are drugs designed to kill breast cancer cells in the process of cell division, or hormonal therapies, which are designed to deprive cancer cells of the estrogen that they need for growth. After many decades of follow up, these therapies have been shown to be very effective at killing cells and reducing the odds that a person will ever develop metastatic breast cancer.
