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.
Should all metastatic breast cancer patients be treated in the same way?
You always treat the patients, you don't treat the disease. You treat what that person needs to have a long life and have a high quality life. No two patients ever should be treated the same.
You have to individualize the care for that person and that depends upon the knowledge of their disease and the function of the other organs of their body, but also many personal characteristics of the individual — what their desires are, what their lifestyle is like, what toxicity they are willing to tolerate or they can tolerate, economic factors, and social factors all play a role. You have to say what is right for this individual, and if you do that you find that you never treat two patients exactly the same ever.
What about individual tumors?
We have to really understand that all disease processes are very complex, and metastatic breast cancer is also a complex disease process. You have to look at how much cancer there is, what organs are involved, and the function of those normal organs. One very important factor is whether the tumor has something called estrogen and progesterone receptors in it. Estrogen and progesterone are female hormones.
We can often treat those tumors very successfully if we deprive those cancer cells of the estrogen that they need to grow. We can do this with a variety of techniques: sometimes in young women we can stop the ovaries from producing estrogen; we can also give medications that block the estrogen at the cancer cell surface; we can also give medications in post-menopausal women that lower the level of estrogen in their blood even further. All of these are very effective therapies for certain individuals.
For some individuals those therapies no longer work or they don't have estrogen or progesterone receptor in their tumor. For those patients we have to use other therapies, and in general we call these other therapies chemotherapies because they're chemical treatments that attack the cell division of those cancer cells.
We have to take into account the characteristics of the tumor, what medicines the patient might have received before, what organs are involved, and how rapidly the tumor is growing. This takes a lot of knowledge and it takes a lot of skill. If I had to give one piece of advice to somebody who has metastatic breast cancer and is seeking the best therapy, is for them to seek the best experts, somebody who's had a lot of experience and special training in dealing with these problems so they can design the therapy that's right for that individual.
So the prognosis is better if you're estrogen positive?
In general, estrogen-receptor positive cells tend to grow more slowly and be responsive to hormone therapies than estrogen-receptor negative cells. On the other hand, estrogen-receptor negative cells often are more sensitive to chemotherapy, so choosing the right therapy's the important thing. I think it's more important to try to individualize care and come out with the best prognosis for that specific individual rather than to look at big global concepts of prognoses.