N. Simon Tchekmedyian, M.D., F.A.C.P., is associate clinical professor of medicine, University of California at Los Angeles School of Medicine, Los Angeles, Calif., and practices oncology and hematology in Long Beach, Calif.
What are the main chemotherapy drugs used for breast cancer?
The main chemotherapy drugs used for breast cancer are Adriamycin and Taxol or Taxotere. Those two compounds currently are the most important drugs and a close third is cyclophosphomide.
Are they effective?
They are effective. Chemotherapy for breast cancer works, and by that we mean it shrinks the cancer at least by 50 percent of its initial size. They work at least 70 to 80 percent of the time, meaning that if you have somebody who has either a large breast lump or has a growth somewhere else in their body, like the lungs or the bones or the liver, you give them these drugs and more than half of the time the cancer will shrink down by more than 50 percent.
It doesn't mean that the cancer is cured. In fact, I should say that if the cancer spreads outside the breast we do not currently have a cure for it. We can control it, often changing it into a more chronic pattern so that the person has a chronic illness like you have diabetes or hypertension or something like that, but you cannot really cure it and completely get rid of it.
How do chemotherapy drugs work?
Chemotherapy drugs work mostly by affecting the genetics of the cell. Cancer cells are immortal: they continue growing, they divide constantly as opposed to normal cells. Normal cells are born, they accomplish a function of some sort and then they die. The cancer cells are constantly dividing and that allows us to focus on them with these drugs. The drugs bind to the genetic material of the cell and when the cell tries to divide, instead of dividing it actually dies.
What are the most common side effects of chemotherapy?
When you talk about side effects of chemotherapy, one of the most important ones that I see as an oncologist is fatigue, just tiredness. It's like you get chemotherapy, you go home and you feel as if you were hit by a truck and you have to rest. Sometimes your family doesn't understand that. They want you to be active, they want you to fight your disease and you just are so tired and so weak that all you want to do is sleep and rest. It's important to recognize that it's probably the most frequent side effect of chemotherapy and it's pretty universal. It happens with most drugs.
There are certain drugs that have some specific side effects. For example, Taxol: that evening or the day after you are given Taxol you get joint pains, you get muscle aches, uh you feel very stiff. Nausea is not a problem with Taxol, but you get hair loss very often. Fatigue is a problem just as it is with all of the other drugs. Adriamycin, on the other hand, can give you mouth sores, can give you some nausea, and makes you very fatigued. It definitely make you have hair loss and if you give it at certain dose levels it can really cause a serious heart condition, with heart failure.
How do you choose which chemotherapy drug to use?
Oncologists have to work with drugs that have a lot of side effects and the ratio of efficacy to side effects is very narrow, so we tend to choose drugs that work well, that have a good level of efficacy and at the same time are well tolerated. When we have to choose which drug to use we look at the person, we look at, for example, what other conditions that person may have and then adjust the drugs that we choose to that condition.
For example, if somebody has breast cancer who is 72 years old and has had a couple of heart attacks you're not going with idiomycin because idiomycin can be toxic to the heart. If you have somebody who has a serious neurologic condition and severe weakness and problems with their nerves you may have a problem using Taxol because Taxol can cause neuropathy or nerve damage.
In terms of efficacy I think it's fair to say that idiomycin, Taxol and cyclophosphomide are the three most active drugs in breast cancer and clearly they are the front line choice in most cases.
How many do you have to choose from?
Oncologists have a fairly wide variety of drugs to choose from, and it goes into dozens but when you look at breast cancer in particular, there are just a handful of drugs that are truly effective, and these include Adriamycin, Taxol, Taxotere, cyclophosphamide. Gemcitabine (Gemzar) or vinorelbine (Navelbine) are other drugs that can be very useful.
How specific are these drugs?
The way we manage breast cancer and many cancers at present is certainly not optimal. ... My brother is a surgeon and I often say that surgery is quite barbaric and primitive; of course he'll tell you that chemotherapy is even worse and I don't disagree.
Chemotherapy has a lot of side effects. It's not a very specific treatment: it goes across the board penetrating to the blood stream because usually we give it intravenously. It will affect your whole body — all of your tissues, your skin, your liver, your kidneys, your urinary bladder, your lungs, your brain — they are all exposed to these toxins as we introduce them in your body although our purpose is to effect just a few cells or sometimes a large number of cells.
We have no way most of the time to specifically target those cells that need to be destroyed and spare the rest of the body. There are some situations where we can do this. For example, in ovarian cancer, if the cancer is completely into the abdominal cavity we can put in a catheter and instil the chemotherapy agent as a belly bath, so to speak ... but most of the time we are affecting your whole body just to kill a few cells.
Let's say for example that you have somebody who had a breast lump removed and whose chance of having the cancer come back is about 50 percent. Well, 50 percent of the time we're going to give chemotherapy to that person and yet it's not going to help because that person may be cured to begin with. It's just that we have no way of telling. And in the other 50 percent of the time we will deliver the chemotherapy and yet get a benefit only in a fraction of those patients, so that maybe 20 or 30 percent of the time on those 50 patients out of 100 we will have efficacy. So when you take the whole group of 100 people, you may end up helping 10 or 15, but you have to treat 100 of them. It's just as non-specific as it gets.