Chemotherapy

Here I want to talk about chemotherapy, its pros and cons. In this type of cancer treatment, we give drugs mostly intravenously. As you know, within seven seconds they are going to get to virtually every cell in the body. The good thing about chemotherapy is that we don’t need a target. This is why it has become so important in metastatic cancer. We don’t need to know where the cancer cells are hiding, the drugs will get there. However, it is very toxic and it isn’t good for handling tumor bulk.

There are a couple of things about this treatment that you need to know. There is something called the Goldie-Coldman hypothesis. This is a huge mathematical concept that I have no idea what is about. I know, however, what Doctors Goldie and Coldman found out. They found out that chemotherapy would fail even in very small numbers of cells unless you go the whole way and get all the possible metastatic cells. You cannot back off and get the same result.

If you’re getting a bad result with surgery or radiation you can always back off for the patient to rest and pick up again. In chemotherapy, however, if you don’t finish the course of treatment because of toxicity, then the patient is very likely to have a lot of resistant cells that escaped through natural selection. You’ll get the most resistant cells.

Goldie and Coldman also say that it’s very unlikely you’re going to be able to do the job with one drug. We usually don’t use one drug. We use multiple drugs so that we can lower the toxicity of each one. We try to get drugs with different toxicities. Maybe we use one that works maybe depressing the bone marrow, which is a bad thing. We may use another that has another toxicity and you get a synergistic effect that kills the cells you want to kill and not make the patient so sick.

Ideally we use eight or ten drugs, but we generally use two or three and try to get the patient to complete the whole cycle. Just about the time things are really getting bad for the patient we back off and pick up again later. These cycles are timed to try to get the cancer cells when they just caught their breath and started to multiply again. Meanwhile, normal cells have probably recovered pretty well.

It is very hard to measure the effectiveness of the treatment unless you have some tumor you can see. The most important type of chemotherapy is the category called adjuvant therapy. Adjuvant cancer therapy has a very specific definition. It means that it is given to a patient in whom we cannot prove that they have metastasis, but we highly suspect it.

What we found out is that if you wait until there are enough tumor cells to produce symptoms it is usually too late to get the best results from any treatment. If you move in to a patient who has microscopic metastasis, you’re going to get the best result. How do we know who that patient is?

Adjuvant therapy, therefore, is defined as drug therapy given to a patient without proven metastasis but who we think has a very high likelihood of having them. Doctors do all the studies they can and say to the patient: “Look, it is likely that you’re cured, but we’ve got a lot of bad biologic markers. We would do you a lot of good if we do the chemotherapy now, before this comes back three years down the road.”

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