Not All Cancers are the Same
Each type of cancer is biologically different from any other type of cancer. For example, skin cancer is biologically different from lung cancer. In addition, each causes a whole different set of problems and must be treated in different ways. That’s one reason you have doctors specializing in treating certain types of cancers and why if you have skin cancer you don’t want to be seen by a lung cancer specialist. Further, not all cancers that develop in the same area of the body are the same. This means that not only are cancers that appear in different parts of the body different from one another, but that, for example, not everyone with lung cancer has the exact same type of cancer.
This helps to explain, in part, the findings we see in clinical trials. We’ll test a drug for lung cancer and we’ll find that only about 30 percent of the people will respond to the drug. Why? We believe it’s because the drug being tested is only effective in lung cancers that have a certain type of genetic mutation and that people who have a lung cancer that has different types of mutations don’t respond. It was this discovery that led us into the new field of personalized health. Personalized health means I go into your cell, I figure out what your mutation is, and then I come up with a treatment that's going to work for you.
One example of this can be seen in how we now treat chronic myeloid leukemia (CML), a cancer of white blood cells. Gleevec, which is used to treat CML, targets abnormal proteins inside the cancerous cells. But Gleevec doesn't work for other types of leukemia. Why not? Because the drug attacks a specific genetic mutation, and not all leukemias have the same genetic mutation.
Adding to the complexity is that fact that we’re all different genetically to begin with. We're different genetically due to race and gender and then there is diversity within each race and gender. We’ve evolved with genetic diversity, and these differences are very, very important for survival. It would be hard for one virus to wipe everybody out, because we are all genetically diverse. So diversity is good to fight viruses, which are big killers. But it also means that when things go wrong, like when cancer begins, it makes finding a treatment that will work for everyone more complex. If everyone in this room had lung cancer, we’d each have different genetic alterations. My DNA and my alphabet are different from your DNA and your alphabet, and so my genes might develop one type of mutation and your genes might develop another. And that means the same drug is not going to work for each of us.