This is a guest post by David Reis. If you're interested in submitting a guest post, please contact me.
What is cancer? How does it develop and what treatments will the future offer?
First it’s important to note that cancer is made out of cells from your own body that have, so to speak, decided to revolt and do their own thing. Our body naturally needs to replace itself as you wear out, and some tissues are constantly growing. On a daily basis, we make hundreds of billions of new blood cells for instance.
Problems arise when the body loses its natural balance. A breast cell, say, that only is supposed to divide 10 times undergoes a mutation that removes some of the checkpoints. But that alone isn’t usually enough. For cancer to develop, typically several things have to go wrong. So the breast cell loses the restriction that prevents it from dividing more than 10 times – and loses the system that tells it to commit suicide (or apoptosis) if it grows too much. The result could be a tumor.
Still, not all cancers lead to disease. The breast cell can grow a little bit then stop. Or it can start growing abnormally but trigger the body’s immune response which either wipes it out or stops it from growing further.
It keeps growing. Things have gotten a little better now than they used to in some situations. In breast cancer especially genetic tests can indicate important information that can guide treatment. In our example, tests indicate that the cancer has an abnormally high levels of the HER2 receptor. This receptor is involved in signaling the cell to grow. 50 years ago that would have been a very bad thing. Now it’s not as bad because we have a treatment, Herceptin, which is a monoclonal antibody specifically to that receptor.
Even then problems arise. Remember, cancer is made of normal cells. More than just cancerous cells express HER receptors – some research has indicated that, among other places, it is in the heart. Herceptin, despite being a powerful treatment, does indeed have some cardiac toxicity issues. The dream of cancer therapy is to find something that only goes wrong in cancer cells and target just that. Failing that, to target something that only harms cancer cells and has minimal side effects to regular cells.
We’re getting better. Take Gleevec, for instance. It was designed to inhibit the Bcr-Abl fusion product which is made by cancerous cells. The clinical trials that led to its approval had incredibly impressive results – if I recall correctly, in one, every person who took Gleevec, except for one, had significant tumor shrinkage. Yet we still have a long way to go.