Cancer is actually a process – when your cells go out of control and start dividing rapidly. There are lots of different reasons this can happen (genetic reasons, or due to radiation, or smoking, or too much sun) and each one gives a slightly different type of disease. There are also lots of different types of cells, and depending on which one the cancer starts in you will get a different type of disease.
So for this reason, pretty much every cancer is different from the one before so it will be very difficult to cure them all. However, it think it is likely that many cancers will be more “treatable” in the future and will be something people live with so long as they take their medicine, rather than something they die from.
One of the really important things we need to do is make the drugs that treat cancer have fewer side effects. Sometimes the side effects of the drugs make the patients feel worse than the cancer did in the first place. People working to cure cancers work in all kinds of areas of science – understanding why cells go out of control and how to stop it or fix it, understanding how certain small molecules (drugs) interact with cells and kill them or stop them multiplying, developing new drugs to kill cancer cells, developing new ways to deliver drugs to reduce side effects.
I think Darren’s right – it will be really difficult to cure all cancer but we are getting better at it and we will keep getting better at it.