John Bermingham asked:
With the recent sequencing of various lung cancer and melanoma genomes, it seems that the specific sets of mutations that cause one type of cancer differ from those that cause another type of cancer.
If this is the case, how does cancer spread from one organ to another?
For instance, if lung cancer spreads to the brain, is it a cancerous lung cell that's somehow got into the brain and is multiplying out of control there?
Well this is a process called metastasis and basically, it happens when, as cancers kind of evolve within the body, eventually the cells evolve the properties that they can start to breakaway from the starting primary tumour. They spread through the bloodstream or through the lymphatic system, and they set up home and start growing somewhere else. Often, this is in organs like the lungs, the liver and the brain. Weíre not entirely sure why they pick those areas. Itís sometimes thought itís because they're areas of high blood flow. But there may also be biochemical properties of different parts of the body that different cancers like to spread to. So itís an area thatís really under a lot of active research, and is an area that hopefully we can make progress in in the future because if we can stop cancer from spreading, that would really be the root to beating it properly.