The NYTimes recently published an article on recent cancer research observing that cancer cells tend to have many swapped blocks of DNA. I have a very good feeling about this line of research.
The short article makes an observation which is especially interesting: the gene RAD51C, which is normally responsible for mending chromosomal breaks, is disrupted in this particular instance. Perhaps, the researchers suspect, this has allowed the rest of the breaks to take place.
These results are of course early, so we should be careful to take them with a grain of salt; but I recommend that readers keep an eye on this field of study.