[philgoetz]

Given that this was whole-genome sequencing, is 1700 mutations higher than other tissues? The paper doesn't appear to say that.

If they were claiming that this were an unusually high mutation rate, I'd wonder why everyone doesn't die of brain cancer. If other tissue had N mutations per genome, and cancer typically takes 10 mutations to create, in the absence of compensatory mechanisms, the ratio of brain cancer to other cancers should be about (1700 choose 10) / 50 * (N choose 10). If N were, say, 100, that number would be so large that not one person would ever had developed any cancer other than brain cancer.