I have been talking about exactly this with a friend yesterday.
We were discussing how dangerous space radiation really is. Consider you want to live on Mars. There's about 12 Sievert (Sv) of radiation that you would be exposed to through your lifetime if you lived in a habitat with absolutely no shielding, about 0.41 mSv/day average (Source).
Wikipedia says that a 1 Sv dose is linked to a 5.5% chance to eventually develop fatal cancer (Source). Based on that, 12 Sv would give you a 50% chance of developing cancer throughout your life. (1 - 0.055)^12^ = 0,507...
But is this really a meaningful way of looking at things? I guess there's ways that life could become much more radiation-hardened, if we only knew how. And fungus like the one in the article are to make us understand how.