Anyway, the only reason that we lose "only 3 years" to cancer is that something else is going to kill us not long after if cancer doesn't. However, if we were able to prevent all other forms of death, cancer would still kill all of us eventually.
I tend to think of curing cancer as not just "adding 3 years of life", but as a small but vital part of developing extreme medical (that is, organic) longevity.
Google's announcement, Time magazine rather sensationalist headline.
In any case, it's nice to know that Google set its sights to "challenge ... aging and associated diseases". Apple's Tim Cook:
For too many of our friends and family, life has been cut short or the quality of their life is too often lacking. Art is one of the crazy ones who thinks it doesn’t have to be this way.
One more step towards "world optimization".