> At the same time, everybody seems to accept that the chance of getting cancer in your lifetime has risen to about one in three for men and one in five for women. And nobody knows why.

Couldn't it simply be that we are curing/reducing the incidence of most other diseases? Cancer is something that typically doesn't occur until the later years of life. By reducing the number of people who die of other causes, you are increasing the potential population of people who end up getting cancer.