Do you have a reference for survival rates? Note that there are many confounding factors - lung cancer incidence has dropped a lot although lung cancer itself remains intractable to average cancer survival rates may have improved.
It also is one where heredity and genetics plays an enormous role (as opposed to purely environmental conditions).
Like I said, molecular biology is something we've only just noticed far less got a handle on.
Ars Longa Vita Brevis.