What's up with all of these posts with no sources and unscientific reasoning? The largest factor that explains differences in cancer rates is simple reporting differences in poor countries which have inadequate diagnosis and bioinformatics capability. The second largest factor simply comes from life span differences. The longer you live, the more risk you have of developing a cancer. Third, you have tobacco.
Fat? No, the proposed links between fat and cancer have been shot down time and time again. There was a huge amount of activity around the theory that fat intake was correlated with breast cancer due to the relationship with estrogen, but that was blown out of the water by several studies. There has been no difinitive link shown between fat intake and cancer, in fact, there have been studies showing that a certain level of fat intake has a protective effect.
Cancers have various proposed causes. Some are known to be viral. Some are known to be catalyzed by some carcinogens and mutagens (note: not everything carcinogenic neccessarily produces cancers) Some are known to be genetic. And some are known to be caused by immune system disorders.
There is no one cause, and there is no cause which you can strictly link to Western living (minus tobacco which isn't exactly a Western only club), not even carcinogens, because poor people often drink well water loaded with higher levels of carcinogens and mutagens than Westerners.
So this is not especially a time to feel guilty of a gluttonous lifestyle. For heart disease and diabetes risk? Yes. For cancer? It is unknown. And certainly, I'll trade a life expectency of 77-80 with adequate care to one of 60-70 in a desert hellhouse hospice.