I'll try to answer your question to the best of my ability given my background. I'm a trained Medical Librarian and without researching your question for hours (which is what one could do with such a question) I'll give you my best immediate thoughts (not really guesses) on the subject.
1. When you say "now", you don't clarify what you mean by "now". Does "now" mean within the last 10 years, 50 years or 100 years? I'll try to answer for all...
a) People are living longer lives as we've discovered vaccines for illnesses that used to kill (i.e., polio, whooping cough) and antibiotics (people don't usually die from syphilis anymore, nor do they have to take arsenic to recover such as Isak Dinesen did [the author of "Out of Africa"]). When people live longer lives, it offers cells more of a chance to mutate. When cells mutate, you have Cancer...
b) Yes, further "industrialization" or what I'd like to refer to as the "Monsanto" effect comes into play-we have more pollution, we have artificial sweeteners, we have Pepperidge Farm Milano cookies (which are delicious) but their Milanos are sometimes made with cottonseed oil - check out the bag!! (cotton is not grown as a food crop and so non-food pesticides can be sprayed on it even though the oil can be used in these cookies and other things [I called PF about this a few years ago and they hung up on me]). Guess, no more Milanos for me!!...;) There's mercury in the tuna fish, there's mercuty in our (old) dental fillings, etc., etc., and so forth...
c) The Information Superhighway...Yup, what we're on right now...the Internet, the worldwide web, The NY Times online, Facebook, etc. News is immediately posted and croses the country and the world in a matter of seconds to minutes. Therefore we (all) know about more cancer than we ever could have known about without the existence of the internet if only we had books, newspapers and journals.
2) I believe that Caesar Rodney, one of the signers of the Declaration of Independence had Cancer. I'm not sure which colony he was from (Rhode Island?), but given the fact that the birthrate has increased incrementally the way it has, I wonder how much higher per capita the cancer rates are given all of the above factors.
3) By the way, in case everyone thinks that eating and drinking everything untainted and off the land is safest, let me assure you that it's not (underline not) the case - please remember that unpasteurized raw milk from a cow that is tainted can cause a person to become ill with TB, and that drinking delicious apple cider that you can purchase from a farm stand (as opposed to pasteurized apple juice or pasteurized apple cider) can cause someone who's immunocompromised to become extremely ill and possibly die (the apples that are used in cider are often those that are no good for eating and could have fallen in a field that has cow manure in it).
I could go on about cancer and rates of other diseases which have risen and fallen as a result of further industrialization or modes of transportation, etc., but I think you see where I'm going here. I think this is a good place for me to stop and hope that some of the medical professionals in the community especially would join in this discussion-anyone else as well!
Thanks for choosing such an interesting and thought provoking question. Sorry if I made eating Milanos not so much fun!! Moosewood cookbook has a great brownies recipe!...;)