This is a common falacy. 150 years ago cancer was extremely rare disease, among the young, the middle-aged, or the old. The average lifespan may have been shorter, but people who did make to an advanced age did not, by and large, die from cancer.
Your assertion that "cancers take a long time to develop" does not gibe with the veritable plague of childhood cancers and breast cancers among middle-aged women these days.
There is a whole lotta evidence that cancer is largely if not wholly a byproduct of modern industrial contamination, but you won't find the NYT's Gina Kolata and other cheerleaders for the "professional-racket-medicine" complex, as Ravi put it, writing this up.
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Colin Brace
Amsterdam