I think I must say something as a Chinese,
, I haven’t read the entire book of the “The China Study”, but I looked the main points in this book is that vegetable diet is good. 
Well, I’m not a scientist, but let me give some examples to challenge such “best sold” book.
My grandpa, died at 64 or 65? when I was a teenager, he died of liver cancer (cirrhosis) around 27 years ago, at that ages, we rarely had meat to eat, we only had meat to eat usually at the end of a year in the winter, even rices were not enough sometimes. Then meat led to liver cancer? Of course not, he was a alcohol drinker and a smoker.
My grandma, died at 6x (I don’t remember the exact age, but sure it’s 6x)?, around 24 years ago, she had a stroke or something related to cardiovascular event, after that, she couldn’t move or talk, slept in a bed for 1 or 2 years I can’t remember, and at the last died. Same as my grandpa, rarely has meat to eat, and furthermore, she didn’t drink alcohol or smoke, 100% a vegetarian eater and rice/flour eater according to the american definition of a vegetarian I think.
My grandma (my mom’s mom), had type 2 diabetics, suddenly died in a night with no one with her at her 6x too, I was 10 or 11 years old at that time, I don’t remember what caused her final death, but I’m sure it’s about the type 2 diabetics. Rarely had meat to eat at that ages too… But she had more rice to eat than my that grandma, because this grandma had more income to buy rice.
After all, I’m quite curious how such best sold book’s author got data to prove her points… But Im sure that her data didn’t include my grandma or grandpa.