It's all diet related and what part of the digestive tract most sensitive to the intake. Weird one in China, from memory so likely partially in error. High rate of colon cancer in an rural area. First thought was long forgotten chemical spill but no industry ever there. Found that main diet was grilled pork with cabbage unique to that area. Not grown elsewhere in China. Fat from the pork hit the coals and vaporized back onto pork. This new compound reacted in stomach with something in the cabbage to form a <cancerous> compound. As I recall rates dropped over time when new cooking methods used.