Don't know if total ignorance is a blessing or not in this case, but....

Perhaps it has to do with how the animal is raised (grain vs grass?), or how the meat is prepared. Maybe there's something else in their diet or culture or even genetics which helps to offset it. Maybe they are dying of something else. Maybe the numbers of under-reported. Maybe cancer rates are more impacted by other factors, like smoking and drinking, and this is, relatively speaking, a drop in the bucket.