alexander7 saidAlso, I have heard that being a bottom decreases the incidence of colorectal cancer but I do not have a source for that information
Don't really see how inserting a penis up your rectum counteracts the free radicals that develops into cancer cells.
i'm gonna wager it's the same line of thought that suggests that at any given time, most people are so backed up in their GI tract that they effectively weigh 10 more lbs than they should. hence, that waste is sitting around with more time culmatively to create exposure to free radicals, etc. so...keeping a more efficient gi tract (which can be done via diet and isn't directly related to bottoming) could be associated with lower incidence. i'm not a clinician, or even backing this theory, just guessing what it's based on.