If it's the study I'm thinking of, they also gave the rats eating the GMO corn a steroid known to produce/enhance cancers in rats, while the non-GMO rats were not given the steroids. Sorry, but if you are doing an experiment you control for all factors expect the one you are testing for.
This is the study that all the "EBIL Monsanto, GMO is the DEBIL!!" folks that I know on FB quote. But if you simply read the study it jumps right out at you that it's fatally flawed and designed to produce the "GMO=Cancer" result.
Found it:
http://gmoseralini.org/wp-content/uploads/2012/11/GES-final-study-19.9.121.pdfHe gave them
Estradiol, and then was "Shocked !! Shocked, I tell you." at the results.
Not to mention that he's been one of the more outspoken Anti-GMO "scientists" that there are. All the "research" that he's done have shown GMO's to be da ebil, yet no one has been able to duplicate his results. He's a hack.