Roy Rooster, the law allowing removal of chicken tumors was in an article that I read years ago but if you google you will see the subject is still around. I only know what I read so I assume it was true then, probably now. There is a chicken "factory" near me and I see chickens taken to be processed frequently. It is an awful sight. It is a fact of life, and I sometimes wonder how the pretty chicken meat in the super market is the same going down the road.
I've never seen a chicken tumor and I didn't mean to alarm you. Evidently, our government feels the meat is safe to eat. I am personally very careful cooking super market chicken, using bleach in the kitchen, etc. There have been numerous articles about our food in various country living magazines. I believe chickens butchered at home would be very safe.