I dont know if Huldas theory about cancer is right or wrong! I know the zapper works! I have one and the parasites to prove it works! I figure it this way if her theory was invalid the medical establishment would,nt pay as much attention to her as they do. I believe for a fact that the toxins she says cause parasites are very dangerous and most people are blind to the seriouness of these chemicals they have laying all over thier homes! And if anybody thinks Hulda is getting rich and thats why she is in it, they are uninformed or misguided!