Answers: Your body can't completely digest certain sugar substitutes resembling f.e. aspartame. So they can build up in your liver and your pancreas.
It can afford you pancreatic cancer (I once read this type of cancer has a fatality rate of roughly speaking 80 %), liver cancer and melanoma.
I don't know the answer to this but would also like to know. My grandmother's diabetic and asked the doctor if she could use something resembling Splenda and he told her not to because it causes cancer.