There is so much controversy surrounding the consumption of all artificial sweeteners and cancer, in particular aspartame, Studies in humans are almost impossible to conduct since the latency period of some cancers is so long (even years). The latency period is the time that passes between being exposed to something that can cause disease (such as radiation, a carcinogen or a virus) and having symptoms. My brother died of pancreatic cancer and drank diet sodas all day – not sure how many , but way over moderation . Of course, one case does not imply cause, but I always felt that there may be some connection through some unknown epigenetic process.
Based on what we know, it may be prudent to limit any type of soda consumption especially if you have any family history of cancer.