I wouldn't worry
Yeah, the cancer claim seems overstated. There are other health concerns with more substance, however, ironically including weight gain.
No, reject aspartame. Fake science support aspartame ; fake science supported tobacco Cartels. End of story.
Smoking is associated with increased risk of many types of cancer, not just lung cancer. For example, it very significantly increases the risk of oral, esophageal and bladder cancer, but is also associated with many others, like colon cancer.
I imagine that if something consumed in such large quantities like aspartame had a clear link to cancer, it would have been noticed by now.
Wasn't there an observation years ago that rats get cancer from consuming dioxin, but guinea pigs don't? Something like that, maybe? (BTW, that's eating or drinking, not much protection against breathing dioxin.)