I'm starting to see why some of you retards don't read the other comments, I wasn't aware that Billy had died almost 7 years ago and Dahlia almost 3 years ago. Wonder who else is cursed from that set like the Poltergeist film set too.
That was the initial story but later it was confirmed he died of ethanol intoxication and the cancer wasn't what killed her but a mixture of battling it and depression caused her to commit suicide. Sad, regardless.