She was 85 and she died of natural causes.
In 1972 Shirley was diagnosed with Breast Cancer. On Feb 14 2014 in California at 85 she died of chronic Obstructive disease despite her family claiming it was natural causes. Link.
You say smoker as if it was a terrible thing to do.
She had quit smoking a long time ago.
Her cause of death was "natural causes". A more comprehensive autopsy was not ordered.
Also reported online she was a closet smoker.
