The 60-year-old wrote on social media that she was "about to go into surgery to have half of my left lung removed".
She said doctors were "very optimistic" and that the cancer had not spread beyond her left lung.
"I should be up and running around as usual in a month or less," said the star, known for her stand-up routines and TV shows like Suddenly Susan.
"The doctors are very optimistic as it is stage one and contained to my left lung," the Grammy and Emmy award winner told her followers.