Swift, 37, has been a performer since 1995.
She discovered the tumor doing a breast self-exam.
"I was watching those City of Hope commercials at 3 or 4 in the morning, watching TV and studying my script," Swift told XBIZ. "I said 'OK, fine, I'll check.' I checked my right breast and I checked my left breast, and there it was.
"People say, 'Stay positive' but it doesn't matter. It is what it is. It's already benign or malignant. Whatever your attitude is or however you feel about it, there's nothing you can do. It's there."
Doctors found a 1 centimeter tumor in her left breast. "I saw it on the ultrasound, and it looks like a little pea," Swift said.
Swift's mother works at St. John's Health Center in Santa Monica, Calif., and she plans to be treated there.
"I've been getting consultations over there and I've elected to do a full double mastectomy, because I don't want to go through this again," Swift said. "I'm on emergency status right now. You're supposed to be operated on no more than a month after you're biopsied, and it's been three.
"The reason I'm waiting for my surgery is that they want so much up front."
Swift wants to make a documentary about her illness.
"I'm talking to Nica at Sweetheart Films and they're possibly interested. I definitely want to document everything that I'm going through. I know for a fact that this can help someone else, because I'm not the only person this is going to happen to.
"My father died of cancer and anything that has to do with cancer, I need to be involved."
Swift also said she wants to start a nonprofit organization to help raise money for her surgery and help people in similar circumstances.
"I want to start a scholarship fund and I want to start a foundation for other people that things happen to," Swift said. "Any kind of tragedy. It doesn't have to be cancer. There are things that happen to people and they have nothing to fall back upon in our business. I want to put that in my name. It's important to me that I do that."
A fund has been set up to assist Swift with her medical bills. Checks should be made out to Swift's mother, Heidi Clark, and sent to:
Stephanie Swift Cancer Fund
P.O. Box 9864
Canoga Park, CA 91309
All who contribute $100 or more will receive a free copy of "Stephanie Loves Girls," from Sweetheart Films an all-girl video featuring Swift, Elexis Monroe and Satine Phoenix.
"Stephanie Swift is one of the greatest performers in the history of adult films," Jon B., owner of Sweetheart Video and Sweet Sinner Films, said. "She has starred in many of our productions, and we consider her part of the family. We're deeply saddened by this news."