The Newburg, Md., native said she has received letters from supporters all over the country, including from fellow "previvors" who say they have been inspired to undergo their own preventive surgeries. The Wynn sports book gives her 25-1 odds of winning the Miss America crown, making her a moderate favorite.
But her decision is drawing criticism as well as praise in the staged-managed world of pageants, where contestants regularly go under the knife for a very different reason.
She also receives hate mail from beauty circuit die-hards who write to insist that she continue filling out her bikini.
"You have people who say, 'Don't have the surgery. This is mutilating your body. You don't have cancer.' They want to pick apart every little thing," she said. Some have even accused her of faking to make herself a more media-friendly candidate.
This kind of pre-emptive surgery has divided the medical community as well. For someone in her early 20s to have the procedure is "very unusual," said Todd Tuttle, chief of surgical oncology at the University of Minnesota.
Sandra Swain, medical director of Washington Cancer Institute in Washington, D.C., fears that women who have lost family members to breast cancer could take Rose's example too literally.
"We're seen a rise in prophylactic mastectomies and a lot of it is not for a medical reason; it is because of fear and anxiety," she said.
Rose does not carry the "breast cancer genes" BRCA1 and BRCA2, but she did inherit a rare genetic mutation which might predispose her to the disease.
Her brother, who works for an oncology association, said he sees the irony in a beauty queen choosing to give up her breasts but supports his sister's choice.
"For me what trumps everything is her living, hopefully to a ripe old age, as opposed to any ancillary things that she might lose from potentially winning Miss America," said Dane Rose, 31.
Rose initially said that if she won the crown, she would postpone her surgery until after her year as a title-holder. But while shopping for earrings to match her black velvet pageant gown Wednesday, she said she was now considering having the surgery during her reign as a way of inscribing her platform of breast cancer prevention on her body.
"I've been thinking how powerful that might be to have a Miss America say, 'I might be Miss America but I'm still going to have surgery. I'm going to take control of my own life, my own health care,' " she said. "So I guess it's up to what happens on Saturday night."
Hannah Dreier can be reached at http://twitter.com/hannahdreier .