When Marianna Mott Newirth, 56, learned she would lose a breast due to cancer, she immediately began trying to wrap her head around reconstruction. It wasn't until her surgeon uttered one word that Newirth changed her mind.

"My doctor used the term flat," Newirth said. "I went on the internet to research flat, and it was like opening a door I didn't know existed."

After discussing the idea with her husband, Newirth, who works as a librettist in Manhattan, decided to forego reconstructive surgery in favor of being a one-breasted woman.

"There's a lot of pressure to look symmetrical," she said in an interview. "Women are supposed to have two breasts, and being one-breasted or flat on one side is a challenge to societal norms, but there is a growing movement."

About 13 percent of women will develop invasive breast cancer, according to Breastcancer.org data. In 2021, about 281,550 new cases of invasive breast cancer are expected to be diagnosed in women in the