After being diagnosed with breast cancer at 36 years old in 2008, Christina Applegate first underwent a lumpectomy. Upon learning that she was a carrier of the BRCA1 gene mutation, she removed both her breasts in a double mastectomy. Later, she opened up about the process to Oprah. It can be very painful," she said. "It's also a part of you that's gone, so you go through a grieving process."