And in a new interview with Access Hollywood's Laura Saltman, Christina shed new light on the decision that saved her life.
"My mom is a breast and ovarian cancer survivor. Also, my cousin unfortunately passed away from ovarian cancer [this] past year, so we have it strongly in our family," Christina said. "I went once a year to get my mammograms and then I would go every six months and get an ultra sound… Eventually my doctor said he just couldn't tell on the mammogram and [he said] that they were finding MRIs were really great for discovering it at an early stage. I had my first MRI and they found cancer."
It was a life saving decision at age 36. Diagnosed with breast cancer in March 2008, that early detection made all the difference for a now healthy Christina who has become an advocate for early screening – both mammograms and MRIs. She even started Right Action for Women, which helps pay for tests for high risk young women who can't afford them.
"An MRI can catch it years before a mammogram can. That's what happened with me," Christina explained. "It was able to be caught at a stage that I didn't have to go through chemotherapy or radiation."
Although Christina only had cancer in one breast, she decided to have a double mastectomy after testing positive for a BRCA1 gene mutation, which increases the odds of cancer returning.
"I had these two lumpectomies and they felt like they had gotten everything," Christina told Laura. "After they did my mastectomy they found more cancer cells that had started to grow, so it was already happening, it was already in the process… If I hadn't done this I would have been in trouble."
Christina's boyfriend, musician Martyn LeNoble, was by her side throughout her journey including months of reconstructive surgery.
"I had pretty good ones before so I kept them the same size," she said of her breasts. "It's sad, but these ones don't move. I'm like an enigma in my running class because everyone else's boobs are doing this [mimics bouncing]."
"On the cover of Women's Health you had a tank top on, so was there no bra there?" Laura asked, referring to the October 2009 cover of the mag.
"No bra. That's them just hanging out. That was my big reveal of them," Christina said. "I had been kind of hiding them a lot."
Clearly empowered now, Christina is the ambassador for Lee National Denim Day. On October 2, supporters will wear jeans to show their solidarity. Supporters are also asked to make a $5 donation. The proceeds benefit Women's Cancer Programs of the Entertainment Industry Foundation.
"I have actually saved people's lives and that is wroth every bit of every bit of pain and struggle that I went through," she said.