The 42-year-old television personality marked the anniversary by sharing an emotional post Sunday on Instagram.
"'Everything will be OK in the end. If it's not OK, it's not the end,'" Rancic wrote. "Ever since I was diagnosed with breast cancer, this quote has been my mantra. These words have been my anthem, my inspiration, my comfort and my prayer."
"Now that I've reached this critical milestone, the odds of the breast cancer coming back are not gone but exponentially lower," she revealed. "Breast cancer is more of my history, less of my present, but that doesn't mean I am leaving this battlefield."
"For me, this week marks a new beginning. I breathe a sigh of relief as I come to the end of this five-year marathon and cross the most significant finish line of my life so far. I can now declare, with immense gratitude and God's love, that I can feel the sun shining on my face. And I can also say that I'm finally...OK," the star said.
Rancic had revealed on the "Today" show in 2011 that she was diagnosed with breast cancer after having a mammogram prior to her third round of in-vitro fertilization treatments. She underwent a double mastectomy the same year.
"I was very fortunate. Because I've gone public with the breast cancer, I hear a lot of stories and some are not as great as others. Whether it's resulting in complications from surgery...whatever the case. I hear it all. And I realize how fortunate I am," the star told CBS News in 2013.
Rancic and husband Bill Rancic welcomed son Edward via surrogate 10 months after the star announced her diagnosis. Rancic is known for hosting E! News from 2005 to 2015, and presently hosts the E! series "Fashion Police."
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