Jennifer Lyon, a contestant on Survivor Palau, has died at age 37, UsMagazine.com has confirmed. Lyon finished in fourth place in the reality competition’s tenth season, which aired in 2005.

A former nanny, Lyon was diagnosed with stage three breast cancer at age 33 in 2005, and spoke to Us Weekly about the news and her eventual decision to get a double mastectomy, followed by chemotherapy. “I was completely shocked and overwhelmed,” Lyon told Us at the time. “I felt fine that day; in fact, I’ve been healthy my entire life.”

The star also offered support for other women struggling with the disease. “Staying positive is half the battle,” she said.

Austin Carty, an alum of Survivor: Panama – Exlie Island (2006), briefly dated Lyon in 2006. “Jen was a genuinely selfless, sweet-natured person,” Carty told UsMagazine.com Wednesday. “She always had a smile. She cared about every person.”

Carty last saw his friend at a breast cancer charity event in New York in November 2008, where she received a standing ovation after giving a speech. “She was engaged in the greatest fight of her life, but she had every intention to fight and spread her positive messages,” Carty said.

“This has really rocked the Survivor community. It’s just so sad.”

Another friend and former Survivor contestant, Johnny Fairplay, tells Us, “Jen was such a beautiful person. I wish life was as simple as survivor because i know for a fact there are 300 of us that would use every immunity idol and jury vote in the world to have her back.”