That hard-fought struggle to survive ended Tuesday, when Lyon died at the age of 37.
"She is the model of grace, and has been so brave," her fellow contestant, Ian Rosenberger, told PEOPLE earlier this month, at a Survivor 10 reunion. Said Lyon: "Survivor taught me there's an end in sight. As hard as it is, it will be over, and you have to appreciate every day."
Felt Something AbnormalIt all began in the summer of 2004, when she "felt something in my right breast that didn't feel normal," Lyon told PEOPLE in October 2005. "I thought it was probably scar tissue related to my breast implants. It was right along the ridge of the implant, so I let it go, and I let it go for a long time."
Asked why she delayed seeing a doctor, Lyon said, "I didn't have insurance, which is a big part of it. And it really wasn't changing much. But a year later, I felt another lump, and then I felt something under my armpit."
By Aug. 9, 2005, Lyon was diagnosed with stage III breast cancer. Her older sister Kim, who was also a nanny, found her a surgeon, Dr. Kristi M. Pado, who performed a 5-hour modified radical bilateral mastectomy later that month. A few weeks after that, Lyon underwent breast reconstruction surgery. "It was a huge boost to my spirit," she said.
Began ChemoLyon then went home to The Dalles, Ore., to face months of chemotherapy. "They are giving me the treatments that do cause hair loss and those kinds of things," Lyon said, "but Survivor has helped me in every sense of the word. Coby [Archa, another contestant] is going to come up and shave my head for me, and he's going to shave his, too!" (As Archa remembered, "With her family in her kitchen, I handed her the clippers and told her to shave mine first.")
Lyon's spirit was infectious, said Rosenberger: "Through the chemo, the surgery, medications, and the months of waiting, and then the hoping, and the letdowns, and then the real sickness and the pain, where others get depressed, self-piteous, and dark, where others may give up hope, Jenn sparkled."
But Lyon's treatment was far from over. "The younger you are when you are diagnosed with cancer, the more aggressive that cancer tends to be," Dr. Pado told PEOPLE in 2005, "and the longer life you have ahead of you, the more likely it is that a cancer can come back."
For a year and a half after drug therapy following chemotherapy, Lyon seemed to be progressing. "I was basically clear," Lyon told PEOPLE in 2008, "but then my blood levels, my blood sugar markers, started going up, and they did some scans and found [cancer] in my bone, the backbone, which is a very common place for it to metastasize. It's not all good news, unfortunately."
Her Final MonthsYet as long as Lyon still had "some sort of notoriety," she said, "I will use it to help other people" – and she did. Last month, "because the previous Christmas had been so rough," Jeff Probst said, "she decided to open a Christmas tree lot so she could extend the holidays for as long as possible. Then in typical Jenn fashion, she made the decision to donate profits to the Susan Love Cancer Research Foundation.
"The tree lot was a major undertaking, yet there she was every day doing her part to try to raise money to make sure nobody else had to ever endure the same struggle."
Ten days before her death, friends and family surrounded Lyon at the Survivor 10-year anniversary party in Los Angeles. "She looked absolutely stunning that night," Probst said. "Certainly a lot of that is because Jenn was always a beautiful woman, but there was a spirit inside her that was palpable. It was clear to me that she knew this was a goodbye."
It was a fitting tribute, said sister Kim: "Jenn would rather go to a Survivor party than anything else. No matter how bad she was feeling. She could always rally for that kind of a celebration."
Observed Rosenberger, "People couldn't help themselves but be drawn to her, and you always felt a little bit warmer inside when she was around. When she found out she was sick, that didn't change. So many people are dying of cancer. Jenn showed everybody how to live because of it."