A network representative confirmed her death Wednesday.
Lyon was raised in the Columbia River city of The Dalles. Her biography on CBS.com says she attended Portland State and Western Oregon universities before graduating from Oregon State.
She joined the "Survivor Palau" competition as a nanny and graduate student from California. Following her diagnosis, she became an advocate for breast cancer awareness.
"Survivor" host Jeff Probst said in a statement he reconnected with Lyon several years ago and stayed in touch during her cancer treatment. In his words, "Her wisdom about how to live a life with quality seemed to grow with each passing day."
Probst said Lyon died in Oregon.