Chicago Teachers Union president Karen Lewis to retire, has faced brain cancer

Chicago Teachers Union president Karen Lewis submitted retirement papers Friday, a union spokeswoman said.

Lewis had a tumor removed in October 2014 when she was diagnosed with an aggressive form of brain cancer.

The effective date for her retirement wasn't immediately clear.

Lewis again had undergone brain surgery earlier this month, when a source close to the union leader said, "Cancer may be back."

Lewis returned to work after her initial surgery, then had a stroke last year in an area of the brain where the tumor was removed - which she called "a minor setback in my recovery from brain cancer."

Lewis' 2014 cancer diagnosis derailed a likely run for mayor. Her supporters were collecting signatures to put her on the ballot when she underwent surgery. She ended up supporting Jesus "Chuy" Garcia, who lost after forcing Mayor Rahm Emanuel into a runoff.

The type of cancer that Lewis was diagnosed with - glioblastoma - is one of the deadliest cancers, typically proving fatal within less than a year and a half.

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