Dana Reeve, who spent nine years caring for her paralyzed husband, Christopher Reeve, until his death last year, announced Tuesday that she has lung cancer.
Reeve, 44, said she decided to disclose her illness following rumors about her health in the media.
"I have recently been diagnosed with lung cancer, and am currently undergoing treatment," Reeve said in a statement.
"I have an excellent team of physicians, and we are optimistic about my prognosis."
"Now, more than ever, I feel Chris with me as I face this challenge," she said.
"As always, I look to him as the ultimate example of defying the odds with strength, courage and hope in the face of life's adversities."
Reeve, who starred in the "Superman" films, was paralyzed in a horse-riding accident in 1995. He died October 10, 2004.
Dana Reeve, an actress, was a constant companion and supporter of her husband during his long ordeal and his work for a cure for spinal cord injuries.
The couple has a 13-year-old son.
She is chairwoman of the Christopher Reeve Paralysis Foundation, which funds research on paralysis.
To date, it has awarded $55 million in research grants and $7.5 million in quality of life grants.