Reeve, 44, says the announcement comes after rumors began about her wavering health.
She says, "I have recently been diagnosed with lung cancer, and am currently undergoing treatment. I have an excellent team of physicians, and we are optimistic about my prognosis."
Reev adds, "Now, more than ever, I feel Chris with me as I face this challenge. 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."
Christopher Reeve became a dedicated activist for spinal cord research after a horse-riding accident left him paralyzed. He died Oct. 10, 2004.
Throughout his ordeal, Dana Reeve, an actress herself, was a permanent fixture by her husband's side and just as outspoken about the need for a cure for spinal cord injuries.
Reeve is chairwoman of the Christopher Reeve Paralysis Foundation, which funds research on paralysis and works to improve the life of the disabled. It has been awarded $55 million in research grants and $7.5 million in quality of life grants.
