Martina Navratilova revealed Wednesday that she is undergoing treatment for breast cancer. She was diagnosed with a noninvasive form of the cancer, called ductal carcinoma in situ, that was detected during a mammogram and doctors have told her the prognosis is excellent.

Navratilova revealed the news to People magazine. She said that she cried when her biopsy came back positive after a mammogram in February, calling it ``my own personal 9/11.''

"I cried. It knocked me on my ass, really. I feel so in control of my life and my body, and then this comes, and it's completely out of my hands."

She had a lumpectomy in mid-March and will begin four-to-six weeks of radiation treatment in May.

In an interview shown Wednesday night on CNN's "Larry King Live.", Martina said how she found out and how she felt about it.

Martina Navratilova reveals she has treatable breast cancer