NEW YORK — Former “Good Morning America” host Joan Lunden, 63, has breast cancer.

She disclosed her diagnosis Tuesday on the ABC show, which she co-anchored from 1980 through 1997. She spoke with host Robin Roberts, who has also been treated for breast cancer recently, as has co-host Amy Robach.

Lunden said her treatment will include surgery and radiation. She said she’s already started chemotherapy.

She said after the initial shock, she vowed to learn all she can about the illness and go into “warrior mode.”