'It's spread': Shannen Doherty, 45, breaks down in tears as she reveals need for radiation after single mastectomy didn't wipe out breast cancer

Shannen Doherty, who has been battling breast cancer for a year-and-a-half, said that the disease has spread despite undergoing a single mastectomy this past May.

'I had breast cancer that spread to the lymph nodes, and from one of my surgeries we discovered that some of the cancer cells might have actually gone out of the lymph nodes; so for that reason, we are doing chemo, and then after chemo, I'll do radiation,' the 45-year-old told Entertainment Tonight Monday.

The actress, who shot to fame playing Brenda Walsh on the Nineties hit series Beverly Hills, 90210, credited the doctor who performed the mastectomy on her about three months ago, explaining the measures the physician took to make sure she was comfortable with her body after the critical operation.