From PEOPLE Magazine Click to enlarge
For the better part of a decade, Maura Tierney played Dr. Abby Lockhart on the hit series ER. So in 2009, when a radiologist put her mammogram on the wall, he assumed she could read it too-and breezily told her that the small lump she'd felt a few weeks earlier "looked bad." "It was the most surreal, crazy moment. Of course I wouldn't know that by looking at it!" Tierney says. "I remember thinking, 'I'm so young. This can't be happening.'"

At 44, Tierney was diagnosed with an early stage of breast cancer, which has a high survival rate. With no family history of the disease and in otherwise good health, "I wasn't angry and never said, 'Why me?' But I was scared," says Tierney, now 47. "My prognosis is good, but I knock on wood."

Tierney opted for a skin-sparing mastectomy, which left her skin intact for reconstructive surgery. After her operation, she was surprised-and initially terrified-when doctors changed their minds and told her she needed three months of weekly chemotherapy. "It's not fun, but it's not as scary as I thought," says Tierney, now a spokeswoman for Amgen's "Chemotherapy: Myths or Facts" campaign (www.chemomythsorfacts.com). "I was able to continue running, riding my bike and hiking, so it was endurable."

While losing her eyebrows and eyelashes as a result of the chemo was upsetting ("That's your expression!" she explains), Tierney wasn't as bothered when her hair began to fall out. In fact, she had her boyfriend at the time shave her head to expedite the process. "It becomes a nuisance," she says. "It was necessary and part of a journey, so it's not so traumatic."

After finishing treatment in 2010, Tierney now gets an annual MRI and mammogram and cooks her own protein-heavy meals to stay strong. And while she's guest-starring on The Good Wife this fall, she says her career has taken a backseat to time at home with her Boston-based family. "In this moment," she says, "I feel very lucky."