Shannen Doherty is fighting for her life in an ongoing battle with breast cancer. Her "Beverly Hills, 90210" character, Brenda Walsh, went through a similar experience 25 years ago.

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Doherty relived the show's 1991 episode, “It’s Only a Test,” in a recent interview with "Entertainment Tonight," talking about the co-stars with whom she keeps in touch since the show ended.

“I remember that episode because it really meant a lot to me,” Doherty said.

In the episode, Brenda does an at-home breast exam and finds a lump in her left breast. She later undergoes a biopsy. While her character receives a clean bill of heath, Doherty herself now faces the worst possible situation.

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Doherty told fans earlier this week that the cancer has spread to her lymph nodes. She underwent a single mastectomy in May and is currently working through eight rounds of chemotherapy. Once she finishes the chemo, Doherty will undergo radiation treatments.

“Back then, I was a kid, man — I thought that I was invincible, I thought I was going to live forever,” she said.

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Doherty had public fallouts with some of her “90210” castmates, but remains close with Jennie Garth, Brian Austin Green, Jason Priestley and Ian Ziering.

“I’ve heard from quite a few of my costars,” she said. “They know who they are. I don’t feel l like I need to point them out, and I thank them from the bottom of my heart for reaching out to me.”

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The conclusion of Doherty’s interview with "Entertainment Tonight" airs Wednesday.