In case there was any confusion in the matter, the tough-as-nails Shannen Doherty plans to fight — and triumph over — her breast cancer.

In a preview of an upcoming interview with Entertainment Tonight, the veteran TV actress says she's adamantly battling her illness, though the clip mentions a "devastating setback."

Doherty publicly acknowledged she'd been diagnosed with breast cancer a year ago in August 2015. She's since documented the intimate details of the experience — including shaving her head down to the scalp — in a series of Instagram photos.

"I started thinking that I wasn't gonna live," Doherty says in the clip. "I don't look past today."

"I want to believe that if I fight, I'm gonna be okay," she adds.

And Doherty's support runs deep — former 90210 co-star Jason Priestley told The Hollywood Reporter that while he hasn't seen Doherty in a while, he's sure she'll fight through.

"It’s incredibly brave what she’s doing. I know she will come out of this," he said. "Obviously, I have a lot of love for Shannen. She’s going to beat this because she’s a fighter and she’s a tough kid. She always has been. I send her nothing but love and light because I have nothing but love for Shannen."

Watch the preview and be sure to check out the full interview on tonight's ET episode.

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