Former Beverly Hills, 90210 star Shannen Doherty broke down in tears and said she lives one day at a time as she discussed her fight against breast cancer.
The 45-year-old opened up about her condition to America's Entertainment Tonight (ET).
In the preview of the episode, which will be screened on Monday, the ex-Charmed star admits that her condition has taken its toll.
"It's hard," she says. "I started thinking that I wasn't going to live... I don't look past today."
Shannen went public with her breast cancer in August last year, after being diagnosed in March. She tells ET: "I don't know if I'll ever look like me again."
The actress will also reveal "a devastating setback" and explain why "her diagnosis is even more heartbreaking than she ever could have imagined".
She says: "I want to believe that if I fight, I'm going to be OK."
Shannen is documenting her breast cancer fight and has thanked her "squad" for helping her through the ordeal.
The actress recently posted images of herself getting her hair shaved on Instagram.
She thanked her friends and her mum for showering her with love and support "every minute".
Best known for her role as 90210´s Brenda Walsh, Shannen was accompanied by her mother Rosa and friends Anne Marie Kortright and Chris Cortazzo in the photo.
In her Instagram post, she said husband Kurt Iswarienko was away for work, but she was "in good hands".
She wrote: "@kurtiswarienko was in Mexico working but knew he left me in good hands. @annemkortright @chriscortazzo #mamarosa I love you. #mycrew #thisisasquad"
In a previous post, Shannen was close to tears as her mother held her in her arms.
In the following candid shots, she was seen first shortening her hair with scissors, before using the razor to shave away the rest.
Appearing on the Dr Oz Show in February, she revealed that she is unlikely to be able to have children due to her cancer treatment.
"I'm 44 and my husband and I wanted children," she admitted, adding that the couple would look at adopting instead.
Shannen's cancer diagnosis was publicly revealed in a lawsuit filed against her former business managers last year. She claimed they mismanaged her money and allowed her health insurance to lapse.
She said she didn't go to the doctor until she had insurance and there was a delay in diagnosing the cancer.