Beverly Hills, 90210 star Jason Priestley has admitted his fears for his former co-star Shannen Doherty, who is battling breast cancer, but said "she is a tough kid".
Jason and Shannen played twins Brandon and Brenda Walsh in the hit 1990s show about teenagers living in the exclusive neighbourhood of Los Angeles.
Shannen, 45, revealed that she was fighting breast cancer in August last year, after being diagnosed in March.
She has been documenting her fight on social media, recently sharing a set of images of herself shaving her head and going through chemotherapy.
Last month she settled a lawsuit against her former business managers, who she said left her without health insurance and caused a delay in doctors diagnosing her.
Jason told the Press Association: "We are all very worried about Shannen and feel for her but we all know her and how tough she is and she has never shied away from a fight.
"We are very hopeful she will beat cancer like she has beaten everything else. She's a tough kid."
Jason, who is soon set to play a private investigator in new show Private Eyes, says he is still inundated with fan questions about his years on Beverly Hills, 90210, despite the show ending its 10-year run in 2000.
He said: "People always want to know about 90210 because that show was iconic for a lot of people. It was on for so long and it was a big part of people's lives, an important part of their lives."
While Jason, 47, is still associated with a role he played in his 20s, he does not begrudge it, saying: "I have always found it to be beneficial for me, it opens doors for me and it always has."
Jason rocketed to fame when he was cast in the show, even appearing on the cover of Rolling Stone with Shannen and their co-star Luke Perry, but said it was harder to be a young celebrity now.
He said: "I think being famous now is more difficult than it was back then. Everyone has a phone and everyone is documenting everything.
"It depends on the person though, I was very conscientious about the work I was doing, I put myself in situations where I was working all the time, I didn't have the opportunities to get into too much trouble. Idle hands are the devil's plaything."
-- Universal Channel UK (@UniversalChUK) September 6, 2016
Jason's new show takes him home to his native Canada, where it has already enjoyed great success.
He said the chance to play an investigator had allowed him the chance to revisit programmes he loved as a child.
She's got the cases, he's got the connections... Jason Priestley stars in brand new Private Eyes. Starts 19th Sept.https://t.co/Glfa21GyPK
-- Universal Channel UK (@UniversalChUK) August 24, 2016
He said: "I grew up on a steady diet of shows like Magnum P.I., that was my generation and we grew up with those characters, that was who we idolised. To get to play a guy like that is a dream."
Private Eyes starts tonight at 8pm on Universal Channel.