'90210' alum Tori Spelling, more stars send love to Shannen Doherty after cancer diagnosis

Stars are sending well-wishes to Shannen Doherty after the "Beverly Hills, 90210" alum revealed Tuesday she's fighting stage 4 cancer. 

In her first social media post since making the announcement on "Good Morning America," Doherty, 48, shared a "Peanuts" cartoon that showed Charlie Brown and Snoopy sitting on a dock, looking out at the water.

"We only live once, Snoopy," a speech bubble over Charlie Brown's head reads.

"Wrong!" Snoopy replies. "We only die once. We live every day!"

The comments section of Doherty's Instagram post was flooded with sweet messages from a "90210" co-star, plus other famous faces. 

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"Sending lots of love, support, and animal vibes to make you smile," wrote Tori Spelling, who played Donna Martin opposite Doherty's Brenda Walsh.

"Beautifully said, my beautiful friend," Sara Michelle Gellar wrote. "I get to live my life with you, that makes me the lucky one."

"You are lighting up the path," Selma Blair wrote. "You are loved." 

Kate Beckinsale posted a handful of heart emojis. 

Doherty, who was first diagnosed with breast cancer in 2015, said Tuesday she has been privately living with cancer again during the past year. She did not specifically name what type of cancer she has, but "Good Morning America" reported it is a resurgence. 

"I don't think that I've processed it," Doherty told Amy Robach. "It's a bitter pill to swallow in a lot of ways. I definitely have days where I say, 'Why me?' And then I go, 'Well, why not me? Who else besides me deserves this?' None of us do." 

Doherty said she worked on the "BH 90210" reboot last year amid her health struggles. Through tears, she said she decided to join the cast in part to pay tribute to the late Luke Perry and to be an example to others battling cancer.

"I thought ... people can look at that and say, 'Oh my God, yeah. She can work, and other people with stage 4 can work, too.' Our life doesn't end the minute we get that diagnosis," she added.

Brian Austin Green, who played David Silver on "90210," was the only cast member who knew what Doherty was going through, she said. 

"Prior to shooting, he would always call me and say, 'Listen: Whatever happens, I have your back,'" she recalled. 

'A bitter pill to swallow':Shannen Doherty reveals stage 4 cancer diagnosis

The actress was diagnosed with breast cancer in March 2015 and revealed to USA TODAY in August 2016 that it had spread to her lymph nodes. After a single mastectomy in 2016, she completed radiation and chemotherapy treatment in February 2017 and announced she was in remission two months later.

"The unknown is always the scariest part," she told USA TODAY in 2016. "Is the chemo going to work? Is the radiation going to work? You know, am I going to have to go through this again, or am I going to get secondary cancer? Everything else is manageable. Pain is manageable, you know living without a breast is manageable, it's the worry of your future and how your future is going to affect the people that you love."

Contributing: Andrea Mandell, USA TODAY.