Just weeks ago, an optimistic Shannen Doherty told fans that she was fighting for her life. Now, her longtime friend Sarah Michelle Gellar is outlining exactly why Doherty embodies "a warrior."

"She's incredible … When they say a warrior, she is a warrior," Gellar told Access Hollywood. 

"And she lives every day and she's fighting."

SHANNEN DOHERTY 'DOING OK' AFTER REVEALING CANCER HAS SPREAD TO HER BRAIN; CELEBRITY FRIENDS SHOW SUPPORT

Shannen Doherty in a black sweater takes a selfie split Shannen Doherty with a head scarf sits next to Sarah Michelle Gellar at an event

Shannen Doherty is the definition of "a warrior," according to friend Sarah Michelle Gellar. The 90210 star is currently battling cancer. (Shannen Doherty Instagram/Getty Images)

LIKE WHAT YOU’RE READING? CLICK HERE FOR MORE ENTERTAINMENT NEWS

"And you know, there's up and downs, right? There are days that are harder than others, and there are some days that are easy. But, she's doing great," Gellar proudly shared.

The "Buffy the Vampire Slayer" actress and "Charmed" star have been friends since the 90s, when they starred in their respective WB shows. 

Sarah Michelle Gellar in a red dress smiles for a photo with Shannen Doherty in a white dress on the carpet

Sarah Michelle Gellar, left, and Shannen Doherty both starred on WB shows in the 1990s. (Phillip Faraone/FilmMagic/Getty Images)

CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTER

In September, while appearing alongside her "Beverly Hills, 90210" co-stars Tori Spelling, Brian Austin Green, Jennie Garth and Jason Priestley at 90s Con, Doherty, 52, spoke about her cancer battle.

"I have a fight for my life, that I deal with every day. I think I am really great," she told the crowd per People magazine.

Luke Perry, Shannen Doherty, Jennie Garth, and Jason Priestley pose for a photo together in a promotional shot for "Beverly Hills, 90210"

Shannen Doherty smiles alongside the late Luke Perry, Jennie Garth, middle right, and Jason Priestley, right, on the set of "Beverly Hills, 90210." (Mark Sennet/Getty Images)

This past summer, Doherty revealed that her stage four breast cancer had spread to her brain in January and that she had undergone further radiation treatment.

"Surgery. I had a tumor in my head they wanted to remove and also biopsy," she captioned a video shared to Instagram. "I am clearly trying to be brave but I am petrified. The fear was overwhelming to me. Scared of all possible bad outcomes, worried about leaving my mom and how that would impact her. Worried that I would come out of surgery not me anymore. This is what cancer can look like," she cautioned.

Shannen Doherty in a black v-neck dress with short black hair on the carpet

Shannen Doherty was first diagnosed with breast cancer in 2015. (Earl Gibson III/Getty Images)

CLICK HERE TO GET THE FOX NEWS APP

Doherty was originally diagnosed with breast cancer in 2015. At the time, it had spread to her lymph nodes. By 2017, she was in remission, only for her cancer to return in 2020.

A representative for Doherty did not immediately respond to Fox News Digital's request for comment.