Shannen Doherty reveals that cancer has taught her what real courage is.

The 45-year-old actress was honored with a Courage Award at the American Cancer Society's inaugural Giants of Science Gala, but as she told ET's Brendon Geoffrion on Saturday, she accepted the award with the courage of others in mind.

"I don't view it as me accepting the Courage Award for myself," Doherty said. "I'm accepting the Courage Award on behalf of every single cancer patient out there because it takes a lot of courage."

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The 90210 alum, who was wearing a gorgeous blue velvet pantsuit, admitted she was feeling nervous ahead of giving her speech. "I'm not quite sure what I'm going to say and Sarah Michelle Gellar is giving me my award -- I have a feeling she's going to make me sob tonight," she joked. "I'm going to get up on stage and have mascara running down my face, but hey, that's OK."

The actress needn't have worried, as she gave an emotional speech about her understanding of courage and how it's helped her battle her own cancer diagnosis.

"For the last year and a half, cancer has been my teacher. It's taught me what love, strength, friendship and support truly looks like," she said during her acceptance speech at the gala. "It's opened my eyes to myself and it's allowed me to not only share my journey with people but it's actually allowed me to share my inner self with anybody who actually wanted to know what it was like... And the end result is that I am nothing but vulnerability and, to me, vulnerability is courage."

"Courage isn't something that comes to you immediately," she continued. "It's not something that you have fully. Courage is something that you gain and it grows. Courage is facing every day and every obstacle one step at a time. Courage is knowing that fear is not going to find a solution; it's not going to help you find a cure. Courage is embracing what you're going through and trying to get through it with as much dignity as you possibly can, while also accepting your circumstances and allowing yourself to feel everything." 

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For the event dedicated to honoring innovators in cancer research, treatment and advocacy, Doherty's speech also paid fitting tribute to her team of doctors and specialists, as well as her husband, film producer Kurt Iswarienko. The Tennessee native also talked about the strength her friends and family gave her with their support. "You guys are my courage. You're the wizard in the Wizard of Oz," she explained. "I was the [Cowardly Lion] and I didn't think I had courage and you all gave me my courage -- and I thank you for that."

Doherty also acknowledged that the award came on the sixth anniversary of her father's death. "He also had his own health problems, and I watched him face life with such joy and love -- and it has just inspired me to be as much like my father as humanly possible, in his battle," she revealed. "So, I want to accept this award not for myself -- I'm accepting this award for all the fathers out there who have taught your children to have courage, and I also accept it on behalf of every single cancer patient out there and all their caregivers." 

It's not surprising that the powerful speech affected the audience. "There was not a dry eye in the room," Iswarienko wrote of his wife's speech on Instagram. "She spoke from the heart and she showed us what grace and courage is in flesh and in spirit."

Some of Doherty's famous besties were in attendance to support her on the night, including Gellar, who presented her with the courage award, and comedian Chelsea Handler. Both women shared photos of the night on Instagram.

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The Charmed actress also had some thoughtful words of support for Michael Buble, who revealed last week that his 3-year-old son had been diagnosed with cancer. Find out what advice Doherty had to give the crooner's family in the video below.