'Why me?': Shannen Doherty tearfully reveals stage 4 cancer diagnosis

Star of Beverly Hills 90210 Shannen Doherty has revealed a stage four cancer diagnosis in an emotional interview. 

Doherty said the news was going to "come out in a matter of days," prompting her to speak out about her health so that her fans could hear it from her. 

"I'm stage four. So my cancer came back. And that's why I'm here," Doherty said through tears on Good Morning America. 

Doherty was first diagnosed with breast cancer in 2015, and went on to document her battle on social media. 

When the cancer returned, Doherty said her main concern had been about how to break the news to her mum and husband. 

"I don't think I've processed it. It's a bitter pill to swallow in a lot of ways," she said. 

"I definitely have days where I say why me. And then I go, well, why not me? Who else? Who else besides me deserves this? None of us do," she said. 

Despite the return of the debilitating disease, Doherty went back to work on the set of the 90210 reboot, which began four months after her friend and co-star Luke Perry died. 

"One of the reasons, along with Luke - that I did '90210' and didn't really tell anybody because I thought, people can look at other people with stage four can work too," Doherty explained. 

"Like, you know, our life doesn't end the minute we get that diagnosis. We still have some living to do."