The 48-year-old had been in remission for three years before being told her cancer had returned.
She appeared on Good Morning America today to share an update about her condition to fans.
She said: "t’s going to come out in a matter of days or week that I am Stage 4, my cancer came back and that’s why I am here.
"It’s a bitter pill to swallow in a lot of ways. I'm petrified. I'm pretty scared.
"My mom is a ridiculously strong courageous human being. So is my husband, but I worry about him."
Doherty added: "I want to control the narrative. I want people to know from me," she said.
The actress said she knew of her diagnosis when Beverly Hills 90210 co-star Luke Perry died of a stroke last year.
She said: "Why wasn't it me? It was so weird for me to be diagnosed and then somebody who was seemingly healthy to go first. It was really shocking and the least I could do to honour him was to do that show. I still haven't done enough in my opinion.
"When I finally do come out, I will have worked and 16 hours a day and people can say, "oh my god she can work and other people with stage IV can work too.
"Our life doesn't end when we get that diagnosis. We still have some living to do.