Shannen Doherty on thriving after stage 4 breast cancer

Shannen Doherty is opening up about her battle with Stage 4 breast cancer.

In an exclusive interview with ABC News, the "Beverly Hills, 90210" actress gave an update on the treatments she's undergoing and how cancer has changed her perspective on life.

"I'm going to keep fighting to stay alive," Doherty told "Nightline's" Juju Chang.

Last year, Doherty told "Good Morning America" about her breast cancer's recurrence after being in remission for five years. Since then, cancer treatment plans, called protocols, have improved.

"I am on my first protocol, which is a very, very big thing," Doherty said. "So it's kind of like you just want to last on your protocols as long as possible so that you don't run out of protocols."

Stage 4 breast cancer is often not curable. But an improved understanding of what treatments to give, and when, has led to increased life expectancy. For some, this could make living with stage 4 cancer more like a chronic disease.

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But despite the treatments and the daily battle with breast cancer, Doherty isn’t letting that slow her down. The actress has two Lifetime movies debuting this month.

"I think work was always very fulfilling to me, but in a way, it's become even more fulfilling," Doherty said. "A lot of people who get diagnosed with stage four, they sort of getting written off. It's assumed that they cannot work or they can't work at their full capacity. And that is not true. And that is something that I would really like for people to sort of stop assuming, and give us a chance to prove them wrong."

Doherty, who was known as a wild child in her 20s, says cancer has changed her perspective on life.

When she was younger, Doherty said being an actress came with the expectation that women were to keep their mouths shut, which led to her wanting to rebel.

"It was a very different time to be an actress because a lot of the men in the business were maybe not as collaborative with women as perhaps they are now," she said. "It was definitely more of a, 'Just get on your mark and say your line and do your job.' And I think because of that, I was extremely rebellious. And I think because of all the names that were the labels that were given to me, I sort of retracted even more into myself and became even more defensive and even more shut down."

Now, she says cancer has helped her trust others again.

"You really have to dig deep to face cancer, and in that you find all the stuff that you had hidden away," she said. "And it's beautiful things that you find. You find the vulnerability, you find your trust in people again, you find forgiveness."