Shannen Doherty, who is battling stage four breast cancer, reflected on the painful decision to shave her head amid chemotherapy treatment in 2016.

In an emotional Instagram post, Doherty wrote that despite trying a cold cap that doctors thought could save her hair, it didn't work. Studies have shown that a cooling cap worn on the head before, during, and after chemotherapy treatment can help some patients keep more of their hair, according to the Centers for Disease Control and Prevention.

As her hair began to fall out and bald spots became "increasingly harder to cover... up," Doherty felt she had no other choice but to shave her head.

"It was a battle on its own. I loved my hair. It had defined me to a certain extent and provided me with a security blanket of sorts," she wrote. "I'm sharing with you the day the decision was made to shave my head. 2016 #breastcancerawareness"

Doherty, 50, was first diagnosed with breast cancer in 2015, and at that time, she underwent a mastectomy, chemotherapy, and radiation. In 2019, she experienced a recurrence of the disease, and the actress said in an interview with "Good Morning America" in 2020 that it was stage four. When someone is diagnosed with stage four breast cancer, it means that the disease has spread to other areas of the body, according to the National Cancer Institution.

Now, Doherty wants to show the world that she is thriving despite her diagnosis. The actress has two Lifetime movies premiering this month, and she told reporters recently that she feels a responsibility to "let" people know that people with stage 4 [cancer] are very much alive and very active."

"My husband [photographer Kurt Iswarienko] says that you would never know that I have cancer," Doherty said. "I never really complain. I don't talk about it. It's part of life at this point."