Shannen Doherty shares heartbreaking photos as she shaves off all of her hair.

Actress Shannen Doherty has shaved her head in a milestone marker of her ongoing battle with breast cancer.

Doherty first revealed her diagnosis in September 2015 in an interview with People.

Doherty, 44, told People she was staying positive in the face of her illness.

“I am continuing to eat right, exercise and stay very positive about my life,” she said.

“I am thankful to my family, friends and doctors for their support and, of course, my fans who have stood by me.”

Step one and two. Source: Instagram.

The 44-year-old documented her shaving journey in a six-part series on Instagram.

Fans applauded Doherty for her brave decision in publicising what for many women is a highly emotional event.

"Stay strong.. you're always a beautiful fighter. I'm sure you will win this war," one user said.

Source: Instagram.

"Shannen you can kick cancer's ass, you're strong and brave and you got lots of people around the world that love, pray and support you. Never give up," another user said.

One fan commented on the power behind posting about such a personal event.

"This is so fucking brave of you showing THE process. Lots of energy from a fellow warrior!" they said.

Source: Instagram.

Doherty appeared in a February 2016 episode of Dr Oz to discuss the surgeries she has considered.

"Ultimately, they're just breasts right?" she said.

"I mean, I love them, they're mine, they're beautiful, but in the grand scheme of things, I would rather be alive and I would rather grow old with my husband [Kurt Iswarienko]."

Doherty is best known for her work on 90s sitcoms Beverly Hills 90210 and Charmed.

Protect yourself by learning how to perform a self-breast check...