Olivia Munn became "instant friends" with Shannen Doherty when they bonded over their battles with cancer.
The 44-year-old actress announced in March she had undergone four surgeries in under a year after being diagnosed with an "aggressive" form of the disease.
After the death of '90210' star Doherty - who passed away on Saturday following a long battle with cancer - Munn admitted that she is "absolutely heartbroken" to hear the news, especially after the pair of them connected over their health.
She wrote on Instagram: "I am absolutely heartbroken over the passing of Shannen Doherty. When I was first diagnosed with breast cancer I remembered how she bravely let the world into her journey and reached out to her.
“We became instant friends- which I honestly couldn't comprehend at times because watching her on '90210' was everything to me when I was 10.
“We bonded through a shared battle and a desire to help other women. Looking back on the last text she sent me just a couple months ago, she asked how I was doing and if she could do anything for me.... True to form, Shannen was offering her support even though she was in the final stage of fighting this horrific disease."
The former 'Newsroom' star - who underwent a double mastectomy, and was then put into a medically-induced menopause - also noted that the former 'Charmed' actress faced up to her battle with "dignity" as she noted how "scary" the disease had been for her.
She added: "Cancer is really f****** scary and Shannen faced it with such dignity, strength and grace.
"I'm sending all of my love to her mother who was her best friend, hero and champion every step of the way. Fly so high, my friend."
IOL Entertainment