Stockard Channing Remembers Late Grease Costar Olivia Newton-John: 'I Will Miss Her Enormously'

Bei/Shutterstock Olivia Newton-John and Stockard Channing in 1998

Stockard Channing is honoring Olivia Newton-John following her death from breast cancer.

The actress — who played Pink Lady Betty Rizzo alongside Newton-John's Sandy in the 1978 musical film Grease — shared a heartfelt tribute to her costar, who died Monday morning at age 73.

"I don't know if I've known a lovelier human being," Channing, 78, says in a statement to PEOPLE. "Olivia was the essence of summer – her sunniness, her warmth and her grace are what always come to mind when I think of her."

She added, "I will miss her enormously."

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Fellow Grease costar John Travolta, who played Danny Zuko, also posted a loving note via his Instagram in remembrance of Newton-John following the news of her death.

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Alongside a throwback photo of the late actress, Travolta, 68, wrote in the caption, "My dearest Olivia, you made all of our lives so much better."

"Your impact was incredible. I love you so much," he continued. "We will see you down the road and we will all be together again."

"Yours from the moment I saw you and forever! Your Danny, your John!" he concluded.

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Newton-John's death was announced Monday by her husband, John Easterling, via her official Instagram page. He noted the late star "passed away peacefully at her Ranch in Southern California," where she was "surrounded by family and friends."

"Olivia has been a symbol of triumphs and hope for over 30 years sharing her journey with breast cancer," he added. "Her healing inspiration and pioneering experience with plant medicine continues with the Olivia Newton-John Foundation Fund, dedicated to researching plant medicine and cancer. In lieu of flowers, the family asks that any donations be made in her memory to the @onjfoundation."

In May 2017, Newton-John announced that she was diagnosed with breast cancer, which had metastasized to the sacrum. At the time, her team said that Newton-John would be completing photon radiation therapy, in addition to natural wellness therapies after consulting with her medical team at the Olivia Newton-John Cancer Wellness and Research Centre in Melbourne, Australia.

RELATED VIDEO: Olivia Newton-John Dead at 73: The Star and 'Grease' Icon Dies of Breast Cancer

In addition to Easterling, Newton-John is survived by her daughter Chloe Lattanzi; sister Sarah Newton-John; brother Toby Newton-John, nieces and nephews — Tottie, Fiona and Brett Goldsmith; Emerson, Charlie, Zac, Jeremy, Randall, and Pierz Newton-John; Jude Newton-Stock, Layla Lee; Kira and Tasha Edelstein; and Brin and Valerie Hall.