"1 in 8 women get breast cancer - today I'm the one," she wrote.
There has been an outpouring of support online from other stars, with her Veep co-star Tony Hale saying: "We love this woman." While even Joe Biden, who lost his son to cancer, took to Twitter to write: "We Veeps stick together. Jill and I, and all of the Bidens, are with you, Julia."

Just when you thought... pic.twitter.com/SbtYChwiEj

— Julia Louis-Dreyfus (@OfficialJLD) September 28, 2017

HBO also released a statement. "We have every confidence she will get through this with her usual tenacity and undaunted spirit, and look forward to her return to health and to HBO for the final season of Veep," said the TV network.

We Veeps stick together. Jill and I, and all of the Bidens, are with you, Julia. pic.twitter.com/JP0c2wtrJ6

— Joe Biden (@JoeBiden) September 28, 2017