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Jenna Fischer in 2019.
CNN  — 

Jenna Fischer is opening up more about her breast cancer journey.

“The Office” star talked exclusively with “Today’s” Hoda Kotb and shared who was one of the first people she reached out to after she was diagnosed.

“I called [Christina Applegate], and she answered the phone, and she said, ‘Which one is it?’ And I said, ‘It’s breast cancer.’ And she said, ‘I effing knew it,” Fischer recalled.

She said she had postponed her routine mammogram before finally going in to get checked.

“Three weeks later, they said, ‘Oh, your mammogram was fine. There were a few spots that were difficult to see. You have very dense tissue. We would recommend that you do another mammogram and maybe follow up with a breast ultrasound,’” Fisher said.

She said she had “no level of concern” when told she needed to get a biopsy and was alone when she received the results from her patient portal.

“I checked the portal on the hike, and that’s when I saw words like ‘invasive,’ ‘ductal,’ ‘carcinoma,’ ‘malignant,’” Fischer said. “And I was like, ‘Those words sound like cancer words.’”

She said she’s leaned on her support system, including Applegate, who was herself diagnosed with breast cancer in 2008. Fischer said her friend’s reaction was not surprising.

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Jenna Fischer and Christina Applegate

“She’s salty,” she said of Applegate. “Salty language that one. I love her for it.”

Fischer has undergone chemotherapy and said the best advice she received was “live your life during this process.”

“I did that. And some days I just walked circles in my own living room,” she said. “Some days I walked all around the block. But I did every day get up and do those things. And I think it made a really big difference.”