Actress Jenna Fischer celebrated a major health milestone Tuesday and announced she was "cancer free" nearly one year after receiving a breast cancer diagnosis.

In honor of Breast Cancer Awareness Month, "The Office" star shared her journey from diagnosis through recovery in a series of posts on Instagram.

"I never thought I’d be making an announcement like this but here we are," she wrote on social media. "Last December, I was diagnosed with Stage 1 Triple Positive Breast Cancer. After completing surgery, chemotherapy and radiation I am now cancer free."

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Actress Jenna Fischer wears white dress

Jenna Fischer celebrated being "cancer free" nearly one year after receiving her diagnosis. (Getty Images)

"I wanted a photo of myself in my patchy pixie looking happy and healthy to go along with this news. A big thank you to Angela Kinsey’s husband Josh Snyder for taking this photo. It’s just one example of the care they showed me during this journey."

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Fischer shared a series of slides detailing her experience, beginning in October 2023 when she posted a photo on Instagram "preparing for my routine mammogram with a joking reminder to ‘take care of your ticking time bags’ a la Michael Scott."

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The mammogram results came back inconclusive, and her doctor ordered a breast ultrasound, which detected something on her left breast, she wrote. A biopsy was then ordered, and on Dec. 1, 2023, Fischer received her diagnosis.

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"Triple positive breast cancer is an aggressive form of breast cancer but it is also highly responsive to treatment," Fischer wrote. "In January, I had a lumpectomy to remove the tumor. Luckily my cancer was caught early and it hadn't spread into my lymph nodes or throughout the rest of my body, however because of aggressive nature of triple positive cancer it still required chemotherapy and radiation to be sure it didn't return."

During the chemotherapy, Fischer admitted she lost her hair, but "thanks to some great wigs and hats with hair (which my family affectionately called Wigats) I have been able to wait until now to reveal all that has been going on for me," she wrote.

Jenna Fischer wears a black blazer and brown blouse.

Jenna Fischer admitted she had great wigs to hide the fact that she lost her hair during chemotherapy. (Slaven Vlasic/Getty Images)

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"It takes a village to fight cancer, and I have had an amazing village," she noted. "Until this happened, I don't think I really knew the generosity and kindness that could rain down from one person to another. It started with a team of doctors and nurses. All of them angels."

She thanked her friends, family, children and husband Lee for helping her throughout treatment. "I'm happy to say that I was recently re-screened, and the treatments worked. I am cancer free. I will continue to be treated and monitored to help me stay that way."

Jenna Fischer as Pam Beesly Halpert, John Krasinski as Jim Halpert

Jenna Fischer starred as Pam Beesly Halpert alongside John Krasinski as Jim Halpert on "The Office." (Chris Haston/NBCU Photo Bank)

Jennifer Garner sent congratulatory wishes to Fischer on Instagram and wrote, "I’m so grateful to know you’re on the other side and cancer free!" Ellie Kemper echoed similar sentiments, "We love you, Jenna. Thank you for sharing and for inspiring."

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Cancer survivor Olivia Munn shared, "You already know how much I love you and how incredibly proud of you I am. But I just want to say it again; I love you and by sharing your story you’re helping so many women and saving so many lives. You’re just the best."