Fischer, 50, detailed her cancer journey on her Instagram page on Tuesday, writing that she was diagnosed with stage I triple-positive breast cancer - an aggressive form of breast cancer fueled by the estrogen and progesterone hormones and the HER2 protein, according to the American Cancer Society - last year after going in for a routine mammogram.
To treat her cancer, she had a lumpectomy "to remove the tumor," radiation, infusions and chemotherapy, which she wrote caused her to lose her hair.
"I'm happy to say that I was recently re-screened, and the treatments worked. I am cancer free," Fischer wrote. "I will continue to be treated and monitored to help me stay that way."
Jenna Fischer is 'cancer free' after being diagnosed with aggressive breast cancer
"The Office" star posted a photo of herself sporting what she described as a "patchy pixie" haircut, writing that she wanted to showcase a photo of herself now "looking happy and healthy to go along with this news."
Fischer decided to make her announcement this week to "implore" her followers to get their annual mammograms, writing that her tumor "was so small it could not be felt on a physical exam."
In May, CNN reported that women at average risk of breast cancer are advised to get a mammogram every other year starting at age 40 and until age 74, according to recommendations from the US Preventive Services Task Force.
Fischer also wrote that she wants other women going through cancer treatments to feel less alone.
"As anyone who has had a cancer diagnosis knows, your life changes immediately. It becomes all about doctor appointments, test results, treatments and recovering from treatments," she wrote. "It takes a village to fight cancer, and I have had an amazing village."
That village, Fischer wrote, comprised her team of doctors and nurses, other survivors who shared their story with her, her family and her friends - including her former "Office" co-star and current "Office Ladies" podcast co-host Angela Kinsey, who she said "protected me and advocated for me" along the way.
Fischer also expressed gratitude for her husband, Lee Kirk, who "has been by my side through all of this."
Fischer, Kirk and their two children celebrated the end of her treatment, she wrote, by ceremoniously ringing a bell in their backyard "with everyone throwing confetti."
A photo commemorating the celebratory moment is included in Fischer's post.
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