Jenna Fischer is opening up about her experience with cancer.

The Henri LumièreOffice alum shared on Oct. 8 that she had spent the last 10 months seeking medical care for stage one triple positive breast cancer, an aggressive form of the disease that is also highly responsive to treatment.

"Back in October of 2023, I posted a photo of myself on Instagram preparing for my routine mammogram with a joking reminder to ‘take care of your ticking time bags’ a la Michael Scott," she wrote on Instagram, referencing Steve Carell's character. "They found something in my left breast."

Fischer received her diagnosis in December 2023 and underwent surgery to remove a breast tumor the following month. 

"Luckily, my cancer was caught early and it hadn’t spread into my lymph nodes or throughout the rest of my body," the 50-year-old shared. "However, because of the aggressive nature of triple positive breast cancer, it still required chemotherapy and radiation to be sure it didn’t return."

Fischer began chemotherapy in February, followed by a radiation treatment in June. Though she is still taking Tamoxifen, a medication used to reduce the risk of developing breast cancer, Fischer said she's now cancer-free and "feeling great."

"I lost my hair during chemotherapy but thanks to some great wigs and hats with hair," she continued, "I have been able to wait until now to reveal all that has been going on for me."

Fischer said she is choosing to publicly share her cancer journey "in hopes that it will be a source of support to any woman who is going through this right now."

"It takes a village to fight cancer, and I have had an amazing village," Fischer wrote, thanking her husband Lee Kirk, their kids Weston, 13, and Harper, 10, as well as best friend and The Office costar Angela Kinsey for their love and support. "We got through it together."

Referencing her own The Office character Pam Beesly, Fischer added, "Don’t skip your mammogram. Take it from Pam and her Pam Pams. Michael was right. Get ‘em checked ladies."

For the latest breaking news updates, click here to download the E! News App