Jenna Fischer — who starred in all 188 episodes of the NBC classic “The Office” — revealed that she had been quietly battling breast cancer for nearly a year.

In honor of Breast Cancer Awareness month, Fischer revealed that she was diagnosed with breast cancer nearly a year ago in an emotional Instagram post.

“October is breast cancer awareness month. I never thought I’d be making an announcement like this but here we are,” Fischer began.

“Last December, I was diagnosed with Stage 1 Triple Positive Breast Cancer. After completing surgery, chemotherapy and radiation I am now cancer free,” the post, which was captioned alongside a photo of Fischer beaming ear-to-ear while holding a cup of coffee, continued.

She went on to thank her “The Office” co-star Angela Kinsey — with whom she has been hosting an award-winning, series-themed podcast titled “Office Ladies” since the COVID-19 pandemic — as well as her husband, Josh Snyder, for taking the photo and supporting her in her battle with cancer.

Fischer further revealed that she was first diagnosed with Stage 1 Triple Positive cancer — an aggressive form of cancer — after going in for a routine mammogram in December, 2023. Thankfully, the condition is highly responsive to treatment.

She then underwent surgery to remove the tumor in January of this year. “Luckily my cancer was caught early and it hadn’t spread to my lymph nodes or throughout the rest of my body,” Fischer wrote. “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 started on 12 weeks chemotherapy treatment in February, 2024 and in June, she underwent three weeks of radiation. Now, “The Office” star is happy to report that she is recovering and “feeling great.”

The actress further revealed that she lost her hair due to treatment, which she was able to conceal with the help of wigs.

She went on to explain that she was making the announcement in order to encourage women to keep on top of mammograms and other forms of preventive measures.

“I’m also sharing in hopes that it will be a source of support to any woman who is going through this right now,” Fischer wrote. “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. Suddenly everything in your life is geared around one thing: fighting cancer.”

Fischer added that it “takes a village to fight cancer” and went on to thank her friends and family, as well as other cancer patients and survivors, for their support.

“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.”