Los Angeles, California - Jenna Fischer has commemorated Breast Cancer Awareness Month with an emotional post revealing her own diagnosis.

The 50-year-old star, who played Pam Beesly in the hit sitcom The Office from 2005 to 2013, has revealed that she had breast cancer.

In December last year, doctors discovered that she had Stage 1 Triple Positive Breast Cancer, as she explained in the post shared Tuesday.

"I never thought I'd be making an announcement like this, but here we are," she wrote under a photo of herself smiling with a mug in her hand.

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Thankfully, Fischer has reason to be happy again, as she revealed she's now cancer-free after completing surgery, chemotherapy, and radiation.

In several slides of her post, the mom of two shared further details of her condition, explaining that doctors had "found something in [her] left breast" during a routine mammogram and ordered a biopsy.

A short time later, she was diagnosed with Stage 1 breast cancer.

Although triple-positive breast cancer is very aggressive, it responds well to treatment.

As the disease was detected early, doctors were able to treat it well, Fischer explained.

Fortunately, the cancer had not spread, and the tumor was successfully removed in an operation.

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Although she continues to receive medication and infusions, the Mean Girls actor is now doing very well, and she encouraged her followers to continue regular checkups and mammograms to protect their own health.

"My tumor was so small it could not be felt on a physical exam," Fischer wrote. "If I had waited six months longer, things could have been much worse."