The Office star Jenna Fischer has revealed she was diagnosed with breast cancer in 2023. (AP PHOTO)

US actress Jenna Fischer has announced she is cancer-free after battling an “aggressive” form of the disease.

The 50-year-old, who starred as receptionist Pam Beesly in the US version of The Office, opposite John Krasinski, said she was diagnosed with stage one triple positive breast cancer in December 2023

“After completing surgery, chemotherapy and radiation I am now cancer free,” she said in a statement on Instagram.

The TV star said she posted on Instagram in October 2023 in preparation for her routine mammogram with a joking reminder to “take care of your ticking time bags”, referencing Steve Carell’s character Michael Scott in the sitcom.

However, after inconclusive results, a biopsy was ordered which found the “aggressive form of breast cancer”.

“In January, I had a lumpectomy to remove the tumour,” she said.

“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 the aggressive nature of the triple positive breast cancer it still required chemotherapy and radiation to be sure it didn’t return.”

Fischer said she had 12 rounds of chemotherapy in February and three weeks of radiation in June.

“I lost my hair during chemotherapy 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 said.