The Office star Jenna Fischer puts on a brave smile after revealing she's cancer-free

Jenna Fischer flashed a reassuring smile as she ran errands in Los Angeles on Thursday in her first public appearance since being diagnosed with stage 1 triple-positive breast cancer last December.

The 50-year-old Office alum – now happily 'cancer-free' – looked in high spirits as she crossed the crosswalk in a white short-sleeved henley waffle top, navy-blue capri pants and gray sneakers.

Jenna (née Regina) sported a happy head of blue flowers around her growing 'bachie pixie' cut – after losing her hair while undergoing '12 rounds of weekly chemotherapy'.

On Tuesday, which marks Breast Cancer Awareness Month, Fischer shared her brave story of how a routine mammogram turned into an ultrasound, followed by a diagnosis, a lumpectomy in January, chemo in February and three weeks of radiation therapy in June.

'Luckily my cancer was caught early and it didn't spread to my lymph nodes or other parts of my body,' Indiana-born Amy Nominee wrote across five Instagram slides.

'I am happy to say that I am feeling better as I continue to receive treatment with Herceptin infusions and a daily dose of tamoxifen.'

Jenna told her 3.9 million followers to get their annual mammograms and 'Ask your doctor to calculate your breast cancer risk assessment score.'

“I'm serious, call your doctor right now,” warned Fischer.

'My tumor was so small I couldn't feel it on physical examination. If I had waited another six months, the situation would have been much worse. It may have spread. Seeing women posting photos of their mammogram appointments on Instagram inspired me to set up my own (I was late). So glad I did. Consider this your kick to get it done.

The Mean Girls star thanked her 'angel team of doctors and nurses' and 'other cancer patients who coached me along the way' and 'friends and family'.

Jenna celebrated her cancer-free status by ringing a bell in the backyard of her $1.9M Glendale home while her second husband Lee Kirk and their 10-year-old daughter Harper and 13-year-old son Weston shot confetti in her direction.

“I have to mention my husband, Lee, who has been by my side through all of this,” Fischer said.

'And I mean literally on my side – the surgeries, the chemotherapy, the doctor's appointments, the endless googling, the late-night ugly cries. He was there for everything. I knew he was a catch when I married him. I was right.'

The 50-year-old Office alum – now happily 'cancer-free' – looked in high spirits as she crossed the crosswalk in a white short-sleeved henley waffle top, navy-blue capri pants and gray sneakers.

Jenna (née Regina) wore a cheerful blue-flowered headband around her growing 'baby pixie' cut – after losing hair while undergoing '12 rounds of weekly chemotherapy'

To mark Breast Cancer Awareness Month on Tuesday, she shared her brave story of how a routine mammogram turned into an ultrasound, followed by a diagnosis, a lumpectomy in January, chemo in February and three weeks of radiation therapy in June.

The Indiana-born Emmy nominee wrote in five Instagram slides: 'Luckily my cancer was caught early and it hasn't spread to my lymph nodes or other parts of my body…and I'm continuing treatment with Herceptin infusions. And a daily dose of tamoxifen, I'm happy to say I'm feeling better'

Jenna asked her 3.9 million followers to get their annual mammogram and breast cancer risk assessment score: 'My lump was so small I couldn't feel it on a physical exam. If I had waited another six months, the situation would have been much worse.

The Mean Girls star celebrated her cancer-free status by ringing a bell in the backyard of her $1.9M Glendale home. Older son Weston (R) shoots confetti in her direction

Jenna gushed: 'I have to mention my husband Lee who has been by my side through all of this. I mean literally on my side – surgeries, chemotherapy, doctor appointments, endless googling, late-night ugly cries. He was there for everything. I knew he was a catch when I married him. I'm right' (Image: May 22)

Fischer and her supportive castmate-turned-BFF Angela Kinsey (L, Oct. 2) remain busy co-hosting their nerdy rewatch podcast Office Ladies, which airs twice a week starting Nov. 6.

The two-time SAG Award winner (M) starred as Dunder Mifflin receptionist Pam Beasley in the Greg Daniels remake that aired for nine seasons on NBC from 2005-2013.

The two-time SAG Award winner met the former filmmaker in 2008, but they both had small acting roles in Craig Mazin's 2000 superhero comedy The Specials – written by James Gunn, and she was married from 2000-2008.

Two years after they married, Lee directed Jenna in his 2012 rom-com The Giant Mechanical Man, but she hasn't had an IMDb-credited job since helming his 2016 comedy Ordinary World.

Fisher and her supportive castmate-turned-BFF Angela Kinsey are staying busy co-hosting their Audacy rewatch podcast Office Ladies , which will air twice a week starting Nov. 6.

The Blue Book Reads actress first rose to fame playing Dunder Mifflin receptionist Pam Beasley in Greg Daniels' remake of The Office, which ran for nine seasons on NBC from 2005-2013.

Ricky Gervais famously co-created and starred in the original mockumentary sitcom which aired for two seasons on BBC Two from 2002-2003.