On Monday, Subritzky will undergo surgery to remove the tumour and lymph nodes which will see her off work for "at least a couple of weeks". This will be followed by chemotherapy, radiotherapy and "a cocktail of drugs for a few years after that".
"So, not the best news I could have got. It hasn't been a great year for me," says Subritzky, who in the past 12 months has endured the passing of her brother, an endometriosis diagnosis and separating from her husband.
"I am going to get through it," the brave host says with a smile. "I'm blessed with fantastic family, wonderful friends, very supportive colleagues. I couldn't ask for more support so don't worry about me. I am going to be okay ..."
Subritzky's previous breast cancer diagnosis, a high-grade DCIS, came after she booked in for a mammogram the day after the funeral of a friend who had died from the disease at just 37.
"It took the death of Helena to spur me into action," Subritzky told the Herald in 2016.
"I was always too busy, or thought I was ... I'll never forget making the promise at her funeral that I would book my screening mammogram the following day - and I kept that promise. Thank goodness, it was then that my early breast cancer was discovered.
"I can't impress upon women enough how vital this screening is. I'm convinced it quite literally saved my life," says Subritzky who, as a Breast Cancer Foundation ambassador, supports the organisation's Give Us Our Mammograms campaign, which includes a petition urging the Government to restore and extend current screening programmes.
According to the Breast Cancer Foundation website, participation in breast cancer screening has dropped to 64 per cent, the lowest seen in 10 years.