Riley, who plays Kim in the internationally acclaimed sitcom Kath and Kim, is being treated at Melbourne’s Cabrini Hospital.
The 51-year-old Melbournian was diagnosed before Christmas and has had the cancer removed.
She is currently undergoing treatment described as “insurance” to be certain that the cancer is fully removed.
Riley told the Herald Sun: “During my regular yearly breast check, a cancer in my breast was discovered.
“For me there was no lump that could be felt by either me or my doctor. It was only that I went to my regular mammogram and ultrasound appointment that it was found.
“The cancer has been found early and is treatable and for that I feel lucky and grateful,” she added.
Riley went on to encourage other women to have regular breast checks as early discovery is key to successful treatment.
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