The 42-year-old was diagnosed with the illness in 2006, but has said she was so determined not to let the disease beat her, she went through treatment and surgery without missing a day of work.
Cynthia's mother fought breast cancer twice.
She joins a ever-growing list of celebrities who have battled with the disease. From Kylie Minogue, who was given the all-clear in 2006, to chat show host Trisha Goddard, who was diagnosed recently.
Even Sex and the City tackled the storyline when Samantha, played by Kim Cattrall, had breast cancer in the show and EastEnders are currently running the storyline with Shirley, played by Linda Henry.
44,000 women are diagnosed every year in the UK with breast cancer. And 8,000 of them are under the age of 50. But survival rates are also going up.
The risk of developing it increases in women over the age of 50, which is why routine mammograms are so important. But you can ask your doctor for a mammogram before you reach 50.
We have professional advice and expert help if you're worried about breast cancer as well as a breast check video so you can check for lumps yourself.
- Breast cancer facts
- Dr Chris Steele's breast check video
- Read Sue's story of how she beat breast cancer
- Get tips from other goodtoknow users on dealing with chemotherapy
- Read how Kylie's experiences have helped others
- See how tea can reduce the risk of breast cancer
- Share your experiences with other women in Chat
More help and advice- www.breastcancer.org.uk