Sarah-Jane had a lump removed from her right breast a year ago, but discovered another lump on her left breast earlier this month.
The star, who hosted ITV2's The Xtra Factor for one year, also had a non-cancerous fibroid removed from her uterus, and has since revealed her worry of going through the same ordeal again.
Speaking to the Sun, the 35 year old said: 'The first thing I thought when I found the lump was that an operation to remove it would be my third in two years.
'I tried to separate emotions from it and told myself that if I needed it removed, that's what I would do. But the operations are traumatic. I'm not very good under general anaesthetic.'
Sarah-Jane is now encouraging other women to know how to spot the signs of breast cancer
She added: 'I cry and panic because there's always the fear you won't wake up.'
Although the star has since been for a biopsy and learned that her second lump is harmless, doctors have warned Sarah-Jane that she is now known as a 'high risk' for breast cancer in the future. 'I'm now considered a high risk for breast cancer, but in a way that makes me less at risk because I know about it,' she said.
Sarah-Jane hopes to use her experience to help raise awareness for breast cancer screenings. 'I'm speaking about this now to encourage other women to keep checking and make sure if there's a problem they insist on screening and ultrasound scans.
'Even if their doctor says it's a lump they should ignore, if they instinctively know something's wrong, they should get a second opinion.'
Referencing other women in the spotlight who've encountered breast cancer, Sarah-Jane said: 'There are lots of women around us making brave decisions, like Angelina Jolie, who had her ovaries removed after a double mastectomy. Women like her give me the courage to think if it was ever recommended that I have a breast removed, I would.
'You do what you have to do. After all, you know your body better than anyone else.'