The 42-year-old has confirmed that she will begin treatment shortly.
“I would be lying if I said I wasn’t scared but I am fearlessly determined to do whatever it takes by focusing on my body, mind and spirit as I take my first trusting steps towards recovery,” she said in a letter to her CAMILLA team.
“Many of my wider CAMILLA tribe have already been on this journey themselves and I know will be an inspiration to me as I begin mine.”
Franks, who is mum to daughter Luna with partner JP, shared the news on Instagram.
"Like anyone who has felt the unrelenting terror of being diagnosed, cancer was certainly never part of my plan. It’s something that JP and I have spent the last few days trying to process and confront," she captioned a family photo.
The designer said she will now embark on this journey for her daughter.
"Like all life’s adversities, we are choosing to unite and face this one with acceptance, endurance and love. This is the only way – and I have the best kind of love by my side. As you know, my beautiful Luna Gypsy arrived only a few months ago, and it is her joy and warmth that remind me that this is a journey I will embark on with courage – for her and for us."