The charity said the survey that shaped the campaign painted “an unvarnished picture of how breast cancer devastates lives, what people want to see Breast Cancer Now do about it and what it means to them to live well”.
Van Santen said she was “not prepared to give up on life yet” and was still working and travelling.
“I want to support the nearly one million people that are living with or beyond breast cancer, just like me,” she said.
“I want them to be able to have the confidence to speak up, get the support they need through Breast Cancer Now and other charities, and I think it’s really important that we bring that forward.”
Charity chief executive Claire Rowney said they were “so grateful” to Paula and the rest of the cast for sharing their experiences and making the campaign “so powerful”.
“Behind these figures are too many human lives being touched and ripped apart by this devastating disease,” she said.
“The need for our work has never been greater and we’re relentless in our determination to be Breast Cancer Now until we’re Breast Cancer Never.”
The charity said it would be doubling its research spend and “supercharging progress” on incurable secondary (or metastatic) breast cancer, exploring how medicine can be tailored to individuals and how existing drugs could be used for treatment.