The most recent newsletter from this study had comments from participants. One mentioned the difficulty in recruiting participants from some ethnicities. The outcome from breast cancer is worse in black women and studies like this may help find out why.
https://breakthroughgenerations.org.uk/home
I'm a participant in the study - after an initial blood test and very long questionnaire it requires very little effort, a shorter questionnaire every few years. They need people as controls - my family have no history of breast cancer, I signed up anyway.