Emily Ranner is planning to have a double mastectomy after both her mother and aunt died from the disease.
Her grandmother and great-aunt have also had breast cancer – the only relative on her mother’s side left unaffected is her other aunt, who underwent the operation over 10 years ago.
Emily, who is being referred for genetic tests, said: “I don’t want to be told everything is ok and then they find a new method of testing in five or six years, by which time I’ve already become ill.
“I am probably going to have it done regardless of what it shows up, just because the only healthy female in my family has had it done.”
She has seen the maternal side of her family struck numerous times. Her mother Shelley died when Emily was nine, while her aunt – who had been diagnosed at the same time – died 10 years later.
“As far back as my grandmother and her sister, they were both affected,” said Emily, from Birstall, Leeds.
“We don’t know any further back but it’s along the maternal side.”
Her other aunt had genetic testing after both her sisters had developed the illness and decided to have surgery.
“She was tested and they said ‘there’s obviously something there, but we don’t know what’,” said Emily.
Over a decade on, it is likely that doctors will be able to find out more about any genetic link when the 25-year-old undergoes tests.
The planner for building firm Morrison said she was going ahead now as her relatives all developed the disease before they were 30.
“It’s not been a long thought process, but it’s been a long time deciding when was the right time,” she said.
“It’s probably a minor interruption to your life compared to getting cancer.”