Is there a blood test that can detect breast cancer? Yes and no.
No, it hasn't been developed. But yes, they think they can develop one.
Scientists have found a genetic trigger that doubles a woman's risk of developing breast cancer.
Once found, they can presecibe medicines and correct behaviors that could lead to developing the disease.
And with the blood test they're developing they believe they'll be able to detect it years in advance.
Science is awesome.