BRCA1 and breast carcinoma: Similarly, the breast cancer risk by age 40 is predicted to be 4–9% for the 5% of BRCA1 carriers at lowest risk compared to 20–49% for the 5% at highest risk, whereas the ovarian cancer risk at age 50 ranges from 3–7% for the 5% at lowest risk and from 18–47% for the 5% at highest risk.