Cohort Profile: The Breast Cancer Prospective Family Study Cohort (ProF-SC)

For breast cancer, like most other common diseases, having a family history of the disease is associated with an increased risk. There is large heterogeneity in absolute and relative breast cancer risks associated with family history, depending on the age of the woman, the age(s) at diagnosis of her affected relative(s) and the genetic relationship(s). Women with one affected first-degree relative are on average at 2-fold increased risk of breast cancer relative to women with no first-degree family history, and this increases to 4-fold for women with three or more affected first-degree relatives 1 .