Risk factors for breast carcinoma in women with proliferative breast disease

We review the evidence that proliferative breast disease increases the risk of breast cancer. Results from six cohorts give consistent estimates of these risks. The combined estimate of the relative risk associated with proliferative disease without atypia is 1.65 with a 95% confidence interval (CI) of 1.5 to 1.9. The relative risk of breast cancer associated with atypical hyperplasia is 4.19 (95% CI 3.7-4.7). Estimates of the cumulative absolute risk of invasive breast cancer in the Nashville Breast Cohort and the Mayo Clinic Cohort are also given. These risks are remarkably consistent and average about 25% in the 25 years after a diagnosis of atypical hyperplasia. The chapter also reviews the evidence on how age, a family history of breast cancer, and proliferative breast disease interact to affect breast cancer risk. The risks associated with fibroadenoma and radial scar are also reviewed, as are the effects of time since diagnosis and the risk of hormone replacement therapy in women with a history of proliferative disease.