Benign breast disease and the risk of breast cancer.

摘要: BACKGROUND Benign breast disease is an important risk factor for cancer. We studied a large group of women with benign to obtain reliable estimates this risk. METHODS identified all who received diagnosis at the Mayo Clinic between 1967 and 1991. Breast-cancer events were obtained from medical records questionnaires. To estimate relative risks, we compared number observed cancers expected on basis rates cancer in Iowa Surveillance, Epidemiology, End Results registry. RESULTS followed 9087 median 15 years. The histologic findings nonproliferative lesions 67 percent women, proliferative without atypia 30 percent, atypical hyperplasia 4 percent. date, 707 have developed. cohort was 1.56 (95 confidence interval, 1.45 1.68), increased persisted least 25 years after biopsy. associated 4.24 3.26 5.41), as 1.88 1.66 2.12) changes 1.27 1.15 1.41) lesions. strength family history cancer, available 4808 that independent findings. No found among no In first 10 initial biopsy, excess occurred same breast, especially atypia. CONCLUSIONS Risk factors include classification lesion