BRCA1 and breast cancer: While many breast cancers are not associated with known risk factors, others do, highlighting with a relative risk [(RR) > 4] the following: females; age: >65 versus <65 years; gene mutations (BRCA1 and BRCA2); two or more first degree relatives with BC in early ages; personal history of BC; high breast tissue density and biopsy-confirmed atypical hyperplasia (Breast Cancer Facts & Figures  2009-2010).