BRCA1 and breast cancer: In contrast to the results previously presented, with no association between exposure to ionizing radiation and the development of cancer, the retrospective cohort study carried out by Andrieu et al., (2006) included 1601 carriers (1187 BRCA1 mutation carriers and 414 BRCA2 mutation carriers) and analyzed the relationship between having chest radiographs, excluding mammography, and an increased risk of developing breast cancer.