BRCA1 and breast cancer: First and second primary breast tumors have been shown to share some risk factors, including mutations in BRCA1 and BRCA2 (Graeser et al. 2009; Metcalfe et al. 2004), family history of breast cancer (Bernstein et al. 1992; Hemminki et al. 2007), and obesity (Druesne-Pecollo et al. 2012).