Parity and the risk of breast and ovarian cancer in BRCA1 and BRCA2 mutation carriers

Modifiers of breast and ovarian cancer risks for BRCA1 and BRCA2 mutation carriers

“…In line with the established associations for the general population, breast feeding for at least 1 year has been found to be protective (RR: 0.50-0.68) (Jernstrom et al 2004, Andrieu et al 2006, Gronwald et al 2006a, Kotsopoulos et al 2012a, as has later age at menarche (Chang-Claude et al 2007, Kotsopoulos et al 2005, 2012a, (RR: 0.91 per year; Kotsopoulos et al 2012a). Later age at first fullterm pregnancy has also consistently been reported to be associated with reduced risk of breast cancer for BRCA1 mutation carriers (Andrieu et al 2006, Milne et al 2010b, Lecarpentier et al 2012 (RR: 0.65 for age ≥30 years vs <30 years; Friebel et al 2014), which is in contrast to what is known about the association with risk for overall breast cancer in the general population. It is not clear why this would be the case, although there is evidence that the association in the general population differs by disease subtype and the protective effect of early childbirth is not observed for triple-negative breast cancer (Yang et al 2011, Barnard et al 2015, which comprises approximately two-thirds of all tumours diagnosed in BRCA1 mutation carriers (Mavaddat et al 2012).…”

“…Findings for these factors and breast cancer risk for BRCA2 mutation carriers have been null or inconclusive (Friebel et al 2014). Observations from studies of parity and breast cancer risk have also been largely consistent for BRCA1 and BRCA2 mutation carriers, and the general population (Kelsey et al 1993), with more full-term pregnancies associated with protection from breast cancer (Andrieu et al 2006, Milne et al 2010b, Lecarpentier et al 2012 (RR: 0.83 per pregnancy, Friebel et al 2014), although contradictory findings have also been published (Jernstrom et al 1999, Cullinane et al 2005, Kotsopoulos et al 2012a.…”

Association of ABO Blood Group and Risk of Breast Cancer

“…Family history of breast cancer, age of menarche, duration of lactation, parity, age of menopause, diet and hormonal levels are known risk factors for the development of breast cancer [2,3]. One of the major antigens in humans is the blood group antigens that are present on the surface of red blood cells and different epithelial cells and alteration of these blood group antigens is associated with cancer [4,5].…”

Reproductive Issues in BRCA Mutation Carriers

“…Increasing age at fi rst live birth was associated with an increased BC risk among BRCA2 mutation carriers but not BRCA1 carriers [ 82 ]. Yet other studies have failed to demonstrate an association between BC risk and age at fi rst birth among mutation carriers [ 83 ]. A meta-analysis by Pan et al demonstrated no association between parity and BC risk in women harboring a BRCA1/2 mutation and late age at fi rst birth was found to be protective among BRCA1 mutation carriers [ 84 ].…”