Life course breast cancer risk factors and adult breast density (United Kingdom)

Abstract

Objective: To determine whether risk factors in childhood and early adulthood affect later mammographic breast density. Methods: Subjects were 628 women who attended a medical examination at the University of Glasgow Student Health Service , responded to a questionnaire (2001) and had a screening mammogram in Scotland (1989Scotland ( -2002. Mammograms (median age of 59 years) were classified using a six category classification (SCC) of breast density percent. Logistic regression was used to determine associations between risk factors and having a high-risk mammogram ( 25% dense). Results: In multi-variable analyses, high-risk mammograms were associated with parity (adjusted odds ratio (OR) per child: 0.77 (95% confidence interval (CI) 0.61-0.99)), age at first birth, OR per year: 1.05 (0.99-1.11), smoking at university, OR smokers versus non-smokers: 0.58 (0.36-0.92) and body mass index (BMI) while at university, OR per 1 kg/m 2 0.75 (0.69-0.82). No associations with SCC were found for age at menarche, birth weight, oral contraceptive (OC) use, height, leg length or exercise at age 20. Conclusions: We confirm previous findings that breast density is affected by reproductive events and some anthropometric measures, however most of the risk factors acting throughout the life course which we examined were not closely related to adult breast density.

Lifecourse predictors of mammographic density: the Newcastle Thousand Families cohort Study

“…The percentage of women in the 'most dense' Wolfe category was higher in this study than that reported in a study of similarly aged women in the United Kingdom [12]. Of the six other studies to investigate the potential association between birth weight and later mammographic density, two used the Wolfe categories [11,12]; two, on one cohort [13,15]; used a six-category classification that showed strong correlation with the Wolfe scale [13]; and two used computer-assisted measurements of density [14,16]. The only previous significant associations were seen in the latter two studies that used computer-assisted estimations of density [14,16], although one was limited to self-reported birth weight data [14], and the other had incomplete birth data due to its retrospective nature [16].…”

“…However, the limited research so far into the association between birth weight and mammographic density has reported inconsistent findings [11][12][13][14][15][16]. A number of other factors have been identified as risk factors for breast cancer, including exposure to oestrogen and other hormones [17], pregnancy-related factors, such as older age at first birth, higher parity, older age at last birth, short duration of breast feeding [18] early menarche [19], and levels of body fat, the risk relating to the latter varying with pre-and post-menopausal breast cancers [20].…”

Influence of factors on mammographic density in premenopausal Chinese women

“…Some studies found that smoking had a negative effect on mammographic density (Jeffreys et al, 2004;Bremnes et al, 2007;Butler et al, 2010), whereas others showed that cigarette smoking did not influence breast density (Gapstur et al, 2003;Ishihara et al, 2013;Dai et al, 2014). We failed to identify a significant association between smoking habits and mammographic density in premenopausal women; however, certain observations warrant cautious consideration because of the extremely low percentage of women in our study population who smoked.…”

Do breast cancer risk factors modify the association between hormone therapy and mammographic breast density? (United States)

“…Previous studies have shown that breast density decreases with BMI and parity, whereas it increases with age at first birth, age at menopause, age at menarche, and family history of breast cancer [16][17][18][19]. Breast density also differs by race; black and Asian women generally have denser breasts than white women [20,21].…”