Boyd Norman, Martin Lisa, Chavez Sofia, Gunasekara Anoma, Salleh Ayesha, Melnichouk Olga, Yaffe Martin, Friedenreich Christine, Minkin Salomon, Bronskill Michael
Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, ON, Canada.
Lancet Oncol. 2009 Jun;10(6):569-80. doi: 10.1016/S1470-2045(09)70078-6. Epub 2009 May 4.
Mammographic density is a heritable quantitative trait and is a strong risk factor for breast cancer in middle-aged and older women. However, little is known about the development of mammographic density in early life. We used MRI to measure the water content of the breast, which provides a measurement of the fibro-glandular content of breast tissue with similar accuracy to mammography, but without the attendant exposure to radiation.
Between December, 2003, and December, 2007, we recruited 400 young women, aged 15-30 years, and their mothers. We used MRI scans to measure daughters' breast water and fat, and on the same day obtained blood for hormone assays in the follicular phase of the menstrual cycle for each young woman. Mothers underwent mammography (n=356), and a random sample (n=100) also consented to have a breast MRI scan.
In mothers, per cent water-as measured by MRI-was strongly correlated with per cent mammographic density (r=0.85). Per cent water in daughters (median 44.8%) was significantly higher than in mothers (median 27.8%; p<0.0001), and was independently inversely associated with both their age (p=0.04) and weight (p<0.0001), and positively associated with their height (p<0.0001) and their mothers' per cent mammographic density (p<0.0001). Serum growth hormone concentrations, adjusted for covariates, were positively associated with per cent breast water (p=0.001) in a subgroup of young women (n=280) who had not used oral contraceptives within 6 months.
Per cent breast water was greatest during the ages when women are most susceptible to breast carcinogens, and was associated with weight, height, and mother's breast-tissue characteristics, and with serum concentrations of growth hormone: a breast mitogen that also mediates postnatal somatic growth. Mammographic density in middle age might partly be the result of genetic factors that affect growth and development in early life.
Canadian Breast Cancer Research Alliance.
乳腺X线密度是一种可遗传的定量性状，是中老年女性患乳腺癌的一个重要危险因素。然而，人们对其在生命早期的发展情况知之甚少。我们使用磁共振成像（MRI）来测量乳房的含水量，这能提供与乳腺X线摄影术测量乳腺组织中纤维腺体量的准确性相似的测量结果，但不存在辐射暴露问题。
在2003年12月至2007年12月期间，我们招募了400名年龄在15至30岁之间的年轻女性及其母亲。我们使用MRI扫描来测量女儿们乳房中的水和脂肪含量，并在同一天为每位年轻女性在月经周期的卵泡期采集血液进行激素检测。母亲们接受了乳腺X线摄影检查（n = 356），并且一个随机样本（n = 100）也同意进行乳房MRI扫描。
在母亲中，通过MRI测量的含水量百分比与乳腺X线密度百分比密切相关（r = 0.85）。女儿们的含水量百分比（中位数为44.8%）显著高于母亲（中位数为27.8%；p < 0.0001），并且与她们的年龄（p = 0.04）和体重（p < 0.0001）独立呈负相关，与她们的身高（p < 0.0001）以及母亲的乳腺X线密度百分比（p < 0.0001）呈正相关。在6个月内未使用口服避孕药的年轻女性亚组（n = 280）中，经协变量调整后的血清生长激素浓度与乳房含水量百分比呈正相关（p = 0.001）。
乳房含水量百分比在女性最易受乳腺致癌物影响的年龄段最高，并且与体重、身高、母亲的乳腺组织特征以及血清生长激素浓度相关：生长激素是一种乳腺有丝分裂原，也介导出生后的身体生长。中年时的乳腺X线密度可能部分是影响生命早期生长发育的遗传因素导致的结果。
加拿大乳腺癌研究联盟。
