International Pooling Project of Mammographic Density

描述（由申请人提供）：与脂肪组织相比，乳房中纤维腺体组织百分比较高的女性在随后的10年或更长时间内患乳腺癌的风险增加（高达5倍）。这种属性，称为乳房X线摄影密度（MD），在不同的女性之间存在差异，并且可以随着时间的推移在同一个女性中发生变化。由于存在遗传和环境决定因素，MD的国家间差异可能导致乳腺癌发病率的6倍以上的国际差异。迄今为止，只有一项研究对此进行了调查，即美国/夏威夷/日本的比较（Maskarinec等人，2007年）。我们的目标是发起一个更广泛的国际乳腺摄影密度汇总项目，以：（i）汇总并获得来自乳腺癌发病率范围内的国家的MD标准化可比数据;（ii）描述总体和年龄特异性MD分布的国际差异，并评估它们是否可以由MD的个体水平风险因素解释;（iii）量化MD的国际变化与相应的乳腺癌发病率和Pike提出的乳腺组织老化模型相关的程度;（iv）评估一系列MD指标（绝对/相对/特定年龄/累积）; ㈤今后继续并扩大这一汇集的资源。国际乳腺摄影密度汇集项目将是MD的第一个此类倡议，以后可以扩展到包括MD测量，成像模式和更广泛的决定因素的新方法。在国际癌症研究机构的领导下，我们强调这一标志物的国际视角，特别是迫切的，因为乳腺癌现在是世界上几乎每个国家妇女中最常见的癌症。如果MD确实支持乳腺癌发病率的国际变化，监测MD分布将成为乳腺癌风险变化的重要早期指标。

DESCRIPTION (provided by applicant): Women with a high percentage of fibroglandular tissue in their breast, as opposed to fatty tissue, have an increased breast cancer risk (up to 5-fold higher) in the subsequent 10 or more years. This attribute, known as mammographic density (MD), varies between women and can change within the same woman over time. Having both genetic and environmental determinants, between-country differences in MD may account for the over 6-fold international variations in breast cancer incidence rates. Only one study has investigated this to date, i.e. a US/Hawaii/Japanese comparison (Maskarinec et al. 2007). We aim to initiate a more widespread International Pooling Project of Mammographic Density to: (i) pool and obtain standardised comparable data on MD from countries spanning the breast cancer incidence range; (ii) describe international variations in overall and age-specific MD distributions and assess whether they are explained by individual-level risk factors for MD; (iii) quantify the extent to which international variations in MD correlated with corresponding breast cancer incidence rates and Pike's proposed model of breast tissue ageing; (iv) assess a range of MD metrics (absolute/relative/age-specific/cumulative); (v) continue and expand this pooled resource into the future. The International Pooling Project of Mammographic Density would be the first such initiative for MD, which could later be expanded to include new methods of MD measurement, imaging modalities and a broader range of determinants. Being led by the International Agency for Research on Cancer, we emphasize an international perspective for this marker, especially urgent as breast cancer is now the most common cancer in women in almost every country worldwide. If MD does underpin international variations in breast cancer incidence, the monitoring of MD-distributions would become an important early indicator of changes in breast cancer risk.