Pollán Marina, Ascunce Nieves, Ederra María, Murillo Alberto, Erdozáin Nieves, Alés-Martínez Jose, Pastor-Barriuso Roberto
Breast Cancer Res. 2013 Jan 29;15(1):R9. doi: 10.1186/bcr3380.
It is not clear whether high mammographic density (MD) is equally associated with all subtypes of breast cancer (BC). We investigated the association between MD and subsequent BC, considering invasiveness, means of detection, pathologic subtype, and the time elapsed since mammographic exploration and BC diagnosis.
BC cases occurring in the population of women who attended screening from 1997 through 2004 in Navarre, a Spanish region with a fully consolidated screening program, were identified via record linkage with the Navarre Cancer Registry (n = 1,172). Information was extracted from the records of their first attendance at screening in that period. For each case, we randomly selected four controls, matched by screening round, year of birth, and place of residence. Cases were classified according to invasiveness (ductal carcinoma in situ (DCIS) versus invasive tumors), pathologic subtype (considering hormonal receptors and HER2), and type of diagnosis (screen-detected versus interval cases). MD was evaluated by a single, experienced radiologist by using a semiquantitative scale. Data on BC risk factors were obtained by the screening program in the corresponding round. The association between MD and tumor subtype was assessed by using conditional logistic regression.
MD was clearly associated with subsequent BC. The odds ratio (OR) for the highest MD category (MD >75%) compared with the reference category (MD <10%) was similar for DCIS (OR = 3.47; 95% CI = 1.46 to 8.27) and invasive tumors (OR = 2.95; 95% CI = 2.01 to 4.35). The excess risk was particularly high for interval cases (OR = 7.72; 95% CI = 4.02 to 14.81) in comparison with screened detected tumors (OR = 2.17; 95% CI = 1.40 to 3.36). Sensitivity analyses excluding interval cases diagnosed in the first year after MD assessment or immediately after an early recall to screening yielded similar results. No differences were seen regarding pathologic subtypes. The excess risk associated with MD persisted for at least 7 to 8 years after mammographic exploration.
Our results confirm that MD is an important risk factor for all types of breast cancer. High breast density strongly increases the risk of developing an interval tumor, and this excess risk is not completely explained by a possible masking effect.
尚不清楚乳腺X线摄影密度（MD）是否与所有亚型的乳腺癌（BC）均有同等关联。我们研究了MD与后续BC之间的关联，同时考虑了侵袭性、检测方式、病理亚型以及自乳腺X线检查至BC诊断所经过的时间。
通过与纳瓦拉癌症登记处进行记录链接，识别出1997年至2004年期间在纳瓦拉参加筛查的女性人群中发生的BC病例（n = 1,172），纳瓦拉是西班牙一个筛查项目完全成熟的地区。从她们在该时期首次参加筛查的记录中提取信息。对于每个病例，我们随机选择四名对照，按照筛查轮次、出生年份和居住地点进行匹配。病例根据侵袭性（导管原位癌（DCIS）与浸润性肿瘤）、病理亚型（考虑激素受体和HER2）以及诊断类型（筛查发现与间隔期病例）进行分类。MD由一位经验丰富的放射科医生使用半定量量表进行评估。BC危险因素的数据通过相应轮次的筛查项目获取。使用条件逻辑回归评估MD与肿瘤亚型之间的关联。
MD与后续BC明显相关。与参考类别（MD <10%）相比，最高MD类别（MD >75%）的比值比（OR）在DCIS中为（OR = 3.47；95%置信区间 = 1.46至8.27），在浸润性肿瘤中为（OR = 2.95；95%置信区间 = 2.01至4.35）。与筛查发现的肿瘤相比（OR = 2.17；95%置信区间 = 1.40至3.36），间隔期病例的额外风险特别高（OR = 7.72；95%置信区间 = 4.02至14.81）。排除MD评估后第一年或早期召回筛查后立即诊断的间隔期病例的敏感性分析得出了相似的结果。在病理亚型方面未观察到差异。与MD相关的额外风险在乳腺X线检查后至少持续7至8年。
我们的结果证实MD是所有类型乳腺癌的重要危险因素。乳腺密度高会显著增加发生间隔期肿瘤的风险，并且这种额外风险不能完全用可能的掩盖效应来解释。
