Department of Public Health, University of Copenhagen, Denmark.
Acta Oncol. 2013 Jan;52(1):48-56. doi: 10.3109/0284186X.2012.698750. Epub 2012 Sep 3.
Long-term data on breast cancer detection in mammography screening programs are warranted to better understand the mechanisms by which screening changes the breast cancer pattern in the population. We aimed to analyze 17 years of breast cancer detection rates inside and outside screening in two Danish regions, emphasizing the influence of organizational differences of screening programs on the outcomes.
We used data from two long-standing population-based mammography screening programs, Copenhagen and Fyn, in Denmark. Both programs offered biennial screening to women aged 50-69 years. We identified targeted, eligible, invited and participating women. We calculated screening detection and interval cancer rates for participants, and breast cancer incidence in non-screened women (= targeted women excluding participants) by biennial invitation rounds. Tumor characteristics were tabulated for each of the three groups of cancers.
Start of screening resulted in a prevalence peak in participants, followed by a decrease to a fairly stable detection rate in subsequent invitation rounds. A similar pattern was found for breast cancer incidence in non-screened women. In Fyn, non-screened women even had a higher rate than screening participants during the first three invitation rounds. The interval cancer rate was lower in Copenhagen than in Fyn, with an increase over time in Copenhagen, but not in Fyn. Screen-detected cancers showed tumor features related with a better prognosis than tumors detected otherwise, as more than 80% were smaller than 20 mm and estrogen receptor positive.
Data from two long-standing population-based screening programs in Denmark illustrated that even if background breast cancer incidence and organization were rather similar, performance indicators of screening could be strongly influenced by inclusion criteria and participation rates. Detection rates should be interpreted with caution as they may be biased by selection into the screening population.
长期的乳腺癌筛查计划中的乳腺癌检出数据对于更好地了解筛查改变人群中乳腺癌模式的机制是必要的。我们旨在分析丹麦两个地区 17 年的乳腺癌筛查内外检出率，强调筛查计划的组织差异对结果的影响。
我们使用丹麦两个长期的基于人群的乳腺筛查计划（哥本哈根和菲英）的数据。这两个项目都为 50-69 岁的女性提供每两年一次的筛查。我们确定了目标、合格、受邀和参与的女性。我们计算了参与者的筛查检出率和间期癌率，以及非筛查女性（=排除参与者的目标女性）的每两年一次的邀请轮次的乳腺癌发病率。为每一组癌症列出了肿瘤特征。
筛查的开始导致了参与者中的患病率高峰，随后在随后的邀请轮次中下降到相当稳定的检出率。在非筛查女性中也发现了类似的乳腺癌发病率模式。在菲英，非筛查女性在前三个邀请轮次中甚至比筛查参与者的发病率更高。哥本哈根的间期癌率低于菲英，且随着时间的推移而增加，但菲英没有增加。筛查检出的癌症与更好的预后相关的肿瘤特征比其他方式检出的肿瘤更明显，因为超过 80%的癌症小于 20 毫米，并且雌激素受体阳性。
来自丹麦两个长期的基于人群的筛查计划的数据表明，即使背景乳腺癌发病率和组织相当相似，筛查的性能指标也可能受到纳入标准和参与率的强烈影响。检出率应谨慎解释，因为它们可能受到筛选人群选择的偏差影响。
