Department of Radiation Sciences, Oncology, Umeå University, 90187, Umeå, Sweden.
Department of Oncology-Pathology, Karolinska Institute, 17177 Solna, Stockholm, Sweden.
Breast Cancer Res. 2018 Dec 17;20(1):153. doi: 10.1186/s13058-018-1082-z.
Overdiagnosis, defined as the detection of a cancer that would not become clinically apparent in a woman's lifetime without screening, has become a growing concern. Similar underlying risk of breast cancer in the screened and control groups is a prerequisite for unbiased estimates of overdiagnosis, but a contemporary control group is usually not available in organized screening programs.
We estimated the frequency of overdiagnosis of breast cancer due to screening in women 50-69 years old by using individual screening data from the population-based organized screening program in Stockholm County 1989-2014. A hidden Markov model with four latent states and three observed states was constructed to estimate the natural progression of breast cancer and the test sensitivity. Piecewise transition rates were used to consider the time-varying transition rates. The expected number of detected non-progressive breast cancer cases was calculated.
During the study period, 2,333,153 invitations were sent out; on average, the participation rate in the screening program was 72.7% and the average recall rate was 2.48%. In total, 14,648 invasive breast cancer cases were diagnosed; among the 8305 screen-detected cases, the expected number of non-progressive breast cancer cases was 35.9, which is equivalent to 0.43% (95% confidence interval (CI) 0.10%-2.2%) overdiagnosis. The corresponding estimates for the prevalent and subsequent rounds were 15.6 (0.87%, 95% CI 0.20%-4.3%) and 20.3 (0.31%, 95% CI 0.07%-1.6%), respectively. The likelihood ratio test showed that the non-homogeneous model fitted the data better than an age-homogeneous model (P <0.001).
Our findings suggest that overdiagnosis in the organized biennial mammographic screening for women 50-69 in Stockholm County is a minor phenomenon. The frequency of overdiagnosis in the prevalent screening round was higher than that in subsequent rounds. The non-homogeneous model performed better than the simpler, traditional homogeneous model.
过度诊断是指在没有筛查的情况下，在女性有生之年不会出现临床明显的癌症，但这种情况越来越受到关注。在筛查组和对照组中，乳腺癌的潜在风险相似，这是对过度诊断进行无偏估计的前提，但在有组织的筛查计划中，通常无法获得当代对照组。
我们使用 1989 年至 2014 年斯德哥尔摩县基于人群的有组织筛查计划中的个体筛查数据，估算了 50-69 岁女性因筛查而导致的乳腺癌过度诊断的频率。使用具有四个潜在状态和三个观察状态的隐马尔可夫模型来估计乳腺癌的自然进展和测试敏感性。使用分段转移率来考虑时变转移率。计算预期的非进展性乳腺癌检出病例数。
在研究期间，共发出 2333153 份邀请；平均而言，筛查计划的参与率为 72.7%，平均召回率为 2.48%。共诊断出 14648 例浸润性乳腺癌病例；在 8305 例筛查检出病例中，预期的非进展性乳腺癌病例数为 35.9 例，相当于 0.43%（95%置信区间[CI] 0.10%-2.2%）的过度诊断。流行和后续轮次的相应估计值分别为 15.6（0.87%，95%CI 0.20%-4.3%）和 20.3（0.31%，95%CI 0.07%-1.6%）。似然比检验表明，非均匀模型比年龄均匀模型更适合拟合数据（P<0.001）。
我们的研究结果表明，斯德哥尔摩县对 50-69 岁女性进行的有组织的每两年一次的乳房 X 线筛查中的过度诊断现象是一个较小的现象。流行筛查轮次的过度诊断频率高于后续轮次。非均匀模型的表现优于更简单的传统均匀模型。
