Gøtzsche P C, Nielsen M
The Nordic Cochrane Centre, Rigshospitalet, Dept. 7112, Blegdamsvej 9, Copenhagen Ø 2100 Denmark.
Cochrane Database Syst Rev. 2006 Oct 18(4):CD001877. doi: 10.1002/14651858.CD001877.pub2.
A variety of estimates of the benefits and harms of mammographic screening for breast cancer have been published and national policies vary.
To assess the effect of screening for breast cancer with mammography on mortality and morbidity.
We searched PubMed (June 2005).
Randomised trials comparing mammographic screening with no mammographic screening.
Both authors independently extracted data. Study authors were contacted for additional information.
Seven completed and eligible trials involving half a million women were identified. We excluded a biased trial from analysis. Two trials with adequate randomisation did not show a significant reduction in breast cancer mortality, relative risk (RR) 0.93 (95% confidence interval 0.80 to 1.09) at 13 years; four trials with suboptimal randomisation showed a significant reduction in breast cancer mortality, RR 0.75 (0.67 to 0.83) (P = 0.02 for difference between the two estimates). RR for all six trials combined was 0.80 (0.73 to 0.88). The two trials with adequate randomisation did not find an effect of screening on cancer mortality, including breast cancer, RR 1.02 (0.95 to 1.10) after 10 years, or on all-cause mortality, RR 1.00 (0.96 to 1.04) after 13 years. We found that breast cancer mortality was an unreliable outcome that was biased in favour of screening, mainly because of differential misclassification of cause of death. Numbers of lumpectomies and mastectomies were significantly larger in the screened groups, RR 1.31 (1.22 to 1.42) for the two adequately randomised trials; the use of radiotherapy was similarly increased.
AUTHORS' CONCLUSIONS: Screening likely reduces breast cancer mortality. Based on all trials, the reduction is 20%, but as the effect is lower in the highest quality trials, a more reasonable estimate is a 15% relative risk reduction. Based on the risk level of women in these trials, the absolute risk reduction was 0.05%. Screening also leads to overdiagnosis and overtreatment, with an estimated 30% increase, or an absolute risk increase of 0.5%. This means that for every 2000 women invited for screening throughout 10 years, one will have her life prolonged. In addition, 10 healthy women, who would not have been diagnosed if there had not been screening, will be diagnosed as breast cancer patients and will be treated unnecessarily. It is thus not clear whether screening does more good than harm. Women invited to screening should be fully informed of both benefits and harms.
关于乳腺癌钼靶筛查的利弊已有多种评估结果发表，各国政策也不尽相同。
评估钼靶筛查乳腺癌对死亡率和发病率的影响。
我们检索了PubMed（2005年6月）。
比较钼靶筛查与非钼靶筛查的随机试验。
两位作者独立提取数据。联系研究作者获取更多信息。
共识别出7项完成且符合条件的试验，涉及50万女性。我们将一项有偏倚的试验排除在分析之外。两项随机化充分的试验未显示乳腺癌死亡率有显著降低，13年时相对危险度（RR）为0.93（95%置信区间0.80至1.09）；四项随机化欠佳的试验显示乳腺癌死亡率有显著降低，RR为0.75（0.67至0.83）（两项估计值之间的差异P = 0.02）。六项试验合并后的RR为0.80（0.73至0.88）。两项随机化充分的试验未发现筛查对癌症死亡率（包括乳腺癌，10年后RR为1.02（0.95至1.10））或全因死亡率（13年后RR为1.00（0.96至1.04））有影响。我们发现乳腺癌死亡率是一个不可靠的结果，且偏向于支持筛查，主要原因是死亡原因的分类错误存在差异。筛查组的肿块切除术和乳房切除术数量显著更多，两项随机化充分的试验中RR为1.31（1.22至1.
