据10月24日《内科学文献》在线发表的一项对乳腺癌发展和死亡风险的评估结果，乳腺X线检查挽救乳腺癌患者生命的几率低于25%。
乳腺X线检查可挽救乳腺癌患者生命的依据大多来自乳腺癌生存者的现身说法。为探索乳腺癌生存者受益于乳腺X线检查的真实情况，新罕布什尔州汉诺威达特茅斯健康政策和临床实践研究所的H. Gilbert Welch博士和Brittney A. Frankel女士利用全国流行病学数据，应用美国国立癌症研究所(NCI)开发的DevCan 6.5.0软件计算乳腺X线筛查挽救患者生命的几率。
•乳腺X线筛查检出癌症风险=乳腺癌发生风险×乳腺X线检查检出乳腺癌患者比例
•受益于乳腺X线检查的死亡绝对风险降幅或死亡率收益=未行乳腺X线检查的20年死亡风险估计值－目前的20年死亡风险观察值
•乳腺癌患者生存受益于筛查的几率=死亡率收益÷筛查检出乳腺癌比例
结果显示，假如50岁女性乳腺X线筛查降低乳腺癌死亡率20%，那么该年龄乳腺癌患者生存受益于筛查的几率为13%；假如筛查导致的乳腺癌死亡率降幅为25%而非20%，则受益几率升至17%；而当筛查降低乳腺癌死亡率仅为5%时，几率则降至3%。最令人惊讶的结果是筛查对70岁年龄组生存率的影响。虽然该年龄组筛查检出乳腺癌比例相对较低(52%)，然而该年龄组乳腺X线检查挽救患者生命的几率仍低于25%。对各种情况分析所得出的筛查挽救患者生命的几率估计值均低于25%。
研究者指出，考虑到最新数据证实受益于乳腺X线筛查的患者比例很小，乳腺X线筛查确诊的典型乳腺癌患者的生存受益于检查的几率实际上可能低于10%。大多数人并没有认识到，许多在出现临床症状后才确证的癌症患者也是可治疗的。另外，一些恶性肿瘤患者则存在过度诊断，即使没有发现癌症和进行治疗，患者也可能不出现症状或死亡。筛查收益随时间推移而下降，一方面是因为女性自我发现乳腺肿块后而得到早期确诊，另一方面是治疗手段不断进步。
明尼苏达大学、明尼阿波利斯退伍军人慢性病预后研究中心的Timothy J. Wilt博士和Melissa R. Partin博士随刊述评中指出，研究者有理由担心，过分夸大乳腺X线检查收益可能会形成毫无根据地要求筛查-过度诊断-过度治疗的怪圈，而支持乳腺X线检查的乳腺癌生存者人数会继续增加。临床医生应该打破过度诊治的怪圈，并与生存者故事及名人效应做斗争。他们可以用简单、准确和具有说服力的话语来做到这一点，如“我推荐50～74岁患者每2年筛查1次” 。
研究者和评论者均无利益冲突披露。
相关英文论文摘要：
Likelihood That a Woman With Screen-Detected Breast Cancer Has Had Her "Life Saved" by That Screening
Background Perhaps the most persuasive messages promoting screening mammography come from women who argue that the test "saved my life." Because other possibilities exist, we sought to determine how often lives were actually saved by mammography screening.
Methods We created a simple method to estimate the probability that a woman with screen-detected breast cancer has had her life saved because of screening. We used DevCan, the National Cancer Institute's software for analyzing Surveillance Epidemiology and End Results (SEER) data, to estimate the 10-year risk of diagnosis and the 20-year risk of death—a time horizon long enough to capture the downstream benefits of screening. Using a range of estimates on the ability of screening mammography to reduce breast cancer mortality (relative risk reduction [RRR], 5%-25%), we estimated the risk of dying from breast cancer in the presence and absence of mammography in women of various ages (ages 40, 50, 60, and 70 years).
Results We found that for a 50-year-old woman, the estimated risk of having a screen-detected breast cancer in the next 10 years is 1910 per 100 000. Her observed 20-year risk of breast cancer death is 990 per 100 000. Assuming that mammography has already reduced this risk by 20%, the risk of death in the absence of screening would be 1240 per 100 000, which suggests that the mortality benefit accrued to 250 per 100 000. Thus, the probability that a woman with screen-detected breast cancer avoids a breast cancer death because of mammography is 13% (250/1910). This number falls to 3% if screening mammography reduces breast cancer mortality by 5%. Similar analyses of women of different ages all yield probability estimates below 25%.
Conclusions Most women with screen-detected breast cancer have not had their life saved by screening. They are instead either diagnosed early (with no effect on their mortality) or overdiagnosed.
