乳がん検診の効果

結論を言うと、マンモグラフィーによる検診は、進行癌を１人減らすためのNNTが12,500と非常に非効率だそうです。

6:04 | "Effect of Three Decades of Screening Mammography on Breast-Cancer Incidence" by Archie Bleyer from St. Charles Health System, Central Oregon.
The introduction of screening mammography in the United States has been associated with a doubling in the number of cases of early-stage breast cancer that are detected each year, from 112 to 234 cases per 100,000 women — an absolute increase of 122 cases per 100,000 women. Concomitantly, the rate at which women present with late-stage cancer has decreased by 8%, from 102 to 94 cases per 100,000 women — an absolute decrease of 8 cases per 100,000 women. With the assumption of a constant underlying disease burden, only 8 of the 122 additional early-stage cancers diagnosed were expected to progress to advanced disease. After excluding the transient excess incidence associated with hormone-replacement therapy and adjusting for trends in the incidence of breast cancer among women younger than 40 years of age, the authors estimated that breast cancer was overdiagnosed (i.e., tumors were detected on screening that would never have led to clinical symptoms) in 1.3 million U.S. women in the past 30 years. The authors estimated that in 2008, breast cancer was overdiagnosed in more than 70,000 women; this accounted for 31% of all breast cancers diagnosed.
These rusults suggests that screening is having, at best, only a small effect on the rate of death from breast cancer. (240 words / 109 sec = 132 wpm)
From NEJM Audio Summaries

注

• mammography: mæmɑ'grəfi アクセントの位置に注意
• concomitantly： 同時に　cf. concomitant chemoradiotherapy
• i.e. (latin: id est) = that is
• at best: よくても　cf. The best of men are but men at best.どんなに立派な人でも、所詮、人以上のものではない。◆ことわざ