Table 1.

Original and adjusted estimate of the absolute benefit of breast cancer screening from four systematic reviews

Systematic review groupAge group, yInterventionScreening period/years of follow-upMortality reductionOriginal NNS/NNIbAdjusted NNSc
UK Independent Panela50–69Screening20 y, ages 50–69/25 y, ages 55–7920%180180
USPSTFd50–59InvitationAvg. 7 y, ages 50–59/Avg. 14, ages 50–5914%1,339
60–69InvitationAvg. 7 y, ages 60–69/Avg. 14, ages 60–6932%337
EUROSCREEN Working Group50–69Screening20 y, ages 50–69/30 y, ages 50–7938%–48%111–14364–96
Nordic Cochrane Institute40–74Invitation10 y, ages 40–74/10 y, ages 40–7415%2,000257
  • aReference population and protocol.

  • bNNS: The UK Independent Panel and EUROSCREEN estimates of absolute benefit are based on the number needed to screen.

  • cDerived from Duffy and colleagues. Original estimates are adjusted to the same scenario used in the UK Independent Review, that is, the impact of screening UK women ages 50–69 years every 3 years for 20 years on mortality in women ages 55–79 years.

  • dThe estimate for the mortality reduction for women ages 50–69 years is based on taking an inverse variance-weighted average of the 2 relative risks in the logarithmic scale [relative risk (RR) = 0.81 (95% CI, 0.72–0.92)].