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Table 1 Relative risk of breast cancer death before screening start in women likely and not likely to participate in screening, and relative risk of breast cancer death after a period of screening with 75% participation.

From: Breast cancer screening: evidence of benefit depends on the method used

   Before screening After years of screening Correction according to Duffy et al.(2002) [18]
   BC death ratea Change in mortality due to screening Change in mortality unrelated to screening BC death ratea Dr A = p × RR × Dr B = 1-[(1-p) × Dr] Corrected RR (= A/B)
Panel A Participants 86 0% 0% 86     
  Non-participants 142 0% 0% 142     
  All womenb 100 0% 0% 100     
  RR breast cancer death, participants versus non-participants 0.61    0.61 1.42 0.65 0.65 1.00
Panel B Participants 86 -20% 0% 69     
  Non-participants 142 0% 0% 142     
  All womenb 100 -15% 0% 85     
  RR breast cancer death, participants versus non-participants 0.61    0.48 1.42 0.52 0.65 0.80
Panel C Participants 86 0% -25% 65     
  Non-participants 142 0% -25% 107     
  All womenb 100 0% -25% 75     
  RR breast cancer death, participants versus non-participants 0.61    0.61 1.07 0.48 0.73 0.66
Panel D Participants 86 -20% -25% 47     
  Non-participants 142 0% -25% 107     
  All womenb 100 -15% -25% 60     
  RR breast cancer death, participants versus non-participants 0.61    0.44 1.07 0.35 0.73 0.48
  1. BC: Breast cancer; Dr: rate in non-participants after screening divided by the rate in all women before screening; p: participation rate of 75%; RR: relative risk. aPer 100,000 women-year. b(rate in participants × 0.75) + (rate in non-participants × 0.25).