Table 2.

Impacta of targeting a subset of European-American women for breast cancer preventive strategies

Percentage of population at high risk (α)Lifetime risk in low-risk (%)Risk for high-risk relative to low-riskRisk for low-risk relative to populationPercentage of cases who are high-risk (Sn)Percentage of noncases who are high-risk (1-Sp)Percentage of high-risk who are cases (PPV)Percentage of low-risk who are noncases (NPV)NNTb
Current knowledge of genetic susceptibility alleles (risk score variance, 0.35)
 10010010012.68a95
 904.113.320.3296.7689.0213.6395.8988
 755.202.920.4189.7472.8615.1794.8079
 675.682.840.4585.2264.3516.1394.3274
 506.642.820.5273.8246.5418.7293.3664
 337.662.990.6059.5429.1522.8892.3452
 258.203.180.6551.4921.1526.1291.8046
 109.544.300.7532.316.7640.9790.4629
 012.681.000087.32
Best-case scenario (risk score variance, 1.44)
 10010010012.68a95
 900.8316.850.0799.3488.6414.0099.1786
 751.5510.600.1296.9571.8116.3998.4573
 671.949.240.1594.9462.9417.9798.0667
 502.927.680.2388.4844.4122.4497.0853
 334.247.040.3377.6126.5229.8295.7640
 255.077.000.4069.9918.4735.5094.9334
 107.517.880.5946.674.6859.1892.4920
 012.681.000087.32
  • aAssuming that the lifetime risk of developing breast cancer is 12.68% based upon estimates for the U.S. white female population (19).

  • bNNT, number of women who must be targeted to avoid one breast cancer death, assuming one sixth of all breast cancers are fatal and targeting prevents death from half of them.