Table 3.
Life-saving proportion: women with screen-detected cancers that have their lives saved by mammography.
| Age | Development risk/1000* | CCDR/1000† | Death risk/1000‡ | 10% RRR§ |
15% RRR |
20% RRR |
20% NND∥ |
25% RRR |
30% RRR |
20% RRR No Rx¶ |
|---|---|---|---|---|---|---|---|---|---|---|
| % | % | % | % | % | % | % | ||||
| 40 | 31.9 | 25.5 | 4.8 | 1.9 | 2.8 | 3.7 | 27 | 4.7 | 5.6 | 4.7 |
| 45 | 41.9 | 33.5 | 6.8 | 2.0 | 3.0 | 4.1 | 25 | 5.1 | 6.1 | 5.1 |
| 50 | 51.0 | 40.8 | 8.8 | 2.2 | 3.2 | 4.3 | 23 | 5.4 | 6.5 | 5.3 |
| 55 | 59.2 | 47.3 | 10.5 | 2.2 | 3.3 | 4.4 | 23 | 5.5 | 6.7 | 5.2 |
| 60 | 64.4 | 51.5 | 11.8 | 2.3 | 3.4 | 4.6 | 22 | 5.7 | 6.9 | 5.1 |
| 65 | 66.3 | 53.0 | 12.7 | 2.4 | 3.6 | 4.8 | 21 | 6.0 | 7.2 | 5.0 |
* Cumulative 15-year development risk for breast cancer for average women, from Figure 1 [28].
† Cumulative cancer detection rate (CCDR) over 15 years assumes a cumulative sensitivity of 80% from repeated screening.
‡ Breast cancer screen-free absolute death risk is from Figure 1.
§ The proportion is the screen-free absolute death risk multiplied by the relative risk reduction (RRR), and then divided by the CCDR.
∥ Number of cancers needed to be detected (NND) is the reciprocal of the life-saving proportion.
¶ Assumes maximum prescreening era (1978–1980) 15-year absolute death risk, with no adjustment for improved therapy.