Table 2.
Model inputs used for the Age trial simulation:
| Model Input | Description | Source |
|---|---|---|
| Population demographics | ||
| Birth cohort | Birth years of women participating in the Age trial | Age trial |
| Life years | Number of life years by trial arm by age | Age trial |
| Natural history of breast cancer | ||
| Incidence | Control arm incidence (incidence in the absence of screening) | Age trial |
| Tumor onset | The moment tumors start to grow (tumor inception) | CISNET1 |
| Sojourn time | Time between when a cancer is first screen-detectable and cancer diagnosis in the absence of screening. | CISNET2 |
| Tumor progression | Tumor growth, tumor progression and regression affect tumor sojourn times and breast cancer survival. | CISNET3 |
| Estrogen receptor distribution | Age-specific ER positive and ER negative distributions | U.K.4 |
| Breast cancer screening | ||
| Attendance | Adherence to annual screening in the intervention arm | Age trial |
| Sensitivity | Probability that the screen will be positive among women with breast cancer by age, screening round (first vs. subsequent) | Age trial |
| Mammography | Two-view mammography for first screens, for all subsequent screens one-view mammography | Age trial |
| Breast cancer treatment | ||
| Treatment dissemination | Breast cancer treatment by age, stage and ER-status | BASO5 |
| Effectiveness | Hazard reduction breast cancer mortality by age and ER-status | EBCTCG6 |
| Breast cancer survival | ||
| Survival | Breast cancer survival by age, stage and ER-status | CISNET7 |
| Other-cause mortality | Probability of dying from causes other than breast cancer | U.K.8 |
Tumor onset, sojourn time and tumor progression are model-specific parameters. These, and other model-specific assumptions about breast cancer natural history are described elsewhere [6, 21–25].
Estrogen receptor status comes from observed U.K. data [26].
The treatment dissemination was derived from BASO reports [26] published by the NHSBSP.
Treatment effectiveness / hazard reduction for breast cancer death was published by the Early Breast Cancer Trialists Collaborative Group (EBCTCG) that included the U.K. trials [27]
Breast cancer survival by age and ER status from the UK is not available for the time period of the trial, the existing survival in the models which is based on U.S. data was used.
Other cause mortality was taken from the Human Mortality Database [30] with breast cancer deaths removed.