Table 2:
Cumulative incidence of breast cancer cases per 100 individuals
| Primary Analysis | Sensitivity Analyses | ||||||
|---|---|---|---|---|---|---|---|
| Age | Exposure | Unadjusted | Adjusted | Cause specific | Logistic Regression | Censored if screened > 8 years after cohort entry | Alternate Screening Definition |
| 70–74 | Not Screened | 4.0 (3.3–4.9) | 4.2 (3.5–5.0) | 5.5 (4.6–6.6) | 4.2 (3.4–5.1) | 3.6 (2.9–4.5) | 4.9 (4.2–5.8) |
| Screened | 6.2 (5.9–6.6) | 6.1 (5.7–6.4) | 7.1 (6.6–7.5) | 6.0 (5.7–6.4) | 5.1 (4.8–5.5) | 5.8 (5.5–6.2) | |
| Difference | 2.2 (1.3–3.0) | 1.9 (1.0–2.8) | 1.6 (0.4–2.7) | 1.9 (1.0–2.7) | 1.5 (0.6–2.3) | 0.9 (−0.1–1.7) | |
| % Excess | 35 | 31 | 22 | 31 | 29 | 15 | |
| Hazard Ratio | 1.56 (1.27–1.91) | 1.47 (1.19–1.81) | 1.29 (1.05–1.59) | 1.48 (1.2–1.83) | 1.41 (1.12–1.78) | 1.19 (0.99–1.43) | |
| 75–84 | Not Screened | 2.4 (2.1–2.8) | 2.6 (2.2–3.0) | 4.1 (3.4–4.8) | 2.6 (2.2–3.0) | 2.3 (1.9–2.7) | 3 (2.7–3.5) |
| Screened | 5.0 (4.8–5.3) | 4.9 (4.6–5.2) | 6.4 (6.0–6.8) | 4.8 (4.5–5.1) | 4.4 (4.1–4.6) | 4.7 (4.4–5) | |
| Difference | 2.6 (2.1–3.1) | 2.3 (1.7–2.8) | 2.3 (1.5–3.1) | 2.3 (1.7–2.8) | 2.1 (1.6–2.6) | 1.7 (1.1–2.2) | |
| % Excess | 52 | 47 | 36 | 47 | 47 | 36 | |
| Hazard Ratio | 2.10 (1.76–2.50) | 1.92 (1.6–2.3) | 1.59 (1.33–1.91) | 1.93 (1.61–2.31) | 1.93 (1.59–2.33) | 1.56 (1.32–1.83) | |
| 85+ | Not Screened | 1.3 (0.9–2) | 1.3 (0.9–1.9) | 3.2 (2.0–5.1) | 1.3 (0.9–1.9) | 1.3 (0.9–1.9) | 1.4 (1.0–2.0) |
| Screened | 2.9 (2.3–3.7) | 2.8 (2.3–3.4) | 5.6 (4.2–7.5) | 2.8 (2.3–3.4) | 2.7 (2.2–3.4) | 2.5 (1.9–3.1) | |
| Difference | 1.6 (0.8–2.4) | 1.5 (0.6–2.2) | 2.4 (0.6–4.2) | 1.5 (0.6–2.2) | 1.4 (0.6–2.0) | 1.1 (0.3–1.7) | |
| % Excess | 55 | 54 | 43 | 53 | 52 | 44 | |
| Hazard Ratio | 2.56 (1.46–3.47) | 2.2 (1.43–3.4) | 1.78 (1.15–2.76) | 2.15 (1.39–3.33) | 2.13 (1.37–3.29) | 1.76 (1.15–2.69) | |
Notes: Tables present the cumulative incidence of breast cancer (breast cancer cases per 100 individuals) at the end of follow up, which occurred at death, breast cancer diagnosis, or through the end of 2017. All values in parenthesis indicate 95% confidence intervals. Hazard ratios compare risk of breast cancer diagnosis in screened and unscreened groups. Logistic models produce odds ratios rather than hazard ratios. All models use the Fine-Gray method, except the logistic model and the cause-specific hazard model. All sensitivity analyses used the same set of covariates as in the primary adjusted analysis. The alternate screening definition reclassifies women who received mammograms billed with diagnostic codes in the absence of claims for breast cancer symptoms as “not screened” rather than “screened.”