Table 2.
Breast cancer risk associated with therapeutic I-131 (considering a ten-year minimal latency time).
| Pooled cohort | ||||
|---|---|---|---|---|
| BC cases/person-years | RRa (95% CI) | AERb | ||
| Therapeutic I-131 activity | ||||
| No | 234/85,715 | 1 | ||
| Yes | 101/27,685 | 1.07 (0.84–1.35) | ||
| P-heterogeneity | >0.5 | |||
| Cumulative activity of therapeutic I-131 (mCi) | ||||
| No I-131 treatment | 234/85,715 | 1 | ||
| <40 | 4/2316 | 0.49 (0.15–1.15) | ||
| 40–100 | 16/6499 | 0.77 (0.44–1.25) | ||
| 100–200 | 53/14,029 | 1.10 (0.80–1.47) | ||
| 200–400 | 19/3731 | 1.55 (0.92–2.44) | ||
| ≥400 | 9/1112 | 2.41 (1.13–4.52) | 42 (−8–93)c | |
| P-heterogeneity | 0.039 | |||
| P-trend | 0.028 | |||
| ERR per 100 mCia | 0.17 (0.02–0.38) | |||
| ERR per 100 mCi among women who received I-131 treatmenta | 0.30 (0.08–0.64) | |||
| Cumulative radiation dose of I-131 therapy (mGy)d | ||||
| No I-131 treatment | 232/83,162 | 1 | ||
| <100 | 5/2644 | 0.54 (0.19–1.18) | ||
| 100–250 | 52/16,637 | 0.91 (0.67–1.22) | ||
| 250–500 | 20/4682 | 1.26 (0.76–1.95) | ||
| 500–1000 | 16/2,043 | 2.34 (1.33–3.81) | 37 (4–82) | |
| ≥1000 | 3/697 | 1.20 (0.29–3.18) | ||
| P-heterogeneity | 0.033 | |||
| P-trend | 0.094 | |||
| ERR per 100 mGya,d | 0.05 (0.00–0.14) | |||
| ERR per 100 mGy among women who received I-131 treatmenta,d | 0.10 (0.01–0.24) | |||
AER absolute excess risk per 10,000 person-years, BC breast cancer, CI confidence interval, ERR excess relative risk, RR relative risk.
aAdjusted for the country, age at diagnosis, and dose of external radiotherapy delivered to the breast in the background risks
bAER are shown only when the corresponding RRs were statistically significant at P < 0.05.
cThe lower bounds could not be estimated with maximum likelihood methods, AER calculated with Wald estimation was shown
dAnalysis conducted among women aged >15 years at thyroid cancer diagnosis.