Table 5.
Estimated incidence rate ratio (RRa) for hypothyroidism (95% CI) by radiation dose to the thyroid gland and pituitary gland: Childhood Cancer Survivor Study.
| RR (95% CI) | |||||
|---|---|---|---|---|---|
| Pituitary dose, Gy (mean) | |||||
| Thyroid dose, Gy (mean) | 0 | >0 - <1 (0.2) | 1 - <10 (2.6) | 10-<35 (21.0) | ≥35 (47.0) |
| 0 | 1.0b | - | - | - | - |
| >0 - <2 (0.6) | - | 1.3 (0.8–2.0) | 2.6 (1.2–5.5) | 1.4 (0.9–1.9) | 5.3 (3.3–8.7) |
| 2- <10 (4.8) | - | 2.0 (0.9–4.2) | 4.2 (1.9–9.3) | 2.4 (1.1–5.3) | 7.6 (3.9–14.7) |
| 10 - <20 (14.7) | - | 3.1 (1.5–6.3) | 3.9 (1.1–13.5) | 3.8 (2.2–6.6) | 4.7 (2.2–9.9) |
| 20 - <30 (24.1) | - | 4.9 (2.8–8.9) | 8.8 (4.5–16.9) | 6.9 (3.7–12.6) | 6.8 (3.8–12.6) |
| 30 - <40 (35.5) | - | 7.8 (3.9–15.4) | 9.0 (5.2–15.8) | 10.1 (4.2–24.4) | 9.5 (4.9–18.4) |
| ≥40 (45.3) | - | 21.0 (8.6–51.5) | 12.2 (6.9–21.6) | 12.4 (6.2–24.5) | 8.0 (3.0–21.6) |
a
RRs computed using Poisson regression analysis for a joint thyroid and pituitary dose-response. Fitted model includes an additive adjustment for an interaction term of chemotherapy and type of cancer (leukemia, central nervous system cancer, Hodgkin lymphoma, and other cancers). Type of first cancer included to account for possible differential surveillance and shared predisposition. Baseline was adjusted for sex, attained age, type of cancer and attained calendar year.
b
Reference category
Abbreviations: CI=confidence interval; RR=incidence rate ratio