Table 4.
Odds ratios (ORs) and 95% confidence intervals (CIs) of IUD use and endometrial cancer risk according to endometrial cancer risk factors
| Cases | Controls | OR (95% CI)1 | Cases | Controls | OR (95% CI)1 | pinteraction | |
|---|---|---|---|---|---|---|---|
| Age at diagnosis | |||||||
| < 65 years (n=15,386) | ≥ 65 years (n=8,745) | ||||||
| IUD use | 0.93 | ||||||
| Never | 4,464 | 7,751 | Ref | 2,904 | 5,291 | 0.97 (0.90, 1.05) | |
| Ever | 1,216 | 1,955 | 0.81 (0.73, 0.89) | 217 | 333 | 0.77 (0.63, 0.94) | |
| Parity | |||||||
| Nulliparous (n=3,458) | Parous (n=20,531) | ||||||
| IUD use | 0.001 | ||||||
| Never | 1,477 | 1,781 | Ref | 5,826 | 11,198 | 0.74 (0.65, 0.85) | |
| Ever | 66 | 134 | 0.48 (0.34, 0.68) | 1,364 | 2,143 | 0.63 (0.54, 0.74) | |
| BMI | |||||||
| <30 kg/m2 (n=18,277) | ≥30 g/m2 (n=5,631) | ||||||
| IUD use | 0.19 | ||||||
| Never | 4,494 | 10,840 | Ref | 2,767 | 2,114 | 2.83 (2.62, 3.05) | |
| Ever | 974 | 1,969 | 0.80 (0.72, 0.88) | 445 | 305 | 2.34 (1.98, 2.76) | |
| Menopausal status | |||||||
| Premenopausal (n=5,446) | Postmenopausal (n=17,497) | ||||||
| IUD use | 0.006 | ||||||
| Never | 1,182 | 2,652 | Ref | 5,732 | 9,920 | 0.99 (0.88, 1.11) | |
| Ever | 561 | 1,051 | 0.93 (0.80, 1.08) | 739 | 1,106 | 0.72 (0.62, 0.83) | |
| OC use | |||||||
| Never (n=13,818) | Ever (n=9,975) | ||||||
| IUD use | 0.26 | ||||||
| Never | 4,527 | 7,846 | Ref | 2,779 | 5,063 | 0.69 (0.64, 0.75) | |
| Ever | 613 | 832 | 0.78 (0.68, 0.89) | 785 | 1,348 | 0.59 (0.53, 0.67) | |
| MHT use2 | |||||||
| Never (n=11,095) | Ever (n=6,248) | 0.008 | |||||
| IUD use | |||||||
| Never | 3,703 | 6,254 | 0.69 (0.64, 0.75) | 2,000 | 3,553 | Ref | |
| Ever | 481 | 657 | 0.57 (0.49, 0.66) | 254 | 441 | 0.60 (0.50, 0.72) | |
| Smoking status | |||||||
| Never (n=14,648) | Former/Current (n=9,338) | ||||||
| IUD use | 0.18 | ||||||
| Never | 4,765 | 7,499 | Ref | 2,559 | 5,457 | 0.76 (0.71, 0.82) | |
| Ever | 986 | 1,398 | 0.77 (0.69, 0.86) | 444 | 878 | 0.68 (0.59, 0.79) | |
| Diabetes | |||||||
| No (n=18,275) | Yes (n=2,040) | ||||||
| IUD use | 0.62 | ||||||
| Never | 5,110 | 10,554 | Ref | 972 | 730 | 1.73 (1.53, 1.95) | |
| Ever | 1,025 | 1,586 | 0.81 (0.73, 0.90) | 209 | 129 | 1.50 (1.17, 1.94) | |
Adjusted for age (continuous), race (White, Black, Asian, Other), BMI (< 25kg/m2, 25–30 kg/m2, ≥30 kg/m2), age at menarche (<11, 11–12, 13–14, ≥15), duration of oral contraceptive use (never, <5, 5–9, ≥10 years), parity/age at last birth (nulliparous, 1–2 births and <25, 1–2 births and 25–29, 1–2 births and 30–34, 1–2 births and ≥35, ≥3 births and <25, ≥3 births and 25–29, ≥3 births and 30–34, ≥3 births and ≥35), menopausal status (premenopausal, postmenopausal), any menopausal hormone use (never, ever), smoking status (never, former, current), and stratified by study. For each effect modifier, women with missing values were excluded from the model
Among postmenopausal women