Table 4.
Risk of ovarian cancer per 5-year increase in number of lifetime ovulatory cycles (LOC, n=60 cycles) across categories of age, oral contraceptive use, parity, body mass index, and smoking status.
| Ovarian cancer risk per 5-year increase in LOC | |||
|---|---|---|---|
| HR* | (95% CI) | P interaction† | |
| 40–49 years old | 1.19 | (0.88–1.60) | 0.99 |
| 50–59 years old | 1.13 | (1.08–1.19) | |
| 60+ years old | 1.14 | (1.10–1.18) | |
| Oral contraceptive use | |||
| Never or ≤1 year of use | 1.10 | (1.06–1.15) | 0.63 |
| >1 year of use | 1.15 | (1.10–1.21) | . |
| Parity | |||
| Nulliparous | 1.11 | (1.02–1.19) | 0.24 |
| Parous | 1.13 | (1.10–1.17) | |
| Body mass index | |||
| <20 kg/m2 | 1.16 | (1.03–1.30) | 0.90 |
| 20–24.9 kg/m2 | 1.13 | (1.08–1.19) | |
| 25–29.9 kg/m2 | 1.14 | (1.08–1.19) | |
| 30–34.9 kg/m2 | 1.13 | (1.04–1.23) | |
| 35+ kg/m2 | 1.18 | (1.05–1.32) | |
| Smoking status | |||
| Never | 1.16 | (1.12–1.21) | 0.47 |
| Former | 1.11 | (1.05–1.16) | |
| Current | 1.13 | (1.05–1.22) | |
*
Hazard ratios (HR) and 95% confidence intervals (CI) were estimated from Cox proportional hazards models stratified on study cohort and adjusted for baseline age (continuous), body mass index (<20, 20–24.9, 25–29.9, 30–34.9, ≥35 kg/m2), smoking status (never, former, current), and duration of menopausal hormone therapy use (never, ≤5, >5–10, >10 years).
†
P interaction from likelihood ratio test.