Table 3.
Associations between continuous total lifetime number of ovulatory cycles and ovarian cancer by histotype considering mutual adjustment for LOC component factors: duration of oral contraceptive use and pregnancies, Ovarian Cancer Cohort Consortium (OC3).
| Serous (n=2,045) | Endometrioid (n=319) | Mucinous (n=184) | Clear Cell (n=121) | Other/Unknown (n=577) | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| HR* | (95% CI) | HR* | (95% CI) | HR* | (95% CI) | HR* | (95% CI) | HR* | (95% CI) | P-Het† | |
| Per 5-year increase in LOC (60 LOC) | 1.13 | (1.09–1.17) | 1.20 | (1.10–1.32) | 0.99 | (0.88–1.10) | 1.37 | (1.18–1.58) | 1.14 | (1.06–1.22) | 0.01 |
| Per 5-year increase in LOC (60 LOC) adjusted for duration of oral contraceptive use and pregnancy‡ | 1.08 | (1.03–1.12) | 1.11 | (0.99–1.26) | 0.94 | (0.81–1.08) | 1.26 | (1.08–1.48) | 1.08 | (0.99–1.18) | 0.15 |
Hazard ratios (HR) and 95% confidence intervals (CI) were estimated from competing risk [Gates et al. 2010]. 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). Competing risk models were based on fixed covariate effects.
The P value for heterogeneity (P het) was calculated using a two-sided likelihood ratio test. [Gates et al., 2010]
Models additionally adjusted for duration of oral contraceptive use and number of pregnancies.