Table 2.
Relative risks of RCC in relation to menstrual/reproductive factors
| Factors | No. of cases | Person-years | Age-adjusted RR (95% CI)* | Multivariate RR (95% CI)* |
|---|---|---|---|---|
| Age at menarche (y) | ||||
| ≤12 | 104 | 554,025 | 1.00 (reference) | 1.00 (reference) |
| 13–14 | 85 | 422,204 | 1.06 (0.77–1.44) | 1.12 (0.81–1.55) |
| ≥15 | 36 | 135,954 | 1.36 (0.90–2.06) | 1.42 (0.91–2.20) |
| P trend | 0.19 | 0.13 | ||
| Age at natural menopause (y) | ||||
| <45 | 20 | 87,695 | 1.00 (reference) | 1.00 (reference) |
| 45–49 | 32 | 171,188 | 0.86 (0.49–1.51) | 1.03 (0.57–1.88) |
| 50–54 | 41 | 221,274 | 0.82 (0.48–1.42) | 0.97 (0.54–1.73) |
| ≥55 | 16 | 57,478 | 1.15 (0.59–2.23) | 1.13 (0.54–2.36) |
| P trend | 0.92 | 0.90 | ||
| Type of menopause | ||||
| Natural | 109 | 537,634 | 1.00 (reference) | 1.00 (reference) |
| Bilateral oophorectomy | 38 | 160,494 | 1.22 (0.84–1.77) | 1.10 (0.74–1.63) |
| Hysterectomy | 35 | 170,383 | 1.03 (0.70–1.51) | 0.90 (0.59–1.35) |
| Age at first live birth (y) | ||||
| ≤20 | 83 | 327,461 | 1.00 (reference) | 1.00 (reference) |
| 21–25 | 82 | 382,319 | 0.92 (0.57–1.10) | 1.06 (0.73–1.54) |
| ≥26 | 30 | 246,886 | 0.55 (0.34–0.88) | 0.66 (0.40–1.09) |
| P trend | 0.02 | 0.15 | ||
| Parity | ||||
| Nulliparous | 25 | 143,747 | 1.00 (reference) | 1.00 (reference) |
| Parous | 201 | 978,375 | 1.13 (0.72–1.77) | 1.14 (0.71–1.85) |
| No. of children | ||||
| 1–2 children | 67 | 393,852 | 1.00 (reference) | 1.00 (reference) |
| 3–4 children | 78 | 379,422 | 1.06 (0.74–1.51) | 0.94 (0.64–1.36) |
| ≥5 children | 56 | 205,101 | 1.31 (0.87–1.98) | 1.11 (0.72–1.71) |
| P trend | 0.22 | 0.71 | ||
| Oral contraceptive use | ||||
| Never | 145 | 623,941 | 1.00 (reference) | 1.00 (reference) |
| Ever | 75 | 471,139 | 0.99 (0.70–1.39) | 1.08 (0.75–1.55) |
| Duration of oral contraceptive use (y) | ||||
| Never | 145 | 623,941 | 1.00 (reference) | 1.00 (reference) |
| ≤5 | 50 | 292,267 | 1.07 (0.73–1.57) | 1.18 (0.79–1.75) |
| >5 | 25 | 172,521 | 0.93 (0.57–1.51) | 1.01 (0.60–1.68) |
| P trend | 0.86 | 0.82 | ||
| Postmenopausal hormone use† | ||||
| Never | 93 | 430,283 | 1.00 (reference) | 1.00 (reference) |
| Former | 54 | 189,344 | 1.31 (0.90–1.91) | 1.28 (0.86–1.91) |
| Current estrogen therapy | 35 | 146,698 | 1.13 (0.69–1.83) | 1.29 (0.78–2.14) |
| Current estrogen-progesterone therapy | 31 | 167,795 | 1.11 (0.71–1.73) | 1.27 (0.80–2.04) |
*
Stratified by study area, race/ethnicity, menopausal status, and adjusted for age. Multivariate RRs were further adjusted for BMI, smoking status, hypertension, alcohol intake, and diuretic use.
†
Among postmenopausal women only.