Table 2. Age-adjusted and multivariate-adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) for the association between lifestyle, reproductive, and hormonal factors and risk of incident renal cell cancer.
| Factor | Cases/person years | Age-adjusted HRa (95% CI) | Multivariate HRb (95% CI) |
|---|---|---|---|
| Parity | |||
| Nulliparous | 16/212 504 | 1.00 (reference) | 1.00 (reference) |
| Parous | 156/1 261 502 | 1.63 (0.97–2.72) | 1.78 (1.02–3.09) |
| 1–2 | 55/522 816 | 1.40 (0.80–2.44) | 1.62 (0.90–2.92) |
| 3–4 | 69/567 220 | 1.61 (0.93–2.78) | 1.77 (0.99–3.16) |
| 5+ | 32/171 465 | 2.48 (1.36–4.53) | 2.41 (1.27–4.59) |
| P for trend | 0.002 | 0.01 | |
| Age at first live birth (years) c | |||
| <20 | 23/212 504 | 1.00 (reference) | 1.00 (reference) |
| 20–22 | 40/469 625 | 1.77 (1.02–3.07) | 0.88 (0.52–1.48) |
| 23–25 | 46/360 111 | 1.68 (0.95–2.97) | 1.00 (0.59–1.69) |
| 26–29 | 37/273 117 | 1.79 (1.00–3.22) | 1.09 (0.63–1.90) |
| 30+ | 10/151 912 | 0.87 (0.40–1.93) | 0.54 (0.25–1.17) |
| P for trend | 0.97 | 0.45 | |
| Age at menarche (years) | |||
| <12 | 25/257 779 | 1.00 (reference) | 1.00 (reference) |
| 12 | 39/341 764 | 1.19 (0.72–1.96) | 1.21 (0.73–2.00) |
| 13 | 52/429 850 | 1.25 (0.78–2.02) | 1.33 (0.82–2.15) |
| 14+ | 56/445 932 | 1.32 (0.83–2.12) | 1.37 (0.85–2.20) |
| P for trend | 0.25 | 0.20 | |
| Menopausal status | |||
| Pre- | 61/725 258 | 1.00 (reference) | 1.00 (reference) |
| Peri- | 35/209 540 | 1.98 (1.30–3.01) | 1.74 (1.12–2.71) |
| Post- | 76/539 649 | 1.67 (1.19–2.34) | 1.47 (1.00–2.16) |
| Oral contraceptives | |||
| Never | 83/611 469 | 1.00 (reference) | 1.00 (reference) |
| Ever | 89/863 819 | 0.75 (0.56–1.02) | 0.80 (0.58–1.09) |
| 1–11 months | 19/170 748 | 0.82 (0.50–1.35) | 0.81 (0.48–1.35) |
| 12–35 months | 21/194 388 | 0.80 (0.49–1.29) | 0.86 (0.53–1.40) |
| 36–95 months | 29/298 430 | 0.71 (0.47–1.09) | 0.75 (0.49–1.17) |
| 96+ months | 29/200 252 | 0.73 (0.45–1.20) | 0.80 (0.48–1.31) |
| P for trend | 0.08 | 0.20 | |
| HRT use d | |||
| Never | 122/1 102 965 | 1.00 (reference) | 1.00 (reference) |
| Ever | 50/372 361 | 1.24 (0.89–1.72) | 0.98 (0.69–1.41) |
| 1–12 months | 18/118 416 | 1.39 (0.85–2.28) | 1.02 (0.56–1.85) |
| 13–59 months | 12/106 984 | 1.04 (0.57–1.87) | 0.98 (0.53–1.82) |
| 60+ months | 13/104 848 | 1.32 (0.80–2.17) | 0.91 (0.51–1.63) |
| P for trend | 0.25 | 0.74 | |
a
Adjusted for age (time to event variable).
b
Adjusted for age (time to event variable), pack-years (never smokers + five levels), body mass index (quintiles), menopausal status (pre-, peri-, postmenopausal), education (three levels), study centre, randomisation group (intervention vs control), and the other variables in the table.
c
Parous women only.
d
Postmenopausal women only.