Table 3.
Breast cancer incidence in the full cohort in relation to selenium levels, overall and stratified for body mass index (BMI)
| Quartile | Mediana (ug/day) | Individuals (n) | Breast cancer cases (n) | Person-years | Incidence/ 100,000 |
All | BMI ≤ 25 kg/m2 | BMI > 25 kg/m2 | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| RR (95 CIb) | RRc (95 CI) | RR (95 CI) | RRd (95 CI) | RR (95 CI) | RRd (95 CI) | ||||||
| 1 | 24.7 | 4,259 | 374 | 87,302 | 428 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| 2 | 30.8 | 4,258 | 341 | 86,359 | 395 | 0.92 (0.80–1.07) | 0.91 (0.79–1.06) | 1.02 (0.84–1.25) | 1.01 (0.83–1.24) | 0.81 (0.65–1.00) | 0.82 (0.66–1.01) |
| 3 | 39.0 | 4,260 | 343 | 85,774 | 400 | 0.94 (0.81–1.08) | 0.91 (0.79–1.06) | 0.94 (0.76–1.16) | 0.91 (0.74–1.13) | 0.90 (0.73–1.10) | 0.90 (0.73–1.11) |
| 4 | 72.8 | 4,258 | 369 | 85,149 | 433 | 1.01 (0.88–1.17) | 0.96 (0.83–1.12) | 1.06 (0.87–1.29) | 1.00 (0.82–1.23) | 0.96 (0.77–1.18) | 0.93 (0.75–1.15) |
| P-trend | 0.82 | 0.65 | 0.77 | 0.81 | 0.95 | 0.71 | |||||
| 1 | 24.7 | 4,259 | 374 | 87,302 | 428 | 1.08 (0.95–1.22) | 1.10 (0.96–1.24) | 1.02 (0.86–1.21) | 1.04 (0.87–1.24) | 1.17 (0.98–1.41) | 1.17 (0.97–1.40) |
| 2 + 3 | 34.8 | 8,518 | 684 | 172,133 | 397 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| 4 | 72.8 | 4,258 | 369 | 85,149 | 433 | 1.09 (0.96–1.24) | 1.06 (0.93–1.20) | 1.08 (0.90–1.28) | 1.04 (0.87–1.25) | 1.12 (0.93–1.35) | 1.08 (0.90–1.30) |
aResiduals of selenium intake quartiles are presented as the median of total dietary intake of selenium
bConfidence interval
cAdjusted for age, socioeconomic index, education, marriage, number of children, age at first childbirth, age at menarche, use of oral contraceptives, hormone replacement therapy, menopausal status, oophorectomy, smoking, BMI, alcohol consumption, season and year of inclusion
dAdjusted for all factors above except BMI. Twenty-six controls were missing BMI data