Table 3.
Anthropometric Risk Factors and Breast Cancer Risk, Reykjavik and AGES Study, 1968–2015
| Study | Risk factor | Categories | Number of cases | Person-years | HRa | 95% CI | ||
|---|---|---|---|---|---|---|---|---|
| Exposed | Unexposed | Exposed | Unexposed | |||||
| Reykjavik Study | Height | Per cm | 16 | 712 | 6,023 | 266,738 | 1.03 | 1.02, 1.05 |
| (N=9,606) | BMI | <18.5 | 0 | 12 | 74 | 5,604 | 0.86 | 0.48, 1.53 |
| ≥18.5 - <25 | 2 | 380 | 1,595 | 148,077 | 1.00 | Ref | ||
| ≥25 - <30 | 6 | 238 | 2,307 | 86,525 | 1.15 | 0.97, 1.36 | ||
| ≥30 | 8 | 82 | 2,046 | 26,531 | 1.38 | 1.09, 1.75 | ||
| AGES Studyb | Height | Per cm | 11 | 82 | 2,912 | 27,857 | 1.02 | 0.98, 1.06 |
| (N=3,103) | BMI | <18.5 | 0 | 1 | 18 | 432 | 0.82 | 0.11, 6.13 |
| ≥18.5 - <25 | 0 | 26 | 532 | 9,168 | 1.00 | Ref | ||
| ≥25 - <30 | 5 | 33 | 1,130 | 11,602 | 1.06 | 0.64, 1.76 | ||
| ≥30 | 6 | 22 | 1,231 | 6,654 | 1.28 | 0.73, 2.23 | ||
a
Hazard ratios (HR) and 95% confidence intervals (CI) obtained by Cox regression with age as time metric and adjusted for birth cohort, education, place of residence, smoking status, physical activity, age at menarche, parity, age at first live birth, and BMI or height.
b
Women in AGES study; models also include alcohol intake, hormone treatment, and breast feeding. Parity and age at first live birth were combined into one variable (no children, parous <25 or ≥25 years).
Abbreviations: T2D=type 2 diabetes; BMI=body mass index.