Table 4.
Bone mineral density and subsequent incidence of breast cancer
| Number in Cohort | Number of Cases | Incidence Rate (cases/100 person years) | Age, Race & BMI Adjusted Rate Ratio (95% CI) | p-value for rate ratio | |
| Breast Cancer (all Women) | |||||
| All | 3108 | 100 | 1.94 | ||
| RA BMD | |||||
| <95 | 890 | 26 | 1.95 | 1 | |
| 95–105 | 635 | 35 | 3.26 | 2.19 (1.27–3.77) | P = 0.005 |
| 105–115 | 635 | 15 | 1.19 | 1.00 (0.49–2.020 | P = 0.99 |
| >115 | 858 | 24 | 1.60 | 1.45 (0.75–2.82) | P = 0.27 |
| Test for Linear Trend | P = 0.74 | ||||
| Breast Cancer (Women over 55 Years Old) | |||||
| All | 1091 | 43 | 2.68 | ||
| RA BMD | |||||
| <80.3 | 272 | 10 | 2.71 | 1 | |
| 80.3–89.7 | 273 | 2 | 0.49 | 0.19 (0.04–0.88) | P = 0.03 |
| 89.7–99.9 | 273 | 16 | 3.90 | 1.65 (0.73–3.75) | P = 0.23 |
| >99.9 | 273 | 15 | 3.59 | 1.66 (0.69–3.99) | P = 0.26 |
| Test for Linear Trend | P = 0.04 |
BMI; Body Mass Index. RA BMD; Bone Mineral Density by Radioabsorbimetry For the analysis of breast cancer in women over 55 years of age, indicator variables were created for quartiles of RA BMD, age, and BMI.