Table 4.
Parameter Estimates From the Main Model, Among Women Aged 50–74 Years, Diagnosed With Postmenopausal Breast Cancer in Sweden During 1993–1995
| Parameter | Coefficient | 95% CI |
|---|---|---|
| Longitudinal submodela | ||
| t (β1) | −0.02 | −0.16, 0.12 |
| t2 (β2) | −0.01 | −0.09, 0.07 |
| t3 (β3) | −0.00 | −0.01, 0.01 |
| TAM × t (β4) | −0.14 | −0.30, 0.03 |
| TAM × t2 (β5) | 0.03 | −0.06, 0.13 |
| TAM × t3 (β6) | −0.00 | −0.02, 0.01 |
| HRT × t (β7) | −0.31 | −0.48, −0.14 |
| HRT × t2 (β8) | 0.08 | −0.02, 0.17 |
| HRT × t3 (β9) | −0.00 | −0.02, 0.01 |
| HRT (δ1) | 0.32 | 0.18, 0.45 |
| Age at diagnosis (δ2) | −0.05 | −0.06, −0.04 |
| BMI quartile 2 (δ3) | −0.38 | −0.56, −0.21 |
| BMI quartile 3 (δ4) | −0.63 | −0.81, −0.46 |
| BMI quartile 4 (δ5) | −0.81 | −0.98, −0.63 |
| Constant (β0) | 7.73 | 7.11, 8.35 |
| Random effects | ||
| SD(b0) | 1.25 | 1.20, 1.31 |
| SD(b1) | 0.13 | 0.11, 0.16 |
| Correlation(b0, b1) | −0.24 | −0.35, −0.13 |
| Survival submodelb | ||
| Slope association for tamoxifen-nontreated within the 3 highest quartiles of baseline density (α0) | 8.63 | 3.08, 14.17 |
| Slope association for tamoxifen-treated within the 3 highest quartiles of baseline density (α0 + α1) | 5.93 | 1.22, 10.63 |
| Slope association for tamoxifen-nontreated within the lowest quartile of baseline density (α0 + α2) | −6.82 | −15.8, 2.15 |
| Slope association for tamoxifen-treated within the lowest quartile of baseline density (α0 + α3) | 0.61 | −6.65, 7.86 |
| Age at diagnosis (φ1) | 0.00 | −0.02, 0.03 |
| BMI quartile 2 (φ2) | −0.13 | −0.54, 0.27 |
| BMI quartile 3 (φ3) | 0.10 | −0.30, 0.50 |
| BMI quartile 4 (φ4) | 0.26 | −0.14, 0.65 |
| Size of tumor, 10–19 mm (φ5) | 0.41 | −0.11, 0.93 |
| Size of tumor, 20–29 mm (φ6) | 1.01 | 0.46, 1.56 |
| Size of tumor, 30–39 mm (φ7) | 0.99 | 0.34, 1.65 |
| Size of tumor, 40–49 mm (φ8) | 1.56 | 0.78, 2.34 |
| Size of tumor, ≥50 mm (φ9) | 1.26 | 0.52, 2.01 |
| Number of affected lymph nodes, 1–3 (φ10) | 0.92 | 0.52, 1.32 |
| Number of affected lymph nodes, 4–9 (φ11) | 1.61 | 1.12, 2.12 |
| Number of affected lymph nodes, ≥10 (φ12) | 2.69 | 2.02, 3.37 |
| ER status, negative (φ13) | 0.49 | 0.10, 0.88 |
| ER status, missing (φ14) | −0.02 | −0.39, −0.35 |
| Grade, moderately differentiated (φ15) | 0.87 | 0.10, 1.65 |
| Grade, poorly differentiated (φ16) | 1.08 | 0.30, 1.86 |
| Grade, missing (φ17) | 0.78 | −0.00, 1.56 |
| Chemotherapy (φ18) | 0.05 | −0.44, 0.55 |
| Radiotherapy (φ19) | −0.14 | −0.47, 0.19 |
| Baseline mammographic density (φ20) | 0.00 | −0.01, 0.01 |
| Tamoxifen treatment (φ21) | 0.03 | −0.47, 0.52 |
| Constant (λ0) | −6.23 | −8.13, −4.33 |
| Time spline 1 (λ1) | 1.46 | 1.23, 1.70 |
| Time spline 2 (λ2) | 0.36 | 0.20, 0.52 |
| Time spline 3 (λ3) | −0.02 | −0.05, 0.01 |
Abbreviations: BMI, body mass index; CI, confidence interval; ER, estrogen receptor; HRT, hormone replacement therapy; SD, standard deviation; TAM, tamoxifen treatment.
a On square root scale.
b On log cumulative hazard scale. For the time-constant covariates φ1–φ21, the coefficients are log hazard ratios; hazard ratios can be obtained by exponentiating the coefficient and the CI.