Table 2.
Multivariable subdistribution hazard models for contralateral breast cancer risk
| Factor (reference) | PredictCBC-2.0A | PredictCBC-2.0B |
|---|---|---|
| sHR (95% CI) | sHR (95% CI) | |
| Age at PBC, years (75th vs. 25th quartile: 66 vs. 48) | 0.87a (0.83–0.90) | 0.82a (0.78–0.85) |
| Body mass index, kg/m2 (75th vs. 25th quartile: 28.4 vs. 22.7) | 1.06 (1.03–1.09) | 1.06 (1.03–1.09) |
| Parity (75th vs. 25th quartile: 3 vs. 1) | 0.85 (0.82–0.88) | 0.86 (0.83–0.90) |
| First-degree family history of BC (yes) | 1.17 (1.12–1.23) | 1.35 (1.29–1.42) |
| BRCA mutation | ||
| BRCA1 versus non-carrier | 4.79 (4.43–5.17) | – |
| BRCA2 versus non-carrier | 3.09 (2.72–4.25) | – |
| PRS313b (75th vs. 25th quartile: -0.49 vs. 0.32) | 1.35 (1.31–1.39) | – |
| CHEK2 c.1100delC mutation (present) | 2.75 (2.85–3.34) | – |
| Nodal status of PBC (positive) | 0.99 (0.93–1.05) | 0.99 (0.93–1.04) |
| Tumor size category of PBC, cm | ||
| (2,5] versus ≤ 2 | 0.99 (0.94–1.05) | 1.01 (0.96–1.07) |
| > 5 versus ≤ 2 | 1.23 (1.10–1.36) | 1.22 (1.09–1.36) |
| Morphology of PBC (lobular including mixed) | 1.19 (1.12–1.27) | 1.17 (1.10–1.24) |
| Grade of PBC | ||
| Moderately differentiated vs. well differentiated (II vs. I) | 0.93 (0.88–0.99) | 0.98 (0.93–1.04) |
| Poorly differentiated vs. well differentiated (III vs. I) | 0.85 (0.79–0.91) | 0.95 (0.88–1.01) |
| Chemotherapy (yes) | 0.75 (0.70–0.80) | 0.75 (0.70–0.80) |
| Radiotherapy to the breast (yes) | 0.93 (0.89–0.98) | 0.95 (0.90–0.99) |
| ER with endocrine therapy | ||
| Negative/no versus positive/yes | 1.53 (1.43–1.65) | 1.78 (1.67–1.90) |
| Positive/no versus positive/yes | 1.95 (1.83–2.07) | 1.94 (1.82–2.06) |
| HER2 with trastuzumab therapy | ||
| Negative/no versus positive/yes | 1.22 (1.09–1.38) | 1.30 (1.15–1.46) |
| Positive/no versus positive/yes | 1.12 (0.97–1.28) | 1.14 (1.00–1.31) |
vs. versus, sHR subdistributional hazard ratio, CI confidence interval, PRS polygenic risk score, BC breast cancer, PBC first primary breast cancer, ER estrogen receptor, HER2 human epidermal growth factor 2
aage was parameterized as a linear spline with one interior knot at 60 years. For representation purposes, we here provide the sHR for the 75th versus the 25th percentile
bPRS standardized by the same standard deviation (SD) used by Mavaddat et al. (SD = 0.61)[25]