Table 2.
Multivariate cox regression model of breast cancer–specific survival and overall survival among breast cancer patients
| Characteristics | BCSS | OS | ||
|---|---|---|---|---|
| HR (95% CI) | P value | HR (95% CI) | P value | |
| Age at diagnosis | ||||
| 18‐35 | Reference | — | Reference | — |
| 36‐50 | 0.849 (0.787‐0.916) | <.001 | 0.796 (0.741‐0.855) | <.001 |
| 51‐65 | 0.897 (0.832‐0.967) | .004 | 0.980 (0.913‐1.051) | .569 |
| >65 | 1.362 (1.261‐1.473) | <.001 | 2.391 (2.228‐2.566) | <.001 |
| Race/ethnicity | ||||
| NHW | Reference | — | Reference | — |
| NHB | 1.222 (1.170‐1.276) | <.001 | 1.144 (1.106‐1.182) | <.001 |
| NHA | 0.770 (0.723‐0.820) | <.001 | 0.748 (0.713‐0.785) | <.001 |
| Hispanic | 0.927 (0.881‐0.975) | .003 | 0.877 (0.843‐0.913) | <.001 |
| Histology | ||||
| IDC | Reference | — | Reference | — |
| ILC | 1.032 (0.973‐1.095) | .291 | 0.929 (0.892‐0.968) | <.001 |
| Othersa | 0.925 (0.886‐0.967) | .001 | 0.953 (0.924‐0.982) | .002 |
| Grade | ||||
| I | Reference | — | Reference | — |
| II | 1.838 (1.719‐1.965) | <.001 | 1.185 (1.146‐1.226) | <.001 |
| III | 2.906 (2.713‐3.114) | <.001 | 1.572 (1.515‐1.632) | <.001 |
| Tumor size (cm) | ||||
| ≤2 | Reference | — | Reference | — |
| 2‐5 | 2.035 (1.958‐2.115) | <.001 | 1.619 (1.578‐1.662) | <.001 |
| >5 | 3.159 (3.006‐3.320) | <.001 | 2.443 (2.351‐2.538) | <.001 |
| Number of positive LNs | ||||
| 0 | Reference | — | Reference | — |
| 1‐3 | 2.126 (2.044‐2.212) | <.001 | 1.575 (1.532‐1.620) | <.001 |
| 4‐9 | 3.832 (3.657‐4.015) | <.001 | 2.622 (2.527‐2.720) | <.001 |
| ≥10 | 5.344 (5.073‐5.630) | <.001 | 3.567 (3.418‐3.722) | <.001 |
| Metastasis | ||||
| No | Reference | — | Reference | — |
| Yes | 3.872 (3.686‐4.067) | <.001 | 3.074 (2.937‐3.216) | <.001 |
| ER status | ||||
| Negative | Reference | — | Reference | — |
| Positive | 0.719 (0.688‐0.751) | <.001 | 0.769 (0.743‐0.796) | <.001 |
| PR status | ||||
| Negative | Reference | — | Reference | — |
| Positive | 0.617 (0.592‐0.643) | <.001 | 0.745 (0.723‐0.769) | <.001 |
| Surgery | ||||
| No | Reference | — | Reference | — |
| BCS | 0.368 (0.332‐0.407) | <.001 | 0.440 (0.402‐0.481) | <.001 |
| Mastectomy | 0.442 (0.401‐0.487) | <.001 | 0.489 (0.448‐0.533) | <.001 |
| Chemotherapy | ||||
| No/unknown | Reference | — | Reference | — |
| Yes | 0.840 (0.809‐0.871) | <.001 | 0.668 (0.650‐0.686) | <.001 |
| Radiation | ||||
| No/unknown | Reference | — | Reference | — |
| Yes | 0.880 (0.851‐0.909) | <.001 | 0.792 (0.773‐0.812) | <.001 |
| Marital status | ||||
| Married | Reference | — | Reference | — |
| Single | 1.160 (1.111‐1.210) | <.001 | 1.252 (1.211‐1.295) | <.001 |
| Separated/divorced/widowed | 1.236 (1.193‐1.281) | <.001 | 1.449 (1.413‐1.485) | <.001 |
| Insurance | ||||
| Non‐Medicaid insured | Reference | — | Reference | — |
| Medicaid | 1.253 (1.201‐1.308) | <.001 | 1.403 (1.359‐1.449) | <.001 |
| Uninsured | 1.274 (1.156‐1.405) | <.001 | 1.334 (1.227‐1.451) | <.001 |
| Residenceb | ||||
| Nonmetro area | Reference | — | Reference | — |
| Metro area | 0.978 (0.926‐1.033) | .434 | 0.977 (0.941‐1.016) | .243 |
| Median household incomeb | ||||
| ≤Quartile 1 (US $54 350) | Reference | — | Reference | — |
| ≤Quartile 2 (US $62 330) | 0.981 (0.929‐1.035) | .485 | 0.915 (0.879‐0.952) | <.001 |
| ≤Quartile 3 (US $78 020) | 0.921 (0.856‐0.991) | .028 | 0.876 (0.831‐0.924) | <.001 |
| >Quartile 3 (US $78 020) | 0.838 (0.769‐0.913) | <.001 | 0.785 (0.738‐0.835) | <.001 |
| Poverty rateb | ||||
| ≤Quartile 1 (10.18%) | Reference | — | Reference | — |
| ≤Quartile 2 (13.33%) | 1.007 (0.945‐1.073) | .820 | 1.024 (0.979‐1.072) | .299 |
| ≤Quartile 3 (16.96%) | 1.002 (0.916‐1.096) | .971 | 0.996 (0.934‐1.063) | .906 |
| >Quartile 3 (16.96%) | 0.977 (0.886‐1.078) | .646 | 0.990 (0.923‐1.063) | .790 |
| Unemployment rateb | ||||
| ≤Quartile 1 (5.68%) | Reference | — | Reference | — |
| ≤Quartile 2 (6.91%) | 0.974 (0.926‐1.025) | .315 | 0.970 (0.936‐1.006) | .103 |
| ≤Quartile 3 (7.80%) | 0.940 (0.890‐0.993) | .026 | 0.929 (0.893‐0.966) | <.001 |
| >Quartile 3 (7.80%) | 0.986 (0.930‐1.045) | .627 | 1.011 (0.969‐1.054) | .615 |
| Education levelb | ||||
| ≤Quartile 1 (82.88%) | Reference | — | Reference | — |
| ≤Quartile 2 (87.54%) | 1.003 (0.956‐1.051) | .912 | 1.022 (0.987‐1.057) | .222 |
| ≤Quartile 3 (91.08%) | 0.963 (0.914‐1.015) | .162 | 0.989 (0.952‐1.027) | .554 |
| >Quartile 3 (91.08%) | 0.916 (0.859‐0.977) | .008 | 0.991 (0.946‐1.038) | .703 |
Abbreviations: BCS, breast conserving surgery; BCSS, breast cancer–specific survival; CI, confidence interval; ER, estrogen receptor; HR hazard ratio; IDC, infiltrating ductal carcinoma; ILC, infiltrating lobular carcinoma; LN, lymph node; NHA, Non‐Hispanic Asian or Pacific Islander and American Indian/Alaska Native; OS, overall survival; PR, progesterone receptor.
a
Including other histology of invasive breast cancer except IDC and ILC.
b
All data are county level. Education level represented the percentage of patients aged ≥25 y with at least a high school diploma.