Table 2. Cox Proportional Hazards Regression Multivariable Analysis of Ipsilateral Breast Tumor Recurrence.
| Patient Characteristic | HR (95% CI) | P Value |
|---|---|---|
| Age, y | ||
| <50 | 1 [Reference] | NA |
| ≥50 | 0.54 (0.41-0.71) | <.01 |
| DCIS grade | ||
| I | 1 [Reference] | NA |
| II or III | 1.59 (1.02-2.46) | .04 |
| Unknown | 1.56 (0.93-2.59) | .09 |
| Tumor size (continuous variable) | 1.15 (1.02-1.29) | .03 |
| Margin status | ||
| Negative | 1 [Reference] | NA |
| Positivea | 1.72 (0.97-3.05) | .06 |
| Unknown | 1.65 (1.13-2.41) | .01 |
| Comedo necrosis | ||
| No | 1 [Reference] | NA |
| Yes | 1.12 (0.78-1.62) | .53 |
| Unknown | 0.51 (0.34-0.77) | <.01 |
| Estrogen receptor status | ||
| Negative | 1 [Reference] | NA |
| Positive | 0.7 (0.39-1.25) | .23 |
| Unknown | 0.85 (0.52-1.38) | .51 |
| Tamoxifen citrate use | ||
| No | 1 [Reference] | NA |
| Yes | 0.56 (0.36-0.87) | .01 |
| Unknown | 0.93 (0.53-1.63) | .81 |
| RT boost | ||
| No | 1 [Reference] | NA |
| Yes | 0.68 (0.5-0.91) | .01 |
Abbreviations: DCIS, ductal carcinoma in situ; HR, hazard ratio; NA, not applicable; RT, radiotherapy.
a
Indicates the National Surgical Adjuvant Breast Project B-17 definition of ink on tumor or 0-mm margin width. The log-rank ratio tested the interaction between age and boost (P = .46), which was not statistically significant.