Table 2.
Univariate analysis for grade ≥2 acute skin toxicity
| Variables | Odds ratio | P-value |
|---|---|---|
| T stage | ||
| Tis | 1 | |
| T1 | 0.76 | .49 |
| T2 | 0.28 | .20 |
| T3 | 0.47 | .87 |
| ER status | ||
| ER negative | 1 | |
| ER positive | 0.46 | .16 |
| PR status | ||
| PR negative | 1 | |
| PR positive | 0.49 | .09 |
| HER2 status | ||
| HER2 negative | 1 | |
| HER2 positive | 1.6 | .43 |
| Boost | ||
| No boost | 1 | |
| Boost | 6.8 | <.0001 (95% CI, 2.8-17) |
| Fractionation regimen | ||
| HFRT | 1 | |
| CFRT | 8.1 | <.0001 (95% CI, 3.0-21) |
| Systemic therapy | ||
| None | 1 | |
| Hormone, chemotherapy, or both | 2.7 | .079 |
| Volume of 105% of whole breast dose (without boost) | ||
| <average (252.4 cm3) | 1 | |
| >average (252.4 cm3) | 4.1 | .0009 (95% CI, 1.8-9.3) |
| Volume of 105% of total prescription (breast plus boost) | ||
| <average (27.3 cm3) | 1 | |
| >average (27.3 cm3) | 0.47 | .15 |
| Breast volume | ||
| <1000 cm3 | 1 | |
| >1000 cm3 | 1.6 | .22 |
| Posterior separation | ||
| <25 cm | ||
| >25 cm | 1.48 | .39 |
Abbreviations: CFRT = conventional fractionated radiation therapy; ER = estrogen receptor; HER2 = human epidermal growth factor receptor 2; HFRT = hypofractionated radiation therapy; PR = progesterone receptor.
Individual chemotherapy, hormone, was omitted because there was not enough of each for the analysis.