Table 4.
Univariate and multivariate linear regression analysis between characteristics and post-SBRT TLC.
| Characteristic | Regression coefficient | 95% CI | P |
|---|---|---|---|
| Univariate analysis | |||
| Sex (female vs. male) | −32.517 | −282.896 to 217.861 | 0.797 |
| Age (year) | −3.266 | −15.486 to 8.954 | 0.596 |
| Karnofsky performance status (10%) | −3.030 | −20.028 to 13.968 | 0.723 |
| Smoker (smoker vs. never smoker) | −16.403 | −231.169 to 263.976 | 0.895 |
| Tumor diameter (mm) | −1.551 | −14.304 to 11.203 | 0.809 |
| Underlying respiratory system disease (yes vs. no) | 97.891 | −148.671 to 344.452 | 0.431 |
| Pre-SBRT TLC (cells/μl) | 0.528 | 0.385 to 0.672 | <0.001 |
| Dosimetric characteristics | |||
| Gross tumor volume (cm3) | −1.125 | −8.857 to 6.608 | 0.773 |
| Planning target volume (cm3) | −1.995 | −6.734 to 2.745 | 0.404 |
| Mean lung dose (Gy) | −73.331 | −139.641 to −7.021 | 0.031 |
| Mean heart dose (Gy) | −34.819 | −73.494 to 3.855 | 0.077 |
| Radiation therapy | |||
| Treatment duration (days) | −38.694 | −69.801 to −7.587 | 0.015 |
| Total beam-on time (seconds) | −0.129 | −0.212 to −0.047 | 0.003 |
| Fractionation (5 fractions vs. 10 fractions) | −215.285 | −466.881 to 36.310 | 0.092 |
| Multivariate analysis | |||
| Pre-SBRT TLC (cells/μl) | 0.524 | 0.393 to 0.656 | < 0.001 |
| Total beam-on time (seconds) | −0.103 | −0.164 to −0.041 | 0.001 |
| Heart V5 | −5.452 | −8.835 to −2.069 | 0.002 |
SBRT, stereotactic body radiation therapy; TLC, total peripheral lymphocyte count; CI, confidence interval; Vn, percentage of organ volume receiving n Gy.