Table 1.
Baseline and dosimetric characteristics grouped according to the occurrence of grade 3+ lymphopenia*
| Characteristic | Total (n = 84) | G0–2L (n = 58) | G3+L (n = 26) | P value |
|---|---|---|---|---|
| Sex (%) | <0.001* | |||
| Male | 47 (56.0) | 40 (69.0) | 7 (26.9) | |
| Female | 37 (44.0) | 18 (31.0) | 19 (73.1) | |
| Age , mean (SD) | 52.6 (12.4) | 52.7 (11.7) | 52.3 (13.9) | 0.892 |
| BMI, mean (SD) | 28.3 (7.5) | 29.3 (8.3) | 26.2 (4.8) | 0.077 |
| GTV, mean (SD) | 47.0 (35.3) | 43.9 (35.7) | 53.7 (34.2) | 0.240 |
| CTV, mean (SD) | 231.1 (93.5) | 221.7 (91.7) | 252.1 (95.8) | 0.167 |
| PTV-50, mean (SD) | 331.4 (125.2) | 317.9 (122.7) | 361.4 (128.0) | 0.139 |
| PTV-60, mean (SD) | 91.6 (65.7) | 87.3 (69.9) | 101.0 (55.4) | 0.378 |
| Baseline ALC, mean (SD) | 1.6 (0.6) | 1.7 (0.5) | 1.3 (0.6) | <0.001* |
| Baseline WBC, mean (SD) | 8.5 (3.8) | 8.2 (3.8) | 9.1 (3.8) | 0.332 |
| Modality (%) | 0.024* | |||
| Protons | 28 (33.3) | 24 (41.4) | 4 (15.4) | |
| Photons | 56 (66.7) | 34 (58.6) | 22 (84.6) | |
| Pre-radiation steroids | 0.023* | |||
| No | 43 (51.2) | 35 (60.3) | 8 (30.8) | |
| Yes | 41 (48.8) | 23 (39.7) | 18 (69.2) | |
| Location (%) | 0.916 | |||
| Left | 37 (44.0) | 25 (43.1) | 12 (46.2) | |
| Right | 44 (52.4) | 31 (53.4) | 13 (50.0) | |
| Bilateral | 3 (3.6) | 2 (3.4) | 1 (3.8) | |
| Whole Brain DVH, mean (SD) | ||||
| Mean, Gy(RBE) | 24.7 (6.8) | 23.2 (6.5) | 28.1 (6.3) | 0.001* |
| V5 (%) | 76.8 (21.1) | 72.8 (22.2) | 85.6 (15.5) | 0.008* |
| V10 (%) | 68 (20.3) | 63.4 (20.4) | 78.2 (16.2) | 0.001* |
| V15 (%) | 58 (18.1) | 54.1 (17.6) | 66.8 (16.2) | 0.002* |
| V20 (%) | 48.2 (15.2) | 44.7 (14.1) | 56.1 (14.9) | <0.001* |
| V25 (%) | 40.9 (12.8) | 38.3 (11.8) | 46.7 (13.2) | 0.004* |
| V30 (%) | 35.7 (11.1) | 33.6 (10.3) | 40.3 (11.8) | 0.009* |
| V40 (%) | 29 (9.6) | 27.5 (8.9) | 32.3 (10.3) | 0.028* |
| V50 (%) | 22.1 (8.2) | 21 (7.2) | 24.6 (9.7) | 0.064 |
*Quantities in parentheses are standard deviations for continuous variable and percentage of patients for categorical variables. Asterisks denote statistically significant parameters
Abbreviations: G0–2L, grade 0‒2 lymphopenia; G3+L, grade 3+ lymphopenia; BMI, body mass index; GTV, gross tumor volume; CTV, clinical target volume; PTV-50 and PTV-60, planning target volumes receiving higher than 50 and 60 Gy respectively; ALC: absolute lymphocyte count; WBC, white blood cells count (in units of 100 cells per liter); DVH, dose-volume histogram; V5, V10, . . . , brain volumes receiving greater than 5, 10, . . . Gy(RBE) dose.