Table 1.
Patient, tumor, and treatment characteristics
| Full Cohort (N = 83) | IMRT (N = 32) | PBT (N = 51) | P-value | ||
|---|---|---|---|---|---|
| Age at RT | Median, y | 10.0 | 8.7 | 10.5 | P = 0.11 |
| Range, y | 1.0–17.6 | 1.0–17.0 | 3.0–17.6 | ||
| N (%) | N (%) | N (%) | |||
| Sex | Male | 46 (55) | 20 (63) | 26 (51) | P = 0.30 |
| Female | 37 (45) | 12 (37) | 25 (49) | ||
| Histology | PA | 50 (60) | 24 (75) | 26 (51) | P = 0.03 |
| Other LGG | 33 (40) | 8 (25) | 25 (49) | ||
| WHO histologic grade | Grade I | 62 (75) | 28 (88) | 34 (67) | P = 0.03 |
| Grade II | 21 (25) | 4 (13) | 17 (33) | ||
| Tumor location | Brainstem | 19 (23) | 7 (22) | 12 (24) | P = 0.36 |
| Cerebral hemispheres | 6 (7) | 0 (0) | 6 (12) | ||
| Thalamus | 13 (16) | 6 (19) | 7 (14) | ||
| Optic pathway/hypothalamus | 29 (35) | 12 (38) | 17 (33) | ||
| Other | 16 (19) | 7 (22) | 9 (18) | ||
| Tumor lateralization | Midline | 54 (65) | 24 (75) | 30 (59) | P = 0.26 |
| Lateralized | 29 (35) | 8 (25) | 21 (41) | ||
| Pretreatment CTV | Median (cc) | 49.6 | 65.9 | 44.9 | P = 0.51 |
| Range (cc) | 4.5–429.2 | 8.1–282.5 | 4.5–429.2 | ||
| N (%) | N (%) | N (%) | |||
| Surgery prior to RT | GTR | 4 (5) | 0 (0) | 4 (8) | P = 0.18 |
| STR | 37 (45) | 19 (59) | 18 (35) | ||
| Bx | 42 (51) | 13 (41) | 29 (57) | ||
| ChT prior to RT | No | 51 (61) | 23 (72) | 28 (55) | P = 0.12 |
| Yes | 32 (39) | 9 (28) | 23 (45) | ||
| ChT regimen(s) prior to RT | Carboplatin/vincristine | 28 (34) | 9 (28) | 19 (37) | |
| Temozolomide | 5 (6) | 0 (0) | 5 (10) | ||
| Vinblastine | 4 (5) | 0 (0) | 4 (8) | ||
| Other | 9 (11) | 2 (6) | 7 (14) | ||
| RT modality | IMRT | 32 (39) | 32 (100) | 0 (0) | |
| PBT | 51 (61) | 0 (0) | 51 (100) | ||
| RT dose | Median (Gy[RBE]) | 50.4 | 50.4 | 50.4 | |
| Range (Gy[RBE]) | 45–59.4 | 45–59.4 | 45–54 | ||
| N (%) | N (%) | N (%) | |||
| RT dose | ≤50.4 Gy(RBE) | 70 (84) | 24 (75) | 46 (90) | P = 0.06 |
| >50.4 Gy(RBE) | 13 (16) | 8 (25) | 5 (10) |
Includes clinical characteristics by RT modality; chi-squared tests utilized for comparison of proportions by RT modality (IMRT and PBT; P-values provided).Abbreviations: cc, cubic centimeter; Bx, biopsy; ChT, chemotherapy.