Table 2. Patient and Treatment Characteristics.
| Characteristic | Value (N = 2142) |
|---|---|
| Age | |
| Mean (SD), y | 67.9 (9.5) |
| Median (range), y | 68 (41-92) |
| Risk grouping, No. (%) | |
| Low risk | 1185 (55.3) |
| Favorable intermediate risk | 692 (32.3) |
| Unfavorable intermediate riska | 265 (12.4) |
| Gleason grade, No. (%) | |
| I | 1355 (63.3) |
| II | 614 (28.7) |
| III | 173 (8.1) |
| Clinical T stage, No. (%) | |
| T1c | 1595 (74.5) |
| T2a | 430 (20.1) |
| T2b | 104 (4.9) |
| T2c | 13 (0.6) |
| Initial prostate-specific antigen level | |
| Mean (SD), ng/mL | 6.4 (3.1) |
| Median (range), ng/mL | 5.7 (0.09-19.9) |
| Equivalent dose in 2-Gy fractions, No. (%) | |
| ≥91 Gy | 797 (37.2) |
| <91 Gy | 1346 (62.8) |
| Treatment platform, No. (%) | |
| Robotic arm–mounted linear acceleratorb | 1479 (69.0) |
| Gantry-mounted linear accelerator | 664 (31.0) |
| Fractionation, No. (%) | |
| Daily | 1013 (47.3) |
| Every other day | 1015 (47.4) |
| Weekly | 114 (5.3) |
| Androgen deprivation therapy use, No./total No. (%) | |
| Total | 115/2142 (5.4) |
| Low | 43/1185 (3.6) |
| Favorable | 47/692 (6.8) |
| Unfavorable | 25/265 (9.4) |
| Duration of androgen deprivation therapy, mean (SD), mo | 3.6 (4.2) |
a
Percentage of positive cores was not available for 248 of 957 intermediate-risk patients (25.9%) who did not have other factors that could classify them as having unfavorable intermediate-risk disease; in instances of ambiguity, patients were classified conservatively as having favorable intermediate-risk disease.
b
CyberKnife (Accuray Inc).