Table 1.
Baseline characteristics of the development and validation cohorts.
| Patients | REQUITE (n=543) | DUE 01 (n=227) | p-value |
|---|---|---|---|
| Age (years), median and IQ range |
72 (67–76) | 70.0 (68-75) | 0.32 |
| T-stage | 0.27 | ||
| T1 | 36% | 61% | |
| T2a | 19% | 19% | |
| T2b | 17% | 8% | |
| T2c | 13% | 10% | |
| T3a | 11% | 1% | |
| T3b | 4% | <1% | |
| T4 | 1% | 0% | |
| Gleason score | 0.0001 | ||
| <7 | 23% | 52% | |
| 3+4 | 38% | 32% | |
| 4+3 | 21% | 9% | |
| >7 | 17% | 6% | |
| pre-RT PSA | 0.001 | ||
| <10 ng/ml | 57% | 84% | |
| 10-20 ng/ml | 30% | 14% | |
| >20 ng/ml | 13% | 2% | |
| Risk Class | 0.0001 | ||
| Low | 12% | 38% | |
| Intermediate | 58% | 48% | |
| High | 31% | 14% | |
| RT Dose | |||
| Prescribed dose at 2 Gy/fr | 76 (74-78) Gy | 78 (76-78) Gy | 0.001 |
| [300 pts] | [98 pts] | ||
| Prescribed dose at 2-2.7 Gy/fr | 75 (65-77) Gy | 70 (70-71.4) Gy | 0.35 |
| [91 pts] | [125 pts] | ||
| in EQD2Gy (α/β = 10 Gy) | 77.2 Gy | 72 Gy | 0.04 |
| in EQD2Gy (α/β = 3 Gy) | 80.2 Gy | 74.9 Gy | 0.03 |
| Prescribed dose at >2.7 Gy/fr | 60 (59.4-60.2) Gy | 70.2 Gy | 0.009 |
| [152 pts] | [4 pts] | ||
| in EQD2Gy (α/β = 10 Gy) | 65.0 Gy | 76 Gy | 0.61 |
| in EQD2Gy (α/β = 3 Gy) | 72.0 Gy | 84.2 Gy | 0.003 |
| Weekly integral dose (L ∗ Gy/week) |
13.1 (10.2-19.3) | 15.8 (13.2-19.3) | 0.001 |
| Irradiation technique | 0.0001 | ||
| 3DCRT | 17% | 15% | |
| SF-IMRT | 13% | 39% | |
| VMAT | 70% | 46% | |
| Hormone therapy | 0.3 | ||
| No hormone therapy | 27% | 58% | |
| Antiandrogen therapy alone | 4% | 8% | |
| GnRH analogs alone | 40% | 24% | |
| Combined androgen blockade | 29% | 12% | |
IQ, interquartile; RT, radiotherapy; PSA, prostate-specific antigen; EQD2Gy, equivalent uniform dose at 2 Gy/fraction calculated using the linear quadratic model; 3DCRT, three-dimensional conformal radiation therapy; GnRH, gonadotropin-releasing hormone, SF-IMRT, static-field intensity-modulated radiation therapy; VMAT, volumetric-modulated arc therapy.
The p-values for comparison of the clinic–pathological/dosimetric variables of the two cohorts are reported. For continuous features, the t-test was considered, while, for categorical variables, the chi-square test was used.