Table 1.
Baseline treatment characteristics among training set, internal validation set, and external outlier validation set.
| Characteristic | Total cohort (n=1029) | Training dataset (n=708) | Internal validation dataset (n=271) | External outlier validation dataset (n=50) | |||||
| Age at sRTa (years), median (IQR) | 70 (64-74) | 70 (64-74) | 69 (63-74) | 72.5 (68-76) | |||||
| pT stageb, n (%) | |||||||||
|
|
2 | 460 (44.7) | 310 (43.8) | 122 (45) | 28 (56) | ||||
|
|
3a | 327 (31.8) | 230 (32.5) | 86 (31.7) | 11 (22) | ||||
|
|
3b | 235 (22.8) | 163 (23) | 61 (22.5) | 11 (22) | ||||
|
|
4 | 7 (0.7) | 5 (0.7) | 2 (0.7) | 0 (0) | ||||
| R statusc in surgery, n (%) | |||||||||
|
|
RO | 673 (65.4) | 448 (63.3) | 181 (66.8) | 44 (88) | ||||
|
|
R1 | 327 (31.8) | 244 (34.5) | 77 (28.4) | 6 (12) | ||||
|
|
R2 | 3 (0.3) | 1 (0.1) | 2 (0.7) | 0 (0) | ||||
|
|
Rx | 26 (2.5) | 15 (2.1) | 11 (4.1) | 0 (0) | ||||
| ISUPd grade in surgery, n (%) | |||||||||
|
|
1+2 | 371 (36.1) | 254 (35.9) | 101 (37.3) | 16 (32) | ||||
|
|
3 | 324 (31.5) | 226 (31.9) | 84 (31) | 14 (28) | ||||
|
|
4 | 156 (15.2) | 102 (14.4) | 44 (16.2) | 10 (20) | ||||
|
|
5 | 178 (17.3) | 126 (17.8) | 42 (15.5) | 10 (20) | ||||
| PSAe persistence after surgery, n (%) | |||||||||
|
|
No | 750 (72.9) | 511 (72.2) | 197 (72.7) | 42 (84) | ||||
|
|
Yes | 279 (27.1) | 197 (27.8) | 74 (27.3) | 8 (16) | ||||
| PSA (ng/mL) before sRT, n (%) | |||||||||
|
|
0.01-0.2 | 246 (23.9) | 178 (25.1) | 63 (23.3) | 5 (10) | ||||
|
|
>0.2-0.5 | 385 (37.4) | 258 (36.4) | 111 (41) | 16 (32) | ||||
|
|
>0.5-1 | 172 (16.7) | 122 (17.2) | 41 (15.1) | 9 (18) | ||||
|
|
>1 | 226 (22) | 150 (21.2) | 56 (20.7) | 20 (40) | ||||
| Local recurrence after PSMA-PETf, n (%) | |||||||||
|
|
No | 592 (57.5) | 396 (55.9) | 153 (56.5) | 43 (86) | ||||
|
|
Yes | 437 (42.5) | 312 (44.1) | 118 (43.5) | 7 (14) | ||||
| Pelvic lymph nodes after PSMA-PET, n (%) | |||||||||
|
|
No | 716 (69.6) | 507 (71.6) | 206 (76) | 3 (6) | ||||
|
|
Yes | 313 (30.4) | 201 (28.4) | 65 (24) | 47 (94) | ||||
| Dose to the prostatic fossa (Gyg), n (%) | |||||||||
|
|
<66 | 103 (10) | 47 (6.6) | 10 (3.7) | 46 (92) | ||||
|
|
66-70 | 551 (53.6) | 390 (55.1) | 157 (57.9) | 4 (8) | ||||
|
|
>70 | 375 (36.4) | 271 (38.3) | 104 (38.4) | 0 (0) | ||||
| sRT to elective pelvic lymphatics, n (%) | |||||||||
|
|
No | 633 (61.6) | 455 (64.4) | 174 (64.2) | 4 (8) | ||||
|
|
Yes | 395 (38.4) | 252 (35.6) | 97 (35.8) | 46 (92) | ||||
| Dose to elective pelvic lymphatics (Gy), n (%) | |||||||||
|
|
<50 | 312 (30.3) | 197 (27.8) | 71 (26.2) | 44 (100) | ||||
|
|
>50 | 47 (4.6) | 34 (4.80) | 13 (4.79) | 0 (0) | ||||
|
|
Unknown | 36 (3.5) | 21 (3) | 13 (4.8) | 2 (4) | ||||
| Irradiation to positive pelvic LNh, n (%) | |||||||||
|
|
No | 712 (69.2) | 505 (71.3) | 204 (75.3) | 3 (6) | ||||
|
|
Yes | 317 (30.8) | 203 (28.7) | 67 (24.7) | 47 (94) | ||||
| Dose to positive pelvic LNs (Gy), n (%) | |||||||||
|
|
<50 | 15 (1.5) | 11 (1.6) | 4 (1.5) | 0 (0) | ||||
|
|
50-60 | 149 (13.5) | 113 (16) | 36 (13.3) | 0 (0) | ||||
|
|
>60 | 128 (12.4) | 63 (8.9) | 20 (7.4) | 45 (90) | ||||
|
|
Unknown | 25 (2.4) | 16 (2.3) | 7 (2.6) | 2 (4) | ||||
| ADTi, n (%) | |||||||||
|
|
No | 704 (68.4) | 475 (67.1) | 189 (69.7) | 40 (80) | ||||
|
|
Yes | 325 (31.6) | 233 (32.9) | 82 (30.3) | 10 (20) | ||||
| Duration of ADT admission (months), n (%) | |||||||||
|
|
<6 | 65 (23.1) | 50 (24.4) | 15 (22.7) | 0 (0) | ||||
|
|
6-12 | 110 (39.2) | 79 (38.5) | 24 (36.4) | 7 (70) | ||||
|
|
>12-24 | 57 (20.3) | 39 (19.0) | 18 (27.3) | 0 (0) | ||||
|
|
>24 | 49 (17.4) | 37 (18.1) | 9 (13.6) | 3 (30) | ||||
|
|
Unknown | 44 (4.3) | 28 (4.0) | 16 (5.9) | 0 (0) | ||||
asRT: salvage radiation therapy.
bpT stage: pathological T stage.
cR status: residual disease status.
dISUP: International Society of Urological Pathology.
ePSA: prostate-specific antigen.
fPSMA-PET: prostate-specific membrane antigen–positron emission tomography.
gGy: gray (a unit of radiation dose).
hLN: lymph node.
iADT: androgen deprivation therapy.