TABLE 3.
Characteristics of the Overall Study Cohort (N = 840) compared to study subjects in Cox Proportional Hazards (PH) models (n = 405)
|
Overall study cohort N = 840 |
Study subjects in Cox PH models n = 405 |
|
|---|---|---|
| N (%) | N (%) | |
| Age at RT (year) | ||
| Median (IQR a ) | 69.9 (63.8, 74.9) | 69.3 (63.6, 75.1) |
| Follow‐up Time after EBRT, (year) | ||
| Median (IQR) | 6.5 (4.3, 10.9) | 5.9 (4.1, 9.1) |
| Time from RT to PSA Nadir b (year) | ||
| Median (IQR) | 2.3 (1.3, 4.3) | 2.5 (1.4, 4.3) |
| Time from RT to BCR, (year) | ||
| Median (IQR) | 5.3 (3.4, 7.8) | 6.2 (4, 8) |
| Time from EBRT to Mets, (year) | ||
| Median (IQR) | 8.1 (3.1, 11) | 8.4 (4.2, 11) |
| Dosage(cGy) | ||
| Median (IQR) for CT based/3DCRT | 7000 (6840, 7040) | 7000 (6840, 7200) |
| Median (IQR) for IMRT | 7800 (7600, 7800) | 7800 (7600, 7800) |
| Prostate volume, (cc) | ||
| Median (IQR) | 36.5 (28.4, 48.1) | 36.5 (28.2, 49.5) |
| Biochemical recurrence (BCR) c , N (%) | 151 (18.7) | 37 (9.1) |
| Distant metastasis, N (%) | 29 (3.5) | 11 (2.7) |
| Overall death, N (%) | 333 (39.6) | 125 (30.9) |
| Race | ||
| AA | 268 (32) | 131 (32) |
| CA | 572 (68) | 274 (68) |
| Primary treatment type, N (%) | ||
| EBRT alone | 748 (89) | 360 (89) |
| EBRT with HT d | 92 (11) | 45 (11) |
| Primary treatment technique, N (%) | ||
| CT based/3D CRT | 530 (63.1) | 224 (55.3) |
| IMRT | 310 (36.9) | 181 (44.7) |
| Secondary HT e , N (%) | ||
| Time from RT to secondary HT (year) Median (IQR) | 6.2 (3.8, 9.4) | – |
| No | 772 (91.9) | 405 (100) |
| Yes | 68 (8.1) | – |
| PSA nadir (ng/ml), N (%) | ||
| Median (IQR) | ||
| <0.2 (undetectable) | 241 (29.9) | 130 (32) |
| ≥0.2 (detectable) | 566 (70.1) | 275 (68) |
| Missing/Unknown | 33 | – |
| PSA at diagnosis (ng/ml), N (%) | ||
| Median (IQR) | 5.9 (4.3, 8.3) | |
| <4 | 173 (20.6) | 87 (21.5) |
| 4–10 | 541 (64.4) | 261 (64.4) |
| 10–20 | 126 (15) | 57 (14.1) |
| PSADT g (months), N (%) | ||
| No BCR | 656 (81.3) | 368 (90.9) |
| <10 | 52 (12.3) | 29 (7.1) |
| ≥10 | 99 (6.4) | 8 (2) |
| Missing/Unknown | 33 | – |
| Clinical T stage, N (%) | ||
| ≤T2a | 758 (90.2) | 371 (91.6) |
| T2b–T2c | 82 (9.8) | 34 (8.4) |
| Biopsy Gleason score, N (%) | ||
| ≤6 | 691 (82.3) | 324 (80) |
| 3 + 4 | 149 (17.7) | 81 (20) |
| Obesity (BMI ≥ 30.0 kg/m2), N (%) | ||
| No | 535 (73.5) | 264 (71.7) |
| Yes | 193 (26.5) | 104 (28.3) |
| Missing/Unknown | 112 | 37 |
| Major Comorbidities f , N (%) | ||
| No | 519 (61.8) | 255 (63) |
| Yes | 321 (38.2) | 150 (37) |
IQR, interquartile range.
PSA nadir was defined as the lowest absolute PSA value following EBRT treatment and prior to secondary HT, if applicable.
BCR = biochemical recurrence was defined as a rise in PSA ≥ 2 ng/ml above the nadir PSA value.
HT, hormone treatment defined as any HT within 9 months prior to or 1 year following EBRT treatment (start date).
Secondary HT was defined as HT >1 year following EBRT and before, distant metastasis.
Any major comorbidity included: chronic obstructive pulmonary disease (COPD), cardiovascular disease (CVD), Cerebral Vascular Accident (CVA), and/or Other Cancer.
PSADT, PSA doubling time was calculated among those who experienced a BCR event (n = 151) using all PSA values within 2 years after BCR, censored at the time of metastasis or use of secondary HT. PSADT was then computed as the natural logarithm of 2 divided by the slope obtained from fitting a linear regression of the natural log(PSA)/time.