Table 1.
Patient characteristics according to pre-SRT serum calcium level.
| Variable | Pre-SRT serum calcium level | P value | ||
|---|---|---|---|---|
| Low: ≤9.0 mg/dL (N = 49) |
Moderate: >9.0 and ≤9.35 mg/dL (N = 59) | High: >9.35 mg/dL (N = 57) | ||
| Pre-RP PSA level (ng/mL) | 11.0 (3.4, 32.5) | 11.1 (2.6, 56.7) | 7.3 (2.0, 44.4) | 0.29 |
| Pre-SRT PSA level (ng/mL) | 0.7 (0.2, 15.3) | 0.6 (0.2, 36.1) | 0.8 (0.1, 4.9) | 0.12 |
| SRT dose (Gy) | 64.8 (60.0, 70.2) | 64.8 (58.4, 70.2) | 66.6 (54.0, 72.4) | 0.16 |
| Age at SRT initiation | 67 (48, 80) | 68 (55, 79) | 68 (44, 85) | 0.38 |
| Time from RP to SRT initiation (months) | 22 (<1, 117) | 20 (2, 126) | 24 (3, 181) | 0.50 |
| Time from serum calcium measurement to SRT initiation (days) | 16 (1, 362) | 21 (<1, 361) | 21 (<1, 362) | 0.73 |
| Pathological tumor stage | 0.68 | |||
| T2 | 22 (45%) | 24 (41%) | 28 (49%) | |
| T3a | 18 (37%) | 20 (34%) | 16 (28%) | |
| T3b | 9 (18%) | 15 (25%) | 13 (23%) | |
| Surgical margin | 0.66 | |||
| Positive | 27 (57%) | 34 (58%) | 37 (65%) | |
| Negative | 20 (43%) | 25 (42%) | 20 (35%) | |
| Gleason score | 0.49 | |||
| 3–6 | 17 (38%) | 18 (31%) | 22 (39%) | |
| 7 | 19 (42%) | 26 (45%) | 25 (45%) | |
| 8–10 | 9 (20%) | 14 (24%) | 9 (16%) | |
| Pre-SRT hormone therapy | 0.81 | |||
| Yes | 7 (14%) | 10 (17%) | 11 (19%) | |
| No | 42 (86%) | 49 (83%) | 46 (81%) | |
| Year of start of SRT | 0.29 | |||
| 1987–1992 | 12 (24%) | 16 (27%) | 14 (25%) | |
| 1993–1997 | 18 (37%) | 13 (22%) | 12 (21%) | |
| 1998–2001 | 16 (33%) | 14 (24%) | 10 (18%) | |
| 2002–2008 | 3 (6%) | 16 (27%) | 21 (37%) | |
The sample median (minimum and maximum) is given for continuous variables. P values result from Fisher's exact test or a Kruskal-Wallis rank sum test. Information was not available for the following variables: preoperative PSA (low: 7, moderate: 2, and high: 6), surgical margin (low: 2), and Gleason score (Low: 4, Moderate: 1, High: 1). RP: radical prostatectomy. PSA: prostate specific antigen. SRT: salvage radiation therapy.