International Scholarly Research Notices

Clinical Study

Evaluation of Serum Calcium as a Predictor of Biochemical Recurrence following Salvage Radiation Therapy for Prostate Cancer

Table 3

Multivariable analysis association between pre-SRT serum calcium and BCR of prostate cancer after SRT.


Model adjustment	Association of pre-SRT serum calcium and BCR of prostate cancer after SRT
	Pre-SRT serum calcium as a continuous variable (0.5 mg/dL increase)		Moderate versus low pre-SRT serum calcium		High versus low pre-SRT serum calcium
	RR (95% CI)	P value	RR (95% CI)	P value	RR (95% CI)	P value

No adjustment for other variables	0.96 (0.74, 1.25)	0.76	0.94 (0.59, 1.50)	0.79	1.08 (0.66, 1.75)	0.76
Adjusting individually for risk factors for BCR
Pathologic tumor stage	0.99 (0.75, 1.30)	0.91	0.89 (0.55, 1.42)	0.61	1.12 (0.69, 1.82)	0.65
Gleason score	0.94 (0.74, 1.25)	0.68	0.96 (0.59, 1.56)	0.86	1.15 (0.69, 1.92)	0.59
Pre-SRT PSA	0.95 (0.73, 1.24)	0.70	0.93 (0.58, 1.49)	0.76	1.10 (0.68, 1.78)	0.71
SRT dose	0.98 (0.74, 1.28)	0.86	0.91 (0.57, 1.45)	0.68	1.10 (0.68, 1.79)	0.70
Adjusting for all four risk factors for BCR	0.95 (0.71, 1.28)	0.75	0.91 (0.55, 1.48)	0.69	1.21 (0.72, 2.04)	0.47
Adjusting for all four risk factors for BCR and:
Preoperative PSA	0.93 (0.67, 1.28)	0.65	0.88 (0.53, 1.47)	0.63	1.11 (0.64, 1.94)	0.72
Age at SRT initiation	0.98 (0.72, 1.32)	0.87	0.93 (0.57, 1.52)	0.76	1.26 (0.74, 2.13)	0.39
Time from RP to SRT initiation	0.96 (0.71, 1.29)	0.76	0.90 (0.55, 1.48)	0.69	1.24 (0.73, 2.09)	0.43
Time from serum calcium measurement to SRT initiation	0.95 (0.70, 1.28)	0.74	0.89 (0.54, 1.45)	0.64	1.21 (0.72, 2.03)	0.48
Surgical margin	0.93 (0.69, 1.26)	0.63	0.88 (0.54, 1.44)	0.61	1.16 (0.69, 1.96)	0.57
Pre-SRT hormone therapy	0.94 (0.70, 1.26)	0.66	0.86 (0.53, 1.40)	0.55	1.20 (0.72, 2.02)	0.48
Year of start of SRT	0.95 (0.70, 1.28)	0.73	0.90 (0.55, 1.47)	0.67	1.19 (0.70, 2.01)	0.51

Relative risks, 95% confidence intervals, and P values result from the Cox proportional hazards regression models. Low pre-SRT serum calcium was considered to be ≤9.0 mg/dL. Moderate pre-SRT serum calcium was considered to be >9.0 mg/dL and ≤9.35 mg/dL. High pre-SRT serum calcium was considered to be >9.35 mg/dL. BCR: biochemical recurrence. RR: relative risk. CI: confidence interval. SRT: salvage radiation therapy. RP: radical prostatectomy.