Table 3. Univariate Cox regression of biochemical progression-free survival.

Parameter	HR (95% CI)	P value
Age	1.010 (0.968 -1.053)	0.654
PSA	1.085 (1.008- 1.168)	0.029
Prostate volume at treatment	0.954 (0.929-0.980)	0.001
V100	0.980 (0.900- 1.067)	0.64
V90	1.018 (0.862-1.203)	0.832
BED	1.005 (0.995-1.014)	0.337
Gleason score	1.020 (0.626-1.662)	0.936
EBRT	0.678 (0.270-1.699)	0.407
ADT	0.607 (0.339-1.087)	0.093
PSAD (> 0.15 vs. ≤ 0.15)	3.490 (1.648-7.390)	0.001
Clinical stage		0.035
T1c (Ref.)
T2a	2.048 (1.161-3.615)	0.013
T2b	1.959 (1.692-5.545)	0.205
Risk group (intermediate vs. low)	1.486 (0.857-2.576)	0.158
PPC (≤ 50 vs. > 50)	1.801 (0.906-3.579)	0.093

HR = hazard ratio; CI = confidence interval; PSA = prostate-specific antigen; EBRT = external beam radiation therapy; ADT = androgen deprivation therapy; V100 = Volume of the prostate receiving 100% of the prescription dose; V90 = volume of the prostate receiving 90% of the prescription dose; D90 = radiation dose delivered to 90% of the prostate; BED = biological effective dose; PSAD = PSA density; PPC = percent of positive cores.