Seed migration after transperineal interstitial prostate brachytherapy by using loose seeds: Japanese prostate cancer outcome study of permanent iodine-125 seed implantation (J-POPS) multi-institutional cohort study

Table 1 Patient characteristics stratified according to the seed migration and treatment methods

	PI			PI + EBRT
	Migration (−)	Migration (+)	p*	Migration (−)	Migration (+)	p*
	(n = 1269)	(n = 372)	p*	(n = 425)	(n = 94)	p*
Age: mean (median)	68.0 (69.0)	67.4 (68.0)	0.1257	69.0 (70.0)	68.4 (69.0)	0.3808
Range	45-89	51-84		52-88	53-82
PSA (ng/mL): mean (median)	7.1 (6.4)	7.2 (6.4)	0.9354	10.7 (9.3)	10.8 (10.4)	0.7603
Range	1.6-41.8	2.0-33.0		1.9-42.0	3.6-27.2
BMI: mean (median)	23.6 (23.4)	23.7 (23.7)	0.1524	23.5 (23.4)	23.5 (23.3)	0.8588
Range	14.7-32.8	17.9-32.1		15.5-35.7	17.3-29.7
Prostate volume (mL)
Mean (median)	26.2 (25.5)	27.5 (26.5)	0.0046	24.1 (23.4)	25.1 (24.1)	0.2927
Range	7.3-71.0	10.4-56.9		7.0-61.9	11.0-60.9
Number of seeds
Mean (median)	72.6 (72.0)	77.4 (75.0)	<0.0001	51.5 (50.0)	53.2 (50.5)	0.1044
Range	34-120	26-120		25-85	35-85
Number of migrated seeds
Mean (median)	-	1.6 (1.0)		-	1.5 (1.0)
Range	-	1-9		-	1-5
Number of needles
Mean (median)	22.9 (22.0)	23.3 (23.0)	0.1913	18.1 (17.0)	18.4 (18.0)	0.3142
Range	10-45	12-41		9-36	11-32
Planning methods
Preplanning	320	60	0.1483	59	11	0.7385
Preplanning + intraoperative	949	312		366	83
Loading methods
Peripheral loading	229	56	0.3308	35	12	0.2408
Modified peripheral loading	1033	313		384	82
Modified uniform loading	7	3		6	-
Androgen deprivation therapy
Yes	699	231	0.0174	117	22	0.4429
No	569	141		308	72
Unknown	1	-		-	-
Clinical T stage
T1	965	302	0.1329	252	48	0.2662
T2	295	70		161	42
T3	2	-		12	4
Unknown	7	-		-	-
Gleason score
6 or less	873	262	0.5907	62	23	0.0028
7	384	108		312	52
8 or more	10	1		51	19
Unknown	2	1		-	-
Risk classification (D’Amico)
Low	733	220	0.9139	9	4	0.0419
Intermediate	505	146		334	63
High	17	4		82	27
Unknown	14	2		-	-
Period of checking for migration
Day 1	164	42	0.4247	29	9	0.3806
1-3 months	1105	330		396	85

*: Wilcoxon signed test for qualitative variables, Fisher’s Exact for quantitative variables
PI = permanent iodine-125 seed implantation; PI+EBRT = PI combined with external beam radiation therapy; PSA = prostate specific antigen; BMI = body mass index

ISSN: 1748-717X