Serum tartrate-resistant acid phosphatase 5b (TRACP 5b) as a marker of skeletal changes in prostate cancer

Figures & data

Table I.  Characteristics of prostate cancer patients with (BM + ) and without (BM − ) skeletal metastases.

	BM −		BM +		p-value
N	105		25
Mean age (range)	69.4	(48–80)	70.5	(57–88)
Grade 1	34	(32%)	2	(10%)	p = 0.094
2	46	(44%)	10	(50%)
3	25	(24%)	8	(40%)
Degenerative changes	60/83	(72%)	11/17	(65%)	p = 0.530
Hormone treatment given	43	(41%)	21	(84%)	p < 0.001
Median Gleason (range)	5	(2–9)	7	(5–10)	p = 0.001
Median TRACP 5b (U/L) (range)	3.20	(1.11–7.07)	6.32	(2.14–30)	p < 0.001
Median ALP (U/L) (range)	157	(72–369)	664	(201–6599)	p < 0.001
Median PSA (µg/L) (range)	1.5	(0.1–270.0)	39.0	(1.7–3700)	p < 0.001

Figure 1.  ROC curves for ALP, TRACP 5b and PSA (n = 102).

Table II.  Area under ROC curve for tALP, TRACP and PSA.

	Area under ROC curve	SEM*	Asymptotic 95% CI	p-value
ALP U/l	0.98	0.01	0.96–1.00	<0.001
TRACP5b U/l	0.84	0.06	0.73–0.95	<0.001
PSA µg/l	0.84	0.05	0.74–0.93	<0.001

* = standard error mean.

Table III.  Determination of clinical specificity and sensitivity of tALP, TRACP 5b and PSA for bone metastases of prostate cancer. The 95% confidence intervals are in parenthesis.

	Best cut-off point	n	Sensitivity (%)	Specificity (%)	Sensitivity×Specificity
ALP	224 U/L	104	96 (78–100)	91 (83–96)	87.5
TRACP5b	4.89 U/L	130	76 (55–91)	89 (83–95)	67.3
PSA	23 µg/L	124	65 (43–84)	81 (74–89)	56.5

Table IV.  Reference range of serum TRACP 5b activity in healthy adults. Upper normal limits (mean + 2 SD of young adults): Women: 4.82 U/L, Men: 5.34 U/L.

Group	n	Mean age (range)	TRACP 5b, U/L (mean±SD)
Premenopausal women	152	39.5 (22–54)	3.24±0.79
Postmenopausal women	46	60.3 (41–81)	4.19±1.12
Young men	31	36.0 (22–54)	3.80±0.77
Elderly men	16	68.5 (55–79)	4.36±0.95