Evaluation of tartrate-resistant acid phosphatase (TRACP) 5b as bone resorption marker in irradiated bone metastases.
BACKGROUND
The aim of our study was to evaluate if the determination of the active isoform 5b of tartrate-resistant acid phosphatase (TRACP 5b) provides the possibility to monitor the effect of local radiotherapy in bone metastases and if TRACP 5b will predict further osseous progression.


METHODS
In 48 breast cancer patients with bone metastases, patients' characteristics, diagnostic imaging and laboratory investigation, tumor- and therapy-related parameters were registered at the beginning and the end of radiotherapy, as well as 6 and 12 weeks afterwards. TRACP 5b activity was measured using a solid phase immunofixed enzyme activity assay with the monoclonal antibody O1A.


RESULTS
During follow-up, progression in another part of the skeleton was diagnosed in 31 patients (65%). There was a significant decrease of TRACP 5b in patients without progression in non-irradiated regions, whereas in progressive disease, TRACP 5b levels remained stable with a slightly increasing tendency (p < 0.007). In patients with < or =3 metastases, all TRACP 5b values were significantly lower than the values of those with >3 metastases (p = 0.01).


CONCLUSIONS
In patients without further osseous progression, TRACP 5b is able to monitor the effectiveness of local radiotherapy. The estimation of sensitivity and specificity based on each TRACP 5b value demonstrates that the ability to discriminate between those patients with or without osseous progression increases with time.
Mose
Stephan
S
Department of Radiooncology, Stiftung Friedrichsheim, Johann Wolfgang Goethe-University Hospital Frankfurt Main, Theodor-Stern Kai 7, D-60590 Frankfurt/Main, Germany. stephan.mose@sbk-vs.de
Menzel
Christian
C
Kurth
Andreas A
AA
Obert
Kirstin
K
Ramm
Ulla
U
Eberlein
Klaus
K
Boettcher
Heinz D
HD
Pichlmeier
Uwe
U
D000135:Acid Phosphatase / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001859:Bone Neoplasms / Q000201:enzymology* / Q000532:radiotherapy / Q000556:secondary*; D001862:Bone Resorption / Q000201:enzymology*; D001943:Breast Neoplasms / Q000201:enzymology / Q000473:pathology; D018450:Disease Progression; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D010146:Pain / Q000209:etiology / Q000532:radiotherapy; D011237:Predictive Value of Tests; D000071681:Tartrate-Resistant Acid Phosphatase
D014408:Biomarkers, Tumor; D007527:Isoenzymes; C000605510:ACP5 protein, human; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase