Serum bone markers could predict prostate cancer metastasis and survival
MedWire News: Japanese research results show that serum bone formation and resorption markers could be used to detect bone metastatic spread and predict survival probability in affected prostate cancer patients.
“Serum bone turnover markers can be determined frequently and easily, with negligible disturbance to the patient,” write Hiroyoshi Suzuki and colleagues from Chiba University in the journal Urology.
Currently, bone scintigraphy is used for the detection of bone metastasis, but bone scans lack specificity in the detection of skeletal metastasis, and their cost-effectiveness has been questioned, note the researchers.
However, recent studies have shown promising results for the diagnostic efficacy of serum bone formation and resorption markers in detecting bone metastases in prostate cancer patients.
Thus, Suzuki and co-workers measured two serum bone formation markers; total alkaline phosphatase (tALP) and bone-specific alkaline phosphatase (BAP), and two bone resorption markers; carboxy-terminal pyridinoline cross-linked telopeptide parts of type-1 collagen (1CTP), and tartrate-resistant acid phosphatase type 5 b (TRAP 5b) in 170 men with prostate cancer, including 58 with bone metastasis.
Average serum tALP, BAP, 1CTP, TRAP 5b, and prostate-specific antigen (PSA) levels were all significantly higher in prostate cancer patients with bone metastasis than in those without, at 366.6 versus 211.9 mIU/ml, 30.2 versus 15.7 ng/ml, 3.6 versus 2.7 ng/ml, and 83.5 versus 45.2, respectively.
Furthermore, as the extent of the men’s metastasis increased, denoted by increasing extent of disease scores, the serum levels of each of these markers also increased significantly.
However, only serum levels of BAP showed a significant association with the incidence of skeletal-related events.
On multivariate analysis, 1CTP and PSA levels were both significant, independent predictors for bone metastasis, with odds ratios (ORs) of 3.21 and 1.05, respectively.
High levels of 1CTP also significantly predicted cause-specific survival. Men with 6.7 ng/ml 1CTP or above were 3.2 times more likely to have survived prostate cancer at the mean follow-up of 35 months than men whose 1CTP levels were below 6.7 ng/ml.
Receiver operating characteristics analysis revealed that 1CTP was also the most reliable predictor for bone metastasis, with an area under the curve of 0.85, where a score of 1.0 denotes perfect discrimination.
“In other words, our study suggests that serum 1CTP level is a reliable marker to detect metastatic spread, and to predict survival probabilities in prostate cancer patients with bone metastasis,” say the researchers. However, they warn physicians that 1CTP can also accumulate in the blood during renal failure.
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By Sarah Guy