Serum bone turnover markers in patients with primary bone tumors

It was the aim of this study to investigate parameters of bone turnover such as serum bone-specific alkaline phosphatase (BALP) and N-terminal midfragment of osteocalcin (N-MID), as well as serum C-terminal telopeptide of type I collagen (CTX) in patients with primary bone tumors and to investigate their validity in differentiating malignant from benign bone tumors.

A total of 219 patients with primary bone tumors entered the study. The patients were divided into 2 groups according to their age, including a teenage (10-19 years old) and an adult group (> or =20 years old). In each group, the patients were divided into several subgroups (osteosarcoma, benign bone tumors or tumor-like lesions, giant cell tumor, and other primary malignant bone tumors). An age- and gender-matched control population was also studied in each group. Blood samples were taken for measurement of serum BALP, N-MID and CTX.

The serum BALP levels in patients with osteosarcoma were significantly higher than those of patients in the other subgroups and the controls, both in the teenage (p = 0.01) and the adult group (p = 0.000). The serum N-MID and CTX levels did not significantly differ among patients of different subgroups and the controls, both in the teenage (p = 0.773 and p = 0.747, respectively) and the adult group (p = 0.163 and p = 0.074, respectively).

A high serum BALP level is valuable for the diagnosis of adult osteosarcoma, but its use in the development of a differential diagnosis in the teenage patients is not advised because serum BALP levels are also affected by age, pubertal stage and growth velocity. Both serum N-MID and serum CTX are hardly useful in the differential diagnosis of primary bone tumors.