[Biochemical bone turnover markers in patients with conventional and nonconventional osteosarcoma]

Biochemical bone turnover markers which reflect bone formation as well as bone resorption processes are sensitive indicators of early bone metabolism disturbances. They are considered to be useful in diagnosis and treatment of many metastatic bone diseases and primary osseous tumours.

of the study was to assess bone turnover markers in patients with conventional and nonconventional osteosarcoma during treatment.

We examined 55 patients (5-20 years) with osteosarcoma. Among them 91% had conventional and 9% had nonconventional histology. Among patients with most frequent conventional osteosarcoma distinguished histological subtypes. Bone turnover markers were determined in serum by immunoenzymatic assay at diagnosis, during preoperative- and postoperative chemotherapy and then after treatment.

We found different values of bone turnover markers in serum of patients with conventional osteosarcoma. At the moment of biopsy the highest value of osteocalcin in patients with fibroblastic subtype was observed. The highest activity of bone alkaline phosphatase and collagen type I crosslinked C-telopeptide in children with osteoblastic subtype of osteosarcoma were obtained. The levels of tested parameters decreased about 20-40% during preoperative and postoperative chemotherapy, then they increased after treatment first of all in patients with chondroblastic subtype (p < 0.05). Next we found that the osteocalcin concentration was 4-fold lower, in nonconventional osteosarcoma in comparison to the conventional. This marker is stable during treatment and remains unchanged after it. Moreover we showed that the changes of the bone alkaline phosphatase activity and the collagen type I crosslinked C-telopeptide concentration during and after treatment were less dynamic in children with nonconventional osteosarcoma.

Observed changes of markers in various histological subtypes of osteosarcoma can indicate different rate of their bone turnover. Changes observed during treatment are more dynamic in conventional than in nonconventional type of osteosarcoma.