Alkaline phosphatase level change in patients with osteosarcoma: its role as a predictive factor of tumor necrosis and clinical outcome.

In osteosarcoma the histological response, measured by the percentage of tumor necrosis, constitutes one of the most significant predictive factors, with better survival in patients whose tumor necrosis is > or = 90%. To determine if the decrease rate of serum alkaline phosphatase (SAP) levels during the first month of neoadjuvant chemotherapy could serve as a predictive indicator of tumor necrosis and clinical outcome. We analyzed the medical files of 53 osteosarcoma patients (19 females, 34 males) (median age 16 years, range 8-24); the disease was metastatic in 12 and localized in the other 41. The histological responses were good in 38 patients (71.7%) and poor in 15 (28.3%). At a median follow-up of 50 months, 34 patients (64.2%) had no evidence of disease and 19 (35.8%) had died from the disease. High levels of SAP at diagnosis correlated with worse survival (P = 0.002). There was no difference in overall survival between patients whose SAP decrease rate was > 25% and those with a rate < 25% (P = 0.14). Among female patients, "rapid" SAP responders had better survival than "slow" responders (P= 0.026). In patients with metastases the SAP decrease rate was positively correlated with survival (P = 0.042). There was no evidence that "rapid" SAP responders had a higher percentage of tumor necrosis than "slow" responders, although female "rapid" SAP responders had a better prognosis than "slow" responders. Patients with metastases at presentation and "rapid" SAP response had better prognoses.