Background: Estimation of survival probability of individual patients with metastatic renal cell carcinoma was difficult owing to diverse prognostic factors. We analyzed serum immunosuppressive acidic protein (IAP) levels and the cutoff value, then tested its validity for assessing patients' prognoses.
Methods: Serum IAP was measured longitudinally in 84 patients with metastatic disease. Before therapy, cutoff levels of IAP were tested every 20 microg/ml between 600 and 1200 microg/ml. The prognostic importance of IAP and its cutoff level was estimated.
Results: The cutoff level of IAP was set at 800 microg/ml for 40 patients who had metastatic disease with the primary tumor in situ and for 44 patients with recurrent disease. IAP was found to be a significant prognostic factor for both patient groups.
Conclusions: Serum IAP is an important prognostic factor for patients with metastatic renal cell carcinoma. Stratification of patients according to prognosis is feasible using the cutoff level.