Serum immunosuppressive acidic protein as a tumor marker for renal cell carcinoma.

Since there are no reliable tumor markers in renal cell carcinoma, the present study was undertaken to evaluate immunosuppressive acidic protein (IAP) in patients with this tumor. Serum IAP levels were measured in 143 consecutive patients before and/or after nephrectomy by turbidimetric immunoassay. IAP levels had increased according to tumor diameter. Positivity rates of IAP were noticed as 45%, 75%, and 100% for patients with stage I/II, stage III, and stage IV diseases, respectively. Three-year survival rates also correlated with IAP: 96%, 81%, and 44% in preoperative levels below 500, of 501-1,000, and of more than 1,001 micrograms/ml, respectively. Serum IAP levels decreased within 3 months after the operation and increased with recurrence. These results suggest that serum IAP may serve as a tumor marker in patients with renal cell carcinoma.