Serum haptoglobin: a nonspecific tumor marker for renal cell carcinoma.

Serum haptoglobin levels were measured in 116 patients with renal cell carcinoma. The overall accuracy of correlation between haptoglobin levels and the presence or absence of known disease was 68% (normal in 87% of patients without clinically apparent disease, and elevated in 58% of patients with disease). The levels appear to correlate with the extent of tumor burden: stable when clinical disease is stable, rising as disease progresses, and falling after effective therapy. Serum haptoglobin is rarely falsely elevated, which suggests an excellent potential for disease surveillance. This nonspecific tumor marker appears to merit further evaluation in patients with renal cell carcinoma.