Significance of serum protein and lipid-bound sialic acid as a marker for genitourinary malignancies.

A prospective study was done to evaluate the roles of serum N-acetylneuraminic acid (NANA) and the lipid-bound subfraction of sialic acid (LSA) concentrations in the detection and staging of cancer, and the follow-up of treatment in patients with genitourinary malignancies. Multiple determinations were obtained in 177 subjects: 90 normal volunteers, 38 patients with prostate cancer, 20 patients with bladder cancer, 15 patients with renal cell cancer, and 14 patients with benign urologic diseases. The results showed a low incidence of elevated values in patients with early stages of cancer and a high incidence of false-positive values with serum NANA concentrations in patients with benign urologic diseases, especially prostatitis. Serum NANA and LSA concentrations were highly correlated with the stage and grade in patients with advanced urologic cancer, and may be used as markers of tumor activity during follow-up under treatment; currently, however, they are not useful in the screening of patients for urologic cancer. Their usefulness in prostatic cancer is at least comparable to that of acid phosphatase determinations by the enzymatic and radioimmunoassay methods, which were elevated in a smaller percentage of patients with prostate cancer than were the NANA or LSA concentrations.