Use and limitations of serum total and lipid-bound sialic acid concentrations as markers for colorectal cancer.

Concentrations of total serum N-acetyl-neuraminic acid (NANA) by high-performance liquid chromatography (HPLC) and lipid-bound sialic acid (LSA) by resorcinol procedure were evaluated and compared to carcinoembryonic antigen (CEA) as markers for colorectal carcinoma. Elevated concentrations of NANA were found in 32% of patients with nonmalignant disorders, 28% of patients with localized cancer, and 87% of patients with metastatic cancer. All three markers correlated with the extent of metastasis of colorectal carcinoma. Strong correlation was found between NANA and LSA measurements, whereas measurement of the sialic acid markers provide information that can not be derived from the measurement of CEA. NANA and LSA show promise as supplemental markers for staging and monitoring colorectal cancer, but they are neither sensitive nor specific enough for cancer screening.