Plasma sialic acid in patients with prostate cancer.

Serum sialic acid (N-acetylneuraminic acid) was evaluated as a tumour marker for prostate cancer and compared with serum prostate specific antigen (PSA). The records of 35 patients suffering from prostate cancer (9 with bone metastases) were analysed and compared with those of 21 healthy individuals. Total serum sialic acid was significantly elevated among the cancer patients. Levels in patients with distant metastases were significantly higher than in those with locally restricted disease and normal individuals, whereas no such difference was seen between the latter 2 groups. A direct association between serum sialic acid and tumour T category and grade could not be established. The difference between the cancer and the control groups was reflected more significantly by PSA. As sialic acid lacks tumour specificity, it is not helpful in screening for prostate cancer, yet might contribute towards the early detection of tumour progression and metastases during both therapy and follow-up.