Assessment of serum CA 19.9 as a tumour marker in patients with carcinoma of the bladder and prostate.

CA 19.9, a carbohydrate structure definable by a monoclonal antibody, is a useful tumour marker in the serum of patients with gastrointestinal malignancy. We report for the first time an assessment of its value in patients with cancer of the bladder and prostate. Elevated levels were found in six of 12 patients with invasive or metastatic bladder cancer but in only two of eight patients with superficial tumours. All patients with cancer of the prostate had levels within the normal range. A long-term study of its value in monitoring disease activity in patients with cancer of the bladder is warranted.