Effects of therapy on carcinoembryonic antigen activity in the urines of patients with cancer of the bladder.

Carcino-embryonic antigen (CEA) levels were quantitated in specimens of urine for 16 patients with invasive transitional-cell carcinoma of the urinary bladder. Four of the patients had received x-irradiation to the bladder and four had been treated with the radiomimetic agent, thiotepa. Urinary CEA levels in these patients (3.7 +/- 2.4 ng/ml) were significantly lower (t = 6.17, P less than .001) than levels from a similar group of eight patients who had not been treated with radiotherapy (20.3 +/- 8.7 ng/ml). These results suggest that "false-negative" urinary CEA levels may, in some cases, be associated with previous radiotherapy.