Urinary pseudouridine as a tumor marker in patients with small cell lung cancer.

The urinary concentration of pseudouridine, primarily a degradation product of transfer ribonucleic acid, was determined by high-performance liquid chromatography in 22 patients with small cell lung cancer, 30 patients with non-small cell lung cancer, 13 patients with pulmonary infectious diseases and 24 healthy controls. The concentration of pseudouridine in both groups of patients with lung cancer was on the average significantly higher than that in the patients with pulmonary infectious diseases or in healthy controls. Thirteen (59%) of the patients with small cell lung cancer and 8 (27%) of those with non-small cell lung cancer had a urinary pseudouridine level above the mean value plus 2 for the healthy controls. In 11 patients followed up during chemotherapy, urinary pseudouridine levels changed almost in parallel with the changes in the clinical responses.