Modified ribonucleosides as biological markers for patients with small cell carcinoma of the lung.

A variety of individual modified ribonucleosides may be elevated in the urine of cancer patients. They can be readily measured quantitatively in a single reversed-phase high-performance liquid chromatographic run. A total of 41 patients with small cell carcinoma of the lung were studied. For 5-ribonucleosides determined in the pretreatment urine of 28 patients, the respective frequency of elevation was directly related to stage of disease. One or more nucleosides were evaluated in the pretreatment urine of 27 out of 28 patients (96%). Included were 11 patients with limited disease and 10 (91%) had 2 or less than 2 nucleosides elevated, whereas 16 out of 17 (94%) with extensive disease had 3 or more elevated. Based on this same discriminant, median survival was significantly extended for patients with 2 or less nucleosides elevated (24 months) in contrast to 3 or more (10 months). Using a single number to represent the summation of equally weighted individual nucleoside values as a composite score, a direct relationship was found between increasing extent of disease or tumor burden. This was in contrast to more variable results for carcinoembryonic antigen analyzed in plasma samples obtained at the same time. When determined serially the composite score paralleled in general the clinical response categories for individual patients.