Serum protein-bound carbohydrates and small cell carcinoma of the lung. Correlations with extent of disease, tumor burden, survival, and clinical response categories.

The levels for serum protein bound neutral carbohydrates (fucose, mannose, and galactose) were determined at specific intervals for 40 patients with small cell carcinoma of the lung and compared to the corresponding carcinoembryonic antigen (CEA) levels. In pretreatment samples, the frequency of elevation was 92.5% for fucose and 77.5% each for mannose and for galactose. CEA determined in these same samples was elevated (greater than 5 ng/ml) in 45.0%. One or more of the three carbohydrate levels were elevated in pretreatment serum of 95.0% of the patients. The individual frequency of elevation for each carbohydrate was significantly related to initial stage of disease (P less than 0.01). Median survival was significantly longer for patients based on a discriminant of less than 3 carbohydrates elevated in pretreatment samples (25 months) to all 3 elevated (11 months) with P = 0.0302. A single value, termed the biomarker index, was calculated to represent the summation of the individual carbohydrate levels per individual serum sample. The biomarker index was found to be directly correlated with extent of primary disease, number of metastic sites, tumor burden, and clinical response categories assessed at serial time points. For patients with both low Biomarker Index values and normal CEA levels in pretreatment samples, an initial rise in both determinations occurred frequently corresponding to partial or complete tumor response. The occurrence of such discordant results must be considered as a likely possibility for those patients with low or normal pretreatment biological marker levels and subsequent response to primary chemotherapy.