Ganglioside metabolism has been linked to the clinical and biological behavior of human neuroblastoma. This study investigated the importance of differences in complex "b" ganglioside (GD1b, GT1b, and GQ1b; designated CbG) expression in this tumor. Gangliosides of 74 neuroblastomas were analyzed by high-performance TLC. Associations of CbG expression with known prognostic markers and with event-free survival (EFS) were evaluated. Higher CbG expression characterized nonprogressive versus progressive tumors (median 41% versus 18% of total gangliosides; P = 0.001) and completely accounted for the observed higher overall "b" pathway ganglioside expression (median 81% versus 68%; P = 0.003). In contrast, expression of the structurally simpler "b" pathway gangliosides (GD2 and GD3) did not differ (median 31% versus 35%; P = 0.4). Absolute CbG content differed even more (median 93 versus 29 nmol/g among nonprogressive versus progressive tumors; P = 0.02) and was most striking in the case of GQ1b content (8-fold higher in nonprogressive tumors). High CbG (> or =35% of total gangliosides) expression was strongly predictive of a favorable outcome in: (a) the entire study population (90% versus 60% EFS at 25 months; P = 0.001); and (b) among patients assigned a low-risk status by a either single genetic or biochemical tumor marker (MYCN, DNA, NSE, or ferritin), or by both unamplified MYCN and aneuploid DNA (22-28% difference in EFS at 25 months). These data suggest that high tumor CbG content may substratify "good prognosis" neuroblastoma patients, identifying patients at very low risk of relapse or death, and that the biological roles of CbG in neuroblastoma will be of importance to define.