Racial and ethnic disparities in survival have been reported for many adult cancers, notably breast and colon cancer, but until now, little has been known about these disparities in neuroblastoma, the most common cancer in infancy.

A new study by the Children’s Oncology Group involving 3,539 children shows that blacks, Asians, and Native Americans with neuroblastoma have significantly worse overall survival than do white patients.

An MRI of a 2-year-old girl with known neuroblastoma

When compared with whites in a univariate analysis, overall survival was significantly inferior for blacks (hazard ratio 1.37), Asians (HR 1.62) and Native Americans (HR 3.0), but not for Hispanics (HR 1.01), said Dr. Susan L. Cohn, who presented the findings at the recent annual meeting of the American Society of Clinical Oncology.

Blacks and Native Americans also had inferior event-free survival than whites, due largely to a higher prevalence of high-risk disease, she said.

When compared with whites, Asians had significantly more diploid tumors, while blacks had more unfavorable tumor histology. Surprisingly, MYCN amplification status, one of the most powerful prognostic factors identified to date, did not differ between groups.

Finally, significantly more late-occurring events were observed in blacks, compared with whites, in multivariate analyses, suggesting that blacks may be more resistant to chemotherapy.

Dr. Cohn acknowledged at the start of her talk that multiple factors such as socioeconomic status, environmental exposure, and notably genetic predisposition can contribute to the racial disparities in survival observed in various cancers.

“We hypothesize that genetic variables in black children contribute to their high prevalence of high-risk disease, chemotherapy resistance, and inferior outcome, and we plan to conduct future studies in which we will be genotyping germ line DNA samples to elucidate the genetic variables that account for the worse outcome observed in this cohort,” said Dr. Cohn, a pediatrics professor at the University of Chicago.

The group’s hypothesis is based on studies showing that germ line genetic variables are strongly associated with clinically aggressive neuroblastoma in white children and play a critical role in drug metabolism as well as racial and ethnic diversity in drug toxicity and effectiveness.