Researchers could not pinpoint which vitamin or vitamins were most responsible for the reduced risk, but say their findings support and are consistent with earlier studies indicating vitamin use during pregnancy seems to help protect against childhood leukemias and brain tumors.
A report on the study, conducted chiefly at the University of North Carolina at Chapel Hill, appears in the September issue of Epidemiology, a scientific journal. Researchers at the M.D. Anderson Cancer Center at the University of Texas in Houston, the U.T. Health Science Center in San Antonio and the University of Minnesota also helped with the study.
"Neuroblastoma is a peripheral nervous system tumor in children," said Dr. Andrew F. Olshan, professor of epidemiology at the UNC School of Public Health and a member of the Lineberger Comprehensive Cancer Center. "It is the most common tumor diagnosed in infants and is usually diagnosed in children under age 3. Typically, fewer than 50 percent of affected patients live five years following diagnosis."
Olshan and colleagues identified 538 children with neuroblastoma in 139 U.S. and Canadian hospitals that belong to the Children's Oncology Group, a collaborative group of health centers that conduct treatment and epidemiologic studies of childhood cancer. Through random digit telephone dialing, they also selected 504 comparable "control" subject children without the illness.
Researchers then interviewed mothers of both groups to learn about their vitamin use before, during and after pregnancy and other possible health- and illness-related factors. They also adjusted for as many potentially confounding factors as they could -- such as education and income -- and compared the two groups statistically.
"Findings of our case-control study suggest a beneficial association but do not prove one," the UNC scientist said. "Also, the specific vitamin or vitamins potentially responsible for the reduction in risk are uncertain."
More study, especially laboratory work, needs to be done to evaluate and prove whether individual vitamins or combinations of them can prevent neuroblastomas from forming or progressing, Olshan said. Still, the new results are encouraging.
"Our finding, combined with previous work on reducing several birth defects with vitamin supplementation and other childhood cancers, supports the recommendation that mothers' vitamin use before and during pregnancy may benefit their babies' health," he said. "We believe physicians and other health care providers should continue to educate women about these benefits and recommend appropriate dietary habits and daily dietary supplements."
Among nutrients researchers believe might reduce the incidence of childhood cancers are folic acid, and vitamins C and A, but the specific vitamin responsible remains unknown, Olshan said. National recommendations and educational campaigns to promote prenatal vitamin use to prevent some birth defects such as spina bifida, specifically folic acid, began in 1992.
Co-authors of the new paper are Joanna Smith of the UNC School of Public Health, Dr. Melissa Bondy of M.D. Anderson in Houston, Dr. Joseph Neglia of the University of Minnesota and Dr. Brad H. Pollock of the University of Texas in San Antonio.
In the United States, 9.1 cases of neuroblastoma occur for every 1 million children under age 15. The National Cancer Institute supports the continuing research.
Note: Olshan can be reached at 919-966-7424.
School of Public Health Contact:
Lisa Katz, 919-966-7467