Prenatal Vitamins May Fend Off Some Childhood Brain Tumors

PHILADELPHIA, Sept. 21 -- Epidemiologists have associated vitamins taken by women around the time of conception and in early pregnancy and the risk of brain cancer for their children.

Mothers of children with medulloblastomas or primitive neuroectodermal tumors of the brain were less likely than mothers of unaffected children to have taken prenatal multivitamins, found Greta R. Bunin, Ph.D., of Children's Hospital of Philadelphia, and colleagues at St. Jude's Children's Research Hospital in Memphis.

The mothers of children with brain tumors also tended to have diets lower in folate and iron, they noted in the September issue of Cancer Epidemiology Biomarkers & Prevention.

But the mothers' consumption of cured meats did not appear to influence risk for brain tumors in children, the authors added. The meats have been implicated as a possible cause of brain tumors because they contain nitrates and nitrosamines that can induce nervous system tumors in animals.

"The results of the study add to the evidence of a protective role for multivitamins, suggest a possible role for micronutrients early in pregnancy, and generally do not support an association between cured meats and medulloblastoma/primitive neuroectodermal tumors," they wrote.

Dr. Bunin and colleagues conducted a case-control study looking at the relationship between medulloblastoma and primitive neuroectodermal tumors and maternal use of vitamin and mineral supplements, micronutrients, and cured meats during gestation.

They surveyed by telephone 315 mothers of children in the United States and Canada who had been diagnosed with medulloblastoma or primitive neuroectodermal tumors before the age of six years. They also surveyed mothers of 315 age- and area-code matched controls who were selected by random-digit dialing.

The participants submitted to an interview that included a 112-item food-frequency questionnaire, as well as questions about their use of supplements during the year before pregnancy and throughout the pregnancy.

The authors wrote that they found that the mothers of children with cancer were less likely to have taken multivitamins than mothers of controls (adjusted odds ratio 0.7, 95% confidence interval 0.4-1.0, P = 0.08).

They recognized that the data did not reach statistical significance. However, they still felt that it was a significant observation.

"We observed an inverse association with multivitamin use close to conception," they wrote "In our previous study of medulloblastoma/primitive neuroectodermal tumors, the OR for multivitamin use in a similar period was 0.6 and was statistically significant. The observation in the current study is weaker, as the OR is 0.7 and of only borderline significance, but as it is similar to our previous finding, we believe that it is unlikely to have occurred by chance."

Mothers of cases were significantly less likely to be in the highest quartile of intake of iron and folate from combined food and supplements than mothers of controls. The adjusted odds ratios and confidence intervals for both iron and folate were identical, at 0.5, 95% CI, 0.3-0.9 (P for trend = 0.008, for iron, and 0.007 for folate).

"There was no indication of increased risk for frequent consumption of individual cured meats, cured meats as a group, or cured meats as a group in the absence of multivitamin use," the investigators wrote. "The odds ratios for the combination of having cured meat intake in the top half and vitamin C in the bottom half were slightly elevated, ranging from 1.1 to 1.5, but were not statistically significant."

Additionally, they did not detect a protective effect of multivitamins against medulloblastoma or primitive neuroectodermal tumors when the vitamins were taken later in pregnancy compared with the periconception period.

"Our findings suggest that the time close to conception may be a critical period in the development of these tumors," Dr. Bunin said "However, most women do not yet know they are pregnant at this very early stage. That is why women of reproductive age are advised to take multivitamins to prevent neural tube defects."

The authors acknowledged that their findings could have been influenced by recall bias or by chance, due to the retrospective case-control design of the study.

The study was funded by the National Cancer Institute.