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【科普】产前服用维生素可预防儿童脑瘤
Women who take multivitamins early in pregnancy may reduce the risk that their child will develop some types of brain tumors.
Public health agencies already urge pregnant women to take multivitamins that contain folic acid early in pregnancy to reduce their fetus's risk of developing a neural tube defect such as spina bifida. "This current study suggests another possible protective effect for the vitamins," said study leader Greta R. Bunin, Ph.D., of The Children's Hospital of Philadelphia. She added, "Children whose mothers took multivitamins close to the time of conception seemed less likely to suffer medulloblastoma and primitive neuroectodermal tumors of the brain."
While childhood brain tumors are, fortunately, relatively rare, medulloblastoma is the second most common brain tumor in children. Occurring in one in 20,000 children under age six, it appears in the cerebellum, the lower portion of the brain, and the area of the brain that coordinates movement. Primitive neuroectodermal tumors of the brain (PNET) are similar to medulloblastoma but occur in other parts of the central nervous system.
Dr. Bunin led a study comparing 315 children diagnosed with those tumors before age six to 315 randomly chosen healthy children. The children with cancer, all of whom were diagnosed between 1991 and 1997, were registered in the Children's Oncology Group, a multicenter collaborative organization of pediatric cancer programs in the U.S. and Canada.
The researchers questioned the mothers in a telephone survey. The study appears in the September issue of Cancer Epidemiology Biomarkers and Prevention.
The protective effect of the multivitamins taken early in pregnancy was weakly significant, but because it was similar to previous, more statistically significant findings by Dr. Bunin's team in 1993, the authors conclude the apparent benefit is unlikely to have occurred by chance.
The researchers found that taking multivitamins later in pregnancy did not significantly reduce the child's risk of medulloblastoma and PNET. "Our findings suggest that the time close to conception may be a critical period in the development of these tumors," said Dr. Bunin. "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 even if they are not trying to get pregnant."
In terms of a possible risk factor, the researchers also questioned mothers about how frequently they ate cured meats, such as ham, hot dogs, lunch meat, sausages and smoked fish. Although those foods contain compounds shown to cause nervous system tumors in animals, Dr. Bunin's team found no increased risk of brain tumors in children whose mothers frequently ate those meats while pregnant.
"Taking multivitamins in the first few weeks of pregnancy definitely helps prevent neural tube defects," concluded Dr. Bunin. "While more research remains to be done, our findings suggest that multivitamins may prevent some brain tumors as well."
### 认领了 产前服用维生素可减少儿童脑瘤的发生
女性在妊娠期服用复合维生素，可预防新生儿脑瘤。
公共卫生组织建议孕妇在妊娠早期服用一些含叶酸的复合维生素，以降低胎儿发生神经管缺陷（如脊柱裂）的危险。“这项研究同样展示了维生素的另外一种可能 的保护作用，”该研究的领导者，来自于费城儿童医院的Ph. D Greta R. Bunin补充道，“如果母亲在受孕期服用过维生素，那么孩子患成神经管细胞瘤和原始神经外胚层肿瘤的可能性将会降低。”
虽然儿童脑瘤相对少见，但是成神经管细胞瘤的发生率在几种常见儿童脑瘤中排第二。6岁以下的儿童中发病率为2万分之一，可以出现在小脑、低位脑干和一些与运动协调相关的脑区。原始神经外胚层肿瘤发病率与之相似，只是主要出现在中枢神经系统的其他部位。
Bunin博士领导的这项试验选取了315名在6岁以前被诊断患有这些肿瘤的儿童，并与315名随机选择的健康儿童做对照。这些儿童均在1991至1997年之间诊断出患有肿瘤，并在儿童肿瘤研究组登记，该研究组是由美国和加拿大两国多个临床中心联合组织的一项儿童癌症研究计划。
研究人员通过电话询问了两组儿童的母亲们，结果刊登在9月份的在《Cancer Epidemiology Biomarkers and Prevention》上。
虽然在妊娠早期服用复合维生素的益处并不明显，但是由于和先前同样由Bunin的团队在1993年所得到的更具有统计意义的发现相似，研究者的结论是维生素显著的的保护作用并非偶然。
研究者们发现，在妊娠末期服用复合维生素并不能明显降低孩子发生成神经管细胞瘤和原始外胚层肿瘤的危险。“我们的成果表明，接近受孕的这段时期是这些肿瘤发生发展的一个关键阶段，”Bunin说道，“然而，恰恰是在这个时期，妇女们往往不知道自己已经怀孕。这就是为什么建议育龄妇女，甚至当她们还未怀孕时，便服用复合维生素的原因，这能有效的预防新生儿神经管缺陷。”
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作者:admin@医学,生命科学 2011-02-08 05:14
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