低维生素D水平与高风险绝经前乳腺癌相关
2013-01-27 20:59:51   来源：37度医学网   作者：  评论：0 点击：

Jan. 24, 2013 — A prospective study led byresearchers from the University of California, San Diego School of Medicine hasfound that low serum vitamin D levels in the months preceding diagnosis maypredict a high risk of premenopausal breast cancer.

The study of blood levels of 1,200 healthywomen found that women whose serum vitamin D level was low during thethree-month period just before diagnosis had approximately three times the riskof breast cancer as women in the highest vitamin D group. The study iscurrently published online in advance of the print edition of the journalCancer Causes and Control.

由加利弗尼亚大学圣迭弋校区医学院的研究者领衔的一项前瞻性研究显示，诊断前1个月较低的血清维生素D水平可能预示着绝经前乳腺癌的风险较高。这项研究检查了1200例健康女性的血清水平，发现在诊断前的3个月时间里，血清维生素D水平低的女性与血清水平高的女性相比，前者的乳腺癌风险是后者的3倍。研究结果已发表于Cancer Causes and Control杂志在线版，纸质版将随后发表。

Several previous studies have shown thatlow serum levels of vitamin D are associated with a higher risk ofpremenopausal breast cancer. "While the mechanisms by which vitamin Dcould prevent breast cancer are not fully understood, this study suggests thatthe association with low vitamin D in the blood is strongest late in thedevelopment of the cancer, "said principal investigator Cedric Garland,DrPH, FACE, professor in the Department of Family and Preventive Medicine at UCSan Diego.

一些既往研究已经显示低水平的维生素D 与绝经前乳腺癌的高风险相关。“然而对于维生素D如何预防乳腺癌的机理还缺乏足够的理解，这一研究提示，在癌症发展的晚期，癌症与维生素D血浆水平低的关联达到最大，”研究的主要负责人Cedric Garland, DrPH, FACE说，他是加州大学圣迭弋医学院的教授。

此项队列研究中，在诊断前90天里对受试者维生素D的血清水平的分析，并不足以明确血清水平与绝经前乳腺癌风险的关联。然而，这一研究指出了有关肿瘤预防的相关时间窗——肿瘤诊断前3个月，这是肿瘤生长的关键生理期。

Analyses of vitamin D levels measured morethan 90 days before diagnosis have not conclusively established a relationshipbetween serum levels and risk of premenopausal breast cancer in the presentcohort. However, this new study points to the possibility of a relevant windowof time for cancer prevention in the last three months preceding tumordiagnosis -a time physiologically critical to the growth of the tumor.

According to Garland, this is likely to bethe point at which the tumor may be most actively recruiting blood vesselsrequired for tumor growth. "Based on these data, further investigation ofthe role of vitamin D in reducing incidence of premenopausal breast cancer,particularly during the late phases of its development, is warranted," hesaid.

The new study drew upon 9 million bloodserum specimens frozen by the Department of Defense Serum Repository forroutine disease surveillance. The researchers thawed and analyzedpre-diagnostic samples of serum from 1,200 women whose blood was drawn in thesame time frame -- samples from 600 women who later developed breast cancer,and from 600 women who remained healthy.

A 2011 meta-analysis by Garland andcolleagues estimated that a serum level of 50 ng/ml is associated with 50percent lower risk of breast cancer. While there are some variations inabsorption, those who consume 4000 IU per day of vitamin D from food or asupplement normally would reach a serum level of 50 ng/ml.

Garland说，这很可能是一个关键时间点，这时肿瘤最急于催生出新血管以满足生长的需要。“基于这些数据，可以认为维生素D在减少绝经前乳腺癌风险中的作用，特别是在肿瘤发展晚期的作用，这些进一步的研究是非常有必要的。”

这一研究利用了国防部血清储存库（Department of Defense Serum Repository）中贮存的用于常规疾病监测的900万份血清样本。研究者融化并分析了1200例女性的诊断前血清样本，其中600例女性此后被诊断为乳腺癌，而另外600例患者是健康人。

Garland及其同事完成了一项2011 meta分析，对50 ng/ml的维生素D血清水平与乳腺癌风险降低50%之间的关联进行了评估。然而试验中受试者对维生素D的吸收出现了差异：受试者每天分别从食物或补充品中摄入4000 IU的维生素D，以使自己的血清维生素D水平维持在50 ng/ml。

Garland added that a consensus of allavailable data has shown no known risk associated with this concentration ofvitamin D, which is measured as serum 25-hydroxyvitamin D. But he urgespatients to ask their health care provider to measure their serum 25(OH)Dbefore substantially increasing vitamin D intake.

"Reliance should not be placed ondifferent forms of vitamin D, such as vitamin D2, and mega doses should beavoided except those ordered by a doctor for short-term use," Garlandadded

Garland 补充说，大家公认这一高浓度的维生素D不会带来任何风险，试验中的浓度以25-羟维生素（25(OH)D）的形式加以测量。但在实质性增加维生素D摄入前，他仍然督促受试者测量自己的血清25(OH)D。他说“没有必要测量其他形式的维生素D，如维生素D2，同时应该避免大量服用维生素D，除非闲遵照医嘱作短期服用。”