適量應用維生素D可減少患結直腸癌的風險,，這是上海交通大學附屬第六人民醫(yī)院外科馬延磊博士在導師秦環(huán)龍教授的指導下開展專項研究所得出的結論。多年來,，他們課題組經(jīng)過前瞻性研究的系統(tǒng)綜述,，發(fā)現(xiàn)了維生素D 與結直腸癌風險間的聯(lián)系，該項最新研究成果在最近一期的《臨床腫瘤學期刊》（JCO）上正式發(fā)表,，引起國際同行的注目,。JCO雜志是美國臨床腫瘤學會（ASCO）的官方刊物，在國際腫瘤學界享有盛譽,，2010年影響因子為18.790,。
大腸癌是全球發(fā)病率和致死率較高的惡性腫瘤之一，在我國,，近年來隨著人民生活水平的不斷提高,，飲食習慣和飲食結構的改變以及人口老齡化，中國結直腸癌的發(fā)病率和死亡率均保持上升趨勢,，因此,，大腸癌的預防尤為關鍵。研究者通過系統(tǒng)綜述的18個前瞻性臨床研究,，共包含了1, 000, 000例參與者,。研究者分別分析了維生素D的攝入水平、維生素D的血液轉化物25-hydroxy 維生素D [25(OH)D] 血液表達水平與大腸癌發(fā)病風險的相互關系,。結果發(fā)現(xiàn)：維生素D攝取量較多或者血液中活性維生素D-[25(OH)D] 表達水平較高的人群,，患大腸癌的概率比較低。維生素D攝取量較低的人群較維生素D攝取量較高的人群,，大腸癌的發(fā)病率增加了67% [0.67 (95% CI,， 0.54-0.80)]。血液中25(OH)D表達水平較低的人群較血液中25(OH)D表達較高的人群,，患大腸癌的風險增加了33% [0.88 (95% CI,， 0.80-0.96)]。同時,，據(jù)Dose-Response線性分析發(fā)現(xiàn)：血清中25(OH)D表達水平每增加10ng/mL,，大腸癌的相對發(fā)病風險將降低74% [0.74 (95% CI,， 0.63-0.89)]。
近十年的流行病學調查研究表明,，絕大多數(shù)成年人和許多兒童攝入維生素D的水平及循環(huán)血液中維生素D轉化物25(OH)D表達水平存在嚴重不足,。因此，通過此項研究分析,，對于維生素D在預防大腸癌的發(fā)病風險中的重要作用將提供充足的證據(jù),。目前，上海交通大學附屬六院的研究者正在利用從美國Jackson Laboratory公司引進的APCmin突變的自發(fā)性腸道成瘤小鼠,，進一步分析維生素D在腸道腫瘤發(fā)生發(fā)展中的分子機制,，初步的研究結果已經(jīng)表明：維生素D可以使腸道腫瘤的數(shù)量減少和體積減小，潛在的分子機制可能由于維生素D缺乏時DNA合成受抑制,，致使腸上皮細胞一種保護性蛋白β-兒茶素在細胞中的構建被破壞,，但具體的分子機制尚在研究階段。（生物谷 Bioon.com）
doi:10.1200/JCO.2011.35.7566
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Association Between Vitamin D and Risk of Colorectal Cancer: A Systematic Review of Prospective Studies
Yanlei Ma, Peng Zhang, Feng Wang, Jianjun Yang, Zhihua Liu and Huanlong Qin⇓
Purpose To conduct a systematic review of prospective studies assessing the association of vitamin D intake or blood levels of 25-hydroxyvitamin D [25(OH)D] with the risk of colorectal cancer using meta-analysis. Methods Relevant studies were identified by a search of MEDLINE and EMBASE databases before October 2010 with no restrictions. We included prospective studies that reported relative risk (RR) estimates with 95% CIs for the association between vitamin D intake or blood 25(OH)D levels and the risk of colorectal, colon, or rectal cancer. Approximately 1,000,000 participants from several countries were included in this analysis. Results Nine studies on vitamin D intake and nine studies on blood 25(OH)D levels were included in the meta-analysis. The pooled RRs of colorectal cancer for the highest versus lowest categories of vitamin D intake and blood 25(OH)D levels were 0.88 (95% CI, 0.80 to 0.96) and 0.67 (95% CI, 0.54 to 0.80), respectively. There was no heterogeneity among studies of vitamin D intake (P = .19) or among studies of blood 25(OH)D levels (P = .96). A 10 ng/mL increment in blood 25(OH)D level conferred an RR of 0.74 (95% CI, 0.63 to 0.89). Conclusion Vitamin D intake and blood 25(OH)D levels were inversely associated with the risk of colorectal cancer in this meta-analysis.
