Gorham Edward D, Garland Cedric F, Garland Frank C, Grant William B, Mohr Sharif B, Lipkin Martin, Newmark Harold L, Giovannucci Edward, Wei Melissa, Holick Michael F
University of California San Diego, Department of Family and Preventive Medicine, School of Medicine, La Jolla, California, USA.
Am J Prev Med. 2007 Mar;32(3):210-6. doi: 10.1016/j.amepre.2006.11.004.
Previous studies, such as the Women's Health Initiative, have shown that a low dose of vitamin D did not protect against colorectal cancer, yet a meta-analysis indicates that a higher dose may reduce its incidence.
Five studies of serum 25(OH)D in association with colorectal cancer risk were identified using PubMed. The results of all five serum studies were combined using standard methods for pooled analysis. The pooled results were divided into quintiles with median 25(OH)D values of 6, 16, 22, 27, and 37 ng/mL. Odds ratios were calculated by quintile of the pooled data using Peto's Assumption-Free Method, with the lowest quintile of 25(OH)D as the reference group. A dose-response curve was plotted based on the odds for each quintile of the pooled data. Data were abstracted and analyzed in 2006.
Odds ratios for the combined serum 25(OH)D studies, from lowest to highest quintile, were 1.00, 0.82, 0.66, 0.59, and 0.46 (p(trend)<0.0001) for colorectal cancer. According to the DerSimonian-Laird test for homogeneity of pooled data, the studies were homogeneous (chi(2)=1.09, df=4, p=0.90. The pooled odds ratio for the highest quintile versus the lowest was 0.49 (p<0.0001, 95% confidence interval, 0.35-0.68). A 50% lower risk of colorectal cancer was associated with a serum 25(OH)D level > or =33 ng/mL, compared to < or =12 ng/mL.
The evidence to date suggests that daily intake of 1000-2000 IU/day of vitamin D(3) could reduce the incidence of colorectal with minimal risk.
此前的研究，如妇女健康倡议研究，表明低剂量维生素D不能预防结直肠癌，但一项荟萃分析表明较高剂量可能会降低其发病率。
通过PubMed检索了五项关于血清25(OH)D与结直肠癌风险相关性的研究。使用标准方法对所有五项血清研究结果进行合并分析。合并结果按五分位数划分，25(OH)D中位数分别为6、16、22、27和37 ng/mL。采用Peto无假设法根据合并数据的五分位数计算比值比，以25(OH)D最低五分位数作为参照组。根据合并数据各五分位数的比值绘制剂量反应曲线。数据于2006年提取并分析。
血清25(OH)D联合研究中，结直肠癌的比值比从最低到最高五分位数分别为1.00、0.82、0.66、0.59和0.46（p趋势<0.0001）。根据DerSimonian-Laird合并数据同质性检验，这些研究具有同质性（卡方=1.09，自由度=4，p=0.90）。最高五分位数与最低五分位数的合并比值比为0.49（p<0.0001，95%置信区间，0.35-0.68）。与血清25(OH)D水平≤12 ng/mL相比，≥33 ng/mL时结直肠癌风险降低50%。
迄今为止的证据表明，每日摄入1000 - 2000 IU/d的维生素D3可降低结直肠癌发病率且风险极小。
