Health Economics and Decision Science, School of Health and Related Research, University of Sheffield, Sheffield, United Kingdom.
Clin Ther. 2010 May;32(5):789-803. doi: 10.1016/j.clinthera.2010.04.024.
The aim of the review was to assess the evidence for the effectiveness of calcium in reducing the recurrence of adenomas and the occurrence of colorectal cancer among populations at high, intermediate, and low risk of the disease.
A systematic review of randomized controlled trials (RCTs) was performed to compare calcium alone, and with other agents, versus placebo. Nine databases (Cochrane Library, MEDLINE, PreMEDLINE, CINAHL, EMBASE, Web of Science, Biological Abstracts, the National Research Register, and Current Controlled Trials) were searched for published and unpublished trials. Searches were not restricted by either language or date of publication. All searches were completed in January 2010. Database thesaurus and free text terms for calcium and adenomas or colorectal cancer were used to search for trial reports; additional terms were used to search for other agents of interest, such as NSAIDs and folic acid. Search terms consisted of a combination of terms for colorectal cancer (eg, colon or colorectal and neoplasm or cancer or adenoma) and terms for calcium and RCTs. The initial searches were conducted in June 2008, with update searches in January 2010 to identify more recent studies. The reference lists of relevant studies were also searched for additional papers not identified by the search of electronic databases. Studies had to satisfy the following criteria to be included: RCTs about calcium, with or without other chemopreventive agents, in adults with familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer, or a history of colorectal adenomas, or with no increased baseline risk of colorectal cancer. Meta-analysis was performed. For discrete and numerical outcomes, relative risks (RRs) and risk differences were reported with 95% CIs. The random-effects model was used to account for clinical and methodologic variations between trials.
The original and update searches of electronic databases produced 3835 citations, of which 6 studies (8 papers) met the inclusion criteria. Supplemental calcium had no effect on the number of adenomas in 1 small trial of patients with FAP. Meta-analysis of 3 trials in individuals with a history of adenomas showed a statistically significant reduction in the RR for adenoma recurrence (RR = 0.80 [95% CI, 0.69-0.94], P = 0.006) for those receiving calcium 1200 to 2000 mg/d, but no effect was seen in advanced adenoma (RR = 0.77 [95% CI, 0.501.17], P = NS). Meta-analysis of 2 trials in populations with no increased baseline risk for colorectal cancer suggested that calcium, with or without vitamin D, had no effect on the RR for colorectal cancer (RR = 0.62 [95% CI, 0.11-3.40], P = NS).
Published reports indicated that supplemental calcium was effective for the prevention of adenoma recurrence in populations with a history of adenomas, but no similar effect was apparent in populations at higher or lower risk.
本次综述旨在评估补充钙对降低高、中、低疾病风险人群腺瘤复发和结直肠癌发生的疗效。
系统检索了比较单独补充钙和（或）联合其他药物与安慰剂的随机对照试验（RCT）。检索了 Cochrane 图书馆、MEDLINE、PreMEDLINE、CINAHL、EMBASE、Web of Science、Biological Abstracts、国家研究注册处和当前对照试验等 9 个数据库（未限制检索语言和出版日期）。使用钙和腺瘤或结直肠癌的数据库词表和自由文本词检索试验报告；使用非甾体抗炎药和叶酸等其他感兴趣药物的附加词检索其他药物。检索词包括结直肠癌的组合词（如结肠或结直肠和肿瘤或癌症或腺瘤）和钙及 RCTs 的词。最初的检索于 2008 年 6 月进行，2010 年 1 月进行了更新检索，以确定最近的研究。还检索了相关研究的参考文献列表，以查找电子数据库检索未发现的其他论文。纳入标准为：关于补充钙（无论是否联合其他化学预防药物）对家族性腺瘤性息肉病（FAP）、遗传性非息肉病性结直肠癌或结直肠腺瘤史患者的 RCT；或基线结直肠癌风险无增加的 RCT。进行了荟萃分析。对于离散和数值结果，报道了 95%CI 中的相对风险（RR）和风险差异。采用随机效应模型来解释试验之间的临床和方法学差异。
电子数据库的原始和更新检索共产生了 3835 条引用，其中 6 项研究（8 篇论文）符合纳入标准。补充钙对 FAP 患者的腺瘤数量无影响。3 项腺瘤史患者的试验荟萃分析显示，补充钙 1200 至 2000mg/d 可显著降低腺瘤复发的 RR（RR=0.80 [95%CI，0.69-0.94]，P=0.006），但对高级别腺瘤无影响（RR=0.77 [95%CI，0.501.17]，P=NS）。2 项基线结直肠癌风险无增加人群的试验荟萃分析显示，钙（联合或不联合维生素 D）对结直肠癌的 RR 无影响（RR=0.62 [95%CI，0.11-3.40]，P=NS）。
已发表的报告表明，补充钙对预防有腺瘤史人群的腺瘤复发有效，但在高风险或低风险人群中未观察到类似效果。
