Schöttker Ben, Kuznia Sabine, Brenner Hermann
Division of Clinical Epidemiology and Aging Research, German Cancer Research Centre (DKFZ), Heidelberg, Baden-Württemberg, Germany
Network Aging Research (NAR), University of Heidelberg, Heidelberg, Baden-Württemberg, Germany.
BMJ Open. 2021 Jan 13;11(1):e041607. doi: 10.1136/bmjopen-2020-041607.
Vitamin D insufficiency is much more common among patients with cancer than the general population. Previous meta-analyses of controlled trials showed an approximately 15% reduction of cancer mortality by vitamin D supplementation compared with placebo or no treatment in the general population.On top of updating the latest systematic review on vitamin D supplementation and cancer mortality in the general population, we aim to conduct the first meta-analyses of trials on vitamin D supplementation and cancer-specific and overall survival of patients with cancer. Besides, we will conduct for the first time subgroup analyses based on individual patient data collected from randomised controlled trials.
A systematic review and individual patient data meta-analysis will be performed on randomised placebo-controlled trials with a vitamin D intervention. All databases are searched from inception without time restriction. The addressed outcomes are cancer mortality in the general population as well as cancer-specific and overall survival of patients with cancer. The quality appraisal of the studies will be evaluated by the Cochrane risk-of-bias tool for randomised trials. Trial results will be reanalysed using adjusted and unadjusted Cox proportional hazard regression models and meta-analyses are planned. Cochran's Q-Test and the I index will be used to statistically assess the level of heterogeneity, while sensitivity and subgroup analyses serve to identify potential causes of heterogeneity. Subgroup analyses will be conducted for vitamin D dosing, follow-up time, age, sex, obesity, vitamin D deficiency/insufficiency, history of cancer and compliance. Publication bias will be assessed by funnel plots and Egger's test.
Ethical approval is not required since no human beings are involved in this systematic review. Results will be published in a peer-reviewed journal with open access. They will be presented at conferences and sent to patient advocacy groups and German oncological rehabilitation centres.
CRD42020185566.
癌症患者中维生素D缺乏比普通人群更为常见。先前对对照试验的荟萃分析表明，在普通人群中，与安慰剂或不治疗相比，补充维生素D可使癌症死亡率降低约15%。除了更新关于普通人群补充维生素D与癌症死亡率的最新系统评价外，我们旨在首次对补充维生素D与癌症患者癌症特异性生存率及总生存率的试验进行荟萃分析。此外，我们将首次基于从随机对照试验收集的个体患者数据进行亚组分析。
将对维生素D干预的随机安慰剂对照试验进行系统评价和个体患者数据荟萃分析。检索所有数据库，无时间限制。所涉及的结局包括普通人群的癌症死亡率以及癌症患者的癌症特异性生存率和总生存率。将使用Cochrane随机试验偏倚风险工具对研究进行质量评估。将使用调整和未调整的Cox比例风险回归模型重新分析试验结果，并计划进行荟萃分析。将使用Cochran's Q检验和I指数对异质性水平进行统计学评估，同时进行敏感性和亚组分析以确定异质性的潜在原因。将对维生素D剂量、随访时间、年龄、性别、肥胖、维生素D缺乏/不足、癌症病史和依从性进行亚组分析。将通过漏斗图和Egger检验评估发表偏倚。
由于本系统评价不涉及人类，因此无需伦理批准。结果将发表在开放获取的同行评审期刊上。将在会议上展示，并发送给患者权益倡导组织和德国肿瘤康复中心。
PROSPERO注册号：CRD42020185566。
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