Sluyter John D, Manson JoAnn E, Scragg Robert
School of Population Health, University of Auckland Auckland New Zealand.
Department of Medicine Brigham and Women's Hospital, and Harvard Medical School Boston MA USA.
JBMR Plus. 2020 Nov 4;5(1):e10420. doi: 10.1002/jbm4.10420. eCollection 2021 Jan.
The relationship between vitamin D status or supplementation and cancer outcomes has been examined in several meta-analyses. To address remaining knowledge gaps, we conducted a systematic overview and critical appraisal of pertinent meta-analyses. For meta-analyses of trials, we assessed their quality using AMSTAR-2 (A Measurement Tool to Assess Systematic Reviews), strength of associations using umbrella review methodology and credibility of evidence using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) criteria. Meta-analyses of observational studies reported inverse associations of 25OHD with risk of cancer incidence and cancer mortality and, particularly for colorectal cancer, fulfilled some of Bradford-Hill's causation criteria. In meta-analyses of trials, vitamin D supplementation did not affect cancer incidence. However, we found credible evidence that vitamin D supplementation reduced total cancer mortality risk, with five out of six meta-analyses reporting a relative risk (RR) reduction of up to 16%: RR, 0.84 (95% CI, 0.74-0.95). The strength of the association, however, was classified as weak. This was true among meta-analyses of high, moderate, and lower quality (AMSTAR-2-rated). Trials did not include large numbers of vitamin D-deficient participants; many tested relatively low doses and lacked sufficiently powered data on site-specific cancers. In conclusion, meta-analyses show that, although observational evidence indicates that low vitamin D status is associated with a higher risk of cancer outcomes, randomized trials show that vitamin D supplementation reduces total cancer mortality, but not cancer incidence. However, trials with larger proportions of vitamin D-insufficient participants and longer durations of follow-up, plus adequately powered data on site-specific common cancers, would provide further insight into the evidence base. © 2020 The Authors. published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
多项荟萃分析已对维生素D状态或补充剂与癌症结局之间的关系进行了研究。为填补尚存的知识空白，我们对相关荟萃分析进行了系统综述和批判性评价。对于试验的荟萃分析，我们使用AMSTAR-2（一种评估系统评价的测量工具）评估其质量，使用汇总分析方法评估关联强度，并使用GRADE（推荐分级、评估、制定与评价）标准评估证据的可信度。观察性研究的荟萃分析报告了25羟维生素D与癌症发病率和癌症死亡率风险之间的负相关，特别是对于结直肠癌，满足了布拉德福德·希尔因果关系标准中的一些标准。在试验的荟萃分析中，补充维生素D并未影响癌症发病率。然而，我们发现可靠证据表明，补充维生素D可降低总癌症死亡风险，六项荟萃分析中有五项报告相对风险（RR）降低高达16%：RR为0.84（95%CI，0.74 - 0.95）。然而，这种关联强度被归类为较弱。在高质量、中等质量和低质量（根据AMSTAR-2评级）的荟萃分析中均是如此。试验中未纳入大量维生素D缺乏的参与者；许多试验测试的剂量相对较低，且缺乏关于特定部位癌症的充足有力数据。总之，荟萃分析表明，尽管观察性证据表明低维生素D状态与更高的癌症结局风险相关，但随机试验表明补充维生素D可降低总癌症死亡率，但不能降低癌症发病率。然而，纳入更大比例维生素D不足参与者且随访时间更长的试验，再加上关于特定部位常见癌症的充足有力数据，将为证据基础提供进一步的见解。© 2020作者。由Wiley Periodicals LLC代表美国骨与矿物质研究学会出版。
