Vitamin D status and risk of non-Hodgkin lymphoma: An updated meta-analysis

Purpose
This meta-analysis aimed to extensively investigate the association between various measures of vitamin D status and non-Hodgkin lymphoma (NHL) and its subtypes.
Methods
We searched MEDLINE (PubMed), Embase, and the Cochrane Library in February 2018. Two authors independently reviewed and selected articles based on predetermined criteria.
Results
A total of 30 studies with 56,458 NHL cases were finally selected, with 24, 9, and 3 studies on sunlight/ultraviolet radiation (UVR) exposure, dietary intake, and serum/plasma 25-hydroxyvitamin D levels, respectively. Significant protective effects of overall sunlight/UVR exposure on NHL and subtypes were observed, with summary relative risks (RRs) ranging from 0.67–0.80 (RR for NHL = 0.80; 95% confidence interval [CI]: 0.71–0.90) among subjects with high exposure compared to those with low exposure. The results were consistent with various classifications of sunlight/UVR exposure. In contrast, when exposure measures of dietary vitamin D intake (RR for NHL = 1.03; 95% CI: 0.90–1.19) and serum/plasma 25-hydroxyvitamin D levels (RR for NHL = 0.97; 95% CI: 0.82–1.15) were used, risk estimates were inconsistent or non-significant for NHL and the subtypes.
Conclusion
While risk estimates varied by different measures of vitamin D status, a protective effect of sunlight/UVR exposure on NHL incidence was verified, across most of the tested subtypes as well as exposure categories.

研究目的
本项荟萃分析旨在全面探讨维生素D状态的各类评估指标与非霍奇金淋巴瘤（non-Hodgkin lymphoma, NHL）及其亚型之间的关联。

研究方法
我们于2018年2月检索了MEDLINE（PubMed）、Embase及Cochrane图书馆数据库。由两名研究者依据预先设定的筛选标准独立完成文献评审与文章遴选工作。

研究结果
最终共纳入30项研究，合计包含56458例非霍奇金淋巴瘤病例，其中针对日光/紫外线辐射（ultraviolet radiation, UVR）暴露、膳食维生素D摄入以及血清/血浆25-羟维生素D水平的研究分别为24项、9项和3项。研究观察到整体日光/UVR暴露对非霍奇金淋巴瘤及其亚型具有显著的保护效应：高暴露人群相较于低暴露人群的汇总相对风险（relative risk, RR）区间为0.67~0.80（非霍奇金淋巴瘤的汇总RR为0.80；95%置信区间（confidence interval, CI）：0.71~0.90），且该结果在不同日光/UVR暴露分类方式下均保持一致。与之相反，当采用膳食维生素D摄入（非霍奇金淋巴瘤的汇总RR为1.03；95%CI：0.90~1.19）与血清/血浆25-羟维生素D水平（非霍奇金淋巴瘤的汇总RR为0.97；95%CI：0.82~1.15）作为暴露评估指标时，针对非霍奇金淋巴瘤及其亚型的风险估计结果并不一致，或无统计学显著性。

研究结论
尽管不同维生素D状态评估指标对应的风险估计存在差异，但本研究证实日光/UVR暴露对非霍奇金淋巴瘤的发病具有保护效应，该效应在绝大多数受试亚型及暴露类别中均成立。