Vitamin D status and risk of non-Hodgkin lymphoma: a meta-analysis.

BACKGROUND: Non-Hodgkin lymphoma (NHL) is among the ten most frequent malignancies in Europe and USA. Results for vitamin D status and risk of NHL have been inconsistent.

OBJECTIVE: The objective was to perform a meta-analysis to summarize the available evidence from case-control studies and cohort studies on the association of vitamin D status and the risk of NHL.

DESIGN: We searched PubMed, ISI Web of Science, the Cochrane Library, EMBASE, and reference lists for relevant articles. Study-specific odds ratios (ORs) or relative risks and 95 % confidence intervals (CIs) were pooled using fixed-effects, random-effects, or linear regression dose-response models.

RESULTS: Nine studies (eight case-control and one cohort studies) were included in the meta-analysis. The estimated summary OR for highest compared with lowest categories of vitamin D status was 1.03 (95 % CI 0.84, 1.26; heterogeneity I (2) = 57.5 %). The subgroup analysis showed the similar results for dietary vitamin D intake group (1.07; 95 % CI 0.82, 1.40) and serum 25-hydroxyvitamin D concentration values group (1.03; 95 % CI 0.84, 1.26). The pooling ORs of NHL most common subtypes were 1.05 (0.73, 1.52), 1.00 (0.63, 1.58), 1.10 (0.56, 2.14), and 1.69 (0.68, 4.20) for diffuse large B cell lymphoma, follicular lymphoma, small lymphocytic lymphomas/chronic lymphocytic leukemia, and T cell lymphoma. The result from the linear regression dose-response model was similar (p = 0.205).

CONCLUSIONS: Higher vitamin D status does not play a protective role in risk of NHL or common NHL subtypes.