Background: Risk factors for B-cell non-Hodgkin lymphoma (B-NHL) have not been assessed among Palestinian Arabs (PA) and Israeli Jews (IJ). Methods: In a case-control study we investigated self-reported medical and lifestyle exposures, reporting odds ratios (ORs) and 95% confidence intervals [CIs], by ethnicity, for overall B-NHL and subtypes. Results: We recruited 823 cases and 808 healthy controls. Among 307 PA/516 IJ B-NHL cases (mean age at diagnosis = 51 [±17] versus 60 [±15] years, respectively) subtype distributions differed, with diffuse large B-cell lymphoma (DLBCL) being prominent among PA (71%) compared to IJ (41%); follicular lymphoma (FL), was observed in 14% versus 28%, and marginal zone lymphoma, in 2% versus 14%, respectively. Overall B-NHL in both populations was associated with recreational sun exposure OR = 1.43 [CI:1.07-1.91], black hair-dye use OR = 1.70 [CI:1.00-2.87], hospitalization for infection OR = 1.68 [CI:1.34-2.11], and first-degree relative with hematopoietic cancer, OR = 1.69 [CI:1.16-2.48]. An inverse association was noted with alcohol use, OR = 0.46 [CI:0.34-0.62]. Subtype-specific exposures included smoking (FL, OR = 1.46 [CI:1.01-2.11]) and >monthly indoor pesticide use (DLBCL, OR = 2.01 [CI:1.35-3.00]). Associations observed for overall B-NHL in PA only included: gardening OR = 1.93 [CI:1.39-2.70]; history of herpes, mononucleosis, rubella, blood transfusion (OR>2.5, P<0.01 for all); while for IJ risk factors included growing fruits and vegetables, OR = 1.87 [CI:1.11-3.15]; and self-reported autoimmune diseases, OR = 1.99 [CI:1.34-2.95]. Conclusions: In these geographically proximate populations we found some unique risk factors for B-NHL. Heterogeneity in the observed associations by ethnicity could reflect differences in lifestyle, medical systems, and reporting patterns, while variations by histology infer specific etiologic factors for lymphoma subtypes.
Bibliographical noteFunding Information:
This study is made possible by the generous support of the American people through the United States Agency for International Development (USAID). The contents are the responsibility of the authors and do not necessarily reflect the views of USAID or the United States Government; Israel Science Foundation; and the Hadassah University Hospital compensatory fund. We gratefully acknowledge Dr. Paul Brennan from IARC for support of the original 2003 Epilymph study and for reviewing the manuscript. The funding sources played no role in the design, execution or analysis of the study.
© 2017 Kleinstern et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.